STS-51L – The ultimate field trip

by Chris Bergin

“Now don’t break our airplane!” Judy Resnik joked.

Hank Hartsfield promised not to. It was October 1985 when the two astronauts shared their moment of camaraderie.

Three months later, the seasoned Shuttle flier would recall Resnik’s light-hearted advice with sorrow; for it was on her flight, rather than his, that the ‘airplane’ – Space Shuttle Challenger – finally broke.
Hartsfield had just returned from a week-long Spacelab mission, sponsored by West Germany, aboard Challenger and immediately flew to Europe for his crew’s public relations tour. He was still there when Resnik and the next Challenger crew blasted-off.

The pair had good reason for their closeness: not only did they share the same career, but they had flown together on the maiden voyage of Space Shuttle Discovery barely a year earlier. “You sort of become family,” Hartsfield remembered two decades later. “We worked together for 13 months, partied together and you do get close”. Whilst in Europe, he had followed with interest his former crewmate’s seemingly fruitless efforts to return to space in January 1986.

Right from the start, launching Challenger’s tenth mission was an exercise in frustration.

It was, however, a frustration that NASA could not afford. The planned six-day flight, designated STS-51L, would feature the first private citizen – a social studies teacher from New Hampshire named Christa McAuliffe – to fly aboard the Shuttle. Selected from over 11,000 applicants, she would teach two lessons from space, providing a much-needed public relations boon for the agency as it sought to demonstrate that its reusable fleet of orbiters were truly the spacegoing equivalents of commercial airliners.

Indeed, years later, McAuliffe’s mother, Grace Corrigan, would insist that the general atmosphere in the weeks leading up to Challenger’s fateful launch was that the Shuttle was actually safer than an airliner, simply due to the higher level of precautions taken by NASA. Even McAuliffe herself, before launch, had expressed light-hearted confidence that her only ‘fear’ was a failure of the orbiter’s multi-million-dollar toilet.

When the 51L crew arrived at the Kennedy Space Center in Florida, their launch was routinely postponed by delays in bringing Challenger’s sister ship Columbia home from her own flight and weather concerns at a Transoceanic Abort Landing site in Senegal. More trouble was afoot. Unacceptable weather in Florida put paid to another attempt and, when Commander Dick Scobee and his six crewmates settled into their seats aboard Challenger on January 27th, they were again thwarted by high winds and a frozen handle on their ship’s hatch. By the following morning, temperatures had plummeted to a few degrees above zero Celsius, producing the coldest conditions under which a Shuttle launch had ever been attempted. Copious amounts of ice on the pad then forced an additional two-hour delay to allow the rising sun to thaw it.

Nonetheless, many of the astronauts’ families, including Scobee’s wife, June, doubted that NASA would conceivably fly under such conditions. She was partially appeased by her husband’s insistence, over the phone that morning, that he felt it was safe to do so. Hank Hartsfield, good-naturedly, had called the 51L crew on a regular basis to jokingly ask what the hell they were up to. Would they ever launch?

Tragically, as we now know, Resnik and her colleagues – Scobee, McAuliffe, Mike Smith, Ellison Onizuka, Ron McNair and Greg Jarvis – would indeed launch that cold Tuesday, with catastrophic consequences. Almost two decades later, the world is familiar with the technical and human causes of Challenger’s destruction, but precious little has been written of what the 51L astronauts would have actually done whilst in orbit. The mission, it seemed, provided a little bit of everything: two satellite deployments, one retrieval, a range of experiments in the Shuttle’s middeck and a comprehensive survey of Halley’s Comet.

The fabled celestial wanderer, which only frequents the inner Solar System every three-quarters of a century, was the focus of not only Challenger’s mission, but also two others in January and March 1986. Two weeks before 51L lifted-off, Columbia’s crew had been unable to examine it in depth, due to problems with their Comet Halley Active Monitoring Program (CHAMP) cameras. In March, another Columbia team would have used a battery of ultraviolet telescopes and a wide-field camera to analyse the comet. Meanwhile, 51L would have employed CHAMP and deployed a free-flying satellite to explore Halley’s tail and the gaseous ‘coma’ around its peanut-shaped head.

