KSP Community CubeSat

[RuBisCO]

I see no chance for anything beyond LEO for now, heck has there even been a cubesat sent beyond LEO?

All These Worlds

Are Yours Except

Europa

Attempt No

Landing There

LOL, 5 internet points to you!

[Rakaydos]

I see no chance for anything beyond LEO for now, heck has there even been a cubesat sent beyond LEO?

The GTO to Solar Orbit tech demo is the only croudfundable possibility for that, I think. Limited scientific payload, simply a proof that such a mission is possible on a budget, and other better funded missions will follow with better equipment.

[Nicholander]

Yes, for our first mission, we can either go to LEO, or we can stay on a sphere going around the sun. For our missions after that, i don't know. Though definitely not Europa, never.

[Rakaydos]

Yes, for our first mission, we can either go to LEO, or we can stay on a sphere going around the sun. For our missions after that, i don't know. Though definitely not Europa, never.

The solar orbit demo is a milestone we'll have to pass if we want to go almost anywhere beyond LEO. There's other places in earth's SoI we can go, but they'd have an even higher Dv requirement than a slingshot.

As for science, it's a tech demo. Internal monitoring, position and direction detection, everything we need to make it fly gives real information back to better funded groups who want to follow.

[Nicholander]

Yeah, indeed Rakaydos. So I think the missions should be:

Kerbal-1/KerbSat-1: 1U CubeSat with a pressurized compartment with plants, and it rotates to give artificial gravity, so that we can study what happens to the plants under those conditions. Stretch goals: Electrodynamic tethered propulsion, maybe an inflatable pressurized compartment. Maybe.

Kerbal-2/KerbSat-2: Perhaps it could be a Lunar flyby CubeSat, and maybe it could fly over The Moon's north pole to take some pictures, since it seems no one has not taken a clear picture of the Lunar north pole that's not a bunch of images from equatorial orbits glued together. It's course would be, like the Phobos one, to hitch a ride from a GTO launch and then burn at perigee to intercept The Moon. Or, maybe, this could be the Phobos Lander mission.

Kerbal-3/KerbSat-3: If Kerbal-2/Kerbsat-2 is the Lunar flyby going over the north pole, then this would be the Phobos Lander mission. This is discussed on a different thread.

Kerbal-4/KerbSat-4: Who knows. Who really knows. Venus, perhaps? Maybe it could have a heat shield and go into the Venusian atmosphere, and it has a giant balloon, so it floats in the higher atmosphere, so we can study the changes of it.

That's just my idea, and I don't know if we could KickStart 4 missions. DO you have any ideas or thoughts on the grand missions plan? Though, we are voting that Phobos will be our grand and ultimate mission, and in that plan the Phobos Lander is the 2nd to last mission.

[Rakaydos]

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.

Edited July 31, 2014 by Rakaydos

[Nicholander]

Well, for Kerbal-2/KerbSat-2 I said maybe. Though now I know that is impossible for the 2nd mission. So could it be done for the 3rd mission? And what do you think of the Lunar Flyby over the Lunar north pole?

[Nicholander]

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.

Hmmm.... that's actually a pretty good idea... So could that be Kerbal-2/KerbSat-2? Could we still do it with a Lunar flyby of the north pole? (All of the missions outside of LEO require a GTO ride with a burn at the perigee to intercept The Moon)

[Rakaydos]

Well, for Kerbal-2/KerbSat-2 I said maybe. Though now I know that is impossible for the 2nd mission. So could it be done for the 3rd mission? And what do you think of the Lunar Flyby over the Lunar north pole?

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?

[Nicholander]

I don't know how much that would incline the Solar orbit, though we can do orbital correction maneuvers on the way to the Earth/Mars, that would mean we need to pack in more delta-v, which means more fuel, and more cost.

[Rakaydos]

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.

[Nicholander]

Interesting! Though, I don't know if we should be using the electro-tether for the post aerocapture orbital correction maneuvers, which we could then use to help in the Phobos sled. I think we should still use the regular propulsion that the spacecraft has, because the effects the atmospheric anomalies would have would be very small. And I'm also not sure about the Phobos sled, it seems to risky. (Though, very Kerbal indeed) I still think it should use it's normal propulsion engine to slow down 7.5 m/s at the surface of Phobos and then "fall over" onto it's side gently, to avoid the need of landing legs.

