Rakaydos

I wonder if you could simply use "stretchytanks" or somethig similar, to scale components DOWN to cubesat size?

We can probably get a poll on the next thread- the one with the fixed OP that the mods have offered to sticky.

Indeed. Mission 1 is a credibility mission. Mission 2 is where we start propulsion tests.

Agreed, which is why we've hardened up on a 5 mission plan: Mission 1: LEO plant lab/credibility mission Mission 2: LEO Propulsion test Mission 3: Solar orbit Mission w/ earth capture Mission 4: Mars capture Mission 5: Phobos This topic is supposed to be for mission 4 and mission 5

I'll just have to use words like "Low velocity Tangental lithobreaking," for the sledding approach, or "Mars-Phobos L1 controlled desent" for an approach that uses how small phobos's SoI is to minimize impact velocity.

That may be, but for OUR kickstarter'd cubesat, I'd prefer to use proven (if still advanced) technoligies to accomplish new feats, instead of squandering kickstarter's money and potentially a LEO ride on a drive system that may still be a hoax. Ion or Electrotether, if not both.

I dont think it's our place to play with drives of uncertian physics. It seems too likely to draw the wrath of the kraken. If an electrotether is viable on the first or second mission, however, it might be interesting to see what kind of maneuvering capability we can get out of only being able to alter trajectory at perigee. (is it possible to make lunar transfer by electrotether alone?)

Pehaps a clearer first post, though...so we dont get another flood of "Phobos? Why not titan!" posts when we've got a relatively solid set of missions planned (LEO plants, LEO propultion, Solar orbit wit aerocapture, and Beyond)

Well, if we have baloons that are carrying oxygen, and fill them with just enough water to keep them in the (cold) upper atmosphere, we should be able to keep most of the water in liquid (or solid) form. Can we break down the sulpheric acid for hydrogen? if we converted all the acid in venus's atmosphere, how much water could we put in balloons? What would be the leftover elements after converting the acid?

what about some kind of magnetic scoop, to collect alpha particles from the solar wind and "burn" them with oxygen to produce water?

My understanding was that the EMdrive and Qdrive were two completely different principles. A Qdrive works by "pushing off the vaccume", that is, magnohydrodynamically accelerating the virtual particle pairs that appear in a vaccume, after which their existance/cancelation becomes someone else's problem. This still requires an exaust, so it is not truely reactionless. An EMdrive, on the other hand, claimsto bounce microwaves in an asymetric chamber to produce thrust. As there is nothing leaving the chamber, you could literally stack the entire volume of a ship with them to improve your "engine by weigth" rather than be limited to the back of the ship. The wired article seems to be confusing them- linking a nasa article on the Qdrive as evidence of the EM drive.

This was posted awhile back.

So basically long term planning.

Electrostat will give 20+ millineutons for a reasonable weight of panels?

No, I just pluged phobos's mass into wolfram alpha and had it spit out a speed. EDIT: but we're eing off topic, we should take this to the other thread.

*shrugs* I didnt fly the mission, I just calculated a single body orbital velocity from phobos' mass. Can you land on phobos with a phobos TWR of .9? Or does orbiter let you try that?

1 km orbit. Or lower. 1m orbit if you can pull it off.

that's 13 km from the point mass. I'm talking about a "true" altitude lower than phobos' mountians. If mars is more powerful than phobos at THAT range, we have a fundamental problem.

According to NASA's website, phobos has a surface gravity of 5.7 milimeters per second per second. However, an ion drive we may be able to power with our u3 cubesat wouldnt be able to generate that much net thrust over a 4kg cubesat- we'd need on the order of 20-24 milineutons of thrust., and the more we have, the less d/v we lose to gravity losses. without a TWR of 1, we'd be struggling against escape velocity of 11m/s, and have to thrust the whole way down. However, plugging in phobos's 1.0659 x 10^16 kg mass and a highest peak of 13.4 KM into Wolfram Alpha, I generated the orbital velocity for a circular orbit at 13 km from the point mass as just below 7.5 M/s. As a circular orbit, it has no impact speed- we'd be able to bleed the velocity horizontally once we touch down. (we just have to be sure we dont bounce back into a suborbital trajectory)

The important thing about the electrotetherm hwever, is that is brings our mission package together. Mission 1: LEO plant lab/credibility check Mission 2: LEO Elecrotether testing Mission 3: Solar orbit mission and earth Aerocapture with electrotether Mission 4: Mars Aerocapture with electrotether, possible phobos mission or phobos preparation mission. Mission 5: Phobos mission.

Despite what it may seem in KSP, 7.5 M/S is still a lot of velocity when it comes to Lithobreaking, especially for a cubesat that is only 0.3m long. (25x it's own length per second) That's why I suggest sledding, to keep the impact velocity down and bleed horizontal velocity slowly. I'm assuming we cant somehow engineer a Phobos TWR of 1+ with the DV we need- it seemed implausible with the ion engines I found information on.

Crew of Apollo 13 didnt asphixiate, even without power, for the time it took them to return home... (though the whole 3 crew/2 man lander thing made it a near thing, but that doesnt apply here) An old fashioned chemical firearm wont be EMPable either.

Actually, I just had a thought that may bring this together. It's been mentioned whenever someone who knows, talks about aerocapture, that you need some way of fine tuning your orbit as you leave the atmosphere, to compensate for atmosphereic anomalies. Can you use a deployable electro-tether, at least after the worst of the heating? I mention this because one of my thoughts for "sledding" to the surface of phobos was to have a line deploy from an end of the craft and drag on the surface- making this line an electrotether seems like the next step.

I havnt played with rosetta slingshots enough to know if we can pull one off from a polar orbit. It may limit our launch window, which means we may need to scrub a polar mission based on our GTO launch provider. Still, it will be doing a lunar flyby in any case- even if we dont get NEW pictures, we'll stilll get pretty ones. What could we do with a camera in solar orbit? What would we do with it for aerocapture... and after aerocapture? K2? your thoughts on a polar lunar slingshot into an (inclined) 1AU solar orbit?

Phobos lander is out for mission 2. Too many new things that need testing- the lunar slingshot, the year+ of solar orbit survival, and aerocapture. Until we have those down, designing a cubesat that can land on phobos (or even sled to a stop from a 7.5m/s orbital velocity) is pointless. But all those things can be tested closer to home with a solar orbit mission and aerocapture back at earth, instead of a Rosetta slingshot.