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OSIRIS-REx Spacecraft Mission Technical ReportFull Kinetic Chain Manipulative Therapy on the Knee

Table of Contents

1. Research 1.1 The Mission Objectives 1.2 The Mission customer 1.3 The date of launch 1.4 The operational life-time 1.5 The system operator 1.6 The system users 1.7 The launch vehicle and launch procedure 1.8 The trajectory followed by the spacecraft

 

The relative effectiveness of full kinetic chain manipulative therapy and full kinetic chain rehabilitation in the treatment of osteoarthritis of the knee.
Brief Synopsis of the Research

Therefore in this study we aim to establish the effect of the KFC manipulative therapy alone, FKC rehabilitation alone and the combination of the two interventions on osteoarthritis of the knee.

This will be done by means of a quantitative randomised comparative clinical trial. 60 patients will have been diagnosed with osteoarthritis of the knee according to the inclusion and exclusion criteria, and will be randomly divided into 3 groups. The first group will receive 6 treatments using FKC manipulative therapy alone, the second will receive 6 treatments using FKC rehabilitation alone, and the third group will receive 6 treatments using FKC manipulative therapy combined with FKC rehabilitation. Subjective (Beck Depression Inventory, McMaster Overall Therapy Effectiveness Tool, Western Ontario and McMaster Universities Osteoarthritis Index and Berg Balance Scale) and objective (Inclinometer) measures will be taken at baseline, 1 week and 1 month follow up.

These results will be recorded and the data analysed using SPSS statistical package at a 95% confidence interval.

Section B:

To be typed in Arial 12-point font in one and half line spacing (expand sections to fit contents, but keep within the specified maximum lengths)

1. Field of Research and Provisional Title

The relative effectiveness of full kinetic chain manipulative therapy and rehabilitation in the treatment of osteoarthritis of the knee.

2. Context of the Research

1. Osteoarthritis is a very common condition, affects 9.6% of men and 18% of women aged >60 years worldwide (Woolf and Pfleger, 2003).

2. Although multi-factorial, falls cause nearly two-thirds of all non-intentional injury related deaths in older adults (Hawk et al., 2006). One of the causative factors is loss of hip and knee proprioception secondary to increased joint degeneration, thus by addressing these problems with the rehabilitation and/or adjustment there may be a decreased risk of fall.

3. There is research to suggest that applying manipulative therapy and rehabilitation to the full kinetic chain yields greater benefits for KOA patients than at home rehabilitation alone (Deyle et al., 2005), however this combination of treatments has never been compared against full kinetic chain manipulative therapy alone.

4. KOA stiffness, pain and dysfunction was shown by Deyle et al., (2000) and Deyle et al., (2005) to improve better when adding manipulative therapy to a rehabilitation program as compared to placebo and exercise alone, respectively.

3. Research Problem and Aims

Aim:

The relative effectiveness of full kinetic chain manipulative therapy and rehabilitation in the treatment of osteoarthritis of the knee.

Objectives:

i) To determine whether manipulative therapy alone is effective in the short term treatment of KOA in terms of subjective and objective measurements.

ii) To determine whether manipulative therapy alone is effective in the intermediate term treatment of KOA in terms of subjective and objective measurements.

iii) To determine whether rehabilitation alone is effective in the short term treatment of KOA in terms of subjective and objective measurements.

iv) To determine whether rehabilitation alone is effective in the intermediate term treatment of KOA in terms of subjective and objective measurements.

v) To determine whether manipulative therapy combined with rehabilitation is effective in the short term treatment of KOA in terms of subjective and objective measurements.

vi) To determine whether manipulative therapy combined with rehabilitation is effective in the intermediate term treatment of KOA in terms of subjective and objective measurements.

vii) To compare short term results and intermediate results, respectively.

viii) To determine whether manipulative therapy combined with rehabilitation is effective in decreasing the risk of fall according to the Berg Balance Scale.

ix) To determine whether rehabilitation alone is effective in decreasing the risk of fall according to the Berg Balance Scale.

x) To determine which treatment method is more effective in decreasing the risk of fall according to the Berg Balance Scale.

4. Literature review

Osteoarthritis is a chronic degenerative disorder with a complex aetiology (Felson, 2000). It is characterized by focal loss of articular cartilage within synovial joints, associated with hypertrophy of bone (osteophytes and subchondral bone sclerosis) and thickening of the capsule, resulting in alterations in biomechanical properties (Woolf and Pfleger, 2003). It is a very common joint disorder, affecting mostly those above the age of 60 and can occur in any joint but is most common in the hip; knee; and the joints of the hand, foot, and spine (Symmons, Mathers and Pfleger, 2003). As many as 40% of people over the age of 65 suffering symptoms associated with knee or hip OA (Zhang et al., 2008), resulting in OA becoming the fourth leading cause of disability in the years 2000 (Symmons, Mathers and Pfleger, 2003). Although no cure exists, a number of treatment options exist to provide symptomatic relief as well as improvement of joint function. Amongst these are non-pharmacological interventions, such as rehabilitation, manual therapies, acupuncture and electromodalities, as well as pharmacological measures such as oral medication and intra-articular injections. In severe cases, where nonsurgical interventions have failed, more invasive approaches may be needed (Scher and Pillinger, 2007).

McCarthy (2004) compared the effectiveness of an at home exercise program on its own or when supplemented with a class-based exercise program. There was found to be a greater improvement in WOMAC score in the class-based exercise group (20.6%) than the at home group (8.8%). These relatively modest effects may be owed to inability of exercise to address a number of factors that prevent patients from maximising results from their exercise program. Fitzgerald (2005) identified quadriceps inhibition or activation failure, obesity, passive knee laxity, knee misalignment, fear or physical activity and self-efficacy as examples of such factors. The necessity for additional interventions to address these factors therefore becomes apparent.

Tucker et al. (2003) compared the relative effectiveness of knee joint manipulation versus a non-steroidal anti-inflammatory drug (NSAID), and found manipulation to be just as effective as NSAID’s in the treatment on KOA. Fish et al., (2008) had similar results when comparing the effectiveness of knee joint mobilisation against Topical Capsaicin Cream. Capsaicin has been previously demonstrated superior to placebo in many painful disorders including knee and general osteoarthritis. Pollard, Ward, Hoskins and Hardy (2008) applied a manipulative therapy protocol, consisting of soft tissue mobilisation and an impulse thrust to the symptomatic knee joint complex. This was found to have a statistically significant improvement in knee pain, mobility, crepitus and function when compared to the control group (interferential current set at zero). Pollard et al. (2008) also noted that knee treatment had a significant improvement in hip movement of those in the intervention group compared to the control group. This may be owing to the effect that treatment to a single joint may have on the full kinetic chain (hereafter FKC).

A number of studies have been conducted on various joints of the full kinetic chain of the lower extremity to determine their effect on the knee. Cliborne et al., (2004) aimed to determine the short-term effect of hip mobilization on pain and range of motion (ROM) measurement in patient with knee osteoarthritis (OA). It was demonstrated that the presence of hip pain and pain on squatting, restricted hip flexion and/or a positive scouring test predicts a better knee OA outcome. Currier et al., (2007) suggest that pain over the hip, groin or anterior thigh; limitations in passive knee flexion and internal rotation of the hip; as well as pain with hip distraction predicts a favourable short-term response to hip mobilizations. In fact it was found that, based on the presence of one variable, the probability of a successful response was 92% at 48-hour follow-up, which increased to 97% if 2 variables were present. Iverson et al., (2008) suggest that the strongest predictor of whether adjusting the lumbopelvic spine will decrease knee pain (in patellofemoral pain syndrome) is if there is a side-to-side difference in hip internal rotation greater than 14°. The presence of this variable increased the likelihood of a successful outcome from 45% to 80%. These studies collectively show that correcting the various dysfunctions within the kinetic chain will have a favourable effect on knee joint dysfunction. However, there has yet to be a study that seeks to improve knee osteoarthritis by treating all indicated joints in the full kinetic chain.