[Rakaydos]

And I'm also not sure about the Phobos sled, it seems to risky. (Though, very Kerbal indeed) I still think it should use it's normal propulsion engine to slow down 7.5 m/s at the surface of Phobos and then "fall over" onto it's side gently, to avoid the need of landing legs.

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.

[Nicholander]

Remember Rakaydos, Phobos only has like 10% of Gilly's gravity! And sorry, if i said it wrongly, but i meant it would slow down 7.5 m/s, not TO 7.5 m/s! so it would slow down to a nice 0.05 m/s or 0.1 m/s so it could "Fall over" safely without damaging any equipment. And, yes, I see some reason for the sled, but like I said, that increases the risk of the landing by unimaginable levels.

EDIT: Since you said that the Ion engine can't get enough TWR to even do that, you could maybe get it to work by:

1. Having some small non-ion engines that activate during landing, to give the CubeSat a high enough TWR to land. I don't know what propulsion they would be, but it has to have a small enough fuel tank to fit in with the ion. Perhaps monopropelant.

2. Similar to the first, but it uses more ion engines that activate during landing, and it has a "Landing battery" that activates during landing to power the ions.

Also, how much will an ion engine cost?

Edited July 31, 2014 by Nicholander
Added stuff about the Ion engine

[Rakaydos]

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.

[Rakaydos]

Remember Rakaydos, Phobos only has like 10% of Gilly's gravity! And sorry, if i said it wrongly, but i meant it would slow down 7.5 m/s, not TO 7.5 m/s! so it would slow down to a nice 0.05 m/s or 0.1 m/s so it could "Fall over" safely without damaging any equipment. And, yes, I see some reason for the sled, but like I said, that increases the risk of the landing by unimaginable levels.

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)

Edited July 31, 2014 by Rakaydos

[Nicholander]

Good plan, Rakaydos. Though, really, I don't see a need to use the electrotether for everything, I think it could only useful for a tech demo as a stretch goal for Mission 1, or the main goal of mission 2. And I really doubt that we will be able to fund 5 missions, so I think we would have to cut the Phobos preparation mission. Though, then again, we could over use the electrotether to prove it's capabilities, but my previous points are still valid.

[Nicholander]

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 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)

I thought it was impossible to orbit Phobos! Because in a scenario in the stock Orbiter, it says that it's impossible because Mars' gravity would overwhelm our spacecraft when it was faraway enough to have an orbit, but in the scenario it has an orbit around Mars which stability keeps the spacecraft 275 km away from Phobos. But that's 275 Km, to faraway for to do any kind of landing.

Edit: I checked the scenario and it actually has the orbit have the spacecraft go from 350 Km from Phobos to 60 Km from Phobos. Maybe you could do something at the Phobos perioapois?

Edited July 31, 2014 by Nicholander

[Rakaydos]

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.

[Nicholander]

I don't know if Phobos' gravity is strong enough to allow a 13 km orbit around it. I'll try it in Orbiter and see what happens.

[Rakaydos]

I don't know if Phobos' gravity is strong enough to allow a 13 km orbit around it. I'll try it in Orbiter and see what happens.

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

[Nicholander]

I tried it in orbiter, and even at 1 Km above Phobos, the spacecraft was only being effected by Phobos by 0.01 Gs. I even tried a 600 m orbit, and i couldn't do it. Maybe I suck at orbiter, or maybe I it's actually not possible. Anyway, my point is I think we should do the "Fall over with a bumper" method rather then the Phobos sled. The sled seems just too risky, but certainly very Kerbal.

EDIT: Did you have non-spherical gravity on? I did.

Edited July 31, 2014 by Nicholander

[Rakaydos]

*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?

[Nicholander]

Absolutely no idea. Maybe you could get the velocity down enough for the bumpers on the spacecraft to be able to touch it down safely, probably with the help of "Phobos landing motors" that I described in a previous post. Also, in your calculations, did you include the gravity of Mars?

[Rakaydos]

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.

Edited July 31, 2014 by Rakaydos