My knowledge of celestial mechanics is quite limited so I may be missing something, but I was expecting the dV of a F9H+Dragon to be able to rendezvous with a sample container on a fairly wide range of trajectories. Is that not the case? To be clear, I'm assuming you know the precise trajectory of the container months in advance, and have the dV to choose to meet up in many places along the way (not just HEO/LEO). If necessary you could launch early, use slingshots, and if necessary use them again afterwards and take your time making it back to Earth.In an extreme case, you could send the return Dragon on a free return trajectory all the way to Mars and meet up with the container as it begins its' journey toward Earth. The Dragon would perform the mid course corrections. In fact, that scenario may allow the max conceivable return mass.On a related note: one possible use of a large-mass sample return capability would be a full intact core from a drill.
Well, in the paper itself it looks like the sample return rocket does a Earth orbit insertion burn, captured into an elliptical Earth orbit. Then, another Dragon capsule does a rendezvous to return the sample to Earth. If it were up to me, I'd just do a direct reentry to Earth like Stardust or whatever.
Quote from: Robotbeat on 03/11/2014 01:40 amWell, in the paper itself it looks like the sample return rocket does a Earth orbit insertion burn, captured into an elliptical Earth orbit. Then, another Dragon capsule does a rendezvous to return the sample to Earth. If it were up to me, I'd just do a direct reentry to Earth like Stardust or whatever.Than you will not get much samples back if you have to include EDL element along with the tiny storage volume available with the EDL element.
I have still never understood why the recent rovers did not include a simple tray for collecting samples. A Red Dragon could have met Curiosity, transferred the tray, and relaunched with a sample set taken across a vastly larger area and years of sampling. Just seemed short sighted.
http://solarsystem.nasa.gov/docs/7B.4_Karcz_Feasibility%20of%20a%20Dragon-derived%20Mars%20lander%20for%20scientific%20and%20human-precursor%20missions.pdfScalability is mentioned several times in this presentation. One wonders if a 6m diameter "super red" version of Dragon would be able to deliver 5-8 tonnes or if changing aerodynamics and area densities throw it out the window.
Would the ascent rocket use the Dragon as a launch platform? Eject the main door and slightly raise the rocket to keep it safe from blowback. I assume launching through the top of Dragon will be a close fit even with an enlarged opening.
Quote from: solartear on 03/11/2014 06:56 pmWould the ascent rocket use the Dragon as a launch platform? Eject the main door and slightly raise the rocket to keep it safe from blowback. I assume launching through the top of Dragon will be a close fit even with an enlarged opening.My guess is the MAV will operated quite similar to a silo based cold gas launched ballistic missile. It will be ejected from the vertical launch silo inside the Dragon with a gas generator powered piston through a frangible cover. The MAV motor will then ignited a few seconds later in the air after the piston is discarded.
Quote from: Zed_Noir on 03/11/2014 10:50 pmQuote from: solartear on 03/11/2014 06:56 pmWould the ascent rocket use the Dragon as a launch platform? Eject the main door and slightly raise the rocket to keep it safe from blowback. I assume launching through the top of Dragon will be a close fit even with an enlarged opening.My guess is the MAV will operated quite similar to a silo based cold gas launched ballistic missile. It will be ejected from the vertical launch silo inside the Dragon with a gas generator powered piston through a frangible cover. The MAV motor will then ignited a few seconds later in the air after the piston is discarded.I am not sure that is necessary. As solartear mentioned, there is the open side hatch to vent exhaust gases.
Nod.Theoretically after the MAV launches who cares about the Dragon, its work is done. The only worry is that launching from a cylinder inside somehow has exhaust impingement issues or something similar. And I don't see that. No need for complex systems to have the launcher be outside the Dragon.