Space Shuttle Discovery launches on mission STS-124

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Saturday, May 31, 2008

Discovery lifts off to begin STS-124

Space Shuttle Discovery has successfully launched from Launch Complex 39A at the Kennedy Space Center in Florida, beginning mission STS-124. Discovery will deliver the main pressurised module of the Japanese Experiment Module to the International Space Station. Lift-off occurred at 21:02:12 GMT this evening, with the ascent to an initial sub-orbital trajectory lasting approximately eight and a half minutes. Orbital insertion occurred shortly afterwards, with a circularisation burn which concluded at 21:42 GMT.

This is the third Space Shuttle mission of 2008. STS-124 is the second of three missions to assemble the Japanese Experiment Module, also known as Kibo. The JEM Pressurised Module (JEM PM or JPM) is the largest laboratory module of the International Space Station, and one of the largest payloads ever launched by the Space Shuttle. The main Japanese robot arm, or RMS, will also be launched on this mission. Discovery's mission is scheduled to last for fourteen days, however it can be extended by two days if necessary. Three spacewalks, or EVAs, are planned to be conducted.

The crew of STS-124

STS-124 has a crew of seven astronauts; Mission Commander Mark E. Kelly, Pilot Kenneth Ham, Mission specialists Karen L. Nyberg, Ronald J. Garan, Michael E. Fossum and Akihiko Hoshide, and Expedition 17 crewmember Gregory Chamitoff. All crewmembers are American, except Hoshide, who is Japanese. The astronauts were awoken at 11:30 GMT on launch day, and began preparations for their launch. This is the first spaceflight for Ham, Nyberg, Garan, Hoshide and Chamitoff, the second for Fossum, and the third for Kelly. The launch coincides with Kelly's father's birthday.

Preparations for launch had been underway for several months. The External Tank arrived at the Kennedy Space Center in late March. Following tests in a checkout cell, it was mated with two solid rocket boosters which had been assembled on a Mobile Launch Platform. Discovery was then rolled from the Orbiter Processing Facility to the Vehicle Assembly Building for mating with the External Tank and boosters. Rollover occurred in late April, and was followed by rollout to the launch pad about a week later.

The JEM Pressurised Module

The Kibo pressurised module arrived at the Kennedy Space Center in May 2003 by ship. It was then moved to the Space Station Processing Facility. Electrical interface tests with the Harmony node were conducted in August 2003. At the end of April 2008, the module was placed in a transportation canister, and moved to the launch pad. The payload arrived at the launch pad about a week ahead of the Shuttle. Once Discovery arrived at the launch pad, the module was placed into Discovery's payload bay. Owing to the size of the payload, there was no room in Discovery's' payload bay for the Orbiter Boom Sensor System (OBSS), a safety device used primarily to inspect the Shuttle Orbiter's heat shield. As a result of this, Endeavour left its OBSS at the International Space Station, during the last Shuttle Mission, STS-123. Discovery's crew will collect this during an EVA.

Fueling of Discovery's External Tank in preparation for launch began at 11:50 GMT. By 12:50, it had been confirmed that initial tests on Engine Cutoff (ECO) sensors in the External Tank had been conducted successfully. ECO sensor failures had caused a number of delays to recent Shuttle launch attempts, and STS-124 is the first mission to use a modified tank, which is intended to eliminate such faults. At the time at which tanking began, weather forecasters predicted an 80 percent chance of acceptable conditions at the scheduled launch time. Fuelling was completed, and topping up of cryogenic propellant began, at 15:36. In addition to the ECO sensor modifications, this was the first mission to use an External Tank manufactured after the Columbia accident in 2003, and therefore the first tank to have all safety enhancements built into it, rather than retrofitted.

Discovery begins its ascent to orbit

The terminal countdown resumed after a planned hold at T-3 hours, at 17:07 GMT. Crew walkout from the Operations and Checkout building at the Kennedy Space Center occurred at 17:12. Following walkout, the crew boarded a bus known as the "astrovan", which was used to transport them to the launch pad. The crew arrived at the launch pad at 17:31, and began boarding Discovery at 17:38. As Mission Commander, Mark Kelly was the first to board the orbiter. He was followed by Chamitoff at 17:42, Ham at 17:52, Fossum at 17:55, Nyberg at 18:08 and Hoshide at 18:11. Ron Garan was the last to board the orbiter at 18:21. Pad technicians known as the closeout crew, assisted the astronauts with boarding the Shuttle, and getting strapped in. The pad technicians were cleared to close the orbiter's access hatch at 19:02 GMT, and the hatch door was closed two minutes later at 19:04. Sealing the hatch was completed at 19:54.

A scheduled ten-minute hold at T-20 minutes began at 19:47 GMT. During this hold, the closeout crew put thermal insulation plugs into screwholes on the orbiter's hatch, removed protective covers, and disassembled the white room, a collapsible structure at the end of the crew access arm which is used to access the spacecraft. The countdown resumed at 19:57. At that time, no problems were being worked.

The launch of STS-124

The final built in hold, at T-9 minutes and lasting for 45 minutes and 12 seconds, began at 20:08. During this hold, flight controllers set the exact launch time to be 21:02:12 GMT, and confirmed that the launch window would end at 21:08:59 GMT. The countdown was set to resume at 20:53:12. Shortly before the end of the hold, the launch director described conditions as a "gorgeous day to launch", and wished the crew "good luck and Godspeed". Mark Kelly thanked him, and replied "whilst we tend to live for today, Discovery, with Kibo, will certainly deliver hope for tomorrow". Countdown resumed on time at the end of the hold, and the automated Ground Launch Sequencer was initiated.

