STS-31

Int. Designation	1990-037A
Launched	24 April 1990
Launch Site	Pad 39B, Kennedy Space Center, Florida
Landed	29 April 1990
Landing Site	Runway 22, Edwards AFB, California
Launch Vehicle	OV-103 Discovery/ET-34/SRB BI-037/SSME #1 2011
	#2 2031 #3 2107
Duration	5 days 1 hr 16 min 6 sec
Call sign	Discovery
Objective	Deployment of the Hubble Space Telescope facility

Flight Crew

SHRIVER, Loren James, 46, USAF, commander, 2nd mission Previous mission: STS-51C (1985)

BOLDEN Jr., Charles Frank, 44, USMC, pilot, 2nd mission Previous mission: STS 61-C (1986)

McCANDLESS II, Bruce, 53, USN, mission specialist 1, 2nd mission Previous mission: STS 41-B (1984)

HAWLEY, Steven Alan, 39, mission specialist 2, 3rd mission Previous missions: STS 41-D (1984); STS 61-C (1986)

SULLIVAN, Kathryn Dwyer, 39, mission specialist 3, 2nd mission Previous mission: STS 41-G (1984)

Flight Log

The launch of the Hubble Space Telescope (HST) deployment mission was originally set for 18 August, but was moved up to 12 April, then 10 April, following the Flight Readiness Review. This was the first time a Shuttle launch had been advanced following the FRR and not put back. However, the 10 April attempt was scrubbed at T — 4 minutes due to a faulty valve in APU # 1. The battery was replaced and the payload batteries on Hubble were recharged. On 24 April, the count was briefly halted at T — 31 seconds when a fuel valve line failed to shut. This was soon traced to a software failure and was overridden by engineers, allowing the count to continue.

Following a nominal ascent, most of the rest of FD 1 was spent preparing for the deployment of the telescope, which included powering up the RMS 2 hours 54 minutes into the flight. The cabin pressure was lowered in order to reduce the time the EVA crew of McCandless and Sullivan would need to pre-breathe pure oxygen should a contingency EVA be required. About 4.5 hours into the mission the umbilical power connection to the telescope was activated. The next day, the two spacewalkers got themselves partially dressed in their coolant garments, to save time should they need

The Hubble Space Telescope, still in the grasp of the RMS, is back-dropped over Cuba and the Bahamas. The solar arrays and high-gain antenna have yet to be deployed. The EVA handrails to support future Shuttle service missions are clearly visible across the main structure of the telescope

to exit the airlock in support of HST deployment. Steve Hawley lifted the telescope out of the payload bay using the RMS. Once the end effector had grasped the starboard grapple fixture of the telescope, the five latches that restrained Hubble in the bay were released.

With the telescope out of the payload bay, its solar arrays were deployed. There was some concern early in the process when they became stuck, and at one point, it looked as though the EVA crew would have to go out and assist in the unfurling of the arrays. Eventually, by disengaging the tension warning system, the arrays unfurled to their full length. Nine hours after lifting the telescope out of the bay, Hawley released it from the grip of the RMS. Discovery then completed two separation burns to move away from the telescope. Until the RMS was stowed, the EVA crew remained in the airlock in case they were required to manually retract the arm for entry and landing.

Following the release of the telescope, the crew focused on their programme of secondary and mid-deck experiments, which included monitoring particles in the payload bay, a protein crystal growth experiment, radiation-monitoring equipment, polymer membrane processing and a student experiment to determine the effects of microgravity on electrical arcs. From their 600 km altitude vantage point, the crew also recorded spectacular images of the Earth. This was the highest apogee in the programme to date, and only Gemini 10 and 11 in 1966 and the nine Apollo lunar missions had ever taken astronauts higher. The IMAX camera was flown to record mission events from outside the crew compartment and a hand-held IMAX captured images from inside the flight and mid-deck. Sequences from STS-31 footage were later used in the IMAX movie presentation The Blue Planet in IMAX theatres. On FD 4, HST controllers managed to open the aperture door of the telescope and, with the astronauts no longer required to support the telescope, the crew turned their attention to preparations for landing on FD 6. Over the coming weeks, the telescope was checked out in orbit. Unfortunately, about two months after its deployment, it became apparent that the mirror on the telescope was not focusing as designed due to a production error. It was decided that a set of corrective optics would have to be developed and then installed, during the first scheduled servicing mission in 1993. This, however, was not the fault of the astronauts or the mission of STS-31, which was a complete success.

Milestones

133rd manned space flight

65th US manned space flight

35th Shuttle mission

10th flight of OV-103 Discovery

1st use of carbon brakes at landing

1st launch set earlier than planning following FRR

Highest orbit in Shuttle programme to date (600 km)