National Aeronautics and Space Administration

STOCC update - Saturday, December 24

Shuttle astronauts yesterday completed installing a new, more powerful computer with advanced software in the Telescope and Hubble's controllers here in the STOCC are continuing their checkout of the new computer. So far those checks are going very well. Engineers are delighted with its performance.

Prior to changing out Hubble's main computer, software engineers here in the STOCC collected telemetry using the old computer, and since the computer changeout have been comparing it to the new telemetry. They are pouring over that information looking for any discrepancies and so far have found none. Software engineers have also been checking the new software in the new computer for any bugs and everything is bug-free.

A refurbished Fine Guidance Sensor was also replaced during yesterday's space walk, and controllers report that tests performed on the new sensor have gone very well. The three guidance sensors are used to provide extremely precise pointing for the Telescope. The guidance unit that Discovery will bring home will be refurbished and installed on the fourth servicing mission.

Controllers have successfully completed testing of the six Voltage/Temperature Improvement Kits, or VIKS, that the astronauts installed Wednesday on each battery.

The STOCC here at Goddard is now preparing for today's third and final space walk.

Astronauts will replace a reel-to-reel tape recorder on Hubble with a new solid state recorder. The new recorder can hold about 10 times more data that the old recorder, and because it is digital, it has no moving parts to wear out and limit its lifetime. STOCC controllers will test both the new and the old solid state recorders by turning them on and playing back to the ground simulated science data.

The crew also will install an S-Band single access transmitter, replacing one that failed in 1998. Hubble has two of these transmitters, used to send data from the Hubble to the ground.

Fine Guidance Sensor specialists are in the STOCC today to monitor the crew's mating of the Optical Control Electronics to the newly-installed fine guidance sensor. The OCE is part of a very specialized electronics package that enables engineers here in the STOCC to send commands to an articulating mirror in the Fine Guidance sensor. The ability to position this mirror just right substantially increases the performance of the Fine Guidance System. Two Fine Guidance Sensors are used to point the Telescope at an astronomical target. The guidance system gives Hubble the ability to remain pointed at a target with a level of stability and precision equivalent to being in New York City, and seeing the motion of a landing light on an aircraft flying over San Francisco.

Controllers in the STOCC have been treated to more television views of the Hubble to gather more information about the condition of the 10-year old Observatory. Engineers at this point have been pleased with the condition of the Telescope. The extensive television and photo surveys taken by the astronauts and JSC mission control will be compared to similar images collected of the Hubble during the second servicing mission to more fully assess how Hubble is faring under the blistering hot and bone-chilling cold temperatures of outer space.

Controllers to date have up-linked several thousand commands to the Hubble, and have encountered very few problems. Ground systems here in the STOCC continue to perform very well, and controllers here at Goddard are ready for today's space walk.

Hubble Space Telescope Project Report
Saturday, December 25, 1999 - 12 a.m. EST

"A very nice Christmas present!" is how Dr. John Campbell, Hubble Space Telescope Program Manager, summed up the day's events. A short time earlier, NASA announced that the STS-103 mission had met all criteria for complete success.

On Christmas Eve, Discovery astronauts Steve Smith and John Grunsfeld completed the mission's third and final space walk. They replaced a radio transmitter and installed a new digital data recorder. The space walkers also added an enhancement kit for Hubble's optical control electronics and installed new insulation on two equipment bay doors. Preliminary tests showed the new equipment functioning normally.

On two previous space walks, astronauts completed the mission's highest priority tasks. This included installing six new gyroscopes and six battery improvement kits, giving Hubble a new, faster computer and replacing one of Hubble's three Fine Guidance Sensors. "What more could you ask for?" said Dr. Campbell. "We're ready to get back to work now!"

On Christmas Day, the crew will release Hubble back into orbit just before 6 p.m. EST.

Johnson Space Center, STS-103, Mission Control Center Status
Status Report # 11
Saturday, December 25, 1999 - 12 a.m. EST

Discovery astronauts completed their third and final space walk Friday evening, replacing a failed radio transmitter and installing a new solid state recorder. After the successful completion of those tasks, Lead Flight Director Linda Ham announced Friday evening that the STS-103 mission had met all criteria for complete success. Discovery astronauts are scheduled to release Hubble a little before 5 p.m. CST on Christmas Day.

Astronauts Steve Smith and John Grunsfeld on Friday installed a transmitter that sends scientific data from Hubble to the ground. The transmitter replaced one that failed in 1998. A second transmitter had successfully carried the load without any disruption to Hubble scientific operations. Since the transmitters are considered very reliable, they were not designed to be replaced in orbit and special tools were developed to make the job easier.

Smith and Grunsfeld also installed a solid state digital recorder, replacing an older mechanical reel-to-reel recorder version. The digital Solid State Recorder provides more than 10 times the storage capacity of the old unit. They also applied new insulation on two equipment bay doors.

