Landing on Duna (The Challenges?)

[cocomoe1002]

Well ive been thinking about how to land on Duna when .17 comes out and people dont seem to notice that if the new update follows the laws of physics and is realistic then i picture it to be pretty hard to land on Duna. Here is why. In real life Mars is much like Duna that will come out in .17. so here is the chiz. You enter the atmosphere around 1500 ~ 2200 meters a second depending on how u do it. But since Duna's atmoshpere is thin it doesn't have enough atmoshpere to do the job...

So obviously you would use a parachute to slow you down even more. But it would be almost impossible to land safely around in my terms of 2 meters ~ 0.5 meters a second. Even if you have 100 parachutes on your space craft it wouldn't matter. you would always still be going around 150 meters ~ 110 meters a second also depending on how you do EDL. But if KSP .17 update doesn't exactly follow realism concepts, then it would be different or you would kill the little squishy Kerbal body's when the G's go sky high. But if the game does it would be impossible to land parachute only.

So the next step would be using rocket powered descent. But if you wanted to return the Kerbals back home i wouldn't try to use any of my fuel because its not that easy to get back. You need to make alot of adjustments to get back. The only way that i can comprehend is having a big ass lander..

But still the math doesn't add up. ??? So how would you land and get back? Its a question we will all ask our self's when .17 comes out. Feel free to discuss this odd and almost rhetorical question. Does it have a answer. Or am i just stupid and late that i haven't seen the answer yet?

And What would the easiest planet to land on for you. Explain....

[2008dragon]

Hmm, well, in real life, no one has attempted landing and returning from mars (or any planet). Also, Ksp does follow a lot of the laws of physics, it's just a different universe, so different planets and stuffs.

Many people I've seen will rendezvous with the landing craft with a different one after the lander gets into orbit again. Then, they will transfer the crew and fly back to Kerbin, but that's too much for me

[swiftgates24]

Well if you burn before you enter the atmosphere you can be going pretty slow, and if you use 1 parachute it always points your craft retrograde and that helps A LOT. I would have a separate stage for powered descent and about 1km from the surface I would get rid of it and start using my lander's external fuel reserves. To take off hmm... I would use small SRB's to get off the surface then use more external tanks. The external tanks get me to about...150km orbit. From there I get rid of them then use the rest of my fuel. If I am able to use my HUGE lander (not likely) I would go to Ike on the way home. I would probably only be able to get high Kerbin orbit using the rest of my fuel and send a ship to get them back down to the surface. Then they will be praised to be the first Kerman's on Duna's surface.

Kermans: Evolving 100x faster than us humans. August: Get out of spacecraft. ???:Land on other planets.

[Zool]

2200 m/s is too low. You will be traveling at a speed greater than Duna's escape velocity. 4-6 km/s is probably in the ball park. You'll aim for a low periapsis, so you can bleed off enough speed to get below escape velocity. It might be worth it to bring wings so you can raise or lower your flight as needed. But yeah, either a huge lander, or an orbiting return stage that you rendezvous with. You could send two rockets, one with a lander, and the other with the return stage (and a crew tank). That means you need to land a rocket just big enough to get into Duna orbit, instead of landing a ship with enough fuel for interplanetary flight.

For a round trip, Duna will be the easiest, you can can aerobrake, gravity is low, and the atmosphere isn't thick enough to really get in the way of getting into orbit. Eve will be easy to land on, but much more difficult to leave. Moho will require a very large DeltaV to get to, and has no atmosphere to help get you slow down when you get there.

[Tommygun]

I think aerobraking with several orbital passes will help save fuel, but Duna's thin atmosphere may make it a slow process.

Also direct atmosphere entry at Kerban can get you down in one pass. Over all I'm not sure how much fuel and weight it saves.

Edit: Ninja'd

[cocomoe1002]

2200 m/s is too low. You will be traveling at a speed greater than Duna's escape velocity. 4-6 km/s is probably in the ball park. You'll aim for a low periapsis, so you can bleed off enough speed to get below escape velocity. It might be worth it to bring wings so you can raise or lower your flight as needed. But yeah, either a huge lander, or an orbiting return stage that you rendezvous with. You could send two rockets, one with a lander, and the other with the return stage (and a crew tank). That means you need to land a rocket just big enough to get into Duna orbit, instead of landing a ship with enough fuel for interplanetary flight.

For a round trip, Duna will be the easiest, you can can aerobrake, gravity is low, and the atmosphere isn't thick enough to really get in the way of getting into orbit. Eve will be easy to land on, but much more difficult to leave. Moho will require a very large DeltaV to get to, and has no atmosphere to help get you slow down when you get there.

I think that is about correct. Since Kerbin takes in pretty fast you come in about 3000 m/s or more. Since Duna has less gravity it would be around 2200 m/s when entering the atmoshpere.

