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:
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:
This is the only one which gives me actual video (though it's just of a computer screen atm, a deathstar-like graphic) - the others had voices, and no video but a small blinking light and vertical bands near the bottom of the screen).
uh oh, now it's also showing a blinking light and bands...
EDIT at last, Dragon sliding across the earth, from the ISS. Amazing seeing one spacecraft from another. Later, a thermal image of ISS from Dragon. But they're mostly showing people in front of computers...
Watching dragon sliding over those clouds is pretty hypnotic. You can see why they say watching earth from space makes the boundaries between countries disappear.
What are the tiny objects that seemed to be criss-crossing all over the background of the blinking light (visible clearly in fullscreen) ? Other satellites?
either a city or another satellite. The first "mysterious light" I saw, which I thought was another lit satellite, was eventually described by the channel narrator as the city of Los Angeles going by far below. It was late at night, and we were seeing the lights from the LA metro area.
Well I spent the last two summers as an intern at SpaceX working on several things, but one was that mechanism that the Canadian arm attaches to. I can't talk much about the specifics, but one of things I did was program the micro-controllers that interface with the motors that open the hatch door (and some other stuff) that contains the hook for the robotic arm to grab. I wish I could write more and even make a blog post, but I'm simply not allowed to do so.
I'm an electrical engineering student. When it came to docking mechanism I was an embedded systems programmer. Yes, to my knowledge the docking is fully automatic.
Around 2:00 AM Pacific/5:00 AM Eastern NASA will decide if Dragon is GO to move into the approach ellipsoid 1.4 kilometers around the space station. If Dragon is GO, after approximately one hour Dragon will move to a location 250 meters directly below the station. Dragon will then perform a series of maneuvers to show systems are operating as expected. If NASA is satisfied with the results of these many tests, Dragon will be allowed to perform the final approach to the space station.
Sometime around 6:00 AM Pacific/9:00 AM Eastern, astronauts on the space station will grapple Dragon with the space station’s robotic arm and the spacecraft will attach to the station."
The monitor view that they're occasionally showing displays a reticle over Dragon. Or it's supposed to, but the reticle is a bit off (Kuipers spent some time talking to houston about it).
It reminds me of the adventures that Pettit had with camera calibration yesterday, I wonder if there's a connection?
Anyway, listening to Pettit talk through the camera calibration yesterday made me think that there's a lot of room for improved UX in the software they use.
As an aside, I strongly dislike the term UX/User eXperience, it makes no sense to me. I could substitute 'UX' for 'design' above and all would be well in my world.
I might say that the operators of the 3 Mile Island nuclear reactor where having a fine "user experience" because the interface was telling them everything was OK...
User experience is the overall feeling you get from a well combined language, graphic design, sound, motion, information design, interface design, interface design, interaction design and programming.
Question: 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 only solution I see is for Dragon to artificially make its elliptical orbit circular by continuously thrusting upward. But I don't see this in the video stream. Have I got this all wrong?
EDIT s/too fast/too slow/ # and related edits, thanks mmaunder
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.
At some point when they were a few meters away, the NASA video mentioned the Dragon was now "free floating". So, I think they were continuously gently firing the thrusters to maintain orbit until they got extremely close.
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.
Lower orbits have higher anglular velocity -- and it is angular velocity that dictates which craft gets ahead on orbit, because we're comparing angular position, not linear one.
For example, geostationary orbit (~36'000km radius) has period of 24h -- i.e., takes whole 24hours to cover all 360 degrees of rotation, having angular speed of 15deg/h, while Hubble's Space Telescope orbit (~560km radius) has period of 96minutes -- i.e., takes just over 1.5h to cover 360 degrees; with angular speed of 240deg/h.
Sure GEO has higher linear velocity and associated kinetic energy, but that's irrelevant.
I guess the Dragon was positioned under the Station so it gains the angular position slowly over time in a natural way.
Looking at the screen with the cross-hairs it seems like the bottom right set of figures shows the distance to ISS, which was sitting at around 255m, and should go down to 235m (EDIT: was originally supposed to be 220m) before the crew on ISS tells dragon to head back to the 250m mark.
Here's hoping that they keep showing these shots from the ISS monitors throughout - kinda like watching someone coding but on a whole different level!
Does anyone know why this has been changed? I'd hazard a guess at dragon being slightly off the target position (slightly northwest), but haven't heard any commentary about why this may be.
I thought the planning and preparation would have some allowance for slight discrepancies, so are the changes to the planned points (220m to 250m) a part of this procedure, or would these "deltas" be a reactive response to real life?
Yes! Goosebumps.. But, I must unfortunately confess.. seeing all that unbranded space on the Dragon had me cynically thinking, how much could they sell that ad space for?
I'm kind of surprised that SpaceX didn't consider that for the outside of the dragon capsule.
Note that the capsule has a camera inside of it (there are pictures from it on SpaceX's site) so when the hatch opens you can see pictures directly from a video camera that isn't under NASA's control.
Watching the Dragon approach from the point of view of the ISS is incredibly exciting in itself, but almost unbelievable when you think about the speeds they are flying at relative to the ground!
What's unbelievable about this? If I approach you on the ground we are both moving fast relative to center of the Earth. Or imagine us onboard the airplane.
Just joined and heard that SpaceX had commanded Dragon to retreat from ISS. Can someone explain why? Also, what is the blinking section on the Dragon spacecraft?
I'm glued to watching this and doing very little work. I was born in 1969 and was fascinated by space as a kid, but then went off and did other things. To see this happening is wonderful but I have done screenshots of a number of places which would make dramatic and beautiful paintings
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:
http://www.n2yo.com/?s=38348
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