John Young called it the \u00e2\u20ac\u02dcDeath Star\u2019. Behind the dark humour, however, lay real concern for the then-chief of NASA\u00e2\u20ac\u2122s astronaut corps. Even with an increasingly confident outlook on the Shuttle\u00e2\u20ac\u2122s capabilities at the dawn of 1986, Young instinctively knew that the STS-61F and 61G flights would be two of the riskiest ever attempted by the reusable spacecraft.\n<\/p>\n
Fellow astronauts Rick Hauck and Dave Walker, who would command the two missions, echoed his concern. \u00e2\u20ac\u0153As with any flight,\u00e2\u20ac\u009d Hauck said in a January 2004 interview, \u00e2\u20ac\u0153if everything goes well, it\u00e2\u20ac\u2122s not risky. It\u00e2\u20ac\u2122s when things start to go wrong that you wonder how close you are to the edge of disaster\u00e2\u20ac\u009d.<\/font><\/p>\n The loss of Challenger during ascent and Columbia upon re-entry have demonstrated how fine the line is between triumph and tragedy; a line \u00e2\u20ac\u201c and risk \u00e2\u20ac\u201c that every astronaut knows and accepts before climbing aboard. Yet Hauck and Walker\u00e2\u20ac\u2122s flights, both scheduled to occur a few days apart in May 1986, would carry additional danger. This was partly due to the important scientific payloads their crews would truck into low-Earth orbit \u00e2\u20ac\u201c a probe called Ulysses to explore the Sun\u00e2\u20ac\u2122s poles on Hauck\u00e2\u20ac\u2122s flight, followed by a spacecraft dubbed Galileo to study Jupiter on Walker\u00e2\u20ac\u2122s mission \u00e2\u20ac\u201c which were both equipped with controversial nuclear powerplants.<\/font><\/p>\n Needless to say, the implications of a launch accident and the consequences of depositing highly-radioactive plutonium dioxide across eastern Florida did not bear thinking about. The risk, though, was compounded still further by the fact that, attached to the base of each nuclear hot potato in the Shuttles\u00e2\u20ac\u2122 payload bays was a thin-skinned, liquid-fed rocket that many astronauts and even managers had condemned as unsafe and unacceptable for use in conjunction with a manned spacecraft. Measuring 30 feet long and 14 feet wide, it was called the Centaur-G Prime and, for Rick Hauck, it was his baby.<\/font><\/p>\n Furthermore, just like a baby, it was both temperamental and unpredictable.<\/font><\/p>\n \u00e2\u20ac\u0153I was assigned to be the Astronaut Project Officer for Centaur, an upper-stage rocket that\u00e2\u20ac\u2122s very thin-skinned,\u00e2\u20ac\u009d he said. \u00e2\u20ac\u0153It\u00e2\u20ac\u2122s pressure-stabilised, which means if it\u00e2\u20ac\u2122s not pressurised, it\u00e2\u20ac\u2122s going to collapse by its own weight. If it were not pressurised, but suspended, and you pushed on it with your finger, the tank walls would \u00e2\u20ac\u02dcgive\u00e2\u20ac\u2122 and you\u00e2\u20ac\u2122d see that you\u00e2\u20ac\u2122re flexing the metal<\/i>!\u00e2\u20ac\u009d Nicknamed a \u00e2\u20ac\u02dcballoon tank\u00e2\u20ac\u2122 because its rigidity thus depended on being fully-pressurised, the Centaur had long been viewed warily by NASA, whose general safety rule of thumb on the Shuttle dictated that no single failure should be capable of endangering the spacecraft or its crew.<\/font><\/p>\n The Centaur-G Prime did more than that. Much of its pressure-regulation hardware, disturbingly, was non-redundant \u00e2\u20ac\u201c without a backup facility \u00e2\u20ac\u201c and, worse, a failure of its internal bulkhead had the potential to rupture both<\/i> its volatile liquid oxygen and hydrogen tanks. Additionally, it was recognised that the sheer mass of its propellants, which totalled close to 45,000 pounds, could cause \u00e2\u20ac\u02dcsloshing\u00e2\u20ac\u2122 and a myriad of other controllability problems that could hinder Hauck or Walker if the need arose to make an emergency landing shortly after liftoff.