Instead of generic ion engines, how about multiple instances of the SEP tug? I have seen images implying it would stack nicely and even is designed to do so. I think this is more in line with the OP's goal of working with what we have (though I admit the term 'have' is a bit flexible here )We could have the DSH being tested out for a few years in high lunar orbit. We could have several SEP tugs visiting asteroids or whatever, and perhaps time the mars orbit mission for the point at which we have most trust in the hardware: not too new, not to old.My layman's feeling is that a single orion would be best, just for the initial push with whatever propellant it can reasonably have on arrival at the DSH, then keep the command module and perhaps immediately dump the service module. Use electric thrust for the rest and aim for Deimos due to it being easier in terms of delta-v.Perhaps the DSH orbit could be nudged into a near earth approach before the mission begins to exploit Oberth effect for this one small burn.About this Orion one year and speed of earth reentry issue, how big a job is that to fix? Seems to me that if we are going to build that Orion thing we should at least have an upgrade path planned. It doesn't need to be the first Orion that flies, but this would have to be a few years later (after the DSH and SEP tug shakedown mentioned)
The problem with that is the Orion Service Module supplies the crew with oxygen and water. The Command Module can only support life for a few hours.https://en.wikipedia.org/wiki/Orion_Service_Module
I ranted about something along these lines at my own blog a couple of months ago (https://chilesfiles.wordpress.com/2016/04/22/halfway-to-nowhere/#more-2489). I'd dearly love to see NASA take advantage of the 2021 free-return window as outlined by the Inspiration Mars crowd. If we can't afford to launch SLS much more than once a year, then let's make it count for something before the whole thing is steamrolled into obsolescence by the private sector.A manned flyby of Venus and Mars would be an audacious and extremely valuable proof-of-concept mission. There's a golden opportunity here for a one-off, Apollo 8-style home run if we only had the stones to pursue it. But that would require focused leadership and political will to see it through over a couple of election cycles. Therefore, it won't happen. But damn if it wouldn't be glorious.
If SpaceX is successful, then NASA can ... either cancel Orion/SLS or use it for lunar or asteroid missions.
Quote from: RonM on 07/17/2016 03:30 pmIf SpaceX is successful, then NASA can ... either cancel Orion/SLS or use it for lunar or asteroid missions.A nit but an important one. NASA cannot cancel SLS; only Congress can do that.
Quote from: Arb on 07/17/2016 10:46 pmQuote from: RonM on 07/17/2016 03:30 pmIf SpaceX is successful, then NASA can ... either cancel Orion/SLS or use it for lunar or asteroid missions.A nit but an important one. NASA cannot cancel SLS; only Congress can do that.Yes, thanks for pointing that out.
How are we going to have even one human qualified Orion, a few SLS launches, or an SEP tug by 2021?
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: 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.