In preparation for 0.17: simulated interplanetary flight and return.

[olex]

As 0.17 looms closer, the introduction of new planets around Kerbol will pose a new scale of challenge for all of us. I have designed this challenge as a test for my own engineering skills, but have now decided to share it with the KSP community to help us all prepare.

Your task, should you choose to accept it, is to build a manned spacecraft and fly a simulated interplanetary mission, with an intermediate landing at the destination and a return to Kerbin. For the current lack of other planets to serve as destinations for this flight, the role of the destination planet will be played by Kerbin itself.

The mission flight plan is as follows:

1. First leg: get to destination planet
   1. 
      
   2. Take off and leave Kerbin's atmosphere. LKO is not strictly necessary but recommended.
      
   3. Escape Kerbin's sphere of influence and reach an orbit around Kerbol not less than 1Gm higher or lower than Kerbin's.
      
   4. Rendezvous with Kerbin, preferrably using a single Hohmann's transfer.
      
   5. Land on Kerbin.
      
      
   6. Second leg: return to Kerbin
      1. In the same flight you landed in the first leg, take off and leave Kerbin's atmosphere. LKO is not strictly necessary but recommended.
         
      2. Escape Kerbin's sphere of influence and reach an orbit around Kerbol not less than 1Gm higher or lower than Kerbin's.
         
      3. Rendezvous with Kerbin, preferrably using a single Hohmann's transfer.
         
      4. Land or splash down on Kerbin. The Kerbal(s) must survive.
         

A ship capable of successfully flying this mission profile should be fully capable of reaching and returning from any landable destination within the Kerbol system in 0.17, since to my knowledge no landable bodies will have denser atmospheres or stronger gravity than Kerbin.

To prove your ship's and your own piloting capabilities, a video or screenshots of the mission will be required. At the very least there should be images showing the initial launcher on the pad, the Kerbin escape trajectory, the Kerbin rendezvous trajectory with a conic projection, the ship landed at the "destination", as well as the takeoff, escape, rendezvous and re-entry of the return leg. The MET display should be clearly visible in all proof material.

Mods are allowed. However, I will frown upon usage of the orbital construction mod, since it would be missing the point of this challenge.

Also, some exploiting of the 0.16 fuel bug is most probably unavoidable here, but please try and refrain from relying on it.

I wish you good luck, my fellow Kerbal engineers and pilots!

For my own entry, I already have a ship capable of flying the complete second leg with a mere 40 tons takeoff weight, and am in the process of fitting it with a launcher and interplanetary stage for the first leg. Rest assured, I will be completing this challenge myself and posting my results.

[illectro]

I previously did this with the old 0.15 parts. Now I have a plan afoot to accomplish this with the new parts.

You might also consider having categories for 1 man and 3

man landings.

[olex]

I previously did this with the old 0.15 parts. Now I have a plan afoot to accomplish this with the new parts.

You might also consider having categories for 1 man and 3

man landings.

Is it in one of your videos? I haven't seen all of them, but love the last ones.

I don't have this separated into categories per se, but this is definitely one of the criteria I would "rank" the submissions by. My own design is currently with a 1-man capsule.

-- edit --

As promised, I've finished my design and made the flight! Jeb was very appropriately spawned as the single Kerbal on board, and went for a ride of his life atop the Interplanetary 1 (I need to get more creative with ship names...):

Jeb went on to orbit and escape Kerbin and returned there in good health:

... only to lift off again mere seconds before splashing down, and go for the ride once more:

And then, finally, Jeb could return home, now feeling ready for any interplanetary mission to come:

Full album with mission images, including Solar orbits, on imgur: http://imgur.com/a/0OXBo

Edited August 16, 2012 by olex

[Boex]

Err...Only one Giga-meter? I'm pretty sure there will be no planets that close to Kerbin...I think we're talking >5 Giga-meters for Charr (the closest planet) and <20 Giga-meters for the Gas Giant... :/

[willow]

Hey...

