They are now looking at a capture time of ~9:40AM CT (about 90 minutes from this comment)
Live: SpaceX Dragon docking with ISS
61–70 of 109 posts
Re: Live: SpaceX Dragon docking with ISS
#62Earlier quoted context omitted.
spaceX says "coverage begins at 4:30 PT" http://www.spacex.com/ Here is that in your local time: http://www.wolframalpha.com/input/?i=4%3A30am+pt+in+local+ti... It's in 1 hour 48 minutes from the timestamp of this comment
"Webcast start time now targeting 5:45 AM PT / 8:45 AM ET. Times are subject to change so please check back for updates." https://spacex.com/updates.php
current estimate: 9:40 AM CT (in the video stream, and they stress it's an estimate).
Re: Live: SpaceX Dragon docking with ISS
#63Question: if Dragon is about 200m lower than ISS, and they are moving at the same velocity at one instant, wouldn't that put them in different orbits? Assuming ISS's orbit was perfectly circular, then Dragon would be moving too slow for its lower orbit, and would sink down, to its perihelion when on the opposite side of the earth, and so on, oscillating up and down, in an elliptical orbit with respect to ISS. The onl…
Aren't lower orbits faster? So wouldn't dragon be moving too slowly to maintain it's orbit, not too fast?
Re: Live: SpaceX Dragon docking with ISS
#64Question: if Dragon is about 200m lower than ISS, and they are moving at the same velocity at one instant, wouldn't that put them in different orbits? Assuming ISS's orbit was perfectly circular, then Dragon would be moving too slow for its lower orbit, and would sink down, to its perihelion when on the opposite side of the earth, and so on, oscillating up and down, in an elliptical orbit with respect to ISS. The onl…
I don't think 200m is enough to put them in significantly different orbits. Every once in awhile, dragon probably fires a thruster to make small adjustments.
edit, clarification: The problem is that the object closer to the earth will experience more gravitational force, which needs to be counteracted by orbiting faster, so that it's constantly falling 'tangent' to the earth. If they had the same angular velocity and the ISS was known to have a static distance from earth, Dragon would be slowly falling towards the earth because in order to maintain a static distance from earth, things above the ISS need to travel slower while things below need to travel faster.
Re: Live: SpaceX Dragon docking with ISS
#65NASA is broadcasting: http://www.nasa.gov/multimedia/nasatv/ustream.html Anyone know what time it's expected to dock at?
The NASA guy is using Windows XP, its pretty funny, he just screen-shared in the stream. I'm sure its some super custom software though.
If NASA had switched to Vista, station would have deorbited.
Re: Live: SpaceX Dragon docking with ISS
#66Earlier quoted context omitted.
They just announced an 8:10 am central time for robotic capture. After the arm makes the capture it's about 3 hours until it is fully docked to the station.
Docking in orbit is harder than it appears. Speed and altitude are linked so you can't just thrust towards the station or you will wind up in a different orbit: http://en.wikipedia.org/wiki/Space_rendezvous#Methods_of_app...
Dragon doesn't autonomously dock. It flies within range of the space station's robotic arm, is grappled, and then is slowly berthed to a docking port.
Re: Live: SpaceX Dragon docking with ISS
#67Dragon now 30m below the ISS
Re: Live: SpaceX Dragon docking with ISS
#68I've been waiting for this for a long time. I spent the past two summers working on the Dragon docking as an intern.
Are you a programmer? Is the docing full automatic? Until know the only automatic thing was the ATV right?
Re: Live: SpaceX Dragon docking with ISS
#69Question: if Dragon is about 200m lower than ISS, and they are moving at the same velocity at one instant, wouldn't that put them in different orbits? Assuming ISS's orbit was perfectly circular, then Dragon would be moving too slow for its lower orbit, and would sink down, to its perihelion when on the opposite side of the earth, and so on, oscillating up and down, in an elliptical orbit with respect to ISS. The onl…
Aren't lower orbits faster? So wouldn't dragon be moving too slowly to maintain it's orbit, not too fast?
Think of energy. The higher orbit has higher energy with respect to the earth -- gravitational, and by virtue of comparing stable orbits, also kinetic. Dragon will "catch up" with the space station by converting some additional chemical energy (propellant) into kinetic energy, moving into and matching the station's orbit (and gaining the additional gravitational potential). (Or, given the small adjustment needed, perhaps mechanical energy, depending upon how the positional thrusters work -- compressed gas?)
Ugh, my physics classes are a long time away. Hope that's worded halfway comprehensibly.
Re: Live: SpaceX Dragon docking with ISS
#70This is just awesome.
I'm sitting in the middle of the French country side in a building that was built during Galileo's life time with these links up across three monitors:
mms://a1709.l1856953708.c18569.g.lm.akamaistream.net/D/1709/18569/v0001/reflector:53708
http://www.nasa.gov/multimedia/nasatv/index.html?param=stati...
Watching all of this makes me realise just how lucky we are to be alive at this point in human history.
Oh and looks like first capture attempt could be as soon as 20ish minutes from now (i.e. 14:02 UTC).
Edit: they've just given a go for capture.
Edit 2: and here's a screen shot of the Dragon capsule and space station arm: http://imgur.com/OWit7