[AS] Power and Speed: Remembering Discovery's Date With Hubble, 20 Years On

[Orionid]

Power and Speed: Remembering Discovery's Date With Hubble, 20 Years On (Part 1)
By Ben Evans, on December 22nd, 2019


Orbital sunrise causes the solar arrays of the Hubble Space Telescope (HST) to glisten in this spectacular view from STS-103. Photo Credit: NASA

Twenty years ago, as the world neared the dawn of a new millennium, the Hubble Space Telescope (HST) circled the globe in urgent need of servicing and repair. By December 1999, NASA’s $1.5 billion scientific showpiece had been in orbit for almost a full decade and had been successfully overhauled, upgraded and recovered from its blurred vision thanks to the efforts of two Space Shuttle crews; in return, it had contributed enormously to humanity’s understanding of the cosmos. A third shuttle servicing was planned for June 2000, but a dramatic spate of Hubble failures the previous year conspired to bring that date much sooner. And on STS-103, which finally flew in December 1999, shuttle astronauts would celebrate Christmas in space for the first and only time.


The STS-103 crew patch, with Hubble and the shuttle at center stage and the surnames of the seven astronauts around the border. Image Credit: NASA

STS-103 could not reach Hubble soon enough. When the four-man Extravehicular Activity (EVA) team of Steve Smith, John Grunsfeld, Mike Foale and Swiss astronaut Claude Nicollier were assigned in July 1998, they anticipated a mission with a record-breaking six spacewalks to extensively upgrade the telescope. The crew would replace Hubble’s Faint Object Camera (FOC) with the Advanced Camera for Surveys (ACS), replace a fine guidance sensor, change both solar arrays for rigid, high-efficiency models, fit a crycooler for the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) and attach six voltage/temperature kits to improve the aging spacecraft’s battery-charge capability.

As the EVA team dug into training, Hubble began to suffer its own succession of woes. Three of its six gyroscopes failed between 1997 and March 1999 and the requirement to have at least half of them fully operational for scientific activities to continue left it perilously close to suspending activity and entering safe mode. Under flight rules, NASA was obliged to consider a “call-up” shuttle mission in such an eventuality and by the middle of March the STS-103 crew had been rounded out with the assignment of Commander Curt Brown, Pilot Scott Kelly and French astronaut Jean-Francois Clervoy. The launch date had been brought forward to October 1999 and would conduct the most critical repairs during four EVAs. But it was now the shuttle itself that had other ideas.


STS-103’s John Grunsfeld prepares for an underwater EVA simulation. Making his first flight to Hubble on STS-103, Grunsfeld went on to become the only human being to visit the telescope as many as three times in orbit. Photo Credit: NASA

An electrical short during Columbia’s STS-93 liftoff in July 1999 knocked out two main engine controllers and prompted a lengthy series of wiring inspections across the fleet. Subsequent missions found themselves extensively delayed and STS-103 on shuttle Discovery was pushed firstly into November and ultimately December. Yet Discovery herself was not immune to trouble. Concerns about a stuck drill bit fragment led to the replacement of one of her main engines, which then went on to fail a series of leak checks. Compounding matters still further was the presence of suspect wiring between the External Tank (ET) and Solid Rocket Boosters (SRBs). As it became increasingly likely that STS-103 would not be off the ground until mid-December, the ongoing hype of a “Y2K” computer bug led anxious NASA managers to identify 14 December as a “drop-dead” launch date. If the shuttle had not launched by then, the flight would slip to January 2000.

In the meantime, the gremlins continued to plague Discovery in the form of frayed wiring and a crushed hydrogen conditioning line. NASA moderately extended its drop-dead launch date to 18 December, and eventually the 19th, although this meant one of the EVAs would need to be deleted and the flight duration shortened from ten to eight days.


