Early Mission StarNav 1 Data from STS-107

Page 1,Total: 1 Early Mission StarNav 1 Data from STS-107 Author(s): I. Carron, T. Pollock, M. Puente, U. Abbas, M. Samaan, C. Akram, A. Katake, O. Godard Revision Number: Draft 5g Date: April 30, 2003 White Paper Spacecraft Technology Center MS-3118 Texas A&M University College Station, Texas, 77843-3118 Phone: 979-845-8768 Fax: 979-847-8857 Web: http://stc.tamu.edu/ Total number of pages: 1 Page number: 1

Abstract Page 2,Total: 2 The star tracker, StarNav1, was a payload flown on the space shuttle mission STS-107. During the mission, StarNav took several pictures of the night sky. These pictures were used to test an algorithm that computed the attitude of the shuttle. The following report contains a study performed on some data collected by StarNav during the early part of the mission. These pictures contain images of light-reflecting objects of unknown origin in the camera s field of view. Because the camera s field of view was in the direction of the left wing of the orbiter, the images collected may be of interest to the Columbia Accident Investigation Board. However, we note that previous star tracker payloads on the shuttle have observed similar floaters in their data that were assumed to be caused by debris particles floating from inside the shuttle bay (e.g., STS-101, SOAR payload). 1. Problem statement The purpose of this report is to provide technical information gathered during the STS- 107 mission by StarNav that might be of interest to the Columbia Accident Investigation Board, NASA and other stakeholders. 2. Description 2.1 Description of StarNav 1 The StarNav1 design is based on an ongoing star-tracker technology development program with the Aerospace Engineering Department at Texas A&M University and the Spacecraft Technology Center (formerly known as Commercial Space Center for Engineering) also at Texas A&M University. The StarNav flight experiment hardware is based on successful ground demonstration units that have been used to test attitude determination algorithms with night sky images. All components were packaged in a custom configuration for mating to the single SpaceHab Inc. QuEST (Q9) platform ( see Figures 1 and 2). The Quest location was provided by Spacehab Inc. The payload structure is comprised of two major components, the flight enclosure and the mounting plate, each fabricated with aluminum. These are mated in such a way that there are no exposed fasteners other than the six bolts required to connect the mounting plate directly to the Q9. The electronics, optical assembly and baffles are all contained within the flight enclosure. Figure 3 illustrates the components within the enclosure. The components used to construct StarNav were primarily commercial off the shelf (COTS) configured to support the unique algorithm development. The CCD array is housed in a small vacuum vessel and actively cooled by a thermoelectric cooler to -30 degrees Celsius. The optical assembly for the StarNav flight hardware was created using a set of optics from a commercial 35mm lens (Canon). The baffle assembly consists of 2 plates with varying hole diameters that create a conical light path to the CCD array of 7 Total number of pages: 2 Page number: 2

Page 3,Total: 3 degrees. The field of view of StarNav1 can be seen in figure 19. The CCD array has an integration time of 80 ms. The minimum distance between StarNav and the payload bay envelope is estimated to be no less than 4 feet. 2.2 StarNav1 Operation Once on orbit, the StarNav1 experiment was activated with a discrete power up signal from the SPACEHAB module EIU (TBR-01). The on-board StarNav CPU controlled the CCD array and its thermoelectric cooler to coincide with predetermined intervals for star viewing. Upon experiment completion, a discrete signal was sent to power-off the electronic hardware. The time period between power on and power off was thirty minutes. A time period of about 6 minutes was expected between the power on signal and the first photo shot. Five photos of the sky were taken at one-minute intervals during each cycle (power on to power off time period). 2.2 Location of StarNav 1 The StarNav1 flight hardware was completely external to the SPACEHAB module and was mounted to the module via a QuEST single cell (Q9) adapter. StarNav was mounted on the forward module segment on the port side. Figure 4 provides an illustration of the entire assembly mounted to the Q9 plate. 3. Results During the mission, we received a total of 32 pictures from StarNav. After studying the StarNav images, we identified nine of those pictures that contained unidentified objects. Since StarNav s field of view was pointing towards the shuttle s left wing, we are providing these images to the Columbia Accident Investigation Board and other NASA investigators. Below is a discussion of the key facts discovered while analyzing the images. All images are in a FITS format and can be viewed and analyzed using the Avis software. This software is used for astronomy image processing and can be downloaded from http://www.sira.it/msb/avis.htm 3.1 Timeline Table 1 summarizes the times when the 32 images were received from StarNav. Table1. STS-107 Image summary Images AERO name Date/time (CT) Date/time (MET) Date/time (GMT) Attitude Beta 1/16/03 20:21 00:10:40 1/17/03 2:21 -ZLV -XVV 2 Alpha a_021600 1/17/03 15:02 01:05:21 1/17/03 21:02 -ZLV -XVV 4 Xi 1/19/03 3:09 02:17:30 1/19/03 9:09 -ZLV +XVV 4 # Pics. Total number of pages: 3 Page number: 3