Few studies have looked at what effect combining manipulation and rehabilitation would have in the treatment of KOA. Deyle et al., (2000) applied manual therapy to the knee as well as to the lumber spine, hip and ankle as required. Additionally patients where given to knee exercise program to perform in the clinic on treatment days and at home. WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) scores are used to detect changes in the patients perception of function and quality of life, specifically related to the disease process. In this study, there was a 55.8% improvement in the treatment group as compared to a 14.6% improvement in those patients receiving placebo (subtherapeutic ultrasound), thus proving the effectiveness of combining manipulation and rehabilitation. Using similar methodologies, Deyle et al., (2005) compared an at home versus in clinic physical therapy program. Those being treated in clinic received supervised exercise, manual therapy to the FKC and a home exercise program, while a second group received at home exercise only. Significant improvements where seen in both groups, however the clinic treatment group had an improvement in WOMAC scores of 52% and only a 26% improvement was seen in the home exercise group. The author attributed this difference between groups to the application of manual therapy to the full kinetic chain. However, the clinic group performed the exercises under supervision and where corrected where necessary while the home group were largely unsupervised and may have performed the exercises incorrectly as a result, thus decreasing the benefit such exercises would have. One should therefore not consider the difference in group performance to be solely due to the addition of manual therapy.

To date there is no study which compares the effect of manual therapy alone versus the above mentioned treatment combinations. Therefore there is a need for a study to determine whether FKC manual therapy combined with a standardised rehabilitation program is more effective than either intervention alone in the treatment of osteoarthritis of the knee.

5. Research Methodology

Design type:

Quantitative comparative clinical trial conducted at the Durban University of Technology Chiropractic Day Clinic (hereafter DUT CDC).

Advertising: [Appendix A]

Old age homes and retirement villages throughout the greater Durban region will be approached, as well as advertisements placed on notice boards of DUT, community halls, shopping centres and places of worship.

Sampling procedure:

A sample size of 60 (n=60) will be selected by means of convenience sampling (Brink, 2006). Those individuals responding to the advertisements will be screened and accepted based on the inclusion and exclusion criteria.

Telephonic interview:

Patients are required to contact the DUT CDC telephonically to determine whether they meet the requirements of the study. This will be determined by asking the patient the following questions;

* Are you between the ages of 38 and 80?

* Have you had knee pain for longer than 1 year?

* Do you have a history of trauma or surgery to the lumbar spine or lower limb?

* Are you able to stand and walk on your own, with minimal need and/or without significant dependence on canes and walkers?

* Do you suffer from a chronic medical condition that would require you to take regular medication?

* Would you be prepared to have radiographs taken of your lower limb?

If the patient meets the criteria for the study, a consultation will be made, at which they will be presented with a letter of information and informed consent form [Appendix B], which they will be required to sign. The following inclusion and exclusion criteria will be assess using a case history [Appendix C]; physical exam [Appendix D]; lumbar and pelvis [Appendix E]; hip [Appendix F]; knee[Appendix G] and; ankle and foot [Appendix H] regional examinations.

Inclusion Criteria:

A. Criteria, as developed by Altman (1991), requires a minimum of one of the first three clinical criteria below (#1, 2 or 3) for diagnosis of KOA (sensitivity 89 % and specificity 88%).

1. Knee pain and crepitus with active motion and morning stiffness ≤ 30 min (with age 38 ≤ 80 years of age).

2. Knee pain and crepitus with active motion and morning stiffness >30 minutes and bony enlargement (with age 38 ≤ 80 years of age).

3. Knee pain and no crepitus and bony enlargement (with age 38 ≤ 80 years of age).

B. The following 4 criteria are all required:

4. Knee pain of ≥ 1 year duration and able to stand and walk without severe varus/valgus deformity and/or severe instability (Kellgren and Lawrence, 1957).

5. Diagnosis of concurrent subluxation/or joint dysfunction (S/JD) complex:

a. Diagnosis of S/JD will be supported throughout using the PART(S) system.

6. A patient must have a score of ≥720 mm (≥30%) on the WOMAC scale to be included (Tubach et al., 2005).

7. No history of meniscal or other knee surgery in the past 6 months (Pollard et al., 2008).

8. A diary will be kept to monitor whether medication consumption is increased, decreased or stays the same.

Exclusion Criteria:

1. Significant visual disorders, severe vestibular disorders, neurological and peripheral sensory disorders which may be a contra-indication to exercise

2. History of knee or hip joint replacement, severe varus or valgus deformity, instability, fracture and severe osteoporosis, Rheumatoid arthritis, or frank avascular necrosis with or without moderate or severe deformity,

3. History of significant lumbar herniated disc injury with sequela,

4. Severe balance and proprioception problems (i.e. inability to stand with and/or without marked spinal or hip deformity)

5. Symptoms of moderate to severe osteoarthritis in both knees and/or hips:

– Note: both knees can be treated if there is KOA or joint dysfunction in the opposite knee and otherwise no other severe complications as noted above. However, only data collected from the worst knee will be used for the purpose of the study.

6. Long term chronicity combined with multiple treatment failure – especially multiple failure with previous physical treatment (≥ 3), with and/or long term severe pain, and/or a severely complicated or complex disorder (such as multiple co-morbidities combined with KOA such as a mix of: knee, hip and lumbosacral OA, and/or cardiovascular and/or auto-immune disease), or a severely disabled and/or a patient with severe and decreased functional ability and/or a severe clinical depression, may lead – on a case by case basis, to exclusion.

A basic guide for #6 to be used on a case by case basis:

I. Pain: The patient gives a history that can be interpreted as having stayed constantly or chronically at a high level of an estimated verbal analogue score (VAS) of ≥ 7 or WOMAC score of 1680-1920mm (70-80%) (out of a maximum worst score of 2400mm) for 3 to 5 years or longer.

II. Complicated or complex: 3 or more disorders at one time in the same patient (with KOA) as listed from #1-5 above.

III. Severely disabled: dependent on a cane, brace or walker 75 to 100% of the time when ambulating; severe cardiovascular disease; severe instability in the knee or other joints or possibly less than, or markedly less than half the normal ROM.

IV. Clinically depressed: determined by history and use the Beck Depression Inventory (BDI). The BDI has been validated for measuring depression in clinical and nonclinical settings (Beck et al., 1961).

Radiological analysis:

Although diagnosis of KOA will be made primarily through clinical examination, knee x-rays will be taken on patients who qualify and consent to participate in the clinical trial. The purpose is to determine the grade of osteoarthritic change (according to the Kellgren-Lawrence scale (reference)), to confirm suspicions of contra-indications to treatment, or to rule out a pathology outside of OA. Additionally, the subject’s history and physical examination may indicate the need for lumbosacral/pelvic, hip, ankle and/or foot x-rays (see exclusion criteria below).

Procedure:

Time

Baseline

2 weeks

4 weeks

6 weeks

1 week F/U

1 month F/U

# Rx

2

2

2

Outcome measurement

WOMAC

ROM

BBS

BDI

WOMAC

OTE

ROM

BBS

BDI

WOMAC

OTE

ROM

BBS

BDI

Once accepted into the study, patients will be randomly allocated into 3 (three) groups using a randomised allocation chart (reference).

Interventions:

Group A will be treated with only manipulative therapy of the FKC.

Group B will be treated with only rehabilitation of the FKC.

Group C will be treated with manipulative therapy combined with rehabilitation of the FKC.

