Hubble Space Telescope’S Contributions to Servicing Spacecraft on Orbit

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The Hubble Space Telescope’s Contributions to Servicing Spacecraft On Orbit

Christopher Gainor Ph.D.

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March 25, 2020 1 Hubble Space Telescope Facts

2 Goddard Space Flight Center Normal Operations

Hubble Space Telescope

Commands Science Data Engineering Data

STScI Command GSFC Research Loads Proposals

Data Products Data Sets Science Program Admin Science Planning Engineering Analysis Mission Scheduling FSW Development & Maintenance Data Processing Control Center System Science Analysis Orbit Determination Archive TDRS Scheduling Real Time Control Space Network Interface Science Data Capture Servicing Operations 3 4/23/03 Inside the Hubble Telescope

4 HST Instruments

Imaging • Wide Field/Planetary Camera WF/PC (1990-1993) • Wide Field Planetary Camera 2 WFPC2 (1993-2009) • Wide Field Camera 3 WFC3 (2009-present) • Faint Object Camera (ESA) FOC (1990- 2002) • Advanced Camera for Surveys ACS (2002-present) Spectroscopy • Faint Object Spectrograph FOS (1990-1997) • Goddard High Resolution Spectrograph GHRS (1990-1997) • Space Telescope Imaging Spectrograph STIS (1997-present) • Near Infrared Camera & Multi-Imaging Spectrometer NICMOS (1997-present) • Cosmic Origins Spectrograph COS (2009-present) Other • High Speed Photometer (1990-1993) • Corrective Optics Space Telescope Axial Replacement COSTAR (1993-2009) • Fine Guidance Sensors (1990-present)

5 HST Servicing Plans

• 15-year lifetime contemplated for HST. • Early concepts called for HST instrument changeout on the ground. • By 1977, NASA called for capability to change instruments out on the ground & on orbit. • NASA decided in 1984 against refurbishment of HST on the ground in favor of shuttle servicing missions. More replaceable units added to HST. • Early rationale for space shuttle was to lower costs by repairing satellites and lengthening their lives. • Frank Cepollina at Goddard began working on satellite servicing in the 1970s, and started work on preparing HST for servicing, including developing Flight Support System where HST would sit in payload bay during repairs. • Bruce McCandless & Kathy Sullivan, assigned in 1985 to HST deployment mission, began simulating repairs on HST, proposing new tools, worksites and design features for HST. Delays due to Challenger disaster gave them more time for this work. • Trouble-plagued EVAs on early shuttle ﬂights showed that handling equipment for EVA work needed to be tested with the actual ﬂight articles, not based on drawings or photos. • McCandless & Sullivan came close to having to EVA unfurling HST solar panel during STS-31 Discovery deployment mission in 1990.

6 HST Mirror Problem

• HST deployed from Discovery on April 25, 1990. • After early images in May were defective, NASA announced on June 27 that HST’s main mirror had spherical aberration. • Allen report investigated causes of this failure, which took place during manufacturing of mirror by Perkin-Elmer in 1980 & 1981. Corners were cut on testing and oversight. • Optical review panel at Goddard determined precise shape of mirror. It had been precisely ground to the wrong shape. • Knowledge of its shape was vital to overcoming spherical aberration. • In spite of this problem, HST images, data at this time were superior to ground-based telescopes. • HST also suﬀered from ‘jitter’ problem that required early replacement of solar panels. • First shuttle servicing mission already on tap for 1993.

7 Solving Spherical Aberration

• In 1990, work was already well underway for a new camera for HST – WFPC2. Corrective mirrors added to WFPC2 to compensate for spherical aberration.

• STScI convened panel to create solutions for other instruments. Twenty ideas considered. • Solution involved removing one axial instrument and installing COSTAR instrument that placed corrective mirrors in optical paths of other three axial instruments. • Veteran crew of STS-61 SM1 began a longer than usual period of intensive training in 1991.