Page 4,Total: 4 Epsilon b_140558 1/19/03 8:12 02:22:32 1/19/03 14:12 -ZLV +XVV 5 Tau f_213001 1/19/03 15:40 03:06:02 1/19/03 21:40 -ZLV +YVV 5 Delta f_073854 1/20/03 1:43 03:16:02 1/20/03 7:43 TDRW/TDRZ 5 Gamma f_091136 1/20/03 3:15 03:17:35 1/20/03 9:15 -ZLI 5 Mu 1/20/03 6:05 03:20:27 1/20/03 12:05 TDRW -ZLV +XVV 2 *StarNav's last working cycle 1-20-03 11:56 pm 3.2 Photographs taken during flight Figures 12 through 16 correspond to the nine images with unidentified objects. These images come from the Beta, Alpha and Tau group of pictures. Each group of pictures has a set of images: the raw image, enhanced image, and labeled image. We divided them in this way so the reader can compare and contrast the enhanced images to the original picture taken. Each set of pictures has one labeled image where the visible objects are identified to help describe each object. On each picture we define a star to be a dot and an unknown object to be of any other shape. Figure 20 shows where the Spacehab rooftop and the top of the StarNav camera are located in every images presented in this white paper. The left side of our images is the rooftop of the Spacehab module. Many of the most intriguing unidentified objects have a rectangular shape. You can find the original and enhanced images in the zip folder called starnav_images_white_paper.zip at the following address: http://starnavcontest.tamu.edu/reports/ (text documents in this zip file are the original FITS images, they can be viewed with the avis viewer by choosing to import the txt files as ASCII 16 bits or File -> Import -> ASCII 16 bit ) The Beta group of pictures contains two images. These pictures were taken on the first day of the mission. Figure 8 [beta img_a_1_4] corresponds to the first picture received from StarNav. The labeled picture contains five objects. Objects Beta_1_A, Beta_1_B, and Beta_1_C have a rectangular shape and objects Beta_1_D and Beta_1_E are circular and brighter than the rectangular objects. Figure 9 [img_a_1_5] corresponds to the second image received on the first day of the mission as well. Here two bright objects Beta_2_A and Beta_2_B, are easily observed. They are both very bright and round. Object Beta_2_A includes a distinctive ray of light. Figure 9e shows the distribution of light in a histogram. Table 3 contains the attitude of the shuttle during this cycle. Mr. Andrew Lalich from USA Inc. was able to provide this information. Total number of pages: 4 Page number: 4

Page 5,Total: 5 Table 2. Summary of Beta pictures (*D = diameter) Name Object Number of pixels Name Object Number of pixels Beta_1_A Unidentified 6 X 1 Beta_1_G Star 1 Beta_1_B Unidentified 3 X 5 Beta_1_H Star 1 Beta_1_C Unidentified 3 x 6 Beta_2_A Unidentified D = 8 Beta_1_D Star 1 Beta_2_B Unidentified D = 6 Beta_1_E Unidentified D = 6 Beta_2_C Star 1 Beta_1_F Star 1 Table 3: Attitude for shuttle for Jan 16, 2003 Time (CT) Quat scalar Quat x Quat y Quat z 20:10 0.11486578-0.24192429-0.52327418 0.80898708 20:11 0.13218808-0.21357715-0.51809418 0.81761009 20:12 0.15018713-0.18550009-0.51141131 0.82552367 20:13 0.16840631-0.15680355-0.50382298 0.83259302 20:14 0.18652618-0.12807190-0.49551684 0.83860964 20:15 0.20466000-0.09910226-0.48666173 0.84347522 20:16 0.22287011-0.07005489-0.47701895 0.84727293 20:17 0.24090493-0.04098588-0.46677035 0.84994566 20:18 0.25877362-0.01202536-0.45575845 0.85157090 20:19 0.27639508 0.01714402-0.44546694 0.85139191 20:20 0.29360080 0.04636025-0.43573701 0.84957629 20:21 0.31043041 0.07539225-0.42570210 0.84659529 20:22 0.32651597 0.10483176-0.41665518 0.84189880 20:23 0.34223592 0.13436890-0.40705383 0.83613628 20:24-0.35483348-0.16327351 0.39668959-0.83070421 20:25-0.36706948-0.19213063 0.38574272-0.82434535 20:26-0.37893087-0.22076285 0.37440491-0.81700289 20:27 0.39041370 0.24918473-0.36249572 0.80875099 20:28 0.40140194 0.27757549-0.35021061 0.79948622 20:29 0.40140194 0.27757549-0.35021061 0.79948622 20:29 0.41224968 0.30641633-0.33699262 0.78904510 20:30 0.41224968 0.30641633-0.33699262 0.78904510 In addition, we also computed an access report of the stars that were in StarNav s field of view during this cycle. This access report was generated using STK/Pro. Table 3 lists all the stars StarNav had access to during the cycle. Total number of pages: 5 Page number: 5