Onizuka, a Hawaiian-born astronaut of Japanese and American parentage, was responsible for the CHAMP hardware and would have buried himself on January 29th under a black shroud on Challenger’s aft flight deck to ensure maximum darkness for his observations. “I will have about two minutes on four different orbits to photograph Halley’s Comet in both the visible and ultraviolet spectrum,” he told an interviewer. “The objective is to try to get this data as the comet approaches perihelion, which is just as it goes around behind the Sun and starts to head back out. It’s a regime where we do not have any data at the present time, so I’ve also been told we’ll probably be the only human beings to see it at that time”.

As Onizuka worked, his crewmates would have been involved in preparing the Shuttle-Pointed Autonomous Research Tool for Astronomy – a mouthful that NASA’s finest acronym-makers had somehow carved into the name ‘Spartan’ – for deployment on January 30th to begin its own series of Halley observations. Built by the agency’s Goddard Space Flight Center of Greenbelt, Maryland, the small, boxy satellite had previously flown in the summer of 1985 and was designed to be serviceable and capable of returning to orbit every six to nine months.

On 51L, it would use a pair of ultraviolet spectrometers and two modified Nikon F-3 cameras to study the composition of the comet’s dirty-snowball-like nucleus and million-kilometre-long shimmering tail. McNair, with Resnik, was responsible for deploying and later retrieving Spartan with Challenger’s Canadian-built robot arm. “Comets,” he said before the mission, “happen to be one of the remnants of the creation of the [Solar System] and it’s just a big mass of ice – of frozen gases – and the last time it came around, we weren’t sophisticated enough to do the type of things that we’re doing now.

“Scientists will be able to analyse the gases, analyse the emissions by looking at the Sun’s reflection and the absorption of sunlight and give some credibility to some of the theories, or possibly tear them down, about the origin of the Universe. Who knows what we’re going to find out of this? But these types of observations can change the way you think”. Several other missions, besides Spartan, were also watching Halley at the time: Europe’s Giotto, the Soviet Union’s Vega and Japan’s Suisei and Sakigake probes were heading for the comet, but NASA believed its Shuttle-based studies had the ‘edge’ by observing it as it neared ‘perihelion’, at its closest point to the Sun.

It was during a narrow, five-week ‘window’ from January 20th to February 22nd that the agency hoped Halley – then some 225 million kilometres from Earth and only 97 million kilometres from the Sun – would be chemically at its most active and yield the most desirable scientific data. The Spartan mission to explore the comet, codenamed ‘203’, would have got underway on the second day of the 51L mission, when Scobee and Smith were scheduled to fire Challenger’s Orbital Manoeuvring System (OMS) engines to nudge them to a slightly higher altitude, about 245 km above Earth.

The assignment of Spartan had already resulted in some changes to the Shuttle’s own launch period; originally targeted for a morning liftoff, the 51L window was moved to the afternoon, in order to provide the best lighting conditions for the satellite’s observations of the comet. However, an afternoon start to the mission would delete the option of touching down in Casablanca in the event a Transoceanic Abort Landing became necessary. Ultimately, as Challenger’s launch was delayed into the final week of January, conditions for optimum viewing of Halley based on an afternoon window could no longer be met and the liftoff time was shifted back to the morning hours.

By January 30th, after the satellite’s software had been satisfactorily uploaded from NASA’s Johnson Space Center in Houston, Texas, and voltage and current checks carried out, it would have been ‘hung’ over the payload bay wall and released into free flight by the robot arm. Spartan would then have executed a slow, minute-and-a-half-long pirouette to prove that it was working properly, after which Scobee would have pulsed the Shuttle’s small Reaction Control System (RCS) thrusters to achieve a maximum separation distance of about 145 km. This would have ensured that sunlight reflected by Challenger’s pristine white surfaces did not ‘confuse’ Spartan’s sensors.

