Twenty-one years ago, yesterday, on 18 October 1993, the longest flight ever attempted in shuttle history—the 14-day STS-58 mission, carrying the second Spacelab Life Sciences (SLS-2) research payload—was launched into orbit. Aboard Columbia were astronauts John Blaha, Rick Searfoss, and Bill McArthur, together with physicians Rhea Seddon and Dave Wolf, biochemist Shannon Lucid, and veterinarian Marty Fettman. As described in yesterday’s AmericaSpace history article, SLS-2 attracted a measure of controversy, in that it represented the first human space mission to feature the euthanasia and dissection of animals as part of a medical investigation in the microgravity environment.
Shortly after Columbia entered orbit, Lucid and Fettman began taking the first blood samples and Wolf took their blood pressures to acquire data on early adaptive processes to the microgravity environment. The findings correlated data from the June 1991 SLS-1 mission by revealing a slightly lower central venous pressure than had been predicted in ground-based studies, coupled with a larger volume in the heart’s left ventricle than would be expected with the lower pressure. This shed new light upon the basic physiology of the human heart in space.
Immediately after the Spacelab module had been opened for business, Rhea Seddon—SLS-2’s payload commander, with responsibility for the scientific success of the mission—took ultrasound measurements of Lucid’s heart with a new echocardiograph imaging device. Both Lucid and Fettman had launched into orbit with catheters threaded into their arms, which ran to the tips of their hearts. Lucid’s catheter was removed late on 18 October, followed by that of Fettman the following day. Data dropouts from the echocardiograph led to the crew resorting to the portable American Flight Echocardiograph (AFE), which Wolf had helped to design in his pre-astronaut days.
Within hours of activation, SLS-2 was already shaping up to be a tremendous success. NASA had invested $175 million in the payload, which featured 14 major experiments, of which eight focused on the crew and six on the rats. Of the 48 Rattus norvegicus carried aboard the mission, six would be euthanized and dissected, with body tissues preserved for distribution to U.S., French, Russian, and Japanese medical scientists as part of an extensive biospecimen-sharing project. In fact, Russia had long been courted as a partner in space sciences and microgravity research and in 1993 was being approached to play a leading role in the International Space Station (ISS) effort.
Indeed, in August 1991, when President George H.W. Bush and Soviet Premier Mikhail Gorbachev met in Moscow to talk about potential co-operation in human space exploration, it was suggested that a physician-cosmonaut might fly SLS-2, in exchange for a NASA astronaut making a long-duration visit to Mir. “The missions will increase knowledge about life sciences and data will be shared by both countries,” explained Flight International on 14 August. “They are also seen by some observers as the first step towards joint flights to Mars.” Although there were no Russians on SLS-2, cosmonauts were included in two other flights and they subsequently flew regularly on shuttle missions to Mir and the ISS.
Rhea Seddon and the members of the SLS-2 science team took frequent blood draws from the rats’ tails during the early stages of the mission and performed additional radioisotope and hormone or placebo injections to measure plasma volumes and track protein metabolism. This was part of a study into how red blood cell masses changed in weightlessness. Ultimately, the six unlucky rats destined to meet their maker in orbit were decapitated by Fettman and Seddon on 30 October, using a modified laboratory dispatcher. Pre-flight studies had already concluded that it was best to decapitate, rather than anaesthetise the rats, because the latter would have degraded their neural tissues and impaired subsequent observations. “Things went pretty well,” Marty Fettman recounted, after the six-hour procedure ended. “We’re happy to accomplish this. It was a big day for us.”
Despite the science, the mood aboard the shuttle was sombre. At one stage, only Seddon and Fettman were at work inside the Spacelab module. Commander John Blaha poked his head over Fettman’s shoulder once or twice to check on their progress, and was quickly gone. After landing, the rat tissues were used as part of a series of neurovestibular and musculoskeletal investigations to explore changes in their gravity-sensing organs and the effect of microgravity upon their limb muscles and bones. “Gravity,” said backup payload specialist Larry Young, “is as profound a factor on the evolution and development of biology on Earth as oxygen and water. Yet we know so little about its influence, because, until the Space Age, we simply couldn’t get away from it.”
It was originally to take a dozen or so organs from each rat and then dispose of the carcass, but NASA issued a Research Announcement for interested scientific parties to use the other body parts. “It became known as the Parts Program,” Seddon remembered, and the astronauts found that it was no more difficult to remove eyeballs and lungs and insert them into little bags of fixative to preserve them. “Some had to be frozen,” she said, “and some of them had to be refrigerated and some of them just needed to be put in the fixatives.” Significantly, the inner-ear mechanisms had to be placed into fixative within two minutes of dissection, and with the inner ear buried deep within the skull, this required immense skill from Seddon and Fettman. Limb muscles, too, had to be attached to muscle clamps and fixed within 10 minutes. “It was just the choreography that was incredible,” Seddon added, “and Marty was just terrific at this stuff.”
In addition to the rat research, a series of joint U.S./Canadian experiments explored motion sickness and human vestibular changes. For SLS-2, the hardware included a rotating chair mounted in the center aisle of the 23-foot-long (7-meter) Spacelab module, which examined changes in the astronauts’ reflexive eye motions. Seddon was the first to use the chair on 21 October, as part of studies of the vestibulo-ocular reflex in the eye, which enables us to see whilst we are in motion. Other experiments featured a rotating dome, placed over the astronauts’ heads, whose interior face was coated with a pattern of dots which seemed to “rotate” in an opposite direction. The subject used a joystick to indicate their perceived direction and velocity. Dave Wolf also donned a special skull-cap, the Acceleration Recording Unit, which was instrumented with motion sensors and used to record the time and severity of space sickness symptoms. Investigators hoped that if the science crew wore the cap throughout their working day it might enable them to correlate instances of sickness with periods of provocative head movement.
