Actually, this is not a problem.At a little after entry into the Martian atmosphere, instead of actively maintaining your trajectory into the atmosphere aerodynamically, you do the opposite.This bounces you out to an eccentric Mars orbit. A few tens of m/s at apogee, and you can make it an orbit which only intersects the edges of the atmosphere at the bottom. Unload the cargo, taking as much as a few hours to do it, and then reenter as normal.Payloads circularise and do other manoevering gradually using aerobraking as mars climate observer did, as well as slow thrusting from a small ion engine.If you additionally have hardware that doesn't mind if it's on Mars or in low mars orbit, this can actually increase the payload to Mars quite notably.
Quote from: speedevil on 04/21/2018 09:27 pmThis bounces you out to an eccentric Mars orbit. A few tens of m/s at apogee, and you can make it an orbit which only intersects the edges of the atmosphere at the bottom. Unload the cargo, taking as much as a few hours to do it, and then reenter as normal.Payloads circularise and do other manoevering gradually using aerobraking as mars climate observer did, as well as slow thrusting from a small ion engine.If you additionally have hardware that doesn't mind if it's on Mars or in low mars orbit, this can actually increase the payload to Mars quite notably. The orbit of the deployed satellites would go quite deep into the atmosphere, deep enough that BFS has used the atmosphere for very significant braking. Those satellites either need a heat shield to survive the next pass or they have a very short time to deploy their solar arrays, get active and do an orbit raising maneuver.
This bounces you out to an eccentric Mars orbit. A few tens of m/s at apogee, and you can make it an orbit which only intersects the edges of the atmosphere at the bottom. Unload the cargo, taking as much as a few hours to do it, and then reenter as normal.Payloads circularise and do other manoevering gradually using aerobraking as mars climate observer did, as well as slow thrusting from a small ion engine.If you additionally have hardware that doesn't mind if it's on Mars or in low mars orbit, this can actually increase the payload to Mars quite notably.
NASA *does*use ground stations. Ever heard of the DSN?
IMO the logical way to go is having dedicated sats with large laser mirrors
Delivering this capability w/ BFS assumes no desire or need to have this capability in place when BFS arrives and heads to the surface. SpX will have enough to handle at that moment, let alone managing the roll-out of a comm sat capability, simultaneously. I’m a strong advocate of an advanced launch, a cycle prior (2 years) to BFS heading to Mars. This capability needs to be in place, shook out, and ready to roll — at BFS entry interface.Splinter
NASA mostly uses orbiters to relay data from ground assets. I fail to see why SpaceX wouldn’t do the same thing. It’s not at all an overcomplication as it simplifies the ground infrastructure.If you think using a ground station alone is so great, then you better be able to explain why NASA doesn’t do it.
The DSN has functions other than Mars. It connects to probes far out and needs very large antenna dishes for the very weak signals. It needs multiple dishes for continuous coverage.Multiple dishes on Mars are not an option. Not yet and not for a long time. So a local constellation ensures continues connectivity from a Mars location. Laser links ensure high data rates without the need of very large dishes.http://www.sciencetimes.com/articles/14680/20170509/nasa-s-deep-space-network-can-be-overwhelmed-by-mars-traffic-jams.htm
For the year 2020, the list of Mars mission is too long. Not only NASA will be launching any spacecraft, but other nations are also in the list. This clearly shows how much NASA's Deep Space Network needs to work out from future telecommunication problems. The list has NASA's Mars 2020 rover, China's orbiter, European Space Agency's ExoMars 2020 rover, United Arab Emirates' Hope orbiter, and India's Mars Orbiter Mission 2.
NASA mostly uses orbiters to relay data from ground assets. I fail to see why SpaceX wouldn’t do the same thing. It’s not at all an overcomplication as it simplifies the ground infrastructure.If you think using a ground station alone is so great, then you better be able to explain why NASA doesn’t do it.A satellite constellation for data relay from Mars isn’t hypothetical. It has been a reality for decades. It is the status quo. There is a fleet of 5 satellites around Mars that are used for data relay from the surface. Today.