• Shuttle EVAs in early 1990s showed problems, tested tools & procedures for SM1.

• SM1 underwent elaborate preparations and multiple reviews before launch.

• Problems on HST mounted before SM1 launch, increasing pressure on mission. Five EVAs, originally thought beyond the shuttle’s capabilities, were set for SM1.

• Flight support system, orbital replacement unit carriers, more than 200 tools and crew aids created for the mission. • STS-61 Endeavour December 2-13 1993 was a complete success. Both WFPC2 & COSTAR worked, along with new solar panels, new gyroscopes and other repairs. • Images from restored HST changed its image from symbol of failure to demonstration of U.S. technical superiority.

8 Payload Bay Equipment

9 Further Servicing Missions

• SM2 (STS-82) Discovery Feb. 11-21 1997 was an ‘upgrade mission,’ installing FGS, along with STIS & NICMOS in place of GHRS & FOS. • STS-95 Discovery Oct. 1998 tested new cooler for NICMOS & new 486 computer for HST. • Loss of gyroscopes & other problems caused NASA to split SM3 into two missions. • SM3A (STS-103) Discovery Dec. 19-27 1999 a ‘rescue mission,’ installing new gyros, computer, FGS. • SM3B (STS-109) Columbia March 1-12 2002 replaced FOC with ACS, installed new solar arrays, NICMOS cryocooling system, power control unit. • Servicing mission work increasingly involved making repairs or changes not originally contemplated. New tools & methods developed. • Equipment for servicing missions processed at Goddard & Kennedy Space Center. Training at Johnson Space Center.

10 De-Orbit HUBBLEHUBBLE MISSIONSMISSIONS SM4 Mission

SM3B

SM3A Cosmic Origins Spectrograph Wide Field Camera 3 Fine Guidance Sensor Aft Shroud Cooling System Batteries Advanced Camera Gyros Solar Arrays SM2 Power Control Unit NICMOS Cooling System Gyros Advanced Computer Fine Guidance Sensor SM1

Imaging Spectrograph Near Infrared Camera Launch! Fine Guidance Sensor

Wild Field Planetary Camera 2 COSTAR Gyros Solar Arrays

1990 1993 1997 1999 2002 2006 201011 051304_MW_HSTRoboticConcept.ppt 1 Servicing Mission 4

• Sean O’Keefe cancelled SM4 in January 2004 due to safety concerns following Columbia disaster. • Amidst public uproar, NASA examined robotic servicing for HST using MDA Dextre robot, Lockmart bus. Dropped due to time, cost. • Mike Griﬃn reinstated SM4 in October 2006 with rescue mission plan. • SM4 (STS-125) Atlantis May 11-24 2009 replaced WFPC2 with WFC3, COSTAR with COS, repaired STIS & ACS, replaced gyros, FGS, batteries. • Astronauts also attached docking ﬁxture for future deorbiting mission. • Shuttle program ended in 2011.

12 SM4 Final EVA

13 Conclusions

• Promise but no plan for HST deorbiting mission. • Extra Vehicular Activities for servicing require a huge amount of preparation, including training & preparation of tools and aids. • Interfaces are crucial – preparation of attachments requires more than engineering drawings. • The hard work that went into preparing for HST servicing missions paved the way for construction of the ISS.

14 References

• Robert W. Smith, The Space Telescope: A Study of NASA, Science, Technology and Politics. Cambridge University Press, 1993. • Kathryn D. Sullivan, Handprints on Hubble: An Astronaut’s Story of Invention. MIT Press, 2019. • Christopher Gainor, Not Yet Imagined: A Study of Hubble Space Telescope Operations. NASA, 2020 (forthcoming). • David J. Shayler & David M. Harland, The Hubble Space Telescope: From Concept to Success, & Enhancing Hubble’s Vision: Service Missions That Expanded Our View of the Universe. Springer-Praxis, 2016.