Hubble SM3A - Flight Day 4

EVA Day 1

Johnson Space Center STS-103 Report # 07 Thursday, December 23, 1999, 12:30 am EST
HST Project Update - Wednesday, December 22, 11:55 pm EST
HST Mission Update, Wednesday, December 22, 9:35 EST
HST Mission Update, Wednesday, December 22, 6:15 pm EST
Johnson Space Center STS-103 Report # 06 Wednesday, December 22, 1999, 11:30 am EST
Space Telescope Operations Control Center, December 22, 11:00 am, EST
HST Project Update - Wednesday, December 22, 8:30 am EST

Flight Day 4 Images

Today's EVA activities get an A+. The only impact on future activities is a minor rescheduling to accommodate the remaining functional tests for three (out of six) of the VIKs.

There are two coolant lines on the exterior of the NICMOS. As they come out (from the same volume) inside the instrument, each of these lines goes through a valve, and then terminates in a "quick-connect bayonet", which operates much like a screw-type garden hose connector.

These two bayonets are how the cooler will eventually be attached during the next servicing mission. NICMOS was installed with caps on these bayonets to seal the lines as well as to protect the bayonets. The valves were also closed to ensure that the volume inside the instrument is isolated from the outside. The astronauts' job was to remove both caps, and then open both valves.

The desired result is to vent (to space) the volume inside the instrument that is connected to the coolant lines. This procedure ensures that the volume and the lines will be absolutely free of water vapor or ice before installing the cooler.

There were some tense moments as the astronauts reported back that the bayonet caps did not open all the way and come off. As they proceeded with their next task, Hubble engineers analyzed the problem and requested that they retrieve a big wrench from their toolbox. Using this wrench, the astronauts successfully removed the two bayonet caps and then opened the two valves.

Johnson Space Center STS-103 Report # 07
Thursday, December 23, 1999, 12:30 a.m. EST

Discovery astronauts completed the two highest priority tasks of their Hubble Space Telescope servicing Wednesday with a space walk that was the second longest in history. Astronauts Steve Smith and John Grunsfeld installed six new gyroscopes and six Voltage/Temperature Improvement Kits in the telescope during their 8 hour, 15 minute spacewalk. Working deliberately, Smith and Grunsfeld replaced three Rate Sensor Units, each containing two gyroscopes. Four of Hubble's gyroscopes had failed, making the telescope unable to point itself precisely enough to do science since Nov. 13. At least three operable gyroscopes are needed to point the telescope with the accuracy required to track its astronomical targets.

The spacewalkers also installed Voltage/Temperature Improvement Kits on wiring from Hubble's solar arrays to each of its six batteries. The kits are designed to improve control of the charging of the space telescope's 10-year-old batteries.

With Hubble latched upright in the payload bay, Smith and Grunsfeld completed all major tasks scheduled for the first of three spacewalks on three consecutive days. A few minor objectives, including applying lubricant to the door of one of the telescope's bays and taking close-up photos of the Voltage/Temperature Improvement Kits, were left undone. Flight and telescope controllers decided to cancel the photography job and schedule the 10-minute lubrication job for Thursday's space walk. The duration of the spac ewalk was second only to the 8 hour, 29 minute space walk from Endeavour on STS-49 in May 1992.

A few minor problems helped account for the length of the space walk. One of the old gyroscope-containing Rate Sensor Units was a tight fit in the box designed to protect it on its return to Earth, though eventually it was placed inside and the lid closed. Another involved opening valves and removing caps on the Near Infrared Camera and Multi-Object Spectrometer, in preparation for restoring it to operation during the next Hubble Servicing mission. That task too eventually was completed.

All in all flight and telescope controllers were delighted with the accomplishments of the day. Major tasks on Thursday's space walk by Michael Foale and Claude Nicollier include replacement of Hubble's outmoded DF-224 computer with a more modern unit 20 times faster and with six times the memory. They also will replace one of Hubble's three fine guidance sensors, used to precisely point the telescope and gather scientific data. The astronauts also may perform "get-ahead tasks," some first scheduled for a fourth space walk. That space walk was cancelled because of delays in Discovery's launch. Discovery remains in excellent condition, in an orbit with a high point of 380 statute miles and a low point of 369 miles. The next status report will be issued at 11 a.m. CST or as events warrant.

Payload Commander Steve Smith and Mission Specialist John Grunsfeld ventured outside Discovery today to successfully complete the mission's first spacewalk. In tightly coordinated and well practiced movements, they replaced all six gyros, installed battery improvement kits and opened valves on the NICMOS science instrument.

The six new gyros appear alive and well in preliminary tests. Ground controllers will conduct more detailed testing tonight. The gyros are a critical part of Hubble's pointing control system. On November 13, 1999, the telescope ceased science operations after the fourth of its six gyroscopes failed. Since then, it has been in safehold while awaiting a visit from the astronauts.

Smith and Grunsfeld also opened valves on the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) to prepare for the next servicing mission. In 2001, astronauts will install a new cooling system on NICMOS to extend its life. The astronauts also fitted Hubble's six batteries with voltage/temperature improvement kits (VIKs) and placed protective covers on several handrails.

Tomorrow, spacewalkers Claude Nicollier and Mike Foale will install Hubble's new main computer and a Fine Guidance Sensor. On Christmas Eve, Smith and Grunsfeld will replace a transmitter, install a digital recorder and fit Hubble with new thermal skin.

In the mission's first spacewalk, astronauts Steve Smith and John Grunsfeld successfully replaced all six gyros. Preliminary tests show the new gyros are alive and well.