Manipulative therapy: [Appendix I]

FKC manipulative therapy (manipulative therapy to the knee, and any indicated axial or appendicular joint dysfunction, such as to the spine, hip, ankle, and foot) for KOA has been hypothesized as superior to localised manipulative therapy (Deyle et al., 2005). Treatment will focus on carefully restoring knee flexion and extension by lesser grades of mobilization as recommended by Deyle et al., (2005) and Fish et al., (2008), and patellar mobilization as per Pollard et al., (2008), along with careful high velocity low amplitude axial elongation of the knee joint as per Fish et al., (2008).

Additionally, manipulative therapy will be applied where needed to the full kinetic chain using other diversified techniques, such as HVLA manipulation or mobilization as outlined in Shafer and Faye (1990), and/or Peterson and Bergman (2002). Also, the hip technique, as outlined by Hoeksma et al., (2004) and the use of HVLA knee manipulation methods from Tucker et al., (2005) will also be utilized when indicated.

The particular joint dysfunction also known as the subluxation complex or manipulable lesion will be chosen based upon findings in the regional examinations.

Rehabilitation: [Appendix J]

Rehabilitative therapy will include exercises, focused soft tissue treatment and stretch to the knee and elsewhere along the full kinetic chain where needed based upon functional assessment (Deyle et al., 2005). Also included in rehabilitation will be patient advice, education and home exercise recommendations for managing their KOA.

The rehabilitation protocol will be standardised across groups B and C, with minor case by case variations.

Intervention frequency:

All patient will receive:

– 6 treatments in the first three (3) weeks (2x treatments/week).

– Training in a rehabilitation program, to be completed daily.

– Regular telephonic communication (every 1-2 weeks) following the completion of the 6th treatment.

All groups will be required to return to the clinic no more than one (1) week after the 6th treatment and at the one (1) month follow up to have readings taken.

Measurement Tools:

All data will be collected previsit 1, no more than 1 week after 6th treatment and at 1 month follow up, with the exception of OTE which will not be collected at previsit 1.

Subjective data will b obtained by means of;

– Beck Depression Inventory [Appendix K]

– The McMaster Overall Therapy Effectiveness (OTE) Tool [Appendix L] will be used to assess patient satisfaction and general improvement.

o The OTE is a valid and reliable questionnaire that allows the patient to classify the change in their health status: whether their KOA symptoms, or overall quality of life has improved, remained the same, or worsened since the last visit (Chan et al., 2006)

– The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) [Appendix M] detects change in function and quality of life in patients suffering from KOA using multiple questions with the visual analogy scale (VAS).

o The WOMAC is valid and reliable for KOA, and has a long history of being broadly and frequently utilized to assess knee and hip OA, thus allowing comparison to a large number of studies and trials (Bellamy et al., 1988).

– Berg Balance Scale (BBS) questionnaire [Appendix N] is a predictor of fall risk and will be delivered if the one legged standing test is failed (Hawk et al., 2006)). KOA patients who are +’ve for the Berg Balance Scale (BBS) will be monitored as a subgroup (with a + OLST and BBS) at all clinic assessments

Objective data will be obtained by means of:

– Inclinometer [Appendix O] readings for knee flexion and extension only to evaluate the patients range of motion (ROM) (reference).

Statistics:

The latest version of SPSS will be used to analyse the data.

6. Plan of Research Activities

Provide a summarised work plan for each year of the project giving information for each research activity per year, under the following headings:

Activity

Timeframes (target dates for the duration of the project)

7. Structure of Dissertation / Thesis Chapters

1. Introduction

2. Review of the related literature

3. Subjects and methods

4. Results

5. Discussion

6. Recommendations and conclusions

7. References

8. Potential Outputs

§ Provide details on envisaged measurable outputs (e.g. publications, patents, students, etc.);

§ Expected national and/or international acclaim for the research and contribution of research outputs to building the knowledge base;

§ Exploitability of outputs, e.g. applicability to community development, improved products, processes, services in SA, region and/or continent;

§ Expected effects of research results.

9. Key References

Brink, H. 2006. Fundamentals of research methodologies for health care professional. 2nd edition. Juta and co. Cape Town.

Cliborne, A., Wainner, R., Rhon, D., Judd, C., Fee, T., Matekel, R., and Whiteman, J. 2004. Clinical hip tests and a functional squat test in patients with knee osteoarthritis: reliability, prevalence of positive test findings, and short-term response to hip mobilization. Journal of Orthopaedic & Sports Physical Therapy, November; 34(11): 676-685.

Currier, L., Froehlich, P., Carow, S., McAndrew, R., Cliborne, A, Boyles, R., Mansfield, L., and Wainner, R. 2007. Development of a clinical prediction rule to identify patients with knee pain and clinical evidence of knee osteoarthritis who demonstrate a favourable short-term response to hip mobilization. Physical Therapy, September; 87(9): 1106-1119.

Deyle, G., Allison, S., Matekel, R., Ryder, M., Stang, J., Gohdes,D., Hutton, J., Henderson, N., and Garber, M. 2005. Physical Therapy Treatment Effectiveness for Osteoarthritis of the Knee: A Randomised Comparison of Supervised Clinical Exercise and Manual Therapy Procedures versus a Home Exercise Program. Physical Therapy, 85(12): 1301-1317.

Deyle, G., Henderson, N., Matekel, R., Ryder, M., Garber, M., and Allison, S. 2000. Effectiveness of Manual Physical Therapies and Exercise in Osteoarthritis of the Knee. Annals of Internal Medicine, 132(3): 173-181.

Felson, D. 2000.Osteoarthritis: New Insights Part 2: Treatment Approaches. In: National Iinstitute of Health Conference, Annals of Internal Medicine; 133: 726-737.

Hawk, C., Hyland, J.K., Rupert, R., Colonvega, M. and Hall, S. 2006. Assessment of balance and risk for falls in a sample of community-dwelling adults aged 65 and older. Chiropractic and Osteopathy, 14(3).

Haynes, S. and Gemmell, H. 2007. Topical treatments for osteoarthritis of the knee. Clinical Chiropractic; 10: 126-138.

Iverson. C., Sutlive, T., Crowell, M., Morrell, R., Perkins, M., Garber, M., Moore, J., and Wainner, R. 2008. Lumbopelvic manipulation for the treatment of patients with patellofemoral pain syndrome: development of a clinical prediction rule. Journal of Orthopaedic & Sports Physical Therapy, June; 38(6): 297-312.

McCarthy, C., Mills, P., Pullen, R., Roberts, C., Silman, A., and Oldman, J. 2004. Supplementing a home exercise programme with a class-based exercise programme is more effective than home exercise alone in the treatment of knee osteoarthritis. Rheumatology; 43: 880-886.

Pollard, H., Ward, G., Hoskins, W. and Hardy, K. 2008. The effect of a manual therapy knee protocol on osteoarthritic knee pain: a randomised controlled trial. Journal of the Canadian Chiropractic Association, December; 52(4): 229-242.

Symmons D, Mathers C, Pfleger B. 2003. Global burden of osteoarthritis in the year 2000 [online]. Geneva: World Health Organization. Available at: URL: http://www3.who.int/whosis/menu.cfm?path=evidence,burden,burden_gbd2000docs&language=english

Tucker, M., Brantingham, J., Myburg, C. 2003. Relative effectiveness of a non-steroidal anti-inflammatory medication (Meloxicam) versus manipulation in the treatment of osteo-arthritis of the knee. European Journal of Chiropractic, 50: 163-183.

Woolf, A.D. and Pfleger, B. 2003. Burden of major musculoskeletal conditions. Bulletin of the World Health Organization, 81 (9).

Zhang, W., Moskowitz, R. W., Nuki, G., Abramson, S., Altman, R. D., Arden, N., Bierma-Zeinstra, S., Brandt, K. D., Croft, P., Doherty, M., Dougados, M., Hochberg, M., Hunter, D. J., Kwoh, K., Lohmander, L. S. and Tugwell, P. 2008. OARSI recommendations for the management of hip and knee osteoarthritis, Part II: OARSI evidence-based, expert consensus guidelines. Osteoarthritis and Cartilage, 16:137-162.