Page 6,Total: 6 Table 4. Access to various stars from STK/Pro simulation Star Start(CST) Duration (sec) Visual mag. Star Start(CST) Duration (sec) Visual mag. HR-161 1/16/2003 20:15 78.251 6.39 HR-697 1/16/2003 20:24 77.121 6.22 HR-248 1/16/2003 20:16 73.604 4.77 HR-710 1/16/2003 20:24 43.716 5.83 HR-353 1/16/2003 20:17 75.15 5.94 HR-713 1/16/2003 20:24 67.38 5.88 HR-368 1/16/2003 20:18 30.502 5.7 HR-745 1/16/2003 20:25 79.59 6.21 HR-373 1/16/2003 20:18 67.105 5.41 HR-826 1/16/2003 20:25 77.382 6.49 HR-387 1/16/2003 20:18 67.306 6.23 HR-827 1/16/2003 20:26 79.832 6.47 HR-401 1/16/2003 20:19 50.752 6.21 HR-844 1/16/2003 20:26 72.075 6.14 HR-402 1/16/2003 20:19 44.619 3.6 HR-850 1/16/2003 20:26 57.139 4.75 HR-404 1/16/2003 20:19 72.945 5.91 HR-862 1/16/2003 20:26 71.408 5.95 HR-406 1/16/2003 20:19 32.54 6.15 HR-883 1/16/2003 20:26 77.543 5.45 HR-444 1/16/2003 20:20 67.485 6.59 HR-889 1/16/2003 20:26 74.576 5.84 HR-448 1/16/2003 20:19 79.056 5.76 HR-901 1/16/2003 20:27 79.784 5.71 HR-466 1/16/2003 20:20 74.061 6.24 HR-914 1/16/2003 20:27 51.966 5.89 HR-492 1/16/2003 20:21 55.739 5.75 HR-919 1/16/2003 20:27 63.149 4.09 HR-50 1/16/2003 20:13 10.887 6.02 HR-943 1/16/2003 20:28 76.02 6.19 HR-531 1/16/2003 20:21 79.759 4.67 HR-963 1/16/2003 20:28 73.279 3.87 HR-539 1/16/2003 20:21 78.177 3.73 HR-97 1/16/2003 20:15 40.651 5.77 HR-59 1/16/2003 20:13 39.775 6.11 HR-974 1/16/2003 20:28 66.79 6.16 HR-608 1/16/2003 20:22 63.79 5.86 HR-980 1/16/2003 20:28 61.927 6.25 HR-625 1/16/2003 20:24 12.909 6.1 HR-990 1/16/2003 20:29 55.948 6.65 HR-693 1/16/2003 20:24 79.381 5.87 HR-993 1/16/2003 20:28 79.882 5.91 The Alpha set of pictures was taken on the second day of the mission. Four images [img_a_1_1, img_a_1_2, img_a_1_3, img_a_1_4] were received during this cycle. Figure 10 corresponds to img_a_1_1. There are six objects on this picture. Object Alpha_1_A and Alpha_1_F have a rectangular shape, object Alpha_1_B is round and bright, and objects Alpha_1_C, Alpha_1_D, and Alpha_1_E seem to be stars. Figure 11 corresponds to img_a_1_2. Objects Alpha_2_A, Alpha_2_B, and Alpha_2_F have a rectangular shape, and Alpha_2_C, Alpha_2_D, and Alpha_2_E are stars. Figure 12 corresponds to img_a_1_3. This picture seems to have the most objects. Objects Alpha_3_A, Alpha_3_K, Alpha_3_L, Alpha_3_E, and Alpha_3_H seem to be stars and objects Alpha_3_B, Alpha_3_C, Alpha_3_D, Alpha_3_F, Alpha_3_G, Alpha_3_J, and Alpha_3_I have a rectangular shape. Figure 13 corresponds to img_a_1_4. Here Total number of pages: 6 Page number: 6