[NovaSilisko]

Actually, from my experimentation, you don't really need much fuel to get back into orbit from Duna. If you can rendezvous with a ship parked in orbit and transfer your crew over, you should be able to manage a round trip.

[Zool]

Can you settle the great Duna approach velocity debate?

(assuming a hohmann transfer from Kerbin)

[NovaSilisko]

Greatly depends on how good your trajectory is. I've aerobraked at 9 km up going 7 km/s, but also had relatively gentle aerocaptures at around 3 km/s.

[LaydeeDem]

Actually, from my experimentation, you don't really need much fuel to get back into orbit from Duna. If you can rendezvous with a ship parked in orbit and transfer your crew over, you should be able to manage a round trip.

This means I am completly ready for my Duna mission.

Craft that can escape Kerbin CHECK

Ability to transfer and rendezvous with other planets CHECK

Lander with enough fuel for landing and ascent CHECK

Now all I need is a return craft.

[Tommygun]

Actually, from my experimentation, you don't really need much fuel to get back into orbit from Duna. If you can rendezvous with a ship parked in orbit and transfer your crew over, you should be able to manage a round trip.

Have you ever made this trip in one ship?

[NovaSilisko]

The only round trip I've ever done was to Eve orbit and back, and even then it was cutting it close. But, mostly it's because I suck at interplanetary transfers.

[what-the]

Need to use lots of aero-braking and a landing stage. Aero-braking also enables low flybys of the land to find a good landing spot, take pictures, ect. Getting back might take awhile but a timed burn at midday Duna time should take me back to Kerbin.

[Tommygun]

Need to use lots of aero-braking and a landing stage. Aero-braking also enables low flybys of the land to find a good landing spot, take pictures, ect. Getting back might take awhile but a timed burn at midday Duna time should take me back to Kerbin.

How does that work exactly?

Do you launch from the surface when the sun is straight above you and go directly back to Kerban?

[what-the]

How does that work exactly?

Do you launch from the surface when the sun is straight above you and go directly back to Kerban?

Oops meant midnight. Day is to go towards the sun.

As long as you are orbiting at 90 degrees. When you pass over midday burn to go towards the sun and burn at midnight to go away from the sun. This works for high escape velocities.

[AncientAstronaut]

But still the math doesn't add up. ???

Interesting, OP. And tell us... What math did you do exactly?

[Tommygun]

OK, thanks for that picture.

Has there been any data released about how high the atmosphere extends above Duna and the other moons and planets?

[Trebuchet-Launch]

Hey, Nova, is Duna at around, what, 20.8 million km orbitally?

I'm beginning to think it might not require a booster too ridiculously oversized to launch a dumb idiot mission that lands everything on Duna and returns with no additional ships.

EDIT: My main enemy is the wimpy large decouplers. Please tell me they fixed that.

Edited September 15, 2012 by Trebuchet-Launch

[Arrowstar]

Oops meant midnight. Day is to go towards the sun.

As long as you are orbiting at 90 degrees. When you pass over midday burn to go towards the sun and burn at midnight to go away from the sun. This works for high escape velocities.

This picture is wrong.

If you want to extend your semi-major axis in the direction opposite Eve's motion (that is, solar retrograde), you need to burn in the morning. Call it 6 AM if you will.

Burning at "noon" will extend your orbit away from the sun, which doesn't get you anything.

[segaprophet]

OMG just release .17 and give us Duna already! I can't wait!

[Kosmo-not]

Oops meant midnight. Day is to go towards the sun.

As long as you are orbiting at 90 degrees. When you pass over midday burn to go towards the sun and burn at midnight to go away from the sun. This works for high escape velocities.

I refer you to the Interactive Illustrated Interplanetary Guide and Calculator. It will show you when you should do your burn.

[Exclipse]

Atmos is thin, but grav is lower as well, so just keep your trajectory shallow and you can airbreak for a much longer period before coming down to surface.

[Tommygun]

This picture is wrong.

If you want to extend your semi-major axis in the direction opposite Eve's motion (that is, solar retrograde), you need to burn in the morning. Call it 6 AM if you will.

Burning at "noon" will extend your orbit away from the sun, which doesn't get you anything.

Isn't that what the picture is showing?

Burning at noon, the arrow curves away from the sun and burning at midnight the arrow curve toward the sun.

[what-the]

This picture is wrong.

If you want to extend your semi-major axis in the direction opposite Eve's motion (that is, solar retrograde), you need to burn in the morning. Call it 6 AM if you will.

Burning at "noon" will extend your orbit away from the sun, which doesn't get you anything.

It does work. As I said you need high escape velocity (the amount needed to go to other planets).

http://imgur.com/a/EpmN9

[EvilotionCR2]

Eve will be hardest because you will need lander what can get to Kerbin orbit with lot of fuel remaining.

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