Appendix L

The McMaster Overall Therapy Effectiveness (OTE) Tool (for general improvement and patient satisfaction)

Patient No.€Œ€Œ€Œ€Œ Visit No. Page No. .

Overall Treatment Evaluation – KOA

We would like to find out if there are any changes in the way you have been feeling since treatment started: after 6 treatments, and also at the 1st week and 1st month follow ups.

Since treatment started, has there been any change in your ACTIVITY LIMITATION, SYMPTOMS AND/OR FEELINGS related to your knee osteoarthritis?

Please indicate if there has been any change by checking ONE of the three boxes below (Better/About the same/Worse):

Better About the Same Worse

⇓ ⇓

If you have checked ABOUT THE SAME,

⇓ Please stop here. ⇓

If you have checked the box If you have checked the box

BETTER: WORSE:

How much BETTER would you say How much WORSE would you say

your ACTIVITY LIMITATION, your ACTIVITY LIMITATION,

SYMPTOMS AND/OR FEELINGS SYMPTOMS AND/OR FEELINGS

have been since treatment started? Have been since treatment started?

Please choose ONE of the options Please choose ONE of the options

below: below:

Almost the same, hardly better at all Almost the same, hardly worse at all

A little better A little worse

Somewhat better Somewhat worse

Moderately better Moderately worse

A good deal better A good deal worse

A great deal better A great deal worse

A very great deal better A very great deal worse

Patient No.€Œ€Œ€Œ€Œ Visit No. Page No. .

Overall Treatment Effect – CHF, continued

Answer the following question whether or not you answered BETTER or WORSE and what your response was. Note if you have improved, the change will be important since you likely will be able to carry out your responsibilities with greater ease and comfort compared to before the study. If on the other hand you are worse, then you will have more difficulty carrying out your responsibilities; this will also be important for you as you have more difficulty with your activities.

Is this change (BETTER/WORSE) important to you in carrying out your daily activities?

Not important

Slightly important

Somewhat important

Moderately important

Important

Very important

Extremely important

THANKS FOR YOUR COOPERATION!

Description of scales and how they will be assessed:

* Pages one and two are graded separately.

* Page one is graded on a 15 point scale. Scored from +7 to -7

* If the answer to the first question is Better then you have a + integer

* If the answer to the first question is About the Same the score is 0

* If the answer to the first question is Worse then you have a – integer

* With a + or – integer, the answers below the better or worse response are numbered sequentially from top to bottom. Almost the same, hardly better is a 1 and A very great deal better is a 7.

* Page two is graded on a 7 point scale. Scored from 1 to 7

* The answers are numbered sequentially from top to bottom. Not important is a 1 and Extremely important is a 7

Later we will dichotomize the scores on page one between scores > 1 (improved) and < 0 (not improved).

Appendix M

The WOMAC – Western Ontario and McMaster Universities osteoarthritis index

KNEE OSTEOARTHRITIS

Name:_________________________________________________

Date:___/___/______DOB:___/___/_____

In Sections A, B and C questions will be asked in the following format and you should give your answers by putting a straight vertical (up-and-down) mark on the horizontal line.

Note:

1. If make a straight vertical (up-and-down) mark on the line, at the left-hand end of the line, i.e.

NO PAIN

EXTREME

PAIN

Then you are indicating that you have no pain.

Note:

2. If make a straight vertical (up-and-down) mark on the line, at the Right-hand end of the line, i.e.

NO PAIN

EXTREME

PAIN

Then you are indicating that you have extreme pain.

3. Please Note:

a) that the further to the right-hand end you place your straight vertical (up-and-down) mark on the line, the more pain you are experiencing

b) that the further to the left-hand end you place your straight vertical (up-and-down) mark on the line, the less pain you are experiencing

c) Please do not place your straight vertical (up-and-down) mark on the line outside the markers.

You will be asked to indicate on this type of scale the amount of pain, s

on its flight to and from its target 1.9 The spacecraft payload 1.10 The space segment architecture 1.11 The ground segment architecture 1.12 The major mission developers 1.13 The communication system 2 Budget Calculations 2.1 Mass Budget 2.2 The Spacecraft Power budget References

1. Research

1.1 The Mission Objectives

The OSIRIS-REx mission objectives centre on collecting data from a distant asteroid, that being 101955 Bennu. This data collection mission includes both the mapping of Bennu and collection of a rock and soil sample. It will then bring the samples back to Earth for further study. This mission will represent the first of its kind to be conducted by the USA. The specific objectives for the mission form the acronym ORIRIS-REX, they are:

  • Origins: Return and analyse a pristine carbon rich asteroid sample.
  • Spectral Interpretation: Provide ground truth or direct observations for telescopic data of the entire asteroid population.
  • Resource Identification: Map the chemistry and mineralogy of a primitive carbon rich asteroid.
  • Security: Measure the effect of sunlight on the orbit of a small asteroid, known as the Yarkovsky effect—the slight push created when the asteroid absorbs sunlight and re-emits that energy as heat.
  • Regolith Explorer: Document the regolith (layer of loose, outer material) at the sampling site at scales down to the sub-centimetre.

(NASA, 2016a) Image: NASA Figure 1 – OSIRIS-REx spacecraft (NASA, 2016b)

1.2 The Mission customer

In 2010 the OSIRIS-REx mission was put forward as a potential New Frontiers mission. This was a collaborative effort with the University of Arizona as the principal investigator and NASA Goddard Flight Space Centre, essentially managing the mission. The OSIRIS-REx mission along with two other mission concepts were selected for a 12 month mission concept study to assess the viability of the planned mission (Rob Gutro, 2010). In 2011 the OSIRIS-REx mission was selected as the winner (University of Arizona, 2011). The principal Investigator for the mission was Dr Michael Drake, Director of the Lunar and Planetary Laboratory at the University of Arizona. Dr Drake was involved in this initial bid phase, when the OSIRIS-REx proposal was initially being put forward. However, shortly after the program was funded, Dr Drake unfortunately died of liver cancer, in September 2011. Professor Dante Lauretta was made Dr Drake’s successor as Principal Investigator of the OSIRIS-REx mission. Due to the nature of the mission, the mission customer is essentially both NASA and the University of Arizona since they take up the role as the principal investigator. This structure of having a principal investigator is typical of New Frontiers missions.

1.3 The date of launch

The OSIRIS-REx spacecraft was scheduled to be launched on the 8th of September, 2016 from Cape Canaveral. There was a 33 day window from this date for additional attempts (NASA, 2016a). The OSIRIS-REx spacecraft was successful on the first day of the launch window, therefore being launched on the 8th of September 2016.

1.4 The operational life-time

The OSIRIS-REx spacecraft’s mission duration commenced in September 2016, when the launch took place and is expected to jettison the SRC capsule on 24th of September 2023, which represents a mission lifetime of 7 years. Since the OSIRSI-REx will not be returning to Earth and will stay in orbit, the plans for the ORSIRIS-REx are not definite as the state of the spacecraft at this time will have to be evaluated for any potential missions afterwards.  Figure 2 – OSIRIS-REx Mission timeline (OSIRIS-REx Project)

1.5 The system operator

The system operator of the OSIRIS-REx mission is predominantly NASA as they funded the majority of the spacecraft and mission. The principal investigator, Professor Dante Lauretta Direction will be providing leadership and direction to NASA for the mission and has control of most parts of the mission (Clark, 2016), Professor Dante Lauretta, is the head of the University of Arizona – Lunar and Planetary Laboratory research team. While NASA is the system operator, they have delegated this task by subcontracting Lockheed Martin to perform mission operations (NASA, 2016a).

