Forty years ago today, on 4 April 1983, America’s second Space Shuttle thundered into orbit for the first time. Challenger went on to spend five days circling the Home Planet, deploying a giant communications and data-relay satellite for NASA and featuring the first U.S. spacewalk in nearly a decade.
Challenger’s story is naturally overshadowed by the dreadful tragedy which befell her in January 1986, but from April 1985 until April 1990 she was the most-flown orbiter in NASA’s shuttle fleet and accomplished several significant feats in rendezvous, retrieval and repair, satellite deployment and untethered spacewalking. But Challenger’s most remarkable achievement is that she almost did not exist at all and, but for a quirk of fate and timing, might have begun and ended her days as a non-descript structural test article.
In April 1981, Columbia became the first shuttle to reach space and it was long hoped that her sister Enterprise—previously used for a series of captive and free flights over the California Desert in the summer of 1977—would be upgraded as the second orbiter. But Enterprise proved too heavy to straightforwardly modify and required a whole new set of plans and a huge array of modifications to make her spaceworthy.
But as part of the shuttle development campaign, NASA had built Structural Test Article (STA)-099 as an engineering facility to simulate the thermal, acoustic and other stresses that the spacecraft would experience during launch, ascent, orbital operations, re-entry and landing. Unlike Enterprise, STA-099 was an incomplete shuttle airframe, which made the process of modification simpler to execute.
On 29 January 1979, under a $1.9 billion contract between NASA and the shuttle’s prime contractor, Rockwell International, STA-099 was selected to be upgraded as a second orbiter. Four days later, on 2 February, she was named “Challenger”, honoring the steam-assisted Royal Navy corvette which undertook a prolonged cruise from December 1872 until May 1876, covering 80,000 miles (128,000 kilometers) and returning a vast quantity of scientific data about the Atlantic and Pacific Oceans.
In November 1982, affixed to her External Tank (ET) and a pair of Solid Rocket Boosters (SRBs), shuttle Challenger was rolled out to historic Pad 39A at the Kennedy Space Center (KSC) in Florida, tracking a launch on her first flight, STS-6, late in January of the following year. Before launch, though, a critical Flight Readiness Firing (FRF) of Challenger’s three main engines was targeted for 18 December.
The engines came alive and burned furiously, as planned, for 15 seconds, but their overall performance fell somewhat short of exemplary. Engineers detected levels of gaseous hydrogen which exceeded allowable levels in the shuttle’s aft compartment during the FRF, forcing a decision to perform a second test.
A month later, on 25 January 1983, a second FRF was performed, but again gaseous hydrogen was again observed. Troubleshooting identified a cracked weld in tubing leading to Challenger’s No. 1 main engine, which was removed and replaced.
But the replacement engine also exhibited a leak in an inlet line to its liquid oxygen heat exchanger and was itself replaced. In the meantime, the shuttle’s other two engines revealed their own hairline cracks, requiring further removal and repair.
If Challenger herself seemed snakebitten by cruel fortune, so too did the STS-6 crew’s primary payload, the first Tracking and Data Relay Satellite—alphabetically identified as “TDRS-A” on the ground but set to be renamed “TDRS-1” in space—and its attached Inertial Upper Stage (IUS) booster. Strong winds at KSC in late February breached a weather seal and deposited a fine layer of particulate material on TDRS-A’s solar array deployment springs. That pushed back STS-6’s launch from late March to 4 April.
TDRS-A was the first of two such satellites (the second, TDRS-B, was provisionally slated to fly STS-8 in August 1983) to facilitate near-continuous voice and data communications between Mission Control and future shuttle crews, as well as supporting ambitious science missions, including Spacelab and the Hubble Space Telescope (HST). But a long and troubled road lay ahead for the hapless first TDRS.
The four men aboard STS-6 were a stark juxtaposition against the youth of Challenger herself, for they earned the unwanted moniker of being the oldest crew ever launched into space. Fifty-year-old Commander Paul “P.J.” Weitz—a veteran of the first Skylab mission—would be joined by 45-year-old Pilot Karol “Bo” Bobko and Mission Specialists Story Musgrave, aged 47, and Don Peterson, aged 49.
Weitz wryly dubbed his men the “F-Troop”, in honor of their being the sixth shuttle crew and offering a tip of the hat to the television series about an aging cavalry unit. But the jokesters within the astronaut office countered by labeling them “Geritol Bunch”, after the dietary supplement famously associated with aging.
The crew took it, to an extent, in good humor. Weitz arranged for tongue-in-cheek portraits to be taken, showing the four men clad in Civil War attire: cavalry hats, braces, red and white neckties, swords, a Winchester lever-action rifle, bugle and flag. According to Peterson, the sword once belonged to a lieutenant in Napoleon’s army. Another portrait saw the men don vintage spectacles.
