6p 10/23 Update: Soyuz TMA-12 landing on tap

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CBS NEWS Coverage of Breaking Space News
Posted: 6:00 PM, 10/23/08

By William Harwood
CBS News Space Consultant

Changes and additions:

10/17/08 (05:45 PM): Engineers troubleshoot Hubble trouble; optimistic about eventual fix
10/21/08 (04:15 PM): Engineers not yet sure what to do about Hubble glitches
10/23/08 (03:45 PM): Hubble engineers restart payload computer; gear up for instrument power up in wake of glitches last week
10/23/08 (06:00 PM): Soyuz TMA-12 hatch closed; undocking, landing on tap

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6:00 PM, 10/23/08, Update: Soyuz TMA-12 hatch closed; undocking, landing on tap

Expedition 17 commander Sergey Volkov, flight engineer Oleg Kononenko and U.S. space tourist Richard Garriott, squeezed into their Soyuz TMA-12 spacecraft today and prepared to undock from the international space station, setting the stage for re-entry and landing later this evening in Kazakhstan. Touchdown is targeted for around 11:36 p.m. EDT.

Kononenko and Volkov, son of Russian cosmonaut Alexander Volkov and the first second-generation space flier, were launched aboard Soyuz TMA-12 on April 8. Garriott, son of former Skylab and shuttle astronaut Owen Garriott, was launched aboard the Soyuz TMA-13 spacecraft Oct. 12, along with Expedition 18 commander Mike Fincke and flight engineer Yury Lonchakov.

Garriott, a successful computer game developer, is the sixth tourist to visit the space station, paying some $30 million - the bulk of his personal fortune - for a 10-day stay aboard the lab complex. He is joining Volkov and Kononenko for the ride home, leaving Fincke, Lonchakov and NASA flight engineer Gregory Chamitoff behind aboard the station.

"This has met and in many ways exceeded my expectations," Garriott told reporters Monday. "There's no question, I've already begun to think about the next trip up. With this trip, I was trying to study and analyze how private citizens might be able to contribute to the success here in space. And I'll have a lot more thoughts on that when I come back down."

Here is an updated timeline of major re-entry events (in EDT and mission elapsed time):

DATE/EDT...DD....HH...MM...EVENT

10/23/08
06:19 PM...198...11...03...US-to-Russian motion control system handover
07:42 PM...198...12...26...ISS maneuvers to undocking attitude
08:05 PM...198...12...49...Russian ground station radio contact
08:06 PM...198...12...50...Sunrise
08:11 PM...198...12...55...ISS to free drift
08:12 PM...198...12...56...Undock command
08:15 PM...198...12...59...Physical separation (dV: 0.3 mph)
08:18 PM...198...13...02...Soyuz separation burn 1 (dV: 1.2 mph)
08:20 PM...198...13...04...ISS maneuver to normal orientation
08:28 PM...198...13...12...Russian ground station loss of signal
09:54 PM...198...14...38...Russian-to-US motion control system handover
10:45 PM...198...15...29...Deorbit burn start (dV: 257.7 mph)
10:49 PM...198...15...33...Deorbit burn complete
11:10 PM...198...15...54...Separation of modules (alt: 87 miles)
11:13 PM...198...15...57...Entry interface (alt: 63 miles)
11:15 PM...198...15...59...Entry guidance start (alt: 50 miles)
11:20 PM...198...16...04...Maximum G-load (alt: 20 miles)
11:21 PM...198...16...05...Command to open parachute (alt: 6.6 miles)
11:36 PM...198...16...20...Landing

"From a personal joy standpoint, the whole journey, frankly even before launch, the opportunity to train for and work with these amazing astronauts and all the very capable people on the ground that pull off this amazing orchestra that it takes to keep all of this up in space, that was really fulfilling even before launch day," Garriott said. "Of course, it's been great icing on the cake to actually take the rocket ride, which was very exciting, and of course, the view from up here is spectacular. So I've really enjoyed all of my time here so far, both in serious science and educational work as well as things like the earth observation photography, which is always a joy."

Garriott's father, Owen, chatted with his son on a daily basis during the station flight and flew from Moscow to Kazakhstan to be on hand for landing.

"That's been a real joy, not just talking to him from space but this whole year we've actually spent working together for this flight," Richard Garriott said. "It's been a great opportunity for us to bond, so to speak, as adults in ways we haven't had a chance to do in many years."

