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Soyuz Breaks Speed Record To ISS
Zothecula writes "A manned Soyuz spacecraft set a record for traveling to the International Space Station (ISS), arriving six hours after launch instead of the usual two days. Soyuz 34 lifted off from Baikonur Cosmodrome in Kazakhstan on Friday, March 28 at 4:43 p.m. EDT (08:43 GMT) and docked with the ISS at 10: 28 PM EDT (03:28 GMT). It was able to catch up and match trajectories with the ISS in only four orbits using new techniques previously tested in ISS rendezvouses with Russian unmanned Progress cargo ships."
I went to see what's ArsTechnica been up to lately, and holy cow has that site grown in the last couple of years! They have all the topics I'm interested in, and apparently, not days late. Also, they don't have contempt for their members.
So, I'm going to type in a random password for my Slashdot account and log out.
G'bye Slashdot editors, go fuck yirselves!
"The agriculture ministry is not in charge of Gundam" - Japanese ministry official.
You'll be back, just like the rest of us: slaves to some long distant memory of a once great site ;-)
The launch window is small because ISS has to be essentially lined up in orbit in a tight tolerance (called the phase angle) to rendezvous this quickly. Usually the Soyuz plays "catch up" over 2 days by flying lower (and faster) than ISS. You can control the closing rate between the vehicles by altering the altitude difference between them, which allows you to make up differences in the orbits between the vehicles. Those differences are usually just fallouts of other things, like having uncertainty in launch dates, getting the altitude just right for other vehicles (there is about a rendezvous a month at ISS), etc. It's not because Soyuz is slow, it's because spreading the rendezvous over 2 days gives you some targeting flexibility.
You have less margin to work with when you are trying to get there in 4 orbits instead of 34 orbits. Hitting that target with both ISS and Soyuz is hard but it's more about ground targeting than performance of the launch vehicle. The launch vehicle didn't give any extra oomph to get there faster, the ground essentially had the vehicle phasing in a tight tolerance at launch. They also sped up some of the tracking that was being done and turning that around into updated burns for the next orbit instead of coasting to a set of burns the next day, which was a bunch of work for the ground in a short period of time.
The Russians that devised this actually published it - it's an interesting read if you have access to the journal or want to spend $32:
http://www.sciencedirect.com/science/article/pii/S0094576510001633
Worst...sig...ever!
The fastest to ISS, but not the fastest docking ever... I believe that record belongs to Gemini 11 which docked on it's first orbit - 96 minutes after launch. Gemini 8 managed the first ever docking between spacecraft in orbit a mere six hours and thirty three minutes after launch.
In the past they've taken four days in order to allow the crew time to get used to weightlessness, and to check out the spacecraft - doubly important for Soyuz since it'll be there for months and doubles as the crew's escape pod. That being said, the 'express' profile has been chosen for no other reason than to save money on mission control personnel... (Though they're trying to spin it otherwise.) In reality, I suspect those controllers are employed year 'round, but the money is only debited from the ISS program when a Soyuz is in [active] flight - making any real savings illusory.