SpaceX COTS Demo 2/3 Updates (THREAD 2)

[mr. mark]

"The private spaceflight company SpaceX plans to launch its unmanned Dragon capsule to orbit Feb. 7 atop the firm's Falcon 9 booster from Cape Canaveral Air Force Base in Florida. The capsule will carry a load of food, clothing and other supplies for the six-man crew of the space station".

http://www.space.com/14146-space-station-astronauts-private-spaceship-excitement.html

Looks like we are finally getting a better picture of what supplies will actually be delivered. Also thanks for posting an interior shot of the Dragon cargo spacecraft. I've been waiting for that shot for sometime.

[SpacexULA]

Looks like we are finally getting a better picture of what supplies will actually be delivered. Also thanks for posting an interior shot of the Dragon cargo spacecraft. I've been waiting for that shot for sometime.

Are they likely to fill the open space in the middle with the loose bags like they do progress or would they leave it empty in the middle?

[Jim]

open

[Space Pete]

Just realised, we are now L-1 month!

[corrodedNut]

It's a Saturday update, y'all:

http://www.spacex.com/updates.php

"For its first mission to the International Space Station, SpaceX’s Dragon spacecraft will use deployable solar arrays as its primary power source for running sensors, driving heating and cooling systems, and communicating with SpaceX’s Mission Control Center and the Space Station. Dragon’s solar arrays generate up to 5,000 watts of power — enough to power over 80 standard light bulbs. The solar arrays, shielded by protective covers during launch, deploy just minutes after Dragon separates from the Falcon 9 second stage, as it heads towards its rendezvous with the Space Station.

While many commercial satellites and NASA missions such as the Hubble Space Telescope use solar arrays, Dragon will be the first American commercial transport vehicle to do so.

Past American spacecraft like Mercury, Gemini, Apollo and Shuttle used fuel cells or battery packs. Fuel cells are limited by the amount of chemical reactants (typically oxygen and hydrogen) that the vehicle can carry. Batteries alone are limiting due to their mass and the amount of power they can carry.

Solar energy provides a key benefit — long-term power. Combining Dragon’s solar arrays with a compact and efficient battery pack provides a reliable and renewable source of power. When in the sun, Dragon’s solar arrays recharge the battery pack, and the charged batteries provide power while Dragon passes through the Earth’s shadow. With solar panels, Dragon will have the power it needs for longer trips, whether to the Space Station or future missions to Mars.

Dragon’s deployable solar arrays were developed from scratch by a small team of SpaceX engineers. To ensure they will survive the harsh environment of space, our engineers put the solar arrays through hundreds of hours of rigorous testing including thermal, vacuum, vibration, structural and electrical testing.

SpaceX conducts most of these tests in-house. The video below shows an array full deployment test using testing equipment developed by SpaceX as part of a NASA Commercial Orbital Transportation Services (COTS) milestone.

After testing was complete, the solar arrays headed to SpaceX’s Cape Canaveral launch site for final integration. The solar arrays and fairing covers that protect the folded arrays during launch have since been installed on the Dragon spacecraft in preparation for their first flight to the International Space Station.

Stay tuned for additional updates as we continue preparations for our first flight to the Space Station!"

Sorry, I'm unable to embed the solar array video, try this:

http://www.spacex.com/assets/video/solar_array_deploy_sideview_small.mpg

[manboy]

It's a Saturday update, y'all:

http://www.spacex.com/updates.php

The newest I see is the Dec 15th update/

[jedsmd]

SpaceX site has the update again

[Space Pete]

Solar Array Deployment Test

[Comga]

It's a Saturday update, y'all:

http://www.spacex.com/updates.php

The newest I see is the Dec 15th update/

I had to force a reload in Chrome and Firefox, holding down the shift key and reloading.

[Comga]

It's hard to see, but it doesn't look like there is sufficient room for the pontoon covers to pivot away from the PICA-X heatshield.  That implies that these covers are ejected.   Has anyone seen this event on a timeline?  There was a CRS CGI video somewhere that showed the solar panels deploying, but it predates this configuration.

