Well, it's that time again! (Okay, fine, it's a little past that time again--I overslept.) Last week, we covered the Galileo probe. This week, we're returning our attention to human spaceflight. You may recall that when we last left, the Russians were preparing to launch their Mir station, while the Americans had just suffered a serious failure of the Spacelab 28 mission. So, without further ado, I give you...1085 replies, 134,816 views
Eyes Turned Skyward, Part II: Post 20
Even as recovery efforts for the aborted Spacelab 28 launch were still underway, with the capsule being lifted aboard the recovery boat Liberty Star, preparation was already underway for the inevitable investigation. In accordance with NASA standard practice, the doors of the Mission Control Center in Houston were locked while all data pertaining to the flight could be properly archived for the impending investigation. Similar efforts were begun by the end of the day at Kennedy Space Center and manufacturing centers at Marshall and Michoud, and the Administrator officially filed a memo by the end of the day appointing what would come to be known as the Spacelab 28 Review Board [1]. September 19th, 1986 was a Friday, and much of the agency had been looking forward to the weekend. Instead, agency and contractor employees worked through the weekend to collate manufacturing records, processing paperwork, photographs, video, inspection reports, and launch telemetry for the board to use in reconstructing the entire history of the flight. As the investigation began to get organized and with little to tell the press in the meantime, NASA public affairs did its best to deflect attention to the success of the crew escape system, and avoid too much public fallout.
While the scope of the investigation was being defined, the implications for operations were already being explored. Spacelab 27 had been due to return to Earth near the end of September, both to allow the traditional “hand-over” period for the Spacelab 28 crew, and for recovery flotilla assets to be transferred from positions used to support the launch to those used for a nominal landing. Even if a second booster and crew could be made ready, the concerns of the investigation cast doubt on the safety of another crew launching before the causes of Spacelab 28’s failure were entirely understood. Instead, the crew of Spacelab 27 began the process of making the station suitable for a potentially extended period between missions. Experiments that required active intervention or excessive power were shut down, while others were setup for remote monitoring. Station systems were configured for ground control, non-essential systems were shutdown to prevent faults and minimize power use, transfer hatches were closed between modules to prevent any damage to the station from compromising the entire pressure volume, and medical supplies and rations that required careful preservation to prevent decay or spoilage were transferred to the station’s Aardvark for pre-emptive disposal. The Spacelab 27 crew’s time on station was extended by two weeks to allow the time required to prepare the station, but finally on October 6th, the crew departed the station, breaking a streak of continuous manned operations for the station lasting since the arrival of Spacelab 4 in November 1978.
By the end of October, the shape of the Spacelab 28 failure had become clear, or at least the portion taking place after the 2:35 PM ignition of the main engine and the subsequent launch. The booster’s inertial guidance system had been matched against ground radar, and verified to have been functioning correctly. Moreover, the commands sent to the engine’s gimbal assemblies from the booster’s computers had also been confirmed—it was simply that the gimbal had not answered them. Pressure to actuate the engine’s thrust vector system was provided from high-pressure kerosene tapped from the engine’s turbo pump, routed via a single valve controller to actuators for pitch and yaw. Due to either a mechanical or electronic failure of the valve controller midflight, the pressure in the lines to the actuators had fallen below levels required for operation, freezing the gimbal off-axis and leading to the loss of the vehicle. Similar valves were pulled from other stockpiled boosters for examination and testing, and inspection reports for the suspect valve assembly were reviewed from its initial manufacture through component testing, integration into the engine, testing of the stage. All efforts were aimed at tracing reasons the assembly might have failed, and why the failure was not caught before flight. It was discovered that the assembly had passed all inspections. When the assemblies from the stockpiled boosters were tested, all passed initial inspections and several function checks, but one failed the tests when repeated. Disassembly revealed that particulates had managed to infiltrate the assembly, and frozen the valve. Disassembly of all the units revealed that another had the same infiltration, but not enough to freeze the valve. The infiltration had been undetectable except by disassembly, and the freezing was apparently only caused by either extended operations, or agitation of the valve—which the shaking of the rocket on ascent had more than provided. The particulates were discovered to have entered the valves through ports which had been inadequately sealed. However, as the seal was up to procedural standards, the checklist for removing the stages from storage had been met. Additionally, since the valve could function before finally freezing, the initial function tests at Kennedy’s incoming inspection had been met. The initial stockpiled stages, which had been given more thorough inspections, had also not shown the particulates, which turned out to be related to construction work at Michoud begun after those initial stages were shipped to the Cape, and which had managed to make their way from the production floor areas which were undergoing conversion to the overflow storage areas that had been used for the stockpile.
