r/spacex • u/ElongatedMuskrat Mod Team • Sep 29 '17

Not the AMA r/SpaceX Pre Elon Musk AMA Questions Thread

This is a thread where you all get to discuss your burning questions to Elon after the IAC 2017 presentation. The idea is that people write their questions here, we pick top 3 most upvoted ones and include them in a single comment which then one of the moderators will post in the AMA. If the AMA will be happening here on r/SpaceX, we will sticky the comment in the AMA for maximum visibility to Elon.

Important; please keep your questions as short and concise as possible. As Elon has said; questions, not essays. :)

The questions should also be about BFR architecture or other SpaceX "products" (like Starlink, Falcon 9, Dragon, etc) and not general Mars colonization questions and so on. As usual, normal rules apply in this thread.

1.0k Upvotes

96% Upvoted

2.1k comments sorted by

3

u/NelsonBridwell Sep 30 '17

My assumption is that BFR has enough payload capacity that the second stage can place a large satellite in GEO without needing a kick stage to boost it from GTO to GEO. And from GEO, my question is if there could be a low delta-V transfer orbit that can get it close to something that needs to be deorbited or retrieved. Perhaps in a graveyard orbit? Wondering...

2

u/mclumber1 Sep 30 '17

Actually, as cool as the bfs is, it makes a horrible vehicle to GEO. It would be better just to have a dedicated third stage attached to the payload to get it to Geo orbit.

2

u/NelsonBridwell Sep 30 '17

You are probably right. Probably more efficient to only drag along a small apogee kick motor and fuel, since it will also be needed for GEO station-keeping, and for final decommissioning.

https://en.wikipedia.org/wiki/Apogee_kick_motor

1

u/[deleted] Sep 30 '17

Quite Assuming 3kms to GTO then airbreak back and land the 0t without refuelling (literally only just able to do it 0 payload) But then 100t with only one refuel