1.6 The system users

The system users of the OSIRIS-REx mission include many different organisations and groups in the scientific community and the different user bases will have varying amounts of access to the mission data. The system users include:

1.6.1 Primary Users

The primary users of this mission include both NASA and the University of Arizona – Lunar and Planetary Laboratory research team. The project was mainly funded by NASA, which essentially gives them ultimate control over the spacecraft. However, as this is a New Frontiers mission, which requires a principal investigator, some of this control is effectively delegated to the principal investigator, which in this case is Professor Dante Lauretta and his team from the University of Arizona. Professor Lauretta’s team, the Lunar and Planetary Laboratory at the University of Arizona will essentially be the primary benefactors of the mission data along with NASA.

1.6.2 Future Users

The OSIRIS-REx mission is rather complex and costly. If the mission is a success, mankind will have access to very unique asteroid samples, which have never been obtained before. Due to the immense amount of effort which was required to obtain these samples, steps have been put in place so that the sample which is collected is preserved for the future. This will enable future generations of scientists, with more advanced technologies to study the sample and potentially find new information about the sample, which present day technology cannot. For this reason NASA have guaranteed that at least 75% of the sample will be preserved for future generations of scientists.

1.6.3 Mapping data generated by OSIRIS-REx

The OSIRIS-REx mission will generate a wide array of various data. An example is the mapping data of Bennu.  This will consist of high resolutions maps of Bennu. This is generated from the suite of sensors mentioned below and are used as described below, to generate the map data. This data, while critical for the mission, represents a product in itself, which can be studied for future generations to come. An explanation of this is detailed below:

  • Bennu Map Data – The OSIRIS –REx spacecraft will complete quite an in-depth mapping campaign as it orbits around Bennu. It will include both global mapping of the entire asteroid and localised mapping in certain locations to provide a high enough resolution in which a penny could be detected on its surface. The mapping data will also include the mineral composition of Bennu. This data will be used to determine the optimal sampling site for the OSIRIS-REx to take samples. The mapping campaign will utilise the complex sensor suite aboard the OSIRIS – REx spacecraft. These sensors include:
    • OCAMS – OCAMS is a camera suite which will be used for the global mapping of Bennu. OCAMS is made up of three cameras, PolyCam, MapCam and SamCam. PolyCam and MapCam will be used for specifically for the mapping. These cameras are detailed further in the Spacecraft Payload section.
    • Laser Altimeter (OLA) – This will allow the spacecraft to determine the distance between it and Bennu thus allowing the exact shape of the asteroid to be mapped. This works in a very similar way to how a laser scanner is used in 3D printing works.
    • Visible and Infrared Spectrometer (OVIRS) – This will allow the OSIRIIS-REx to measure both the visible and infrared light from Bennu and can be used to assist in determining the surface composition of the asteroid.

1.7 The launch vehicle and launch procedure

The Launch vehicle used for the OSIRIS-Rex mission was an Atlas V 411 rocket. The Atlas 5 launch system is operated by a joint venture between Boeing and Lockheed Martin called United Launch Alliance (ULA). The Atlas V rocket is a dual stage expendable rocket. The first stage, is referred to as the Common Core Booster (CCB). This burns 284,450 kg of liquid oxygen as well as RP-1 and is a Russian RD-180 main engine. This is supplemented with a single additional strap-on solid rocket booster. The subsequent stage is a Centaur second stage engine propelled by a cryogenic propellant with an Aerojet Rocketdyne RL10A-4-2. As previously mentioned, the launch took place from Cape Canaveral Air Force Station with the launch date being set for the 8th of September 2016 with a 33 day launch window. Luckily, the OSIRIS-REx was able to be launched on the first day of this period.  Figure 3 – Launch Configuration of the Atlas V rocket carrying the OSIRIS-REx spacecraft (NASA, 2016a) OSIRIS-REx Launch Profile - Credit: NASA/United Launch Alliance Figure 4 – Launch profile of the Atlas V rocket with the OSIRIS-REx on board (NASA/United Launch Alliance, 2016)

1.8 The trajectory followed by the spacecraft on its flight to and from its target

The OSIRIS-Rex was launched from Cape Canaveral, with a hyperbolic escape velocity of 5.4km/s. Once the OSIRIS-REx leaves Earth’s atmosphere it will perform a series of Deep Space Manoeuvres, which will change the velocity by 0.52km/s. The OSIRIS-REx spacecraft will then spend a year orbiting the Sun. After this year of orbiting the Sun, the OSIRIS-Rex will perform what is known as a ‘slingshot manoeuvre’. It will fly relatively close to Earth and thereby enter back into Earth’s gravitational field, which will pull it towards Earth. This allows the OSIRIS-REx to borrow a small amount of Earth’s orbital energy. This will result in both a changed orbital inclination and a push back into space, towards a rendezvous with Bennu for the OSIRIS-REx craft. When approaching Bennu in August 2018, the OSIRIS-REx will use an array of small on board rocket thrusters to match the velocity of the asteroid. When the ORISIRS-REx is approaching Bennu it will have a relative approach velocity of 20cm/s. When the OSIRIS-REx has arrived to less than 10km of Bennu it will start to basically orbit Bennu, thus allowing the on-board sensors to map every part of the asteroid. Once all tasks have been completed and a sample of the asteroid is safely stowed away, OSIRIS-REx will commence the return trip back towards Earth. The first opportunity for departure of Bennu is March 2021. When this time arrives the OSIRIS-REx will fire its main engines and will depart Bennu. This will place the spacecraft on a trajectory, which intersects the orbit of Earth in September 2023. When the spacecraft is four hours away from reaching the atmosphere of Earth, the OSIRIS-REx will jettison the Sample Return Capsule (SRC) towards Earth. OSIRIS-REx will then perform a deflection manoeuvre which will place the spacecraft in a stable orbit around the Sun. Once the OSIRIS-Rex returns the SRC, the craft would have travelled 7 billion kilometres (Lockheed Martin Space Systems, 2017). As mentioned in 1.4, depending on the state of the spacecraft will depend on what the spacecraft is tasked to do next. The jettisoned SRC will be traveling towards the Utah desert at a speed of 12.4km/s as it travels through the top of Earth’s atmosphere. After entry the SRC will free fall towards Earth until it reaches an altitude of 33.5km, which will trigger the deployment of the drogue parachute. As the SRC is travelling towards the Utah desert, the main parachute is released, which will enable the capsule to have a soft landing in a US military test range in Utah. The estimated date will be September 2023 (NASA, 2016a). Orbit of Asteroid Bennu - Image: OSIRIS-REx Project / Dante Lauretta Figure 5 – The orbit of Bennu relative to the Earth and Sun (Lauretta) Earth Gravity Assist Trajectory - Image: University of Arizona Figure 6 – The trajectory created by the Earth Gravity Assist manoeuvre (University of Arizona)

1.9 The spacecraft payload

The payload which will be carried by the OSIRIS-Rex consists mainly of imaging instruments, along with collection equipment to collect samples of the Bennu asteroid. In total, there are eight instruments carried on OSIRIS-REX, six being imaging and two being related to the collection and return of a sample of the asteroid. The eight instruments on the OSIRIS-REx include a Camera Suite (OCAMS), Laser Altimeter (OLA), Thermal Emission Spectrometer (OTES), Visible and Infrared Spectrometer (OVIRS), X-Ray Imaging Spectrometer (REXIS), Touch and Go Sample Acquisition Mechanism (TAGSAM), Touch and Go Camera System (TAGCAMS), Sample Return Capsule (SRC) (NASA, 2016a). These seven instruments are explored in detail below: The imaging instruments consist of six instruments, which will allow scientists to map with a high resolution and determine the composition of the asteroid so that there is information known about the distribution of elements, minerals and organic material. This will then allow the optimal sampling site to be determined so that a successful sample can be taken. The imaging instruments consist of:

  • OSIRIS-Rex Camera Suite (OCAMS) – This system will observe Bennu and provide global image mapping as well as detailed mapping of recommended sites to obtain a sample of the asteroid. The OCAMS consists of three cameras and were provided by the University of Arizona and consist of:
    • MapCam –The MapCam is a high resolution camera which will be used to map the surface of Bennu in four colours from a distance of approximately three miles.

http://spaceflight101.com/osiris-rex/wp-content/uploads/sites/103/2016/08/OCAMS-Schematic-MapCam-663x1024.png Figure 7 – MapCam Overview (NASA, 2015a)

  • PolyCam – Polycam is the largest of the three cameras on the OSIRIS-REx, it is a dual-purpose camera, which has very high zoom. It is highly versatile as it can both function as a telescope, thereby acquiring the image of an asteroid which is very far away and can also function as a microscope, which can be used to analyse rocks and pebbles on the surface of the asteroid.