Both the transmitter and the recorder checked out normally on early tests by telescope controllers.

Two previous space walks on Wednesday and Thursday had completed the highest priority tasks of the mission. Those tasks included installation of six new gyroscopes and six Voltage/Temperature Improvement Kits, giving Hubble a new computer 20 times faster and with six times the memory of the old computer, and replacement of one of Hubble’s three Fine Guidance Sensors.

Friday's space walk lasted 8 hours and 8 minutes, ending at 9:25 p.m., making it the fourth longest in history. Part of the reason for the length of the space walk was difficulty in hooking Grunsfeld’s suit up to orbiter power after he had returned to Discovery’s airlock. Friday's space walk brings the total time of STS-103 extravehicular activity to 24 hours, 33 minutes. This mission's three space walks bring the total amount of time spent servicing Hubble to 93 hours, 13 minutes. Space Shuttle Program space walks now total 317 hours, 3 minutes. And Steve Smith now is the astronaut with the second longest combined space walk time, with 35 hours, 33 minutes behind only Jerry Ross, with 44 hours, 11 minutes.

Discovery is in an orbit with a high point of 380 miles and a low point of 363 miles. All of the orbiter’s systems continued to function normally. The next status report will be issued at 11 a.m. Saturday or when events warrant.

HST Project Update, December 24, 4:20 pm EST

Payload Commander Steve Smith and Mission Specialist John Grunsfeld left Discovery at 2:17 p.m. EST to begin the mission's third and final scheduled space walk. After installing a a new optical control electronics unit and radio transmitter, they will add a digital data recorder and apply new insulation to several bay doors.

For identification, Smith is wearing a solid red stripe on each leg of his suit, while Grunsfeld's suit has no markings. This team performed the first space walk of the mission on December 22, but worked inside Discovery yesterday while Claude Nicollier and Mike Foale ventured out. Smith and Grunsfeld expect to wrap up their space walk just before 10:00 p.m. EST before settling in for Christmas Eve in orbit.

Johnson Space Center, STS-103, Mission Control Center Status Report # 10, Friday, December 24, 11 am EST

The Hubble Space Telescope is scheduled to receive its final upgrades today as astronauts Steve Smith and John Grunsfeld perform the last of three planned space walks to refurbish the orbiting observatory.

Today’s planned 7 ½ hour-long space walk will see Smith and Grunsfeld install a transmitter that relays Hubble’s scientific data from the telescope to the ground and an upgraded digital recorder replacing an older mechanical version.

The transmitter to be installed today replaces one that failed in 1998. Since that time, the second on-board transmitter has successfully carried the load without any disruption to Hubble operations. The transmitters are considered very reliable, and unlike most of the equipment aboard Hubble, were not designed to be changed out in orbit. Special tools were developed to enable astronauts to do the job more easily.

The digital Solid State Recorder being installed on the telescope will replace an older mechanical model and provide more than 10 times the storage capacity. Smith and Grunsfeld also will apply some new insulation on equipment bay doors to minimize any degradation of the telescope’s protective thermal coverings.

The space walk currently is scheduled to being at 1:20 p.m. Central Time and is expected to last about 7 ½ hours.

Mission Control awakened the crew at 8:50 a.m. today to the sounds of Steppenwolf’s “Magic Carpet Ride” played for Smith and the children’s song “Skinnamarink” by Kimbo for Grunsfeld. Discovery remains in excellent condition, in an orbit with a high point of 380 statute miles and a low point of 364 miles.

HST Project Update - Friday, December 24, 8:00 am EST

Planning is complete and all systems are ready to support EVA day 3 activities.

Overnight functional testing confirms that the Fine Guidance Sensor installed yesterday works as intended. Thus, all of the planned work for the first two spacewalks is completed, and all the installed hardware is confirmed to be working.

Photographic surveys revealed some unexpected features in the Solar Arrays (SAs). The Hubble has two identical SAs, one on each side of the spacecraft. Each SA is made up of 10 Solar Array Panel Assemblies (SPAs). These SPAs are held to each other by piano hinges with a long hinge pin that is the width of the SA (about 8 feet wide). The new photographs show that some of the hinge pins have migrated out of their intended positions, and are sticking out the sides of the SAs. Six pins show this effect, ranging from very small to about 10 inches in length.

Investigation of previous photographs show that this effect was present during the past Servicing Mission in 1997, but it was much smaller and went unnoticed. The pins are very small diameter, and are difficult to see in the images. Some of the pins appear to have reversed direction compared to their SM2 positions.

Analysis confirms that the pins could migrate in an "inch worm" fashion from the thermal excursions during Hubble's day/night transitions (up to a 200F temperature change). Tests on a SA on the ground show that even if the hinge pin were removed, the SA structure would remain intact from the wiring and other material.

Based on these results, the Project has decided not to attempt any improvised (and risky) fixes to this problem.

Once again, our astronaut team is eager to get to work. We anticipate another early start for EVA 3.