After the detective work of establishing the cause was completed in early November, the resolution was simple: the seals would be reviewed, as well as storage of the stockpile at Michoud. The suspect valve assemblies could be replaced outright from new-build units intended originally for Multibody--while some changes had been made to the guidance systems, they did not extend to the level of the actual actuators. Thus, the “go” was given to continue processing on the Spacelab 29 mission, which had been on hold pending the results of the investigation. Thanks to work done to continue training the crew, including the required re-start procedures for the station and the dedication of the ground handling staff at Kennedy, they were able to resume processing, aimed at the same January launch window they would have been targeting without the failure.
With the stand-down of Saturn IC, the ongoing investigation, and the de-manning of Spacelab, the American program was particularly challenged to respond to ongoing Soviet advances. Spacelab’s (temporary) shutdown left Salyut 7 the only operational station in orbit, while the end of October saw the maiden launch of a multicore rocket, as the tri-core Vulkan-Herakles lofted a massive demonstration payload to orbit. In actuality, the payload was intended to be a demonstrator for exactly the kind of massive orbital weapons platform that the American SDI was aimed to match and counter, but an error in the coding of the station’s powerup routines unintentionally sent a signal, intended for safing on the ground, which “locked out” the entire attitude control system during startup instead of activating it. The lockout was not merely electronic but physical, and irreversible without manual intervention. With the vehicle uncontrollable and in a lower than intended orbit which would decay long before any mission could be staged to intervene, the Soviets found it convenient to pass it off as a ballasted demonstration payload, with limited instrumentation to monitor orbital position and thus the success of the rocket.This (apparent) success of Vulkan contrasted sharply against the continuing doldrums of the American program, as exemplified in the public eye by the “retreat from orbit” in the wake of Spacelab 28. Congressional hearings were convened on the state of the Freedom program, potential availability of Multibody, and the investigation into the Spacelab 28 launch accident, but it was clear that the Soviets would not simply wait for the Americans to catch up to their feats. In February, a second Vulkan-Herakles carried the first MOK module of Mir into orbit. Half of the on-orbit Salyut 7 crew transferred to the station by TKS, while the other three remained to see to deactivating the older station, and preparing it for its fiery retirement. Once MOK 1’s successful activation was confirmed, the last crew of Salyut 7 departed, and the the station’s control thrusters were used one last time to send it into an unstable orbit and eventually to a breakup over the waters of the Indian Ocean. The “interim” station had served for 5 years, almost double the life intended when Glushko conceived it, but it had taught the Soviets many lessons which would hopefully streamline Mir’s construction and operation.
Meanwhile, in the United States, the preparations for Multibody were finally bearing fruit. The first Multibody core was acceptance-tested in March, on-schedule for a maiden flight later in the year. Production of the Apollo Block IV’s augmented Mission Module and the enhanced Block II Aardvark was also moving ahead at Rockwell’s facilities. On orbit, though, things were less rosy. When Spacelab 29 arrived at the station February 15, 1987, they discovered that the three months of quiescence had exacerbated several previously noted issues. Some were minor, such as failed sensors in old experiment racks or minor wiring issues. Others were more serious, as with the fans that circulated air from the main OWS into the lab annex (the adapted LOX tank). These fans had been balky for years, and the period of inactivity lead to a total breakdown of one of the two redundant blowers. There was no immediate risk as long as the second was still functional, but it too had already been experiencing minor but persistent problems, creating significant concerns about air in the lab annex stagnating and becoming over-saturated with carbon dioxide. In the end, with the assistance and ingenuity of engineers of the ground, the crew of Spacelab 29 was able to retrofit a replacement intended for the ERM’s links to the main environmental control/life-support system (ECLSS) to bypass and replace the failed unit. However, the station was definitely beginning to show the near-decade since its launch in 1978. More and more crew time on Spacelab 29, 30, and 31 was spent on ensuring the operational capabilities of the station were sufficient, with correspondingly less time available for the station’s scientific facilities. Moreover, with the station’s end-of-mission approaching rapidly (Spacelab 32 was to be the last to fly to the station, with de-orbit to