PolyCam - Photo: OSIRIS-REx Project / Dante Lauretta Figure 8 – PolyCam (Lauretta, 2014a)

  • SamCam – The SamCam will be used during the sampling phase of the mission. The SamCam will be used to check the collected asteroid rocks, thereby ensuring that there has been a successful collection.]

SamCam - Photo: OSIRIS-REx Project / Dante Lauretta Figure 9 – SamCam (Lauretta, 2014b) OCAMS Coverage - Image: University of Arizona Figure 10 – OCAMS Coverage (University of Arizona, 2013)

  • Touch and Go Camera System (TAGCAMS) – The Touch and Go Camera System is used to support the spacecraft for navigation and engineering purposes (Lakdawalla, 2016). The system consists of two camera systems, that being:
    • NavCams – Navigational cameras which form part of the navigation, guidance and control system on the OSIRIS-REx. By analysing the sky and certain stars, they are used for optical navigation of the spacecraft. There are two Malin Space Science CAM-M50 5 megapixel cameras, which makeup the NAVCAMS system.
    • StowCam – This high definition Malin Space Science CAM-C50 5 megapixel colour camera will image the transfer of the asteroid sample from the TAGSAM to the Sample Return Capsule (SRC).

 Figure 11 – TAGCAMS System (Malin Space Science Systems, 2014)

  • OSIRIS-REx Laser Altimeter (OLA) – The OLA is an active device in that it is a scanning LIDAR (Light Detection and Ranging) instrument which will be used to collect data from the surface of Bennu, thus in turn will produce three dimensional topographic maps of the asteroid. It can do so from a distance of up to 7.5km away. A LIDAR essentially functions very similarly to a radar, in that it sends out a pulse of light and waits for it to return. The time taken for this pulse to be received is halved and then can be converted to a distance. The OLA utilises two lasers, the first one is a high powered laser in that it can operate between 1-7.5km while the second is lower powered and can be used at distances of less than 1.5km. The OLA was contributed from the Canadian Space Agency especially for the OSIRIS-REx mission.

Photo: MDA Figure 12 – OLA (MacDonald Dettwiler and Associates Ltd (MDA), 2015)

  • OSIRIS-REx Thermal Emission Spectrometer (OTES) – The OTES is a passive device, in that it is a spectrometer, which will collect thermal infrared data with wavelengths between 5 and 50µm. The OTES’s primary purpose is to develop thermal emission and spectral global maps as well as local potential sample sites. Secondly the OTES will also measure the surface temperature and the total thermal emissions originating from Bennu. The OTES was contributed from Arizona State University (ASU) especially for the OSIRIS-REx mission.

Image: OSIRIS-REx Project / Dante Lauretta Figure 13 – OTES (Lauretta, 2015b)

  • Visible and Infrared Spectrometer (OVIRS) – The OVIRS is a passive device, in that it is a spectrometer, however, unlike the OTES, this will measure much narrower wavelengths of light reflecting off the surface of Bennu, between 0.4-4.3µm. Like OTES this data will be used to produces spectral maps of the asteroid to help determine potential sample sites for the mission.

Photo: NASA Figure 14 – OVIRS Instrument (NASA, 2015b)

  • X-Ray Imaging Spectrometer (REXIS) – The last imaging instrument carried on the OSIRIS-REx spacecraft is the REXIS. This is also a passive device, as it is a spectrometer which is designed to collect and image fluorescent X-rays, which have been emitted by the Asteroid. This is designed to collect data about the regolith of Bennu. The REXIS is a student science experiment, from both students of Harvard University (HU) and Massachusetts Institute of Technology (MIT).

Photo: OSIRIS-REx Project / Dante Lauretta Figure 15 – REXIS Instrument (Lauretta)

  • Touch and Go Sample Acquisition Mechanism (TAGSAM) – The TAGSAM will collect regolith samples from Bennu. It comprises of a sampling head with surface contact pads, which resembles a net with Velcro, which contains a nozzle of nitrogen. When sampling, the sampler head makes contact with the surface of Bennu and the jet of nitrogen is applied to disturb the surface. Once sampled, the robotic arm will move the sampler head to within view of SamCam to verify that a sufficient sample has been captured. The sample will be weighed. If the sample is successful the robotic arm will place the sampler head into the SRC for secure storage. If a sufficient sample has not been collected, the process of collecting a sample will repeat with enough nitrogen for two more attempts.

Image result for tagsam Figure 16-Testing the sampling head (Lockheed Martin Space Systems) Figure 1: Artist view looking from the spacecraft down at the extended arm, and the sampling device during the descent to the surface. Figure 17- The testing of the TAGSAM (Lockheed Martin Space Systems)

  • OSIRIS-REx Sample return capsule (SRC) – The Sample Return Capsule is one of the most important payloads on the spacecraft. Its job is to return the sample of the asteroid in a pristine condition. The successful return of surface samples of the asteroid is the major objective of the OSIRIS-REx mission. For this reason, after the sample has been taken, the OSIRIS-REx mission risk profile will become very conservative, with no additional experiments to take place and the OSIRIS-REx craft will be sent directly back towards Earth (NASA, 2016c).

 Figure 18 – Instrument Deck of the OSIRIS-REx(NASA, 2016a)

1.10 The space segment architecture

The OSIRIS-REx spacecraft consists, of two main sections – the spacecraft bus and the payload (instruments which will be used to fulfil the mission) in this case collect data from Bennu. The spacecraft bus is responsible for facilitating the mission objectives, which is the collection of data from Bennu. To enable the spacecraft to facilitate these objectives it has a complex network of systems which include Propulsion, Attitude Control, Navigation, Thermal Management, Power, Data Processing and Communications.

1.10.1 Propulsion System

For the spacecraft to control its trajectory it requires a method of changing direction and velocity. The OSIRIS-REx spacecraft utilises 28 different Hydrazine Monopropellant thrusters. The different categories of thrusters on the spacecraft are:

  • 4 x High Thrust, Aerojet Rocketdyne (AR) MR-107S, for large delta v manoeuvres including the Earth Flyby, Asteroid Approach Braking Burn and the Asteroid Departure Burn. These thrusters have a Nominal thrust of 275N
  • 6 x 22N Medium Thrust AR MR-106L thrusters used for pitch and yaw control during High thrust manoeuvres.
  • 16 x low thrust 4.5N AR AMR-111G thrusters provide attitude control thrust.
  • 2 x ultralow thrust AR MR-401 AR thrusters– Used for the Touch and Go manoeuvre.

All 28 thrusters are fed from a central Hydrazine tank in the spacecraft with a volume of 1300litres and the capacity to hold up to 1245kg of propellant. The Propulsion system on the OSIRIS-REx spacecraft is based on the type of system which was used on various Mars missions including the orbiter and MAVEN.