Following two orbits of further tests, the aperture doors covering the satellite’s two ultraviolet spectrometers would have automatically retracted to kick off an aggressive, 40-hour-long phase of free flight, of which more than half would be devoted to studies of the photodissociation of water in the comet and analysis of its various nitrogen-, carbon- and sulphur-containing molecules. Meanwhile, its cameras would have provided an ongoing record of the ‘large-scale’ activity of Halley itself, including nuclear outbursts and asymmetries in its coma. Retrieval of Spartan would have followed on February 1st and the satellite replaced in the payload bay.

Had Onizuka and his crewmates survived their violent climb to orbit on January 28th, however, the delicate and tricky Spartan deployment, two days of station-keeping and retrieval would have actually been the secondary task of their mission. By far the largest, most expensive and most powerful payload aboard Challenger was NASA’s second $100 million Tracking and Data Relay Satellite – known as ‘TDRS-B’ – which, it was expected, would ultimately enable future Shuttle astronauts to communicate directly with Mission Control for up to 85% of each 90-minute circuit of the globe.

“That’s going to be a big improvement,” Smith told an interviewer in the weeks leading up to the 51L launch, “not only for the Shuttle, but also for the space station when it gets up later on”. Until the early 1980s, American missions had relied on a network of ground stations to relay communications between orbiting crews and Houston-based controllers. The TDRS network of at least two large communications satellites, positioned in ‘geosynchronous’ orbits 35,680 km high, would gradually bring this era to a close.

Onizuka was simply thrilled at having the chance to help deploy “one of the largest communications satellites…ever!” His words were, to say the very least, an understatement. The 2,540 kg TDRS-B would, when fully functional in its operational orbital ‘slot’, resemble a colossal windmill with four ‘paddles’ extending from beryllium booms affixed to a hexagonal ‘bus’. Two of those paddles held electricity-generating solar panels, while the others carried umbrella-shaped S-band and Ku-band antennas. Between the tips of its solar panels, TDRS-B would have spanned an impressive 12 metres when fully unfurled in orbit.

However, in spite of its size and appearance, it would have neither processed or altered communications: instead, it was designed to serve as a space-based ‘switchboard’, receiving transmissions from ground stations, amplifying them and retransmitting them on another frequency to another satellite, and vice versa. When operational, in addition to acting as a communications relay for Shuttle crews, TDRS-B would have handled traffic from several important scientific missions, most notably the Hubble Space Telescope, Gamma Ray Observatory and Upper Atmosphere Research Satellite.

In order to achieve its high orbit, it was attached to a Boeing-built Inertial Upper Stage (IUS). This two-part, solid-fuelled booster would have delivered the satellite, over a period of about seven hours, into its operational position. Deployment of the 14-metre-long combo would have consumed the majority of Challenger’s first day in space and, although all seven crew members would have been involved, the lengthy procedure would have been conducted under the auspices of Onizuka and McNair.

Shortly after reaching orbit and opening the payload bay doors – thus exposing the folded-up satellite and its booster to the space environment for the first time – the two men, located at control panels on the aft flight deck, would have run through a series of checks and eventually hoisted the ‘stack’ to a pre-deployment angle of 29 degrees using a doughnut-shaped ‘tilt table’. As Scobee and Smith manoeuvred Challenger into her deployment attitude, Onizuka and McNair would have switched TDRS-B over from the Shuttle’s electricity supply to the IUS’ internal power.

Next, they would have commanded the tilt table to raise the combo to an angle of 59 degrees and, precisely ten hours after leaving Earth, spring-ejected it, such that it swept smoothly away over Challenger’s cabin. Nineteen minutes later, Scobee would have fired the OMS engines to create a safe separation distance in anticipation of the ignition of the IUS’ first-stage engine. After computing the stack’s correct attitude, the engine would have fired almost an hour after deployment and run for about two-and-a-half minutes. An additional burn by the second stage, lasting just under two minutes, would then have placed TDRS-B into near-geosynchronous orbit.