Studies of muscular atrophy included the ingestion of amino acids, labelled with non-radioactive isotopes of nitrogen, enabling the astronauts to track protein metabolism. Urine, saliva, and blood samples were routinely acquired to determine the rates of protein synthesis and catabolism. Other experiments upon the rats looked at the performance of their hind limbs in microgravity, which showed an almost 40 percent reduction of muscle fibres at the end of the 14-day mission. The rats tended to rely more heavily on their forelimbs for bipedal locomotion and used their hind limbs only as grasping aids. After their return to Earth, they exhibited slow motions and an abnormally low body posture, all of which pointed clearly to a weakened muscular state, fatigue, and co-ordination difficulties. Moreover, muscle protein “turnover” in rats is much more rapid than in humans, and two weeks of weightless exposure for them was roughly equivalent to two months for a human.
Other experiments focused on the astronauts’ cardiovascular and regulatory systems. Data from SLS-1 highlighted increases in heart rate, size, and output, which researchers attributed to the initial increase in central blood volume caused by fluid shifts within the body. Three SLS-2 studies assessed the functional capabilities of the system by monitoring the astronauts’ cardiac outputs, heart rates, arterial and venous blood pressures, blood volume, and the amount and distribution of blood and gases in the lungs. Cardiovascular “deconditioning” had long been recognized as a problem after the return to Earth. Astronauts complained of light-headedness, an increased heart rate, and decreased pulse pressure. Echocardiograph data, together with the catheters, an exercise bicycle, and a Gas Analyser Mass Spectrometer supported much of this research.
Unusually for a Spacelab mission, STS-58 followed a single-shift system, although the whole crew typically put in 14-hour working days or more. In view of the long flight, and in line with Extended Duration Orbiter (EDO) protocols, each astronaut received several periods of free time to relax. “The crew members are an important part of these investigations,” stressed SLS-2 Mission Scientist Howard Schneider. “We want to assure ourselves that we continue to study the physiological effects of space flight and not the physiological effects of fatigue! If the crew is up there and is overly stressed, we don’t get good science.”
In aid of his own free time, Pilot Rick Searfoss took a huge atlas of the world in his personal effects. “Rick really wanted to focus on that,” Seddon told the NASA oral historian. “He didn’t have an awful lot of other things that he needed to do, other than managing the orbiter and when we asked he would come back and do some experiments for us. He was really our [photography] specialist and he got some really great pictures on that flight.” Every so often, from Columbia’s flight deck, Searfoss would call Seddon upstairs to the windows to take a look at the southeastern United States, as her home state of Tennessee came into view. It was difficult to get a good glimpse of her hometown, Murfreesboro, but she managed to pick out the curvaceous lines of the Cumberland River in Nashville and the parallel lines of the I-24 and Nashville Highway. STS-58’s 39-degree-inclination orbit had been designed in part to keep the astronauts’ sleep-wake cycles approximately the same throughout the flight and to effect a landing at Edwards Air Force Base, Calif. The crew could see all the way up to Long Island and Cape Cod, as their orbital track carried them across the United States’ eastern seaboard, and even saw the Himalayas on a number of occasions.
During the mission, John Blaha—who had offered during training to be the crew’s on-board videographer—spoke for all of them when he declared that “we have a beautiful planet” and “we ought to take care of it and we ought to take care of ourselves.” As STS-58 entered its final days, it was becoming clear that it would come close to the 13 days and 19 hours record set by the first EDO mission in July 1992. In order to keep their flying skills sharp for the return home, Blaha and Searfoss took turns on a computer program known as the Portable In-flight Landing Operations Trainer (PILOT), which consisted of a high-resolution color display and hand controller and offered them both the “look” and “feel” of the orbiter. Housed in a middeck locker when out of use, PILOT was assembled on the console in front of the pilot’s seat and its joystick was attached to the top of Searfoss’ own hand controller. The astronauts also participated in the customary Lower Body Negative Pressure suit runs to better prepare their bodies for the punishing onset of terrestrial gravity.
Early on 1 November, the final SLS-2 experiments were concluded and then Dave Wolf supervised the deactivation of the Spacelab module in time for the first landing opportunity at Edwards. Several hours later, Blaha fired Columbia’s Orbital Maneuvering System (OMS) engines to commence the hour-long glide back to Earth. He guided the vehicle perfectly onto concrete Runway 22 at 8:05 a.m. PST (11:05 a.m. EST) to end a mission of 14 days and 12 minutes, which established STS-58 as the longest shuttle mission to date and the United States’ fourth-longest human space flight at the time, after the three Skylab missions. For the astronauts, and particularly the science crew, it was the start of a week of post-mission medical experiments. NASA put them up in a resort called “Silver Saddles” and despite the discomfort of frequent blood draws—“We began to look like drug addicts,” joked Seddon, “because they kept drawing blood from us”—it was a pleasant time, being able to relax in the evenings and eat with their families.
This is part of a series of history articles, which will appear each weekend, barring any major news stories. Next week’s article will focus on the Gemini VI mission, planned for October 1965, which should have performed the United States’ first rendezvous with an unmanned Agena target vehicle … but which fell foul to the unforgiving nature of rocketry and space exploration.