The seven STS-103 astronauts, when fully assembled, marked the most flight-experienced shuttle crew in the program’s 30-year history. Between them, they had chalked up 18 flights when they walked to the pad on launch morning. Photo Credit: NASA

As these ground-based technical woes unfolded, Hubble itself continued to suffer. In mid-November 1999, the program’s worst fears were realized when the telescope endured a fourth failure of its aging, embrittled gyroscopes. Launch of STS-103 was still several weeks away and flight controllers accordingly put Hubble into “Zero-Gyro Sun-Point Safe Mode”, closing its aperture door, reorienting its solar arrays and rotating slowly once every hour. It was not an ideal situation as the telescope could return only engineering data and precious scientific observing time was lost. Discovery’s arrival could not come soon enough.

And 19 December really was the last-of-the-last drop-dead dates for STS-103; any further delay would push STS-103 into January. On this last-gasp occasion, the gods of technology and weather came into unison and the shuttle speared into orbit at 7:50 p.m. EST, right on the opening of a 42-minute “launch window”. With Brown on his sixth spaceflight, Foale on his fifth, Nicollier on his fourth and Smith, Clervoy and Grunsfeld all on their third, STS-103 carried the most flight-experienced shuttle crew ever launched into orbit. Only Kelly had no prior spaceflight time and he described the launch with just two words: Power and Speed. But from the pilot’s seat, he had little time to examine the enormity of what was occurring around him. When the crew went weightless, Brown had to “float” a checklist in mid-air for a delighted Kelly to realize he was finally in space.


STS-103 turns night into day at the Kennedy Space Center (KSC), launching on 19 December 1999, bound for the Hubble Space Telescope (HST). Photo Credit: NASA

Two days later, at 7:34 p.m. EST on 21 December, Brown and Kelly maneuvered their ship to within range of Hubble and Clervoy grappled the telescope with the 50-foot-long (15-meter) Remote Manipulator System (RMS) robotic arm. The capture occurred a few minutes ahead of schedule and was lauded by Mission Control, who told the astronauts that both shuttle and telescope had been seen by ground-based observers in Houston, a little dimmer than Jupiter and just brighter than Saturn.

Over the next week, as Christmas came to Earth and space, there was much work to do.

Source: https://www.americaspace.com/2019/12/22/power-and-speed-remembering-discoverys-date-with-hubble-20-years-on-part-1/

[Orionid]

Picture of Santa: Remembering Discovery's Date With Hubble, 20 Years On (Part 2)
By Ben Evans, on December 30th, 2019


The STS-103 astronauts were the only Space Shuttle crew to celebrate Christmas in orbit, way back in 1999. Photo Credit: NASA

Twenty years ago, seven astronauts spent Christmas Day in space, peering from the windows of shuttle Discovery. STS-103 in December 1999 marked the only occasion in the shuttle program’s three decades of service that a mission took place entirely over the festive period. As outlined in last weekend’s AmericaSpace history article, a yuletide flight in the final days before the new millennium was not the original plan, but technical woes with the shuttle fleet and with the Hubble Space Telescope (HST)—Discovery’s primary objective—during the course of 1999 had pushed STS-103 into high priority.

The long-serving scientific showpiece had begun to falter in March 1999, when the third of its six gyroscopes failed, putting it at the barebones minimum capacity necessary to achieve astronomical pointing. A shuttle servicing mission was already planned for June 2000, but NASA decided to bring the STS-103 launch date forward to October 1999 to tend to the most urgent repairs. But another shuttle launch in July of that year suffered a short circuit soon after liftoff, which knocked out two main engine controllers and almost forced an emergency landing. The fleet was grounded for extensive wiring inspections and after several additional technical challenges Discovery finally set off on 19 December.

By this time, and with much hype over the “Y2K” computer bug, STS-103 had been shortened from ten to eight days and the number of scheduled Extravehicular Activities (EVAs) had been cut from four to three, to ensure that the shuttle was back on the ground before clocks turned over to the new millennium. Two days into the flight, Commander Curt Brown and Pilot Scott Kelly maneuvered their ship close to the school-bus-sized Hubble and French astronaut Jean-Francois Clervoy deftly grappled the telescope with the 50-foot-long (15-meter) Remote Manipulator System (RMS) robotic arm.


