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SpaceX Discussion Thread


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32 minutes ago, Elthy said:

Did SpaceX say anything about the "payload" of this starship? I think flying it empty could mess up the launch profile, as the acceleration would be way higher and they end up with lots of extra fuel, which would mess up the reentry...

No payload, but its probably heavier than  final version. weight balance will differ between ships anyway so you either have to have upper and lower header tanks or just use the flaps to compensate. between ships anyway so you either have to have upper and lower header tanks or just use the flaps to compensate.  

Edited by magnemoe
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38 minutes ago, tomf said:

After a scrub line this are they venting the methane/oxygen or are they able to pump most of it back into the storage tanks?

I think they at least try to recapture the methane. I certainly hope so, anyway. It's an extremely potent greenhouse gas, so just dumping a huge tank of it would be a big no-no environmentally. Oxygen is no big deal, as long as you don't dump it all at once, because that's obviously a fire/explosion hazard.

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2 hours ago, AVaughan said:

Assuming you have a decent clock and decent optics, then measuring the position of the Earth/Moon/Venus/Mars/Jupiter/Saturn against the stars should be enough to triangulate your position.  (You can also cross-check and calibrate your IGU's orientation against the stars the same way).  

This gives your orientation, not your position unless you watch over time. However interplanetary space is not very crowded, yet. Orientation it the critical one for pointing solar panels and antennas. 
But you can simply use earth stations and note how you and earth move.
 

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41 minutes ago, magnemoe said:

This gives your orientation, not your position unless you watch over time. However interplanetary space is not very crowded, yet. Orientation it the critical one for pointing solar panels and antennas. 
But you can simply use earth stations and note how you and earth move.
 

Noting the location of a celestial body against the stars gives you more than orientation.  Each such observation gives you a vector from that body to your position at that time.  Two or more simultaneous observations of different celestial bodies in different areas of the sky should give you a point where the vectors intersect (or their closest approach to each other, since no measurement is error free).      

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A genuine Weegee board would have a bottle of rotgut moving around and pointing to the letters. Most commonly used letters, in no special order are U, F, K, and C.

For those that don’t know, a Weegee is one local nickname for a Glaswegian, or somebody hailing from the fair Scottish city of Glasgow. Surprisingly, it’s not a particularly insulting nickname.

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Well, NASA has some interest in what's going on. Also:

1 hour ago, JoeSchmuckatelli said:

Should have gone with the 7th grade sleepover favorite "weegee board"! 

Spoiler

img-16652.jpg

 

Edited by tater
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4 hours ago, Elthy said:

Did SpaceX say anything about the "payload" of this starship? I think flying it empty could mess up the launch profile, as the acceleration would be way higher and they end up with lots of extra fuel, which would mess up the reentry...

The fully loaded Starship + Superheavy is over 5,000 tonnes. The impact of having or not having a 100-150 tonne payload will be an acceleration difference of 2%. Negligible.

3 hours ago, mikegarrison said:
4 hours ago, tomf said:

After a scrub line this are they venting the methane/oxygen or are they able to pump most of it back into the storage tanks?

I think they at least try to recapture the methane. I certainly hope so, anyway. It's an extremely potent greenhouse gas, so just dumping a huge tank of it would be a big no-no environmentally. Oxygen is no big deal, as long as you don't dump it all at once, because that's obviously a fire/explosion hazard.

Oh, they pump everything they can back into the tanks. Both LOX and methane.

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9 minutes ago, sevenperforce said:

The fully loaded Starship + Superheavy is over 5,000 tonnes. The impact of having or not having a 100-150 tonne payload will be an acceleration difference of 2%. Negligible.

Only at the time of launch. The payload becomes a bigger and bigger fraction of the total mass as the propellant is burned off and the stages are dropped.

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