In every animation/simulation that shows this, the pontoons are jettisoned post Dragon-2nd stage sep. Assuming that Dragon is directly injected like the last flight, to me this seems like unnecessary orbital debris. At the very least it's a mass penalty. Why not jettison them at the same time as the nose cap? Of course, these animations may not be accurate.

Today's update reiterates "The solar arrays, shielded by protective covers during launch, deploy just minutes after Dragon separates from the Falcon 9 second stage."  That much is obvious.  However, it does not really say when the pontoons are jettisoned.  It would reduce the mass-to-orbit penalty to eject them as soon as possible.  On one hand, there are less mechanisms and potential failure points if the pontoons are held on by the second stage, and come off on their own once released.  Like keeping the interstage part of the first stage rather than being a separate, jettison-able element, this would reduce the complexity and risk at some expense to performance.

edit: The pontoons should have very low ballistic coefficients and should not remain in orbit for very long.  They should be easy to track and be an inconsequential from a debris standpoint.

[sojourner]

So, 4 panels per array?  That's pretty big from the looks of things.

[Robotbeat]

Interesting that they're doing it all in-house, basically.

In addition to being a vertically integrated rocket company, they're becoming a vertically integrated satellite manufacturer (though they've got a long ways to go before they can compete for a real commsat, but a lot of the pieces are starting to develop). Probably more profit margin there, anyway, compared to being a launch company.

[A_M_Swallow]

SpaceX may now have most of the technology to make an in-space only vehicle.  This could be used for round trips between LEO and EML-1 spacestations.

[baldusi]

I was wondering how much of that technology is applicable to a space habitat or ISS style module. Could they do a Node 4 on the cheap? I mean, structural, CBM, cabling and basic EECLS should be mastered.

[MikeAtkinson]

I was wondering how much of that technology is applicable to a space habitat or ISS style module. Could they do a Node 4 on the cheap? I mean, structural, CBM, cabling and basic EECLS should be mastered.

This is off-topic, its an interesting question but please ask in a more appropriate thread.

[MikeAtkinson]

The solar panels are I believe only rated for 2 months as they use commercial grade cells. I think SpaceX are also working on panels rated for 2 or more years for DragonLab and crewed Dragon, but these will be considerably more expensive. A major factor in the cost differential of short duration DragonLab ($90M) and long duration ($120M) is the cost of the solar panels [1].

[1] BIS talk on DragonLab by Richard Godwin 1 Dec 2011.

[manboy]

The solar panels are I believe only rated for 2 months as they use commercial grade cells. I think SpaceX are also working on panels rated for 2 or more years for DragonLab and crewed Dragon, but these will be considerably more expensive. A major factor in the cost differential of short duration DragonLab ($90M) and long duration ($120M) is the cost of the solar panels [1].

[1] BIS talk on DragonLab by Richard Godwin 1 Dec 2011.

I didn't realize the solar panels were so expensive.

[Robotbeat]

I highly, highly doubt there's a $30 million difference for just the cells themselves.

[Lurker Steve]

The solar panels are I believe only rated for 2 months as they use commercial grade cells. I think SpaceX are also working on panels rated for 2 or more years for DragonLab and crewed Dragon, but these will be considerably more expensive. A major factor in the cost differential of short duration DragonLab ($90M) and long duration ($120M) is the cost of the solar panels [1].

[1] BIS talk on DragonLab by Richard Godwin 1 Dec 2011.

I didn't realize the solar panels were so expensive.

That PR release also needs a bit of work. The Solar arrays can power 80 light bulbs. Really ? Is 80 light bulbs really the best comparison you could make ? Sounds really expensive just to turn a light on.

[docmordrid]

It's a comparison lay people can put into context, even members of Congress and their similarly ill informed staffers. The only improvement I'd make is to specify the rounded off wattage (60w)