1.10.2 Power System

The power system on the OSIRIS-REx utilises a complex system of power components. Power is generated from 2 x Gallium Arsenide solar panels. These high performance solar panels have a span of 6.2m with an active area of 8.5m^2 and an approximate efficiency of around 38%. The solar panel cannot actively track the Sun but requires the spacecraft to move. The solar panels do however, have a gimbaling function which will allow them to rotate away from the surface of Bennu, during the sampling event to ensure that they do not get coated in dust. Power is stored in 2 x 30Ah EaglePicher lithium-ion batteries (EaglePicher Technologies, 2016) with integrated Battery Management Systems (BMS). The power supply system on the spacecraft handles the distribution and regulation on the spacecraft.

1.10.3 Attitude determination and Control

For a spacecraft to control its attitude it requires a control system to detect and then control its attitude. The OSIRIS-REx utilises an advanced system of sensors and actuators to keep its attitude aligned. The sensor system consists of a primary and secondary system. The primary system utilises two star trackers, which acquire optical images of the star filled sky and utilise on-board algorithms, which rely on data from a database of known stars and from that a 3 axis orientation of the spacecraft can be determined. The secondary system consists of two Inertial Measurement Units (IMU), which can also derive the attitude of the spacecraft. Additionally, Sun sensors are also installed on OSIRIS-REx in case the systems safe mode is activated. This way if an event occurred on the spacecraft, which trigged the safe mode, such as a system fault etc., the Sun sensors would be used to enable the spacecraft’s solar panels to point towards the Sun to ensure the spacecraft would have sufficient power. Attitude Control on the OSIRIS-REx is provided by various actuators on the spacecraft. These include the medium and low thrust thrusters and reaction wheels installed on the spacecraft. Different actuators are used depending on the objective of the attitude adjustment.

1.10.4 Navigation

Navigation is provided on-board the OSIRIS-REx from the data derived from the two different sensors. The first sensor is TAGCAMs, which is a three camera, wide field of view system which forms part of the payload of the spacecraft. This can be used for optical navigation predominantly when the spacecraft is within view of Bennu. The second sensor is a 3 dimensional LIDAR. The LIDAR (Light Direction and Ranging) is used to measure the distance between itself and a target. The transmitting component is a Laser which sends pulses of light. When the light returns it will be measured and therefore distance can be obtained. Additionally, since this LIDAR is a 3D type, there are 16384 separate receivers essentially. These are arranged on a 128×128 matrix which is similar to an image sensor on a camera. By detecting the time difference of the light which has been received on each of the sensors, 3D data of the target surface can be determined. OSIRIS-REx GNC - Image: NASA/Lockheed Martin Figure 19 – OSIRIS-REX’s Attitude Control and Navigational System (NASA/Lockheed Martin, 2015a)

1.10.5 Data and Processing

The processing choice on OSIRIS-REx has never been released to the public (SPACEFLIGHT101, 2016). Based on the hardware reuse which the OSIRIS-REx mission utilises from other Mars missions, we can assume it was most likely the RAD750. The BAE Systems RAD750 is a single board computer (SBC). The CPU can tolerate very high radiation doses, up to 1 million times the fatal radiation dose for a human. The SBC is also very reliable, on average over 15 years the device is specified to only encounter 1 interrupt (system failure). The RAD750 only consumes 10W of power and can operate over a temperature range of –55->155°C.  Figure 20 – OSIRIS-REx’s Functional Block Diagram (NASA/Lockheed Martin, 2015b)

1.11 The ground segment architecture

Due to the enormous distance which the OSIRIS-REx spacecraft is from Earth, it will communicate to Earth via NASA’s Deep Space Network (DSN). The DSN utilises 3 ground stations located at unique sites around the world, which typically provides 24/7 tracking while the Earth rotates. The three sites are located in:

  • Madrid, Spain has 7 antennas, with its largest being a 70m parabolic reflector.
  • Goldstone, USA has 5 antennas, with its largest being a 70m parabolic reflector.
  • Canberra, Australia has 4 antennas, with its largest being a 70m parabolic reflector.

Due to the distance that OSIRIS-REx is away from Earth and the power being transmitted, only a 34m parabolic ground station antenna is typically needed for the tracking of the spacecraft. If we compare this to a spacecraft like Voyager 2, generally a 70m antenna is needed for its increased gain, in order to receive a good quality Voyager 2 signal.  Figure 21 – Screenshot showing that the OSIRIS-REx is being tracked by a 34m parabolic antenna in Goldstone, USA (NASA, 2017)

1.12 The major mission developers

The OSIRIS-Rex mission was quite a complex mission and it had many different stakeholders involved in the design of the spacecraft and the various instruments, which make up the payload. NASA’s Goddard Space Flight Centre provided the overall mission planning, safety assurances, project management and requirements to each of the relevant subcontractors involved in producing the different parts for the mission.

1.12.1 Lockeheed Martin Space Systems

Lockheed Martin Space Systems built the OSIRIS-REX spacecraft bus and performed the system integration. They are also responsible for the mission operations.

1.12.2 Malin Space Science Systems

The OSIRIS-REx mission utilises three Malin Space Science Systems cameras which form the TAGCAMS system. The two major components of the TAGCAMS system are NavCams and StowCam. As previously mentioned, the NavCams consist of two CAM-M50 5-megapixel monochromatic cameras. Two are used to bring a level of redundancy to the navigational system on-board the OSIRIS-REx. The third Malin Space Sciences camera is an ECAM-M50 5-megapixel colour camera which is referred to as StowCam. All three cameras are capable of acquiring still images and high definition video. http://www.msss.com/images/cameras/20130503_c50_tn.jpg Figure 22 – ECAM-C50 (MSSS, 2017)

1.12.3 Canadian Space Agency (CSA)

The Canadian Space Agency contributed the OSIRIS-REx Laser Altimeter (OLA) to the mission. This was a project which was run in collaboration with a Canadian-US led team, led by Michael Daly who was the OLA instrument scientist at York University, while Catherine Johnson was the deputy OLA instrument scientist at the University of British Columbia. Oliver Barnouin also assisted and was from Johns Hopkins University (NASA, 2016a).

1.12.4 Arizona State University (ASU)

ASU contributed to the OSIRIS-REx mission by building the OSIRIS-REx Thermal Emission Spectrometer (OTES). This team was led by Phillip Christensen, instrument scientist at ASU with assistance from Victoria Hamilton, who was the deputy instrument scientist at Southwest Research Institute (SwRI).

1.12.5 Harvard University (HU) and Massachusetts Institute of Technology (MIT)

HU and MIT ran a collaborative student project to design and build the Regolith X-Ray Imaging System (REXIS) for the OSIRIS-REx mission.

1.12.6 University of Colorado (CU)

The Radio Sciences team helped develop the telecommunications subsystem aboard OSIRIS-REx and will use high and low gain antennas to communicate with the Deep Space Network (DSN). They will use the Doppler shift from the carrier wave to make a range of measurements about the mass and gravity field that is being faced by the OSIRIS-REx. The radio science team is led by Daniel Scheeres from CU.

1.12.7 NASA Goddard Space Flight Centre

As described above, apart from the overall mission planning, safety assurances, project management, The Goddard Space Flight centre developed the OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) system specifically for the OSIRIS-REx mission.