Page 7,Total: 7 Alpha_4_D seems to be a star and Alpha_4_A, Alpha_4_B and Alpha_4_C have rectangular shapes. Table 5. Summary of Alpha pictures Name Object Number of pixels Name Object Number of pixels Alpha_1_A Unidentified 3 X 6 Alpha_3_C Unidentified 1 X 7 Alpha_1_B Unidentified 4 X 5 Alpha_3_D Unidentified 1 X 7 Alpha_1_C Star 1 Alpha_3_E Star 1 Alpha_1_D Star 1 Alpha_3_F Unidentified 3 X 6 Alpha_1_E Star 1 Alpha_3_G Unidentified 3 X 7 Alpha_1_F Unidentified 1 X 4 Alpha_3_H Star 1 Alpha_2_A Unidentified 3 X 19 Alpha_3_I Star 1 Alpha_2_B Unidentified 3 X 3 Alpha_3_J Unidentified 2 X 2 Alpha_2_C Star 1 Alpha_3_K Star 1 Alpha_2_D Star 1 Alpha_3_L Star 1 Alpha_2_E Star 1 Alpha_4_A Unidentified 2 X 4 Alpha_2_F Unidentified 2 X 13 Alpha_4_B Unidentified 4 X 7 Alpha_3_A Star 1 Alpha_4_C Unidentified 4 X 9 Alpha_3_B Unidentified 1 X 5 Alpha_4_D Star 1 Tau set [img_f_1_1, img_f_1_2, img_f_1_3] contains the most intriguing images. This group of pictures has more resolved unknown objects. Figure 14 corresponds to img_f_1_1. Here, objects Tau_1_C, Tau_1_D, Tau_1_E, and Tau_1_F seem to be stars and objects Tau_1_A, Tau_1_B and Tau_1_G have a rectangular shape. Figure 15 corresponds to img_f_1_2. Here objects Tau_2_A, Tau_2_C, and Tau_2_E appear to be stars, and objects Tau_2_B, Tau_2_D, and Tau_2_F have a rectangular shape. Figure 16 corresponds to img_f_1_3. This picture shows objects Tau_3_A, Tau_3_C, and Tau_3_E to be stars and Tau_3_B and Tau_3_D appear to be rectangular. Table 5. Summary of Tau pictures (*D = diameter) Name Object Number of pixels Name Object Number of pixels Tau_1_A Unidentified 8 X 30 Tau_2_C Star 1 Tau_1_B Unidentified 8 X 9 Tau_2_D Unidentified 20 X 40 Tau_1_C Star 1 Tau_2_E Star 1 Tau_1_D Star 1 Tau_2_F Unidentified 2 X 4 Tau_1_E Star 1 Tau_3_A Star 1 Tau_1_F Star 1 Tau_3_B Unidentified 9 X 11 Tau_1_G Unidentified 20 X 42 Tau_3_C Star 1 Tau_2_A Star 1 Tau_3_D Unidentified D = 3 Tau_2_B Unidentified 8 X 20 Tau_3_E Star 1 Total number of pages: 7 Page number: 7