<\/font><\/p>\n In spite of the hazards, the Centaur\u00e2\u20ac\u2122s key advantage was that, pound for pound, its liquid propellants provided considerably more oomph to push large payloads out of low-Earth orbit and en-route<\/i> to other planets than solid-fuelled rockets could achieve. It was also well-known that liquid-fed boosters generally produced a much \u00e2\u20ac\u02dcgentler\u00e2\u20ac\u2122 thrust than the notoriously harsh impulse of solids. <\/font><\/p>\n SpaceX (adsbygoogle = window.adsbygoogle || []).push({});<\/p>\n Still, the safety concerns rightly overshadowed and ultimately overwhelmed these benefits. \u00e2\u20ac\u0153The Shuttle was obligated to launch Ulysses and Galileo,\u00e2\u20ac\u009d explained Hauck, \u00e2\u20ac\u0153and [NASA] needed the most powerful rockets they could have [and] at some point the decision was made to use the Centaur, which was never meant to be involved in human spaceflight. That\u00e2\u20ac\u2122s important because rockets that are associated with human spaceflight have certain levels of redundancy and certain design specifications that are supposed to make them more reliable.<\/font><\/p>\n \u00e2\u20ac\u0153Clearly, Centaur did not come from that heritage, so, Number One, that was going to be an issue in itself, but Number Two is [that] if you\u00e2\u20ac\u2122ve got a Return to Launch Site abort or transatlantic abort and you\u00e2\u20ac\u2122ve got to land, and you\u00e2\u20ac\u2122ve got a rocket filled with liquid oxygen [and] liquid hydrogen in the cargo bay, you\u00e2\u20ac\u2122ve got to get rid of [it], so that<\/i> means you\u00e2\u20ac\u2122ve got to dump it while you\u00e2\u20ac\u2122re flying through this contingency abort. To make sure that it can dump safely, you need to have redundant parallel dump valves, helium systems that control the dump valves [and] software that makes sure contingencies can be taken care of.<\/font><\/p>\n \u00e2\u20ac\u0153Then, when you land, here you\u00e2\u20ac\u2122re sitting with the Centaur in the bay that you haven\u00e2\u20ac\u2122t been able to dump all of it, so you\u00e2\u20ac\u2122re venting gaseous hydrogen out this side [and] gaseous oxygen out that side and this is just not<\/i> a good idea!\u00e2\u20ac\u009d To support the new rocket on 61F and 61G, both Challenger and Atlantis underwent a series of lengthy modifications \u00e2\u20ac\u201c costing around five million dollars apiece \u00e2\u20ac\u201c which included extra plumbing to load and vent the Centaur\u00e2\u20ac\u2122s propellants and control panels in the flight deck to monitor its performance. As NASA\u00e2\u20ac\u2122s newest orbiter, Atlantis had been made Centaur-capable during her initial construction and was destined to spend the first few months of 1986 out at Pad 39A undergoing validation tests of the new hardware. <\/font><\/p>\n Following her return from 51L on February 3rd 1986, Challenger was expected to receive the Centaur modifications before being transferred to Pad 39B, while sister ship Discovery was earmarked for similar upgrades to support Department of Defense missions from Vandenberg Air Force Base in California. During typical, pre-launch loading operations, the liquid propellants would have been fed through plumbing \u00e2\u20ac\u02dctapped into\u00e2\u20ac\u2122 the Shuttle\u00e2\u20ac\u2122s main propulsion system feedlines. Emergency dumping vents were situated on either side of the aft fuselage and close to the vertical stabiliser tailfin, none of which filled Hauck or Walker with confidence due to the risk of leakages or explosions.<\/font><\/p>\n In fact, doubts over the reliability of the Centaur-G Prime flying aboard the Shuttle had already, in the autumn of 1981, obliged NASA to cancel it and opt to place Ulysses and Galileo onto \u00e2\u20ac\u02dcsafer\u00e2\u20ac\u2122 \u00e2\u20ac\u201c though less powerful \u00e2\u20ac\u201c solid-fuelled Inertial Upper Stage (IUS) boosters. For the exceptionally-large Galileo, which comprised both a Jupiter orbiter and atmospheric-entry probe, the swap from Centaur to IUS meant that its journey time to the giant planet would almost double to four-and-a-half years and most likely require the mission to be split into two \u00e2\u20ac\u02dchalves\u00e2\u20ac\u2122.<\/font><\/p>\n Predictably, Galileo\u00e2\u20ac\u2122s pricetag soared as a result, peaking at close to a billion dollars, until Congress pressed NASA in late 1982 to resume work on the Shuttle-borne Centaur and reduce the Jupiter travel time to around two-and-a-half years. Not only Galileo, but also Ulysses, required close encounters with the giant planet \u00e2\u20ac\u201c the latter as a means of altering its trajectory to rendezvous with the Sun\u00e2\u20ac\u2122s poles \u00e2\u20ac\u201c and both missions were duly allocated to the same<\/i>, week-long launch window in mid-May 1986. Hauck\u00e2\u20ac\u2122s crew would liftoff from Pad 39B aboard Challenger on the 15th, followed by Walker\u00e2\u20ac\u2122s team from adjacent Pad 39A aboard Atlantis on the 20th.