1.13 The communication system

The OSIRIS-Rex space craft’s Telecommunications Subsystem will use any one of three antennas that being a low gain (LGA), medium gain (MGA) and high gain antenna (HGA) to communicate back to Earth. The telecoms system is essentially a clone of the system on board NASA’s Mars Atmosphere and Volatile Evolution mission (MAVEN). The core of the OSIRIS-REX’s telecommunication system is a Small Deep Space Transponder (SDST) and a Travelling Wave Tube Amplifier (TWTA). There are two sets of these devices installed on the OSIRIS-REx spacecraft in the interests of redundancy. The SDST is a NASA/JPL design and is typically used for deep space missions as it integrates numerous functions into a single unit including receiver, telemetry, command detection, modulation, exciters, control and tone generation. The unit supports frequencies in both the X and Ka band and has a mass of 4kg. Depending on the distance away from Earth, data rate needed and ability to accurately point the spacecraft dictates whether a low, medium or high gain antenna is used on the spacecraft. The three antennas offer different features including:

  • Low Gain Antenna (LGA) – The LGA utilises two chocked horn antennas. The result of these antennas give the spacecraft Omni-directional coverage, therefore allowing the spacecraft to be pointed in any direction. However, the data rate is very low as the system uses MFSK tones.
  • Medium Gain Antenna (MGA) – The MGA is a circular horn antenna, which allows an increased data rate, however it has a limited beamwidth. This works well when the spacecraft is roughly pointing in the right direction and essentially offers a middle ground between the other two antennas. For this reason, the MGA will be used in the critical Touch and Go sampling operation when the OSIRIS-REx takes a sample of the asteroid.
  • High Gain Antenna (HGA) – The HGA is a highly directional antenna. It is a 2.1m diameter parabolic antenna. Since we know the frequencies used are both X-band and Ka Band, this results in a 3dB beamwidth from the antenna of between 0.2°-1.2°. This allows the spacecraft to send data back to Earth at a much higher data rate of up to 914kbits/s, while the spacecraft is accurately pointing towards Earth.

As mentioned above, communication to Earth will be via NASA’s Deep Space Network (DSN). This network can obtain accurate Doppler and range measurements of the spacecraft, which can be used to measure the mass and gravity field of Bennu. The communications side of the mission is led by Daniel Scheeres at the University of Colorado. Photo: NASA/Lockheed Martin Figure 23 – OSIRIS-REx’s HGA parabolic antenna (NASA/Lockheed Martin) Image: NASA/Lockheed Martin Figure 24 – OSIRIS-REx Telecommunications subsystem schematic (NASA/Lockheed Martin)

2. Budget Calculations

2.1 Mass Budget

2.1.1 Research

Two of the key masses of the OSIRIS-REx spacecraft are published, that being the Dry and Wet mass. For the system’s mass budget to be determined, there are still two masses which need to be obtained as from extensive research, a payload mass and a Launch Vehicle Capability is unable to be obtained. There are generic Launch vehicle capabilities for the Atlas V rocket, however the OSIRIS-REx utilises a custom configuration of the Atlas 5. Therefore, going forward, some reasonable estimates shall be made for the remaining masses. Since the On Orbit dry mass is given of 880kg, this mass can be used to estimate a payload mass. Figure 2.7 of Elements of Spacecraft Design (Brown, 2002), illustrates that for a planetary spacecraft with an on orbit dry mass of 880kg, a typical payload mass would be approximately 116kg. From these three masses, all that is left is a Launch Vehicle Capability mass or a Launch Vehicle Adaptor mass and then we can deduce the entire set of spacecraft specific masses. This mission is quite unique in that in the initial design stage there was a small mass margin of 33kg (Lauretta, 2015a). However, it was determined that the wet mass will actually be greater than the launch vehicle capability of 1955kg. The launch mass with the propellant tanks full will be 2110kg. As a result of this, the launch provider United Launch Alliance (ULA) performed a study to determine the absolute limit which can be launched. The study concluded that the Atlas V can support a launch mass of 2078kg, and hence the propellant tanks were therefore filled until the entire spacecraft had a wet mass equal to the launch capability and thus there was a margin of 0kg (Lauretta, 2015a). However, a NASA press release after this study states the wet mass at launch was 2110kg (NASA, 2016a). This tell us that the propellant tanks were at 100% capacity upon launch. It is important to note when conducting research and hence the findings above, when talking about Launch Vehicle Capability, I believe that the sources are ignoring the Launch Vehicle Adaptor mass in the Launch Vehicle Capability calculations therefore, I assume its mass has already been accounted for and included in the Launch Vehicle mass. I believe this to be the case as Professor Dante Lauretta, Principal Investigator of OSIRIS-REx mission states that “We will simply add the extra fuel until the wet mass equals the launch vehicle capability”(Lauretta, 2015a). The Launch vehicle adaptor mass can be estimated based on historical missions by the following equation, as given in Elements for Spacecraft design (Brown, 2002): LVA=0.0755*LM+50 Since the Launch Mass in this standard formula includes the LVA (unlike the OSIRIS-REx Launch mass/wet mass) we can say that LM=LM_rex+LVA, LM_rex=2110kg. LVA=0.0755*LMrex+LVA+50 This results in a LVA mass =226kg.  Figure 25 – Payload Mass vs On Orbit Dry Mass (Brown, 2002)  Figure 26 – Launch Vehicle Adaptor Mass (Brown, 2002)

2.1.2 Calculations and Results

Dry Mass=Md=880kg (NASA, 2016a){Arizona`;, 2015 #5}{NASA,  #6} Wet Mass=Mw=2110kg (NASA, 2016a) Payload Mass=Mp=116kg Mass of Propellant + Pressurant = Mpp=Mw-Md=1230kg Bus Mass=Mb=Md-Mp=764kg Launch Vehicle Adaptor = LVA= 226kg Launch Vehicle capability=2326kg 

Figure 27 – OSIRIS-REx Mass Budget estimates

2.2 The Spacecraft Power budget

2.2.1 Research

The OSIRIS-REx spacecraft’s primary source of power is from two solar arrays which generate between 1226W to 3000W depending on the spacecraft’s distance from the Sun. Electricity will be stored in two 8 cell 28V 30Ah (1680Wh) Li-ion batteries with integrated battery management systems (BMS) as previously discussed. Since this data tells us that when the spacecraft is further from the Sun, the minimum power being produced will be 1226W, we can say that the spacecraft will typically be able to operate on this minimum level of power. This is based on the trajectory of the mission, in that it will be away from the Sun for some time, and since the OSIRIS-REx has only 1680wh of battery storage, the spacecraft will effectively need to be able to sustain its operations from the minimum power of 1226W. However this is not to say that the system won’t survive on less power, it most likely would, it only says that the spacecraft can most likely function, (at least at a minimum level) for extended periods on 1226W of power. Attempts have been made to quantify the power requirements of the payload, however, there was not much success on this front, due to a lack of published specifications, therefore exact payload and subsystem power requirements could not be made. As a result we can use estimates based on previous planetary missions. The textbook “Elements of Spacecraft Design” (Brown, 2002), Table 2.9, page 33, demonstrates that for a typical planetary mission, the payload power requirement can be expressed as: Pt=332.93*ln⁡Ppl-1046.6 Pt=Total Power P_pl=Payload Power

2.2.2 Calculations and Results

Payload Power -> 1226=332.93*ln(Pl)-1046.6, P_Pl=921W Therefore we can estimate a subsystem power of =1226-921=305W Since we are making estimations it would be prudent to use a conservative margin value. For this reason, a margin value of 0.7 will be used for calculations This results in a margin of 0.7*305=213.5W In the Textbook “Elements of Spacecraft Design” (Brown, 2002) Table 2.10, outlines the figures of a typical power distribution for a Planetary mission, from these figures we can estimate the power used by each of the subsystem components as:

Subsystem Power distribution for planetary spacecraft (Brown, 2002) % Power Allocation for OSIRIS-REx based on 100%=305W W
Thermal control 28 85.4
Attitude control 20 61
Power 10 30.5
CDS 17 51.8
Communications 23 70.15
Propulsion 1 3.05
Mechanisms 1 3.05

Figure 28 – Power Estimation of various subsystem components on OSIRIS-REx

References

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