* NASA doesn't need BFR at the ISS. SpaceX doesn't cannot use BFR for the ISS contracts.* NASA payloads or crew will not fly on non-certified launchers.* There is no new station except DSG, and if you have something like BFR, with more space than the ISS and an ECLSS that can support 100 people for 6 months, you don't need a DSG.
(1) * NASA doesn't need BFR at the ISS. SpaceX doesn't cannot use BFR for the ISS contracts.(2) * NASA payloads or crew will not fly on non-certified launchers.(3) * There is no new station except DSG, and if you have something like BFR, with more space than the ISS and an ECLSS that can support 100 people for 6 months, you don't need a DSG.
If they do it I see them putting Dragon on the nose of a cargo or tanker BFS. So outside the cargo pod and free to use its abort engines.
* It gives you a 100x safety improvement while you are working up the confidence in your vehicle.. and NASA may point blank refuse a vehicle without a LAS for a good long time.* Surely NASA is not so bureaucratic that they cannot separate launching and docking risks.* Probably true, but the same issue may apply to the next station we have not seen yet.Another advantage of this is that you can start with just one variant, the Cargo variant. This also happens to be the most immediately useful and a lot cheaper than the Crew variant.
LAS gives you about a factor of 10 improvement in safety, at best. It can also introduce new failure mechanisms, and is only useful in a fraction of the total mission time. And can easily cost a billion or two to design, build, verify, and operate. Might be cheaper to just fly BFR 1000 times.
I just can't get behind this idea. If a les was needed for the bfs, the very capable engineers at SpaceX would no doubt have found some clever way to design one. They didn't. There's a reason they didn't and I just can't see them ever flying this configuration - it would be tantamount to admitting they aren't confident in their launch vehicle. If they want to be cautious, launch Dragon on F9 and meet on orbit.
Quote from: octavo on 10/07/2017 07:13 amI just can't get behind this idea. If a les was needed for the bfs, the very capable engineers at SpaceX would no doubt have found some clever way to design one. They didn't. There's a reason they didn't and I just can't see them ever flying this configuration - it would be tantamount to admitting they aren't confident in their launch vehicle. If they want to be cautious, launch Dragon on F9 and meet on orbit.This wasn't intended as a long term idea.* It assumes there may be a fair period with just a cargo version, learning how to ramp up to significant flight rates launching com sats. possibly an iteration or two before the passenger version is attempted.* NASA will probably take a long time to accept a crew launcher without a LAS. And they may simply refuse anything that size docking with whatever station they have at the time.* And the passenger version will probably be quite a bit of work, another reason it's arrival could be delayed.
Every real (BF) spaceship needs a (Dragon) shuttle-craft! But in all seriousness, I can only see SpaceX considering this in case NASA does not let them dock the BFS with the ISS (whatever the reason might be). Then they could use a Dragon in the payload bay to shuttle the supplies over to ISS. Otherwise, Dragon would also seem to be quite over-engineered for an "excursion module", with the heavy heatshield, parachutes, detachable trunk, deployable solar, etc. At best, in the long term SpaceX might think about a including a potentially human-tended, Dragon-based "space drone" for all kinds of in-space operations in proximity of the BFS (e.g., overseeing and supplying repair operations, shuttling crew and goods between BFSs and/or space stations where direct docking is not possible, for heatshield inspections, servicing satellites or safing them before capture by a BFS, excursions to asteroid surfaces, etc.).