Whilst still attached to the now-exhausted second stage, the satellite’s solar arrays would have opened – “like an insect coming out of a cocoon,” astronaut Mike Lounge, who deployed TDRS-C in September 1988, would later remark – and eventually so too would its communications payload. Over a period of several weeks, during a series of extensive tests, it would have gradually drifted westwards to its final orbital position over the Pacific Ocean, south of Hawaii, at 171 degrees West longitude.

It was a complex task and one for which the IUS itself had made a rather inauspicious start. When TDRS-A was hauled aloft in April 1983, its booster had malfunctioned and delivered it into a lower-than-planned orbit; this required controllers to use three-quarters of the satellite’s precious hydrazine fuel to limp into the correct slot and reduced its operational lifespan. The investigation into the embarrassing failure had led to the postponement of several other IUS-dependent Shuttle missions and the TDRS-B launch, originally targeted for 1984, was repeatedly delayed. Additional problems with a timing circuit aboard TDRS-A pushed it back yet further.

However, following his first mission in January 1985, which featured the successful deployment of a top-secret Department of Defense satellite attached to an IUS, Onizuka expressed confidence in the training and procedures involved with releasing the enormous TDRS and its troublesome booster. “The basic Shuttle training was the same,” he told an interviewer of the comparison between his first flight and 51L. “Once we enter the area of payload and mission operations, there were some differences, [but] I’m very familiar with the IUS; very comfortable with it”.

Capable of handling up to 300 million bits of information per second – roughly equivalent to processing a couple of hundred 14-volume sets of the Encyclopedia Britannica every minute – TDRS-B would technically bring the system up to fully operational status. Nevertheless, a third satellite was scheduled to be ferried into orbit by another Challenger crew in July 1986 to replace the doddery TDRS-A.

Despite its important contributions to astronomy and communications, the 51L mission naturally attracted media attention, as NASA had intended, thanks to the presence of teacher-observer McAuliffe. Explorers, journalists and entertainers were considered in the early 1980s as the agency weighed-up options for which profession would yield ‘the best’ private citizen to send aloft on the pioneering mission. Ultimately, in August 1984, President Ronald Reagan announced that a teacher would fly first. Dick Scobee agreed that it was the right decision.

“Teachers teach the lives of every kid in this country through the school system and if you can enthuse the teachers about doing this, then you enthuse the students and impress on them that’s something to expect in their lifetime,” he told an interviewer in the weeks leading up to Challenger’s launch. “Man needs to explore and that’s part of the thing we have to do to ensure our future. So as far as I’m concerned, it’s a good insurance policy for the human race”.

McAuliffe’s selection as the primary candidate for the mission, with Idaho teacher Barbara Morgan backing her up, was revealed by Vice-President George Bush in July 1985 and a few weeks later both women arrived at the Johnson Space Center to begin training in earnest. Her tasks included performing two, 15-minute-long lessons: the first, entitled ‘The Ultimate Field Trip’, was a guided tour of the Shuttle to familiarise students with on-board living and working conditions, while the second, called ‘Where We’ve Been, Where We’re Going’, focused on NASA’s fledgling plans for a permanent space station.

Both were to have been aired by the Public Broadcasting System on February 2nd and McAuliffe would have explained the roles of her six crewmates, identified, summarised the experiments aboard Challenger and enthused ‘her’ students with a vision of the future. “I think it’s going to be very exciting for kids to be able to turn on the TV and see the teacher teaching from space,” she said. “I’m hoping that this is going to elevate the teaching profession in the eyes of the public and of those potential teachers out there. Hopefully, one of the secondary objectives of this is students are going to be looking at me and perhaps thinking of going into teaching as professions”.