Ground controllers will conduct more detailed testing tonight while the astronauts sleep. Smith and Grunsfeld are now installing improvement kits to Hubble's batteries.

All systems continue to be in excellent shape and ready to support EVA 1 this afternoon. The crew is very eager to get to work. Plans are being made for starting the EVA 30 minutes to an hour ahead of schedule.

We have been taking extensive photos of Hubble's exterior condition. A few hundred electronic pictures have already been collected and are being analyzed. Preliminary reports show that the exterior condition of Hubble is not much different from when we released it in 1997.

Johnson Space Center STS-103 Status Report # 06
Wednesday, December 22, 1999 - 11:30 a.m. EST

With the Hubble Space Telescope securely latched in the payload bay, the astronauts board Discovery today will turn their attention to the primary objective of their flight -- restoring the capability of the 12.5-ton telescope to observe the universe.

Astronauts Steve Smith and John Grunsfeld are scheduled to begin the first of three planned maintenance spacewalks today at about 1:40 p.m. The crew was awakened this morning to the song "Hucklebuck" performed by Beau Jocque and the Zydeco Hi-Rollers, a tune that the spacewalkers heard many times while training hundreds of hours for the mission in the 6.5-million gallon water tank at the Johnson Space Center in Houston.

Although not scheduled to begin until 1:40 p.m., Smith and Grunsfeld could begin the planned six-hour spacewalk earlier if they complete preparations ahead of schedule. Once outside Discovery's cabin, the first task they will perform will be to replace the telescope's three Rate Sensor Units, each of which contains two gyroscopes. Of the six gyroscopes currently installed in Hubble, four have failed. At least three operable gyroscopes are needed to point the telescope with the accuracy required to track its astronomical targets.

After the rate sensor units have been installed, the two spacewalkers will then open valves on the telescope's Near Infrared Camera and Multi-Object Spectrometer to purge nitrogen coolant from that instrument in preparation for its servicing on the next Shuttle maintenance mission. Next, they will install six Voltage/Temperature Improvement Kits for the Hubble's batteries that will increase the batteries' efficiency and reduce a potential for them to overcharge and overheat. If those tasks are completed and the spacewalkers have extra time, they may perform some additional small jobs such as installing handrail covers and inspecting brackets.

While Smith and Grunsfeld are outside, inside the cabin European astronaut Jean-Francois Clervoy will control Discovery's robotic arm, maneuvering the spacewalkers into position to work on the telescope. Discovery's other spacewalking team, astronaut Mike Foale and European astronaut Claude Nicollier, also will assist from inside the cabin. Foale and Nicollier are scheduled to perform the mission's second spacewalk tomorrow. Smith and Grunsfeld are planned to again venture outside on Friday for the flight's third and final spacewalk.

Discovery remains in near-perfect condition with no mechanical problems of concern to flight controllers, as has been the case since its launch on Sunday. It is orbiting at an altitude of 380 by 365 statute miles. The next Mission Control Center status report will be issued at 10 p.m. or as events warrant.

Controllers here in the STOCC are anxiously awaiting today's first space walk, scheduled to begin less than four hours from now.

Engineers in the STOCC got their first up-close view of the Hubble in almost three years last night after a flawless capture and berthing of the Telescope by Discovery's crew.

While the crew slept, Mission controllers in Houston guided Discovery's payload bay cameras through a detailed survey of the Telescope so that engineers here in the STOCC could see Hubble's condition and compare it to the way it looked when it was last serviced in February 1997.

Engineers here in the STOCC report they were encouraged by what they saw, with little apparent change to the Telescope's condition compared to three years ago.

They were particularly pleased to see no visible signs of peeling paint over the areas of the Telescope currently visible - welcome news as flecks of peeling paint could pose a contamination risk to the Telescope's ultra-sensitive optics.

Controllers in the STOCC completed a couple of important checks following the berthing in Discovery's payload bay. The source for electrical power to the Telescope was switched from Hubble's solar arrays to the orbiter's fuel cells without a hitch, and the reconfiguration of the communications path between the ground and Hubble was accomplished with no significant problems.

Controllers report they have a good data and command path to the Telescope, critical to their ability to check out the new components installed on Hubble by the EVA astronauts.

The primary objective for today's EVA will be to install three new Rate Sensor Units, each containing a pair of gyroscopes. This will give Hubble six new gyros, needed for pointing the telescope, and enable the Telescope to resume its scientific mission to collect images of very faint galaxies, planets and stars not visible from Earth.

As soon as each Rate Sensor Unit is installed, controllers in the STOCC will perform an "aliveness test" to check the connection and ensure power is getting to the box. A complete functional test of all six gyroscopes will be performed later on today.

Another task for Discovery's EVA astronauts today will be to install Voltage/Temperature Improvement Kits, or VIKS, on each battery. The batteries provide the source for the Telescope's electrical power at night when there is no Sun. Hubble's 10-year old batteries work well, but are more susceptible to overheating than when they were brand new. The VIKs will prevent battery overcharging and associated overheating.

Before the astronauts attach the VIKs, controllers will disconnect power to the Hubble's six batteries so there is no danger of electrical shock to the astronauts. After the VIKs are installed, controllers will perform an aliveness check to test the connection, and follow that with a more comprehensive functional test of the system later on.

Ground systems here in the STOCC continue to perform well, and controllers here at Goddard are ready for today's first space walk.

National Aeronautics and Space Administration

Goddard Space Flight Center

December 22, 1999 - Flight Day 4 Activities