<\/font><\/p>\n The two flights each had scarcely an hour available to them in which to launch and, in order to minimise weight, both would carry just four astronauts: Hauck was joined by Pilot Roy Bridges and Mission Specialists Mike Lounge and Dave Hilmers, while Walker\u00e2\u20ac\u2122s crewmates were Pilot Ron Grabe and Mission Specialists Norm Thagard and James \u00e2\u20ac\u02dcOx\u00e2\u20ac\u2122 van Hoften. Additionally, the two-day-long Death Star flights were headed for lower-than-normal, 105-nautical-mile-high orbits because, said Hauck, \u00e2\u20ac\u0153you need the performance to get the Centaur up because it was so heavy\u00e2\u20ac\u009d.<\/font><\/p>\n Throughout the second half of 1985 and into the spring of 1986, in addition to their rigorous training regimes, Hauck and Walker found themselves frequently questioning their own judgement over how many potential failure modes and problems they could live with. \u00e2\u20ac\u0153In early January 1986,\u00e2\u20ac\u009d Hauck recalled, \u00e2\u20ac\u0153we were working an issue to do with redundancy in the helium actuation system for the liquid oxygen [and] liquid hydrogen dump valves and it was clear that the [Shuttle management] was willing to compromise on the margins in the propulsive force being provided by the pressurised helium. We were very<\/i> concerned about it. <\/font><\/p>\n \u00e2\u20ac\u0153We had discussions about it with the technical people, but we went to a [review] board to argue why this was not a good idea to compromise on this feature. The board turned down the request. I went back to the crew office and said to my crew, in essence, \u00e2\u20ac\u02dcNASA is doing business differently from the way it has in the past. Safety is being compromised and, if any of you want to take yourself off this flight, I will support you\u00e2\u20ac\u2122. Two or three weeks later, Challenger blew up. Now, there is no direct correlation between my<\/i> experience and Challenger, but it seemed to me that there was a willingness to compromise on some of the things that we shouldn\u00e2\u20ac\u2122t compromise on\u00e2\u20ac\u009d.<\/font><\/p>\n Years later, Hauck remained undecided as to whether or not he would have refused, himself, to fly 61F, but admitted that the Shuttle management were taking unacceptable risks in the months leading up to Challenger\u00e2\u20ac\u2122s fateful launch. Only days after the tragedy, any lingering doubts were resolved for him. The Kennedy Space Center\u00e2\u20ac\u2122s Safety Office refused to approve advanced processing of the first Centaur-G Prime, citing \u00e2\u20ac\u0153insufficient verification of hazard controls\u00e2\u20ac\u009d from both NASA and the booster\u00e2\u20ac\u2122s contractor, General Dynamics. Additional safety concerns, and cost overruns to the tune of $100 million, ultimately led to the project\u00e2\u20ac\u2122s cancellation in June 1986.<\/font><\/p>\n Fortunately, a few years later, the Galileo and Ulysses missions went ahead, reverting to the less-powerful IUS to get them successfully \u00e2\u20ac\u201c though not without incident, and requiring considerably longer journey times \u00e2\u20ac\u201c to their celestial targets. History has shown us that both achieved considerably more than expected and truly revolutionised humanity\u00e2\u20ac\u2122s understanding of both our parent star and our planetary big brother, Jupiter.<\/font><\/p>\n","protected":false},"excerpt":{"rendered":" John Young called it the \u00e2\u20ac\u02dcDeath Star\u2019. Behind the dark humour, however, lay real concern for the then-chief of NASA\u00e2\u20ac\u2122s astronaut corps. Even with an increasingly confident outlook on the Shuttle\u00e2\u20ac\u2122s capabilities at the dawn of 1986, Young instinctively knew that the STS-61F and 61G flights would be two of the riskiest ever attempted by […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[],"class_list":["post-42248","post","type-post","status-publish","format-standard","hentry","category-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/42248"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=42248"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/42248\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=42248"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=42248"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=42248"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}