Astro1 Comes Alive

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Activation of the observatory began almost immediately after the pilots had established Columbia in her 300-km orbit; the Red Team - consisting of astronomers Parker and Parise and led by Gardner - took charge of activating the telescopes and their support equipment. Meanwhile, the Blue Team of astronomers Hoffman and Durrance and shift leader Lounge bedded down for a shorter-than-usual sleep period. They would awaken for their first 12-hour work shift at 6:00 pm on 2 December. Although not specifically assigned to either shift, as Commander of the mission, Brand's schedule was more flexible and he coordinated both teams.

ASTRO-1 marked the first use of the new Spacelab Mission Operations Control Facility at NASA's Marshall Space Flight Center; this was heralded at 10:56 am on 2 December when Parker opened his space-to-ground communications lines with the words, ''Huntsville, this is ASTRO''. He was quickly answered by Michelle Snyder, the crew interface coordinator at Marshall, who radioed, ''Bob, we just want to let you guys know that everyone here [at] Huntsville is really excited and we're looking forward to a great ten-day mission and a lot of terrific astronomy. And we've got a lot of smiles.''

''Michelle, this is Ron,'' Parise then called. ''We know there's a lot of people down there that did a lot of work on this mission, and we're hoping to make it a real success for everybody. So let's get this show on the road.''

By this time, the Red Team had turned on the BBXRT and at 12:36 pm, Parker received a go-ahead to unlatch and raise the IPS and ASTRO-1 telescopes from their horizontal position in the payload bay. This was completed within just seven minutes and by the time STS-35 was 16 hours old and the Blue Team had taken charge of the flight deck, the ASTRO-1 telescopes had finished their initial checks and were ready to begin calibratory observations. ''That is a real star, folks,'' Durrance radioed as he performed the first stellar observation of the star Beta Doradus using the HUT.

This particular star, in the constellation Dorado (the Swordfish), was chosen because of its suitability when aligning and focusing the telescopes. The sighting was part of the so-called 'joint focus and alignment' process, a lengthy procedure in which the three ultraviolet telescopes were focused on a common target as a prelude to upcoming observations. Unfortunately, a computer failure in the WUPPE prevented it from participating in this alignment. Ground-based engineers diagnosed the problem as having been caused by an unactivated heater and, when this was switched on early on 3 December, the telescope's checkout could get underway.

Overall, however, ASTRO-1 operations were running smoothly. Typically, the 'duty' Mission and Payload Specialists, stationed on Columbia's aft flight deck, used two Spacelab keyboards and two Data Display Units (DDUs) to command the IPS and the telescopes. Closed-circuit television monitors then provided the astronauts with images of the starfields being observed by the HUT and the WUPPE and allowed them to check their data. Meanwhile, the shift leader - Gardner for the Reds and Lounge for the Blues - was responsible for firing the RCS thrusters to orient Columbia properly. Observations took between 10 minutes and a full hour to complete.

Mike Lounge records data during his shift in charge of Columbia's flight deck.

More problems, of potentially greater severity, were afoot, when the IPS experienced difficulties 'locking-on' to guide stars. An alternative plan was worked out to help the astronauts to manually point the telescopes and track targets on the HUT's television camera using a 'hand paddle'. This allowed them to aim the telescopes with an accuracy of within three arc-seconds. ''The mood is one of concern,'' said Flight Director Bob Castle. ''We'd certainly like the system to work perfectly, but there is no panic. People are working to solve the problem and we have confidence we will solve [it] in a fairly short time.''

Worse, though, was to come. Late on the afternoon of 2 December, while working on Columbia's flight deck, Brand picked up the scent of warm electrical insulation; it turned out that one of the two DDUs had overheated. It was bad news because these units enabled the crew to point the IPS and also the ASTRO-1 telescopes. By 3 December, Castle was telling journalists that the IPS problems and the resultant work-around had thrown ASTRO-1's observation timetable at least six to eight hours behind schedule.

By midday on the 4th, when observations resumed, Flight Director Al Pennington described the outlook as brighter, although two dozen celestial targets scheduled for that day had been lost. ''What we have to do,'' said Mission Scientist Ted Gull, ''is make sure we reallocate what is left to the higher-priority objects that have been lost.'' By the day's end, the pace had picked up - with ASTRO-1 scrutinising the bright galaxy NGC 4151, thought to contain a massive black hole at its centre, and

ASTRO-1 comes alive 131

the BBXRT acquiring spectra of the Crab Nebula - but the crew was still well behind schedule.

With its computer woes finally rectified, WUPPE came on-line around 10:30 pm on 4 December and was directed to observe a 'variable binary system' of two stars called HR-1099 and HD-22468; these consist of a pair of close-by stars, one of which 'stirs up' the other and causes massive blobs of material to spiral away from it. Next it was used to study a rapidly rotating star known as 21 Velpecula. The telescopes, however, were still being handled with kid gloves. ''We're still learning to use the observatory,'' said Gull. ''It's taking longer to make the observations that we'd like.''