As for the Geritol Bunch name, Peterson did not recall that one with quite so much fondness. “Maybe that was something everybody said about us when we weren’t around,” he said, “but when we were in orbit, somebody was talking about how old you guys are.” Peterson couldn’t resist.
They had a bunch of F-Troop photographs on-board and he retorted that after landing they would not be shown to anyone under the age of 35. And when Vice President George H.W. Bush spoke to them on-orbit, they could not resist but showing him an F-Troop flag…and proudly displaying a hand-crafted placard, whose legend read: “111 Years of Aviation Experience”.
When he was assigned to STS-6 in March 1982, it seemed inconceivable that Peterson and Musgrave would be the first astronauts to perform an Extravehicular Activity (EVA) from the shuttle. Technical problems and space sickness which impacted Joe Allen and Bill Lenoir’s planned EVA on STS-5 in November 1982 changed all that and the first shuttle spacewalk was reassigned to STS-6.
The new shuttle-era space suits needed to be thoroughly tested ahead of the retrieval and repair of NASA’s Solar Max satellite, an ambitious mission, scheduled for early 1984. And the addition of an EVA to STS-6 correspondingly increased the flight’s duration from two to five days.
“It didn’t give us much time to train,” Peterson recalled. “I didn’t have much experience in the suit, but the advantage was that Story was the astronaut office’s point of contact for the suit development, so he knew everything there was to know.
“He’d spent 400 hours in the water tank, so he didn’t really have to be trained!” By his own admission, Peterson’s EVA training “was pretty rushed.”
He recalled being underwater on only 15-20 occasions. However, the tasks for their excursion were relatively straightforward evaluations of the performance of the suit and of the airlock; if any of the equipment tests went awry, he and Musgrave could quickly curtail their spacewalk and return to Challenger’s cabin.
For the spacewalk on STS-6, Musgrave would take the lead as “EV1,” wearing red stripes on the legs of his suit. And although it was scheduled for only four hours, the EVA consumed the crew’s entire working day on 6 April 1983.
Aided by Bobko, who would choreograph the spacewalk, Musgrave and Peterson rose early that morning to begin readying their suits and equipment in Challenger’s airlock. They spent three and a half hours “pre-breathing” to avoid an attack of the bends and clear dissolved nitrogen from their blood.
Since reaching orbit, two days earlier, on 4 April, Weitz, Bobko, Peterson and Musgrave had checked and rechecked their equipment: testing a third, “spare” upper torso in accordance with flight rules, verifying that oxygen regulators and fans operated normally, inspecting for leaks and confirming that communications were satisfactory.
In fact, the only problem raised was a need to replace some flat floodlight batteries. With everything in place, suit donning began and, in true F-Troop fashion, it ran as crisply as a military campaign.
At length, at 4:05 p.m. EST, Musgrave initiated the final depressurization of the airlock and, 16 minutes later, pushed open the outer hatch into the payload bay. The plan called for three hours of activities, but he and Peterson had six hours’ worth of consumables.
“You remember little things like sound,” Musgrave told a post-flight press conference. “Even though there’s a vacuum in space, if you tap your fingers together, you can hear that sound because you’ve set up a harmonic within the space suit and the sound reverberates within it. I can still ‘hear’ that sound today. But the main impression is visual: seeing the totality of humanity within a single orbit. It’s a history lesson and a geography lesson; a sight like you’ve never seen.”
The spacewalkers’ first task was to tether themselves to slidewires running along the sills of the payload bay walls (one on either side, to prevent mutual interference) and move towards the aft bulkhead, in the process evaluating their ability to handle tools. During the EVA, the slidewires were used as part of a safety procedure to prevent Musgrave or Peterson from inadvertently floating away from the shuttle.
Meanwhile, the two men began conducting their first “real” evaluations of the new suits: comfort, dexterity, ease of movement and performance of their communications and cooling systems and the payload bay floodlights. One of very few concerns expressed by Peterson after the mission was that “the gloves are hard to work in—extremely stiff—and I had to get my hands strengthened with a little hand exerciser.”
Despite this, both astronauts reported that the suits’ mobility enabled them to satisfactorily accomplish each of their tasks. Most of their work focused on identifying suitable locations from which future spacewalkers could best work on the malfunctioning Solar Max, and on practicing some of the intended repair techniques.
This kind of work was essential for the successful reactivation of the $240 million solar observatory. Musgrave and Peterson also evaluated the manual system for closing Challenger’s payload bay doors in the event of a failure.
At another point during the EVA, in what NASA labeled a “high metabolic period,” Peterson received a “high O2 usage” warning on his chest display. Although the message cleared quickly and did not recur, it was attributed to flexure within the suit and his high work rate whilst using a wrench.