Page 8,Total: 8 3.2.1 Stray light from the SpaceHab rooftop As can be seen from this photograph taken during the flight (Figure 7), the MLI shroud over the SpaceHab module is a diffuse scatterer. Initial star pictures taken by StarNav had large amounts of sunlight reflected off this shroud which led the StarNav team at the POCC to request windows of opportunity during night sky portions of the orbit. Subsequent night sky pictures revealed that reflected sunlight was a significant factor in the day sky pictures. Mission success for StarNav was obtained by analyzing subsequent pictures of the night sky tests. A preliminary analysis of this scattered sunlight from the SpaceHab rooftop was performed using C&R Tech Thermal Desktop/RADCAD. Our initial assessment shows a larger light flux at the bottom of the photograph. This qualitative assessment is shown in Figures 17 and 18. 4. Conclusions Our initial assessment of data during the early part of the flight was focused on obtaining a picture of adequate quality so StarNav could autonomously identify starts. The less than ideal condition caused by scattered sunlight led us to request photographs be taken during orbital night. As a result, we set the early pictures aside and did not examine them closely until recently. The early pictures, because of the presence of sunlight, contained the unidentified objects discussed above. We have no way of knowing the origin, size, or actual location of the unidentified objects in these images. We also note that previous star tracker payloads on the shuttle have observed similar floaters in their data, assumed to be caused by debris particles floating from inside the shuttle bay. 5. Acknowledgements We would like to thank the following individuals for their contribution to this report Andrew Lalich ( NASA-USA Inc), Michael Jacox (Starnav1 Program manager), Mark Welsh (C&Rtech). 6. References Jacox, M. and Pollock, T., Phase III flight Safety Data Package for the StarNav Experiment, September 19, 2000 Total number of pages: 8 Page number: 8

Page 9,Total: 9 7. Appendix Figure 1. StarNav Flight Hardware Figure 2. StarNav during testing phase inside a vacuum chamber. Total number of pages: 9 Page number: 9

Page 10,Total: 10 Electronic Boards Flight Enclosure Baffles CCD Vacuum Housing Optical Assembly Figure 3. StarNav components Figure 4. StarNav Total number of pages: 10 Page number: 10

Page 11,Total: 11 Figure 5. QuEST Figure 6. STK simulation of STS-107 mission. The red cone represents StarNav s FOV. View from the sun, shuttle payload bay is aiming Nadir. Total number of pages: 11 Page number: 11

Page 12,Total: 12 Figure 7. Photograph of the SpaceHab module taken during the flight. Please note the apparent diffuse scattering off the top MLI of the SpaceHab module. Starnav is located right behind the square box (ESA s Com-2-plex two phase flow experiment) on the left side of the picture above the Spacehab marking. Total number of pages: 12 Page number: 12

Page 13,Total: 13 Figure 8a. Beta_1 raw image: img_a_1_4 [1/16/03 20:21CT] Figure 8b. Beta_1 enhanced image: img_a_1_4 1 [1/16/03 20:21CT] Total number of pages: 13 Page number: 13

Page 14,Total: 14 E D F G C H B A Figure 8c. Beta_1 labeled image: img_a_1_4 [1/16/03 20:21CT] Total number of pages: 14 Page number: 14

Page 15,Total: 15 Figure 9a. Beta_2 raw image: img_a_1_5 [1/16/03 20:21CT] Figure 9b. Beta_2 enhanced image 1: img_a_1_5 [1/16/03 20:21CT] Total number of pages: 15 Page number: 15

Page 16,Total: 16 Figure 9c. Beta_2 enhanced image 2: img_a_1_5 [1/16/03 20:21CT] Total number of pages: 16 Page number: 16

Page 17,Total: 17 B A C Figure 9d. Beta_2 labeled image: img_a_1_5 [1/16/03 20:21CT] Total number of pages: 17 Page number: 17

Page 18,Total: 18 Figure 9e. Light distribution around object A in Beta_2 (please note saturation of the camera for most of the spot, star access show no bright star in the field of view of StarNav 1 at the time): img_a_1_5 [1/16/03 20:21CT] Total number of pages: 18 Page number: 18

Page 19,Total: 19 Figure 10a. Alpha_1 raw image: Img_a_1_1 [1/17/03 15:02CT] Figure 10b. Alpha_1 enhanced image: Img_a_1_1 [1/17/03 15:02CT] Total number of pages: 19 Page number: 19

Page 20,Total: 20 E D C B F A Figure 10c. Alpha_1 labeled image: Img_a_1_1 [1/17/03 15:02CT] Total number of pages: 20 Page number: 20

Page 21,Total: 21 Figure 11a. Alpha_2 raw image: img_a_1_2 [1/17/03 15:02CT] Figure 11b. Alpha_2 enhanced image 1: img_a_1_2 [1/17/03 15:02CT] Total number of pages: 21 Page number: 21

Page 22,Total: 22 A F Figure 11c. Alpha_2 enhanced image 2: img_a_1_2 [1/17/03 15:02CT] Total number of pages: 22 Page number: 22

