Image: Soyuz TMA-9
The Soyuz TMA-9 crew capsule closes in on the space station with Earth as a backdrop, as seen in this September 2006 photo taken from the station. TMA-9 is due to become the longest-serving Soyuz craft in space history, with its landing coming 214 days after launch.
By NBC News space analyst
Special to NBC News
updated 3/28/2007 6:10:11 PM ET 2007-03-28T22:10:11

Flight records in the risky world of aerospace are often achieved by "pushing the envelope," poking beyond the "red lines" and charting new operational regimes. And that’s just what astronauts on the international space station will do when they head home in mid-April.

With the space station set to receive a new crew, the current team keeps setting new records to delight statisticians: Station commander Michael Lopez-Alegria has attained top status in the U.S. record book for spacewalking, and his American colleague Sunita Williams (who will remain aboard across the handover) now holds the women's spacewalking record . Their Russian crewmate Mikhail Tyurin has done some of his own record-grabbing, including his famous " space golf" shot .

The crew due to fly up to the station in a Russian Soyuz capsule — incoming Russian expedition commander Fyodor Yurchikhin, his flight engineer (and Soyuz vehicle commander) Oleg Kotov and billionaire space passenger Charles Simonyi — are also in line to make history when they lift off April 7.

It will be the first time in the space station's history that a three-person Soyuz crew has been commanded by a space rookie. And because of a scheduling modification, the visiting crew will be aboard the station for two extra days — making this the longest "short-term" visit to the space station.

But the most significant "longest ever" record is more than merely a bigger number for a record book. It’s a question of current crew safety, as well as potential improvements in space transportation as the station evolves into a permanent six-person crew.

The crew coming back to Earth — Lopez-Alegria, Tyurin and Simonyi — will be landing in a spacecraft with an "expired warranty." Their Soyuz TMA-9 capsule will be the oldest-ever Soyuz to bring crewmen back to Earth.

The official on-orbit lifetime of the Soyuz TMA spacecraft — an upgraded version of the same basic design that first carried a cosmonaut into orbit on April 23, 1967 — is 210 days. If current schedules hold, the crew will be landing 214 days after launch.

Since it was introduced in 2001, the Soyuz TMA model has averaged about 188 days per flight, with none lasting more than 195 days. An earlier model, supporting visits to the Mir space station, flew as long as 198 days in the late 1990s.

The 210-day lifetime is not a hard-and-fast "drop dead" boundary, so operators at Moscow’s mission control center do not expect any problems. It is unclear how much NASA officials have been told about any extra Russian attention to the possible effects of the longest-ever mission duration.

What could go wrong?
Space engineers tell that the limit is based on the chemical stability of hydrogen peroxide within a tank in the Soyuz descent module, where the crew rides. This chemical, liquid at room temperature, is used for roll control during atmospheric entry. The jets, aligned along the capsule’s rim, turn the capsule about its long axis. This allows its heavier side to dig into the air flow at different angles and create some aerodynamic lift, which in turn allows the falling capsule to be steered toward its desired landing point.

Over a long period of time, hydrogen peroxide decomposes into water, and the resulting mix loses its force when expelled through the steering nozzles. But the status of the tank's contents can be monitored by Moscow, so the extent of decomposition can be noted.

Even if the tank’s chemicals become unusable, the capsule’s return can still be performed safely in what is called a “ballistic” (non-steered) mode. This is done by placing the spacecraft in a slow roll. This cancels out any lift and allows the spacecraft to plunge more quickly into the lower, thicker layers of the atmosphere rather than skim the thinner upper layers and slow down more gently. Deceleration forces can be up to 50 percent greater — but the crews have trained for this contingency and in the past have endured them safely.

Making virtues out of necessities
The extra record-breaking duration was not originally planned, and the flight has ended up about a month longer than originally scheduled. The preliminary March 20 landing date conflicted with NASA’s then-scheduled shuttle mission (now delayed into May or June by the “hail from hell” ).

Slideshow: Month in Space: January 2014 Also, the Russian side had wanted to shift their twice-yearly Soyuz launches from March and September to April and October anyway — mainly because climate changes in Kazakhstan in the early spring had led to much more standing water on the steppes where the recovery must occur.

So this scheduling shift — which may become permanent — was desirable even before Russia agreed to NASA’s official request to delay the Soyuz landing, to avoid conflicting with the now-delayed shuttle mission. The Russians turned out to get what they had themselves wanted, but now NASA owes them a favor for doing it. And it also means that the Soyuz TMA-11 launch in the fall will coincide with Russian celebrations of the 50th anniversary of Sputnik's launch on Oct. 4, 1957 — an event that marked the birth of the Space Age.

Extending the warranty
In the long term, Russian space engineers want to extend the Soyuz mission length from seven months to 13 months. This will be important in two years when the space station evolves to a six-person permanent crew. With six-month Soyuzes, Russia needs to launch four per year, double its current production rate. Longer duration in orbit can mean fewer required launches, as long as the crew can handle the extra duration as well.

Meanwhile, Michael Lopez-Alegria will be able to use the bonus three weeks in space to grab the record for the longest single U.S. spaceflight, now held by two astronauts on a mission in 2002 that lasted 196 days (they went up and came down by shuttle).

Russian duration records are much longer — one is more than twice as long. Those records will probably stay in Moscow until astronauts head out for Mars a few decades from now.

An earlier version of this story misstated the historical precedents for the TMA-10 crew heading to the station.

NBC News space analyst James Oberg had a 22-year career as a space engineer in Houston, where he specialized in NASA space shuttle operations for orbital rendezvous. He has written numerous books about the U.S. and Russian space efforts, including "Star-Crossed Orbits: Inside the U.S./Russian Space Alliance."


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