“I stopped and said ‘I’ve got an alarm’,” Peterson recalled. “Story stopped what he was doing and came over. We were trying to check what was going on and the seal popped back in place and the leak stopped.
“Now, in those days, we didn’t have constant contact with the ground,” Peterson added. “They weren’t watching at the time that happened. By the time we dumped the data from the computers to the ground that showed the leak, we were back inside the orbiter.”
It seemed that Peterson’s alarm was caused by overworking and breathing excessively rapidly; this depleted his oxygen, forced a higher feed level, and triggered the warning. Biomedical data confirmed that his heart rate was around 192 beats per minute whilst cranking the wrench, but Peterson doubted he could have worked so hard as to breathe enough oxygen to set off the alarm.
After returning to the airlock, the data on Peterson’s alarm was pored over by flight controllers with dismay. “They were upset about it,” he said later, and, this being the suit’s first outing in space, the astronauts would almost certainly have been directed back to the airlock had the problem occurred whilst in communication with Mission Control.
But the EVA was just one element of a multi-faceted mission which began at 1:30 p.m. EST on 4 April 1983. “The value of our simulators ends when those engines light and you lift off,” Weitz reflected later. “They try to fake you out a little bit by tipping the shuttle simulator, but it doesn’t compare with…three main engines and two solids going. You know you’re on your way, and you’re going somewhere, and you hope they keep you pointed in the right direction, because it’s an awesome feeling.”
Less than two hours after launch, Challenger’s payload bay doors were open and the crew stepped smartly through the campaign to deploy TDRS-A. But the highly complex task had caused some confusion shortly before the flight.
“We were in quarantine in the crew quarters at the Cape and a couple of nights before launch, two guys showed up from Boeing,” Peterson remembered. “It turned out that the software we’d trained on in the simulator was not exactly the same as the software that was flying and a lot of the codes were different.
“Story and I copied a bunch of stuff down with pen and ink and used that on orbit and that’s really scary because we were taking these [Boeing] guys’ words for it,” he continued. “We’d never seen some of this stuff in the simulator. Suppose what they told was not right and we messed up the payload? We’d never find those two guys again! They’d be gone and it’ll be ‘Why the hell didn’t you guys do it the way you were trained to do it?’ Story called somebody in Houston to confirm the codes, but it was pretty vague.”
Commands were issued by dialing in sets of three numbers, then hitting an execute button, but the vagueness of the change left Peterson and Musgrave unsettled. Both men knew that TDRS-A was extremely expensive and important to get on-orbit.
Fortunately, the changed commands proved accurate and a little under ten hours after launch, the TDRS-A/IUS stack swept smoothly out of the shuttle’s payload bay. But despite the success of its deployment, it marked the start of several difficult months for the giant satellite itself.
During the firing of the IUS’ second-stage engine, the booster suffered a failure in a manifold on the baffle of the gimbal actuator, which effectively lost its ability to point the motor nozzle. The result was that the entire stack began to tumble, leaving TDRS-A not in a circular geostationary orbit, but in a lopsided one, with a perigee of 13,600 miles (22,000 kilometers) and an apogee of 21,000 miles (34,000 kilometers).
Worse yet, communications with the tumbling payload were lost. It took several weeks to fully restore contact, regain control and stabilize TDRS-A. By June 1983, after using 840 pounds (380 kilograms) of the satellite’s precious attitude-control propellant, engineers had enabled the satellite to limp into a circular geostationary orbit and tests of its communications payload got underway the following month.
But TDRS-A still was not out of the woods. One of its Ku-band single-access diplexers failed, then a Ku-band traveling-wave tube amplifier conked out. The satellite managed to provide some support for the critical first Spacelab mission in late 1983, but it was not until the fall of the following year that it was declared fully operational.
The crew of STS-6, of course, could have done nothing to prevent the IUS fault and the rest of their five-day mission proceeded smoothly. And their return to Earth on 9 April was aided immeasurably, for the first time, by the inclusion of a Heads-Up Display (HUD) in Challenger’s cockpit. Bobko considered it “a great aid” in achieving a safe landing at Edwards Air Force Base, Calif.
During re-entry, Musgrave broke established procedure—as he would do again on his final mission, STS-80—by unstrapping from his seat and standing fully upright on the flight deck. He later admitted that he wanted to demonstrate that an astronaut could stand during the transition from weightlessness to terrestrial gravity.
“I had my Hasselblad camera and was taking some photos,” Musgrave said later. “Also, I wanted to prove that I could do it. That’s important if an astronaut ever has to leave the flight deck and go below to throw a switch or circuit breaker. I wanted to show that the cardiovascular system doesn’t have any problem going back into gravity and you don’t have to be strapped down.”