Page 23,Total: 23 A B F C D E Figure 11d. Alpha labeled image: img_a_1_2 [1/17/03 15:02CT] Total number of pages: 23 Page number: 23

Page 24,Total: 24 Figure 12a. Alpha_3 raw image: img_a_1_3 [1/17/03 15:02CT] Figure 12b. Alpha_3 enhanced image 1: img_a_1_3 [1/17/03 15:02CT] Total number of pages: 24 Page number: 24

Page 25,Total: 25 Figure 12c. Alpha_3 enhanced image 2: img_a_1_3 [1/17/03 15:02CT] Total number of pages: 25 Page number: 25

Page 26,Total: 26 J I H G K E D F C B L Figure 12d. Alpha_3 labeled image: img_a_1_3 [1/17/03 15:02CT] A Total number of pages: 26 Page number: 26

Page 27,Total: 27 Figure 13a. Alpha_4 raw image: img_a_1_4 [1/17/03 15:02CT] Figure 13b. Alpha_4 enhanced image 1: img_a_1_4 [1/17/03 15:02CT] Total number of pages: 27 Page number: 27

Page 28,Total: 28 Figure 13c. Alpha_4 enhanced image 2: img_a_1_4 [1/17/03 15:02CT] Total number of pages: 28 Page number: 28

Page 29,Total: 29 D C B A Figure 13d. Alpha_4 labeled image: img_a_1_4 [1/17/03 15:02CT] Total number of pages: 29 Page number: 29

Page 30,Total: 30 Figure 14a. Tau_1 raw image: img_f_1_1 [1/19/03 15:40 CT] Figure 14b. Tau_1 enhanced image 1: img_f_1_1 [1/17/03 15:02CT] Total number of pages: 30 Page number: 30

Page 31,Total: 31 Figure 14c. Tau_1 enhanced image 2: img_f_1_1 [1/17/03 15:02CT] Total number of pages: 31 Page number: 31

Page 32,Total: 32 G F E D C B A Figure 14d. Tau_1 labeled image 2: img_f_1_1 [1/17/03 15:02CT] Total number of pages: 32 Page number: 32

Page 33,Total: 33 Figure 15a. Tau_2 raw image: img_f_1_2 [1/17/03 15:02CT] Figure 15b. Tau_2 enhanced image 1: img_f_1_2 [1/17/03 15:02CT] Total number of pages: 33 Page number: 33

Page 34,Total: 34 Figure 15c. Tau_2 enhanced image 2: img_f_1_2 [1/17/03 15:02CT] Total number of pages: 34 Page number: 34

Page 35,Total: 35 E D C F B A Figure 15d. Tau_2 labeled image: img_f_1_2 [1/17/03 15:02CT] Total number of pages: 35 Page number: 35

Page 36,Total: 36 Figure 16a. Tau_3 raw image: img_f_1_3 [1/17/03 15:02CT] Figure 16b. Tau_3 enhanced image 1: img_f_1_3 [1/17/03 15:02CT] Total number of pages: 36 Page number: 36

Page 37,Total: 37 Figure 16c. Tau_3 enhanced image 2: img_f_1_3 [1/17/03 15:02CT] Total number of pages: 37 Page number: 37

Page 38,Total: 38 E D C B A Figure 16d. Tau_3 labeled image: img_f_1_3 [1/17/03 15:02CT] Total number of pages: 38 Page number: 38

Page 39,Total: 39 Figure 17. Scattered light as computed for the Beta series with Thermal Desktop (coarse). Total number of pages: 39 Page number: 39

Page 40,Total: 40 Figure 18. Scattered light as computed for the Beta series with Thermal Desktop.(fine 100 x 100) Total number of pages: 40 Page number: 40

Page 41,Total: 41 Figure 19: Approximate location of cone of sight of StarNav I from the SpaceHab rooftop during the STS-107 mission, location of StarNav I cannot be exactly shown here because of the blurriness of the photo taken by the Air Force Maui Optical Telescope. Picture source: Air Force Maui Optical & Supercomputing site, available at http://www.spaceref.com/news/viewsr.html?pid=8128 The distance a is estimated to be no less than 4 feet. Total number of pages: 41 Page number: 41

Page 42,Total: 42 X Spacehab Module Rooftop X Top of Starnav camera Figure 20. How to read image Beta_2 raw image: img_a_1_5 [1/16/03 20:21CT]. Total number of pages: 42 Page number: 42