Mike Foale prepares to close the airlock hatch behind Steve Smith and John Grunsfeld, before one of STS-103’s EVAs. Photo Credit: NASA

It was then the task of STS-103’s four spacewalkers—Steve Smith, John Grunsfeld, Mike Foale and Swiss astronaut Claude Nicollier—to kick off the three EVAs. On 22 December, Smith and Grunsfeld spent eight hours and 15 minutes outside, performing the second-longest spacewalk in shuttle history at that time. The duo replaced all six aging gyroscopes and installed battery voltage regulator kits to keep Hubble’s batteries properly conditioned. They then opened a pair of valves to vent residual nitrogen from the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS), which had suffered a thermal short and been out of action since January 1999 due to dwindling coolant supplies. A new gaseous neon cooling system was set to installed by another shuttle crew to bring NICMOS back to life.

When an exhausted Smith and Grunsfeld returned inside Discovery, there was jubilation, for replacing the six gyroscopes constituted the completion of 80 percent of STS-103’s most critical tasks.


Astronauts Michael Foale and Claude Nicollier perform an EVA during the STS-103 mission, Hubble Servicing Mission 3A. Photo Credit: NASA

Next day, Foale and Nicollier were outside for eight hours and ten minutes, the major focus of which was installing a new computer with radiation-hardened Intel 486 processor into the telescope. This would replace Hubble’s vintage 1970s-era technology. The chair-sized computer was 20 times faster and carried six times greater memory than its predecessor, whilst running on only a third of the electrical power.

However, it was a tricky task, requiring Foale to feel around for hard-to-see connectors on the left side of the computer box. He also had to take great care not to hit connectors on a nearby data-management unit. Nicollier provided visual cues for Foale and in relatively short order the new computer was installed. “Most excellent,” radioed Grunsfeld from Discovery’s cabin. “Hubble’s brains have been replaced.” The spacewalkers then installed a fine guidance sensor, which had been plucked out of Hubble on the previous servicing mission in 1997 and returned to Earth for refurbishment. After some trouble aligning it properly, the sensor was fitted and ready for a rejuvenated second life in orbit.


Spectacular view of the top of the Hubble Space Telescope, the limb of Earth and a full Moon, as captured by one of the STS-103 astronauts. Photo Credit: NASA

Next day, Smith and Grunsfeld ventured outside for the first U.S. spacewalk ever performed on Christmas Eve. For the next eight hours and eight minutes, they labored to replace an engineering science tape recorder with a new solid-state recorder and a new S-band Single Access Transmitter to replace a similar unit which had failed. The transmitter assisted with data transfer through NASA’s Tracking and Data Relay Satellite (TDRS) network and was never intended for orbital replacement, requiring the spacewalkers to handle many fiddly screws and cable connectors. This put them rapidly behind schedule and Grunsfeld likened the problem to fixing a watch whilst wearing winter gloves. When they finally declared success and returned inside Discovery, STS-103’s EVA tally ran to over 24 hours of spacewalking over three days.

Nor was the work of the astronauts inside the shuttle any less taxing. Clervoy was required to operate the RMS arm for many hours of concentrated focus, backed up by either Grunsfeld or Nicollier. The crew deployed Hubble perfectly back into space as Christmas arrived and the only shuttle crew ever to spend the festive day in space tucked into a dinner of duck liver and other delicacies from southwest France, provided by Clervoy. Later that afternoon, NASA Administrator Dan Goldin congratulated the astronauts on their accomplishments and Brown expressed fervent hope that, just as Hubble had done, humanity would continue to search “for a deeper understanding of life and for greater wisdom”.

Discovery returned smoothly to Earth on 27 December, wrapping up almost eight days in space. Standing on the runway, there was time for a few philosophical words. Foale stressed that at the dawn of the 20th century even powered flight remained a dream, much less the fallacy of leaving the planet and traveling into space. And for Kelly, who closed out his first spaceflight on STS-103, a strong family thread ran through the mission. Before launch, he had struggled to explain to his young daughter that he could not be with her on Christmas morning. But Kelly did have one promise for her. He would, he pledged, turn Hubble towards the North Pole and snap a picture of Santa, just for her.

Source: https://www.americaspace.com/2019/12/30/picture-of-santa-remembering-discoverys-date-with-hubble-20-years-on-part-2/