SpaceX Tuesday...

[p1stonhead]

Is this the first re-use of a first stage which has been up already?

[MartG]

p1stonhead said:

Is this the first re-use of a first stage which has been up already?

No, that's the next one IIRC. This is a NASA payload this time, so new booster

[Beati Dogu]

First daylight launch and landing back at the Cape apparently, so it should make an interesting show.

They're already warning residents that they'll hear a sonic boom.

The supply capsule will take a couple more days to make it to the ISS.

[MartG]

[MartG]

"Gwynne Shotwell just confirmed Falcon Heavy will launch from 39A this summer. No payload scheduled yet."

Pop a used Dragon on it and send it around the moon

[MartG]

[Eric Mc]

Leak?

Hope they sort that out.

[Eric Mc]

Press conference here -

https://www.youtube.com/watch?v=ulzHxIt--00

[Flooble]

Is there such a thing as a small leak, for a spacecraft?

[MartG]

[Beati Dogu]

Flooble said:

Is there such a thing as a small leak, for a spacecraft?

I suppose it depends on what's leaking, where it is and the rate of loss.

This is a helium leak apparently. Helium is used to help push the LOX and RP1 (kerosene) propellent through to the engine and displace the fuel as the tanks empty. There's all sorts of plumbing to facilitate this, although on the upper stage, the helium tank is located inside the big liquid oxygen tank.

They've haven't said if it's a pipework leak or the tank itself. If the tank is pissing out helium, it could potentially overpressurise the LOX tank and cause it to rupture. That's what they suspect to be the cause of both Falcon 9 total losses so far.

[Flooble]

Interesting!

Perhaps it's always leaked but after the last failure they've put in some extra monitoring so can now see the leak ... the tweet from musk about go for launch subject to a check on pressure decay suggests they can monitor it at least.

Where's the tank for the "spin start system"?

[Beati Dogu]

As I understand it, the upper stage engine doesn't have a dedicated helium tank attached to the back of the engine itself. They use the main helium pressurisation system to also spin up the engine's turbopumps before the fuel arrives.

If the helium pressure is too low, it could cause problems with that too, so if they detect a significant enough drop they'll abort the launch countdown with a minute to go. Helium is inert of course, so it's not a danger in itself.

[MartG]

I hope they sort it - another launch failure could spell major problems for SpaceX

Even if helium leakage is deemed to be within limits before launch, vibration during launch could make it worse

[leglessAlex]

Jesus, pulling the plug with 13 seconds to go, tense stuff. I was fairly surprised they were ever going to risk launching with an issue, even if it was a really small one.

[MartG]

Damn - better safe than sorry though. Try again tomorrow

[callmedave]

Scrubbed due to TVC - Thrust vector control on second stage, nothing to do with the Helium pressure mentioned earlier.

Next launch window will be tomorrow around 14:30 (PM)

[0000]

Boo. Hope it's a go tomorrow.

[Eric Mc]

This launch from 2015 was scrubbed because of the same issue.

https://www.youtube.com/watch?v=HgMXEs68VLo

[Flooble]

Also one in 2010 I believe. Seems to be a recurrent challenge.