There is no need to bring any Orions along for the ride. A simple mission like this could be staged out of L1, L2, or DRO. Have the crew launch on Orion out there to meet the Mars bound spacecraft. The return the crew to one of these places to meet up with a waiting return craft.
Hey, engineers of the past would've KILLED for a simulator like Kerbal.
Quote from: A_M_Swallow on 07/18/2016 05:11 pmThe back end of the Asteroid Redirect Robotic Mission (ARRM) spacecraft is a Solar Electric Propulsion (SEP) tug. This is due to be launched in December 2021. So by about 2021 NASA will be able to buy SEP tugs.The tug design may need upgrading to reach human rating standards.NASA can buy SEP tugs now if it wants to. See Dawn.
The back end of the Asteroid Redirect Robotic Mission (ARRM) spacecraft is a Solar Electric Propulsion (SEP) tug. This is due to be launched in December 2021. So by about 2021 NASA will be able to buy SEP tugs.The tug design may need upgrading to reach human rating standards.
Quote from: Jim on 07/18/2016 05:26 pmQuote from: A_M_Swallow on 07/18/2016 05:11 pmThe back end of the Asteroid Redirect Robotic Mission (ARRM) spacecraft is a Solar Electric Propulsion (SEP) tug. This is due to be launched in December 2021. So by about 2021 NASA will be able to buy SEP tugs.The tug design may need upgrading to reach human rating standards.NASA can buy SEP tugs now if it wants to. See Dawn.Is a 0.09Newton (0.02lbf) 'SEP tug' for a 212 tonne (466,400lb) mission a bit undersized for a manned mission in deep space rad environment?
Quote from: AncientU on 07/20/2016 09:41 pmQuote from: Jim on 07/18/2016 05:26 pmQuote from: A_M_Swallow on 07/18/2016 05:11 pmThe back end of the Asteroid Redirect Robotic Mission (ARRM) spacecraft is a Solar Electric Propulsion (SEP) tug. This is due to be launched in December 2021. So by about 2021 NASA will be able to buy SEP tugs.The tug design may need upgrading to reach human rating standards.NASA can buy SEP tugs now if it wants to. See Dawn.Is a 0.09Newton (0.02lbf) 'SEP tug' for a 212 tonne (466,400lb) mission a bit undersized for a manned mission in deep space rad environment?The NSTAR thruster is fairly low-power at 2.3kW. But commercial units are at least 4.5kW and can be ganged together. And the NEXT thruster is 7kW. Gang 15 together, and you have >100kW, which is good enough for a basic tug.
Power and thrust are proportional to each other, and the proportionality constant is exhaust velocity. THAT'S why I said power.Power = thrust*exhaustvelocity
Quote from: Robotbeat on 07/21/2016 05:30 pmPower and thrust are proportional to each other, and the proportionality constant is exhaust velocity. THAT'S why I said power.Power = thrust*exhaustvelocityThanks, that (proportionality) is pretty much what I figured, as you can see from my post. However, now I'm curious as to the power ratings of the thrusters that you mentioned. Is that the power output of the thruster, using the equation you gave? Or is it the electrical power input required to operate the thruster at the given thrust level? When you stated the thrusters' power levels in watts, I thought it was the latter. Given the context of your reply, it would seem to be the former.Anyway, the bottom line seems to be that you need ~1 MW of power for every 10 lbf of thrust. Please correct me if my math is wrong, or if I have a bad understanding of the underlying principles.Thanks again.
What most people fell to appreciate is that the Falcon 9 Heavy, with its kerolox upper stage, has low performance beyond LEO. nothing beats LH2 there.
So what? Stage in LEO. We have lots more experience there anyway.
Quote from: Archibald on 04/15/2017 08:15 pmWhat most people fell to appreciate is that the Falcon 9 Heavy, with its kerolox upper stage, has low performance beyond LEO. nothing beats LH2 there. True.OT but I'm surprised Spacex never designed a third stage for the Falcon vehicles as even something like a Star derivative would help enormously on high energy orbits.