“Ready. Ready. Grab!”
The words of Rick Hieb echoed through the silent Mission Control Center (MCC) at the Johnson Space Center (JSC) in Houston, Texas.
The view through Space Shuttle Endeavour’s aft flight deck windows on the evening of 13 May 1992—a quarter-century ago, this coming week—was quite different from anything ever seen before. Not only was this the maiden voyage of NASA’s newst shuttle, built to replace the fallen Challenger, but it also marked the first Extravehicular Activity (EVA) to involve as many as three people. In fact, having as many people outside, simultaneously, on a spacewalk, has never been equaled, much less surpassed. The nine-day mission, STS-49, commanded by then-Chief Astronaut Dan Brandenstein, had long been anticipated to be most visible shuttle flight of 1992, but it demonstrated that human space exploration always retained the ability to deliver surprises.
When Brandenstein and his six crewmates—spacewalkers Hieb, Pierre Thuot, Kathy Thornton and Tom Akers, robotic arm operator Bruce Melnick and Pilot Kevin Chilton—were assigned to STS-49 in December 1990, their mandate was to retrieve the Intelsat 603 communications satellite. It had been delivered into an improper orbit by its Commercial Titan III booster in March 1990 and its prime contractor, Hughes, had later entered into a $90 million contract with NASA for a shuttle salvage mission. Original plans called for Thuot and Hieb to venture into Endeavour’s payload bay and attach a new rocket motor, after which Intelsat 603 would be boosted into its 22,300-mile (35,800 km) geosynchronous orbit, ahead of a pivotal role covering the 1992 Summer Olympics in Barcelona.
After the Intelsat activities, a further two spacewalks—the first with Kathy Thornton and Tom Akers, the second with Thuot and Hieb—would rehearse Space Station Freedom construction techniques. Thornton’s inclusion made her only the third woman, after Russia’s Svetlana Savitskaya and NASA’s Kathy Sullivan, to perform an EVA.
If everything ran as timelined, STS-49 would thus be the first shuttle flight to feature as many as three spacewalks and include two teams of spacewalkers—both of which were critical prerequisites if NASA was to execute as many as five EVAs per mission to service Hubble and build Space Station Freedom. On the face of it, retrieving and repairing Intelsat 603, for all its drama, offered something of a backward glance to the shuttle’s pre-Challenger heyday and was unusual, for in the wake of the disaster it had been mandated that the reusable orbiters would henceforth not be used for commercial missions. STS-49 was thus the last of its kind. At the same time, as Space Shuttle Program Director Bob Crippen explained in June 1990, it offered “an opportunity for expanding our experience base in the planning, training and performance of EVA” by “helping preparations for Freedom”.
Others agreed that such a mission was useful for other purposes. It was “a throwback to the good old days”, said Endeavour’s first processing manager, John Talone, “when we used to go out and do these kinds of things”. Added NASA Associate Administrator for Space Flight, former astronaut Bill Lenoir: “It’s a mission we wanted to do. It gave me the opportunity to have real work that really mattered; that was going to get measured, where we either succeeded or failed.”
Weighing 9,200 pounds (4,170 kg) and measuring 11.8 feet (3.6 meters) in diameter and 17 feet (5.2 meters) tall, Intelsat 603 was an exceptionally large payload for the shuttle. “One of my first concerns when we first got assigned and started working with Hughes on the mission,” he told the NASA oral historian, “was if we try and grab it, if we bump it, is it going to go out of whack and float away? Part of the requirements from the customer were that we didn’t touch any sensitive area, which left you a very small ring that…had a limited accessibility and that was supposed to the way we grabbed it.”
The mechanism by which Thuot and Hieb would grab Intelsat was a “capture bar,” designed by engineers in the Crew and Thermal Systems Division at JSC. It measured 15 feet (4.6 meters) long by about 3.3 feet (1 meter) wide and included detachable beam extensions and a “steering wheel”. As Thuot rode on the end of Endeavour’s Remote Manipulator System (RMS) mechanical arm, he would be positioned close to the base of Intelsat 603 and after grappling it would lower it delicately into a Hughes-built cradle assembly. “There was a lot of analysis done,” continued Brandenstein, “and we were assured that because it was spinning slightly and it had a lot of mass, we could bump it and it would stay pretty much in place and wasn’t going to be a problem.”
As detailed in last weekend’s pair of AmericaSpace history articles, Endeavour arose from a set of already extant shuttle “spares”, assembled before the loss of Challenger for repairs, but pressed into service in July 1987 to build a new vehicle. Three years later, she was completed and in April 1991 was rolled out of prime contractor Rockwell International’s facility in Palmdale, Calif., ahead of delivery to the Kennedy Space Center (KSC) in Florida. A year later, in April 1992, Endeavour’s trio of Space Shuttle Main Engines (SSMEs) were test-fired on Pad 39B, clearing a final hurdle before launch.
Her maiden voyage was originally targeted to begin on the evening of 4 May, but was moved to the 7th, in order to permit greater conditions of daylight for photographic coverage of ascent. The countdown clock was held for 34 minutes, due to marginal weather conditions at one of STS-49’s Transoceanic Abort Landing (TAL) sites, but Endeavour roared into the steadily darkening Florida sky at 7:40 p.m. EDT. Riding the shuttle for the fourth time, Brandenstein later recalled that it was the first time he had flown through cloud—as Endeavour punched through a low deck, shortly after liftoff—and that he could physically feel the heat of the Solid Rocket Boosters (SRBs), radiating back into the cockpit.
With the possible exception of Columbia, which flew the very first shuttle mission in April 1981, there is perhaps no other orbiter besides Endeavour which made her entrance on-stage in such a dramatic manner. STS-49 would be the longest maiden voyage of any shuttle and was already timelined to include a record-breaking three periods of EVA. As circumstances transpired, Endeavour would eclipse even that record…and would go on to make more records for the remainder of her 25-mission career.
The second part of this article will appear tomorrow.