As the telescopes found their feet, efforts were underway to obtain full capabilities from the IPS's Optical Sensor Package (OSP), whose star trackers provided one means of locking onto celestial objects. Thanks to support from Houston and Huntsville, successive refinements were made to its pointing geometry. These proved successful on 4 December, when Durrance accomplished the first operational identification of a desired celestial target: a white dwarf star. ''Intensive efforts continue in trying to get good optical holds with the [IPS] to obtain the desired science targets that we have selected,'' said ASTRO-1's Assistant Mission Manager Stu Clifton.

On the whole, the mission seemed to have recovered from its IPS problems and the DDU failure and at a press briefing on the afternoon of 4 December, Mission Manager Jack Jones told journalists that ''we have a good healthy payload. All the instruments are up and working and all the pointing systems appear to be pointing nominally at this time. Eliminating any unforeseen events, I think we're off and ready to go. There may be some minor refinements, but I believe we're in the mode to start getting science.''

Gull agreed. ''We have an observatory that's really coming alive,'' he said early on 5 December. ''I can smile now!'' After exhaustive troubleshooting by members of the ASTRO-1 ground team, a stream of successively more refined calibrations of the star-tracker optics had been sent up to Columbia. This now enabled the observatory to perform, at last, automatic acquisitions of celestial targets. Already, late on 4 December, Hoffman and Durrance had demonstrated the observatory's new capabilities by acquiring one target, followed immediately by another, with no need for recalibration of the instruments between each sighting.

The pointing stability continued to be lower than expected, because control of the Spacelab pallets, the IPS and the telescopes were being conducted from the only-remaining DDU on the aft flight deck. It was hoped that both situations should improve, leading to an increase in the quality of ultraviolet data, but such hopes seemed to be dashed at 12:15 pm on 6 December when the second DDU overheated and failed. Initial efforts to restart it were unsuccessful and Mission Control asked the crew to remove its lower panel, look at the internal components and check the air-intake filters for lint.

''No joy,'' Hoffman radioed dejectedly, after vacuuming a small amount of lint from the vents which cooled the DDU. At the time of the failure, ASTRO-1 had completed 70 of its scheduled 250 celestial observations; it was a success thus far, but a devastating blow for the remainder of the mission. ''I'm not sure whether to smile from ear-to-ear or cry,'' admitted the HUT's Assistant Project Scientist William Blair.

Parker would recall years later that the prognosis for Columbia's crew was grim. ''Suddenly, we couldn't point [the telescopes]. The ground came up with a scheme where they could control the telescopes. It was not part of the plans, but unlike the Apollo Telescope Mount [on Skylab] they could push a little 'go' button on the ground as well as the crew can push it up there, so they basically controlled the instruments. What they couldn't do in near-real-time was guide the telescopes. I was used to sitting there for hours, guiding a star on a cross-hair. We really had insisted all along that 'we need to be sure we have that capability, because if all else fails, we need to be able to do that'. We observed maybe a third of what we had intended to. Everybody put a good face on it, but it was a far cry from what it was supposed to be.'' In fact, for several hours on 6 December, after the second DDU failure, Durrance was left with nothing to do. ''We're just sitting here enjoying the view,'' he told Mission Control.

Yet, still, the remarkable ground team managed to bounce back from the computer failures and by 7 December were able to command all but the final movements of the telescopes. It was then left to the astronauts to fine-tune them for each observation run. ''We've had a lot of setbacks, but success is at hand,'' said Art Davidsen. Ted Gull, after watching his colleagues practising commanding the telescopes during simulations, agreed and thought the successful acquisition of celestial targets should be possible with JSC controlling the IPS and Marshall the instruments.

He added, however, that ''it is going to be a close teamwork effort. Instead of one Mission Specialist and one Payload Specialist on the flight deck, there are going to be a lot of people on the loop, each having to do something in sequence to get the task accomplished.'' The revised procedures took the form of operating the ASTRO-1 telescopes sequentially - first the UIT, with the largest field-of-view, then the HUT and lastly the WUPPE - and even affected the BBXRT which, although mounted on a separate pointing system, was still compromised because it had to cease operations whenever Columbia entered a 'safe' attitude.

''Looks great!'' radioed backup Payload Specialist Ken Nordsieck just after 11:00 pm on 6 December, as he guided Durrance to acquire the long-awaited Supernova 1987A with the UIT. As the astronaut on board Columbia controlled the telescope manually with a joystick, Nordsieck provided him with second-by-second pointing instructions. A total of six minutes of high-quality ultraviolet spectra were collected. More was to come and by the following evening - after ASTRO-1 had successfully observed a radio-quiet, extremely luminous quasar called Q1821 + 643 - Stu Clifton would be describing the day's observations as the proudest achievement of the mission so far.

''Following the loss of the [DDUs], ASTRO-1 has recovered substantially in less than 22 hours,'' Clifton told journalists. ''All experiments are recording excellent data.'' By this time, the astronauts had established and were efficiently executing a smooth working pattern with their counterparts on the ground to maximise their observation time. Typical clipped exchanges between Nordsieck and Durrance on

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