The Soyuz TMA-12 re-entry has generated more interest than usual because the previous two Soyuz entries were marred by module separation problems that led to steep, "ballistic" trajectories resulting in off-course landings that subjected the crews to extreme vibrations and G forces.

The Soyuz spacecraft is made up of two pressurized modules and an aft propulsion module. Just before atmospheric entry, the aft propulsion and forward orbit modules separate from the central descent module carrying the crew. Only the descent module is equipped with a heat shield and parachutes. The other two modules burn up in the atmosphere.

In the previous two Soyuz entries, the propulsion modules failed to separate properly from the crew capsules and the vehicles entered the atmosphere connected, in a nose-forward orientation. Atmospheric stress and heat eventually caused the modules to separate, but not before triggering ballistic descents.

During a spacewalk July 10, Volkov and Kononenko removed one of five explosive bolts that normally fire to ensure separation of the descent and propulsion modules. The bolt in question is believed to have malfunctioned during the previous two entries and it is being returned aboard the TMA-12 vehicle for a detailed engineering analysis.

Russian engineers believe the TMA-12 modules will separate normally. But if they don't, a software patch is on board that will re-orient the craft to ensure a quick separation.

"First of all, we removed this pyrobolt that our experts thought was the cause of the previous two ballistic re-entries," Volkov said in English during a news conference Monday. "During the re-entry, our engineers will add special software program patch that will move our vehicle to another attitude that will allow us, in case of non-separation on time, go into the atmosphere in right attitude. The atmosphere will help us separate and stay in the normal attitude."

Garriott said he had no concerns, adding the crew trained in a centrifuge that simulated high-G ballistic entries.

"Of course, I've paid close attention to the last two ballistic re-entries and watched all the reports and analyses as to what was the cause and what was done to repair it," he said. "But I have no concerns about re-entry. Even if there was a ballistic re-entry, that's still a normal mode of re-entry, really, and so I'm excited about the trip home regardless."

Russian space program recovery forces are staged to assist the crew after a normal landing northeast of Arkalyk, Kazakhstan, or a ballistic entry, which would result in a landing 300 miles or so short of the normal touchdown point.

"Our Russian colleagues have spent an enormous amount of time, a very structured effort, to create a fault tree and then work off the fault tree to come to a most probable cause," Mike Suffredini, NASA space station program manager, told reporters in late September. "They have concluded the most probable cause to be related to the (electrically charged) plasma environment and the (difference in) potential between the plasma environment, the environment around space station, and the space station itself.

"The way the space station is wired together, there actually is a voltage, a delta voltage potential, between the environment around the ISS and the ISS itself and what happens over time is occasionally that potential tries to equalize. And when it tries to equalize, you get what essentially is a spark to the ISS. This is an environment we've been living in since we starting flying ISS, it's why we have what we refer to as the plasma contactor units that we operate during EVAs to prevent that from occurring during EVAs."

The plasma contactor units use xenon gas to equalize electrical potential around the station. The xenon supply is limited and the PCUs are only operated during spacewalks to prevent any chance of arcing while astronauts are working outside. Testing showed no obvious threat to the station's systems when the PCUs were turned off.

"What our Russian colleagues have determined is because of the very specific configuration of the pyros ... on the Soyuz, where it's failed to separate each time, they've determined that there's been some arcing, if you will, or equalizing of voltage in this area," Suffredini said. "And this over time has caused the pyros to be ineffective."

The culprit apparently involves insulation on the Soyuz near the pyro in question that includes an ungrounded aluminized layer.

The huge U.S. solar arrays that provide most of the station's power affect the electrically charge plasma around the lab. The recent Soyuz problems occurred after a major change in the configuration of the arrays. Another major change is expected next year, when a fourth and final set of arrays is added to the starboard side of the station's main power truss.

While some NASA engineers are not convinced the evidence supporting the arcing theory is conclusive, "it's a plausible scenario," Suffredini said.

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Quick-Launch Web Links:

CBS News STS-126 Status Reports:
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NASA ISS Expeditions Page:
http://www.nasa.gov/mission_pages/station/expeditions/index.html

NASA Shuttle Web: http://spaceflight.nasa.gov/shuttle/index.html
NASA Station Web: http://spaceflight.nasa.gov/station/index.html
Spaceflight Now: http://spaceflightnow.com/index.html
GoogleSatTrack: http://www.lizard-tail.com/isana/tracking/

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