McAuliffe and Jarvis were both ‘Payload Specialists’ – candidates chosen by their respective companies, agencies or organisations to operate specific experiments, but not ‘career’ astronauts like their five crewmates – and both joined the 51L line-up relatively late in the training flow. Yet both were quickly accepted and grew to become highly respected members of the team.

“It’s always refreshing to have somebody on board that’s really dedicated and enjoys doing what they’re doing, but also she goes into the training with a good positive attitude and stays out of the way when she needs to stay out of the way, she gets involved when she needs to get involved and she does basically all the right things, and so does Greg Jarvis,” Scobee said. “Both of them, from our standpoint, are good Payload Specialists. They came on-board with a good, open mind, they’re accommodating to our system, we try to be accommodating to theirs and it’s a nice tradeoff”.

The level of respect was, of course, mutual and Jarvis, a Hughes aircraft engineer, recalled one particular training session as an example of the career astronauts’ ability to operate seamlessly together. “When you watch them work through the malfunctions they work through, you get very comfortable that they know what they’re doing,” he said. “One time when we were in the Motion Base Simulator, the lights went out for the visual for the landing. It was not a malfunction; it was just something happened. The Commander called down and said ‘Aren’t the lights out?” And they [Mission Control] said, “I think so, we’ll get back to you on that’.

“The conversation went on for about two or three minutes and it turns out they had mistakenly turned the lights out on the visuals. The thing you didn’t realise was that he made a perfect landing without any lights!”

The arrival of Jarvis in October 1985 had come particularly late in the crew’s training period. During the mission, he was assigned to conduct a battery of investigations using spinning, fluid-filled plastic models on Challenger’s middeck to evaluate ‘optimum’ shapes for future satellite fuel tanks. The reason for his late assignment was primarily linked to the fact that payloads for Shuttle missions were in constant flux prior to 51L; indeed, the cargo for Dick Scobee’s flight had changed several times, as had the identities of ‘his’ Payload Specialists.

Even when the five NASA crew members were assigned in early 1985, the mission’s payload was changing every few months: first they would deploy an Australian communications satellite and operate a pharmaceutical processing factory, then for a short time ‘their’ orbiter was switched from Challenger to Atlantis and, finally, back to Challenger again…

At length, with everything (TDRS-B and Spartan) and everybody in place, their mission-specific training commenced in the late autumn of 1985, with the astronauts averaging 49-hour workweeks to ensure proficiency in robot arm operations, Spartan deployment and retrieval activities, IUS systems, ascent and entry procedures and each of the experiments crammed into Challenger’s middeck. The 51L mission itself was deemed ‘moderately complex’ in view of the Spartan commitment, although both it and a TDRS deployment had already been ‘baselined’ on previous flights.

Still, despite a hectic six days in space, all seven astronauts intended to spend some moments appreciating the uniqueness of where they were. “We have a fairly busy timeline and it’s nice to have time to go look out the windows,” Scobee, who had flown once before on Challenger in April 1984, said during one of his last interviews. “I guess one of the things that pleasures me most is to have a quiet time where you can go look out the windows, turn out the lights and look at the stars and Earth and thunderstorms. Just the sheer joy of doing it is probably the most fun part because it’s hard to single out one thing, but even the hard work of it is generally fun.

“I enjoy the flying. I enjoy the excitement and thrill of the ascent, because it is really dramatic. Entry is fiery – just an amazing light show – and the fires of hell are burning outside your window and you’re sitting there nice and comfortable watching all this go on and it’s just a neat feeling”.

Nonetheless, Scobee had already announced before setting off that 51L would be his last space mission; doubtless, he intended this one to count even more so than his previous flight. His last comments of encouragement to his crewmates over Challenger’s intercom in the final seconds of the countdown were words that conveyed enthusiasm, dedication, professionalism, childlike wonder…and an uncanny, though unwitting, preview of what would happen.

“Everybody strap in tight,” he told them cheerily. “We’re about to go for the ride of our lives”.

Lest we forget – the video:

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