Dragon Update
SpaceX’s Dragon Carrying NASA Cargo Resupplies Space Station
“The Space Exploration Technologies Corp. (SpaceX) Dragon spacecraft was berthed to the International Space Station at 8:56 a.m. EST Sunday. The delivery flight was the second contracted resupply mission by the company under NASA’s Commercial Resupply Services contract.”
SpaceX Dragon Docks with the International Space Station (Video)
Folks:
I found it interesting that Houston would berth the Dragon from the ground. I know they’ve done robotic ops before from the ground before but I don’t know if they’ve even dared walk off from one data/grapple fixture to another from the ground, let alone berth a spacecraft. The Dragon is the only spacecraft that Houston could rightfully ‘play with’ being the only American spacecraft and all. Almost like having another crew member up there really.
[edit] I was wrong! The folks at the Canadian Space Agency get to berth Dragon. Well, it is their arm kinda.
tinker
They are probably using the German telepresence software to do this.
Dennis:
Seriously? How does it work?
tinker
Tinker and Dennis, there’s no Geman telepresence software being used to berth the Dragon. The ground controllers are sending commands to pre-position the vehicle above the common berthing mechanism, and the crew will do the final install.
Belay my last. The ground is taking the vehicle all the way to the install position, but they’re still not using a German telepresence software. They’ll be using the onboard cameras for positioning.
The German telepresence software was originally developed as far back as Spacelab D1 and has been further developed over this whole time. I was working with DLR when the ISS program accepted it for use on the main ISS arm. I have not kept up over the past few years though so my information may be out of date.
I seriously doubt they will ever attempt that from the ground. The time delays are too large. [Thanks Steve!]
Richard,
If things have been implemented as originally proposed, then they should be able to berth it, slowly, from the ground. The on-board software of the both the Dragon and the ISS would be in the loop as well, and would override any commands that were leading them into trouble, and let them pull off and retry.
I think this was a good idea because they need to know whether or not it can be done reliably from the ground before encountering a situation where it has to be done from the ground (imagine everybody on the ISS becoming too sick to participate, and supplies or medicine have been sent up on an unmanned spacecraft; unmanned so that no one else is infected). I am surprised, though, that they did it this early on, this being only the second Dragon delivery.
Folks:
Three for three, and this Dragon was an hour early! Trying to make up for being late, I guess. “I’m late, I’m late, for a very import…” oh, right, that was a rabbit! Well, SpaceX really pulled a rabbit out of the hat this time. 🙂
tinker
Tinker
I read that at the Brownsville location that they will only fly once a month MAX??
Thats nothing????? Any thoughts?????
More launch sites maybe?
To put it into prospective. No other pad in the world will do more than 8 launches annually.
Wonder how many launches SpaceX can do from CCAFS, VAFB & possibly TX annually? Remember there eas a mention of 20 launches evenly split between Falcon 9 & Falcon Heavy annually from SpaceX a while back.
I think we’d see that, aside from the actual need for launches, the major time delay between launches is related to the time required for any integration that’s done on the pad and integrated testing. Both of these, however, are typically becoming shorter with newer LV and spacecraft designs. They could be shorter still if certain parties didn’t insist on vertical integration. We may find that launch sites which accommodate horizontal integration will in the future provide greater launch rates than what we’ll see in Florida.
I’ll be interested to see what SpaceX and others who fly both NASA and non-NASA flights do about this. Will they develop designs with the ability to be integrated and transported to the pad both vertically or horizontally? This will be a consideration if they want to launch from Russian and/or ESA pads.
The other delay factor with the potential to slow things down is, of course, weather. All it takes is one bad weather day to make you miss a launch window that doesn’t come again for days or weeks, or even months, which means you slip everybody a day or two, or scrub the flight and spend days undoing everything, tying up facilities.
And, of course, after every launch there’s pad refurbishment to do.
Add SLC-40 at the Cape and you have the theoretical capability of 24 equatorial, GSO or BEO launches a year. Plus another twelve polar from Vandenberg.
FWIW, I doubt they’ll ever need that number of launches but it does give them lots of flexibility for multi-launch missions.
Part of their real estate deal?????
Actually it was a day late.
Does SpaceX test fire all of Dragon’s thrusters before flight? If not, why not?
Those thrusters produce some pretty toxic fumes and residue.
Building a test stand to deal with that seems better than getting to orbit and finding that one or more or all of them don’t work.
A typical test stand doesn’t simulate the temperature, microgravity and vacuum environment that the thrusters were in when the problem occurred. You can do that in a test chamber but even then you can’t simulate microgravity which is a possible contributor to the problem. And I’m not even sure that in the test chamber they can test an entire pod including the helium tanks and lines.