follow around January of 1988), the number of new experiments began to fall off dramatically, as most investigators were more interested in fighting for space aboard Freedom than in spending effort on experiments with such a short potential life. Instead, the focus was on concluding the experiments already onboard and conducting tests to prepare for Freedom, including tests of new space suits. Johnson and Ames had continued parallel work on new suit designs, with Ames creating the AX-4 hardsuit, and Johnson developing the A9, a “semi-rigid” suit derived from the existing Apollo-heritage A7L. Prototypes of both suits had been tested on the ground, on “Vomit Comet” flights, and in vacuum chambers, but for final testing functional models of both suits were flown to Spacelab and put to use in EVA trials in November 1987. For both suits, the principal design goals were to achieve a higher operating pressure, allowing a reduction in the pre-breathe time needed before each EVA, and to allow a “one-size fits (nearly) all” capability, rather than the customized tailoring needed for each A7L. By using a generic design, most components could easily be swapped between suits, with only smaller components like the gloves needing to be fit for any specific user. Thus, the main components of the chosen suit could be left on-station, instead of requiring change-out every flight. Two astronauts acted as test subjects, selected to put the versatility of the suits’ fit to the test: rookie pilot Chris Valente (a member of Astronaut Group 10, the class of 1983) and veteran spacewalker Peggy Barnes. As part of the several days of EVAs carried out during trials, Barnes set new records for lifetime total spacewalk time. The two noted that the A9 put in a solid performance, and matched the mobility of the existing A7L for both astronauts. While the mobility of the AX-4 was a notable improvement over the A7L and the A9, the suits’ constant-volume design proved less adaptable for the two users over extended periods in microgravity and vacuum. Despite padding inside the suit, Barnes would note that the mobility increases were more than countered by what was referred to in the final report as “intolerable chafing,” a considerably less colorful evaluation than Barnes’ original comments. Some of the issues had been noted in ground testing, but the extended duration in microgravity exacerbated problems that had been less apparent during ground trials. Thus, the A9 became the suit of choice for Space Station Freedom.
However, the most significant preparation for Freedom operations conducted with Spacelab came in November 1987, and would be the last contribution of Spacelab to the birth of its successor. After months of work, the first VAB cell and mobile launch platform adaptations for Multibody had been completed in July, and the cell was “stood up” to support the inaugural launch of the Saturn M02. Bearing AARDV-14, the last of the Block I Aardvark supply craft, it launched from from the Cape November 18th. Thanks in part to the procedural revisions resulting from the Spacelab 28 Accident Review Board, the launch was flawless. Additionally, the launch preparation flow incorporated many suggestions from years of experience with Saturn IC that would hopefully reduce the time and effort required to prepare Multibody family launchers. This not only promised reduced costs in “touch labor” during preparation, but a faster processing cycle that would hopefully ease pressures that the Freedom assembly schedule might otherwise cause. Spacelab 32’s reduced three-man crew eagerly awaited the launch, and greeted the craft on-orbit. The mission commander was Don Hunt, whose arm had finally healed from his injuries sustained during Spacelab 29 and who had received the honor of being the last commander of the station. After the crew made the final preparations, including using racks installed in place of the outboard two seats to remove some of the original 1978-vintage experimental equipment and station control systems for analysis of the effects of a decade in space, the crew stood by for a decommissioning ceremony to see off the station, removing the U.S. pennant which had been flown during the Spacelab 2 mission, along with flags of several other nations who had flown to the station. The crew then retired to their Apollo, with Hunt being the last to board, and departed. After their recovery, AARDV-14’s thrusters were fired (using excess fuel that the M02’s mass margin had allowed) to send the station to a fiery death over the Indian ocean. With the requirements of Spacelab support removed, the final modifications to Kennedy Space Center followed in short order. The remaining VAB cells and MLP were stood up, and preparations began in January 1988 for the maiden launch of the Saturn Heavy later that year.
[1] This is standard NASA practice. Challenger was an exception IOTL with its Presidential Commission, largely due to the public nature of the failure and the deaths of the crew. With Spacelab 28’s crew safely on the ground, like Apollo 13 before it, Spacelab 28 receives an in-agency investigation.