When giving clearance to retract the Orbiter Access arm from the Shuttle, seven minutes before launch, the Orbiter Test Conductor wished the crew "best of luck delivering JEM to the International Space Station". Four minutes before launch, the engines were purged of gasses, and tests of the flight control surfaces began. Liquid hydrogen tanks were pressurised shortly after at T-3 minutes, and the fuel vent cap was retracted. Two minutes before lift-off, the crew were instructed to close and lock their visors, and the liquid oxygen tank was pressurised. At T-50 seconds, the orbiter switched to internal power, and the Shuttle's flight computers took over control of the countdown at T-31 seconds.

SRB separation

Launch occurred on schedule at 21:02:12 GMT. The Solid Rocket Boosters separated about 120 seconds into the flight, and around eight and a half minutes after launch, the Main Engines (SSMEs) shut down, and the External Tank was jettisoned. At this time, Discovery was on a 65km x 217km x 51.6° sub-orbital trajectory. Orbital insertion followed about thirty minutes later, with a firing of Discovery's OMS engines. This burn started at 21:39 GMT, and ended at 21:42, lasting two minutes and 44 seconds.

At the time of launch, the International Space Station was flying over the Atlantic Ocean, South-East of Canada. Following launch, a fault was detected with the backup electrical system controlling the left OMS engine gimbal actuator. As it was a backup, flight controllers predicted that it would have no effect on the mission, and all scheduled burns will go ahead. The fault was later traced to the failure of both transducers in the unit, and it was reported that the problem was probably due to an equipment malfunction as opposed to a faulty sensor. When asked about the faulty actuator, NASA Administrator Mike Griffin stated that at the "worst case it would be a loss of redundancy but we will still be able to use that system". Discovery's payload bay doors were opened at 22:35 GMT. At 23:09, the crew were cleared to begin on-orbit operations.

Processing and countdown progressed smoothly, and were described by Discovery's processing and launch flow director, Stephanie Stilson, as being "a very clean flow". Mission Commander Mark Kelly remarked that there had been a "historic low on spacecraft issues". Around four hours prior to launch, Stilson remarked that there had been 73 anomalies detected so far. The smallest number of anomalies during the countdown for a previous mission was 76, for STS-103.

Moron AFB in Spain was considered the primary transoceanic abort landing (TAL) site, should an engine failure, or other major problem have occurred during early ascent. Istres in France was considered the backup TAL site. The weather at both of these sites was good, however no abort was required during the launch.

This is the 123rd Space Shuttle mission, and the 35th to be flown by Discovery. Ten further missions are planned, including two contingency logistics flights, prior to the Shuttle's retirement in 2010. Discovery is assigned to three of these missions. It is next scheduled to fly in early 2009, on mission STS-119. The next Space Shuttle mission will be conducted by Atlantis, which will fly STS-125, the final mission to service the Hubble Space Telescope. This is the fourth manned, and 27th orbital launch of 2008.

At a press conference following launch, NASA Administrator Mike Griffin stated that it was "a huge day for the space station partnership", and that the International Space Station was "a place in orbit where we can learn to live and work in space". He congratulated JAXA on the launch of the Japanese Experiment Module, saying that "Japan has now built a first class laboratory...which is capable of supporting humans in space", and that "with this step Japan has shown itself to be capable of performing at the highest levels of space exploration". Griffin also stated the STS-124 is "an essential step" in the Space Station programme. When asked by a reporter how he felt about recent NASA successes, including the STS-124 launch, and the landing of the Phoenix probe on Mars last Sunday, he joked that it felt "so great that not even having to do a press conference, two press conferences in a week can ruin it". When asked about the difficulty of what NASA was doing, he remarked that flight controllers "make it look easy", but "it is so far from being easy that I could talk until 6am tomorrow, and I wouldn't touch on how difficult it is".

NASA Associate Administrator for Space Operations Bill Gerstenmaier said that it was "a great day for the launch", and described STS-124 as a "pretty challenging mission". Gerstenmair stated that five foam debris impacts had been identified during ascent, but that NASA "don't consider this a big deal, they were all late". When asked what he meant by 'late', he explained that after 123 seconds into the flight, pieces of falling foam debris "can't build up enough velocity to hit the orbiter, or if they hit the orbiter they will just bounce off" He went on to say that "things look really well and look really good", and that NASA have "no concern" about foam, "It's not an issue to us".

Launch Integration manager LeRoy Cain described it as a "flawless countdown and a flawless launch". He said that STS-124 is "a big milestone for us", and went on to explain that "this is the most important mission we have going right now". He also stated that the "tank's performance looks really good".

Launch Director Mike Linebach stated that it was a "Fantastic launch", that was tying for the lowest faults during a countdown, with 74 issues reported. Stephanie Stilson has previously stated that the record was 76 issues, so it is unclear whether STS-124 has set a new record, or is tying with the previous record. Linebach went on to describe the launch as "outstanding".

Keiji Tachikawa, the President of JAXA said that he "was very delighted to see the Shuttle Discovery successfully launched". He stated that the Kibo module would "significantly enhance the capability to perform experiments in orbit", and that experiments conducted aboard the Space Station, and the Kibo module, would lead to "better daily lives for the people of our planet". He also expressed his "profound appreciation to NASA, and all international and domestic organisations" involved in the launch, explaining that the mission is "very significant to Japan".


Sources

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