I’m sure the engineers are looking forward to being able to examine and test the actual thruster pods when Dragon returns, which is another very valuable benefit of return capability.
Yes they do test fire all their engines including the thrusters prior to instalation in the spacecraft at their McGregor test facility.
Ah: “prior to installation in the spacecraft”. There’s many a slip ‘twixt the cup and the lip. It will be interesting to see what examination of the returned hardware shows.
I have always wanted to go to
space. I had space wallpaper as a child. PLEASE vote for me. It will take 20
seconds. Below is the URL
https://www2.axeapollo.com/…
Folks:
My latest Dragon Desktop image. Based on an image taken by @Cmdr_Hadfield on station today. (1024×768)
tinker
Congrats to Elon and his team. Just in time for Bolden’s response to the sequester to b*gger up continuing progress. Sigh.
I remember an article about 2 years ago that the ground would do the berthing. They have done them all I think. The timeline might say.
How does a helium tank pressurize a fuel tank? No gravity so it must have a diaphragm like my well water tank. Actually a rubber bag. A piston would work. Don’t ask NASA they can’t give details like they did with Shuttle. Might help China.
Getting too lazy to do research I guess. Here is the answer. I was correct. The PMD would last longer.
The tanks can be assembled as one of three variations. They can be assembled “empty” for use as a xenon tank for xenon ion propulsion, units. They can be assembled with metal or elastomeric bladders for positive expulsion. Or, they can be assembled with a propellant management device (PMD) that uses surface tension of the fuel to collect and separate the liquid fuel and deliver it to the external manifold system.
The propellant management device is a structure made of formed sheet, sheets and tubes that have hundreds of thousands of laser drilled holes in them, and other highly machined titanium components.
The He is under high pressure itself, so, when the valves to the fuel or oxidiser tanks are open, it pushed in, increasing the pressure in tanks and forcing the propellent into the engine’s combustion chamber. This method goes back about as far as hypergolic engines do, maybe further.
You missed my point. The fuel is not sitting over the outlet like it does on Earth. At partial fuel it is in globs. As the gas comes in it goes out the nozzels instead of being on top like a piston. For large engines they fire a thruster to settle the fuel over the outlet. A cold jet could be fired first,but they fire the thrusters rapidly.
Ben I’ve seen systems that use a vane system (surface tension) to keep fuel near the pickup of the tank… so adding helium as a pressurant works in zero g
Folks:
If you go to NASA TV’s ISS live feed (below), you’ll notice that the camera is pointed at the Dragon capsule! I expect it will remain that way til Dragon departs. A little reminder that an American spacecraft is at the station. You might consider emailing that link to your representatives in Washington to remind them too.
http://www.nasa.gov/multime…
tinker
Thanks for the link.
That is beyond cool.
Folks:
Wow, Brownsville really wants to adopt SpaceX!:
http://www.brownsvilleheral…
On March 6th, 2013, the first few videos on their list are all about SpaceX.
I don’t blame them. SpaceX isn’t the kind of company that poaches off of a community & then leaves when the mood strikes them. They haven’t yet and they’ve taken measures to assure the communities they co-exist with that they are in for the long game. Brownsville can expect decades of consistent and expanding operations that will help their economy and self worth.
tinker
Folks:
Here’s a good family portrait from the ISS feed!
tinker
I found this
Anyone have any comments of this?
“Gaetano Marano
CRS-1… 400 kg of net cargo at $332,500 per kg.CRS-2… 848 kg of net cargo at $156,840 per kg.these are the “cheap” prices of the (95%+ subsidized) “commercial” space! :(just to remember the Space Shuttle “high” prices… :)$600M to 1.1 Bn per launch / 24,000 kg max cargo = $25,000 to $45,800 per kg.+ SEVEN ASTRONAUTS PER MISSION! (a $470M saving in Soyuz seats).
DTARS:
Aren’t the CRS prices higher then the Shuttle? Am I missing something here? Your number look right. They are right!
Ah, you meant to ask a question there. Hmmm, when SpaceX starts carrying four tons of cargo each flight it’ll start to look like Shuttle prices.
Looks like there’s a brick wall here that only full reusability will hurtle. Cheap rockets that you throw away as apposed to a partially reusable one that’s a high maintenance case and you end up in the same place.
Good to know.
BTW: If NASA wasn’t so hell bent on having new Dragon’s for each cargo flight, that sticker price could have been much lower.
tinker
Folks:
Hey partners! Meanwhile, back on the ranch…
http://www.youtube.com/watc…
tinker 🙂