I'm surprised you managed it. I really liked this challenge so I tried it yesterday.. Only I got into trouble where my spaceship would suddenly start spinning out of control pretty much from a standstill and anything I tried only made it spin faster. I figured it was my first encounter with the famed space kraken so I aborted there. Perhaps I went in too high an orbit. To simulate a proper transfer to another planet I wanted to circularize an orbit at about where I'd figure mars to be if it where there and then lower my orbit back to kerbin after I got there. Another weird glitch made almost all the craft I have in orbits around Kerbin and the Mun suddenly transferred into a solar orbit. It was a massacre I tell you at least 10 kerbals were instantly marooned. (I cheated and just ended their flights )

Perhaps I should have gone the other way round, lower the orbit to about venus then increase it back to rendez vous with Kerbin.

Up to this point I practiced the relevant maneuvering by travelling from the mun to minmus, and then landing back on the mun. It requires the same skill set, just a lot less fuel and less patience.

Can't wait to .17 with the panets!

[DEADBEEF]

Err...Only one Giga-meter?

As far as fuel use is concerned it actually counts as far more than that though.

In this simulation you're lowering/raising your orbit twice (once for each trip to Kerbin). If you were actually aiming to rendezvous with another planet you'd only need to do this once, (once to get to the planet, once to get back again).

Also, in reality you'd try to exit Kerbin on a direct intercept trajectory with whatever planet you're aiming for so wouldn't ever need to circularize your orbit around the star, which is where most of your fuel is burned.

[Douglasdtlltd]

A direct intercept would require a bigger rocker and more fuel. It's more efficient to do interplanetary orbits around Kerbol, like you would from Kerbin to the Mun.

[Tim_Barrett]

Did everyone forget that you can use other bodies to slingshot yourself around the solar system?

[olex]

Yes, that's another factor that will help save fuel in 0.17 as compared to this. You can try and use a slingshot around the Mun or Minmus for this challenge, I just didn't figure out yet how to do it properly, with the required timing and whatnot.

[Boex]

Also, in reality you'd try to exit Kerbin on a direct intercept trajectory with whatever planet you're aiming for so wouldn't ever need to circularize your orbit around the star, which is where most of your fuel is burned.

No, you wouldn't need to circularize your orbit around the star, but you'd actually need to slow down when you reach the planet to get into orbit/land. This is the same as circularizing your orbit around the star when you think about it, because if you slow down to the same speed as the planet at the same altitude, then your orbits are identical, and you will crash into it.

Of course, this problem of slowing down is avoided if you aerobrake through the planet's atmosphere, but that all depends on it's thickness...free Delta-V!

[DEADBEEF]

Yeah, where possible you'd do as they do in real life, aim your orbit so it enters the planet's atmosphere (at least temporarily) and use that to slow you down before either getting back into a stable orbit, or landing.

[DEADBEEF]

Oh yeah, here's my attempt at the challenge...

The phases of its first test flight were as follows...

* Lift off from Kerbin.

* Enter a stable orbit around Kerbin.

* Leave Kerbin's SOI and enter an orbit around the sun.

* Reduce the orbit size to a stable circular orbit at 11Gm.

* Wait nearly a year until we catch back up with Kerbin and can initiate a transfer burn.

* Adjust our landing point on Kerbin so we land back at KSC.

* Line up for a powered landing without parachutes.

* Touchdown!.

* Get out and stretch our legs. We've been in the capsule nearly an Earth year (356 days) so far.

---

Second Phase... Return 'home'

* Second llft off

* As soon as they're empty, dump the fuel tanks we used for landing.

* Get to orbit again.

* Leave Kerbin's SOI once more.

* Re-circularize (to speed up the time waiting for us to catch up with the planet I did a 10Gm orbit this time)

* Wait nearly a year again (much quicker this time as we're at 10Gm rather than 11), then initiate second transfer burn to send us back to Kerbin.

* When we enter Kerbin's SOI, do another small burn to adjust our landing point to be near KSC.

* Not quite gonna be enough fuel for a powered landing. Panic!!

* Quick, switch to the backup plan.

* Touchdown (again)

* Where are the crowds waiting to greet me after my two year voyage

[olex]

Nice work! You can take one fame and glory from the shelf for that, and a +rep is headed your way

[bsalis]

I confess I have not done this challenge but I have been working on something for the new planets. I'm not spending any more time on it until 0.17. Since who knows what will change, or even if 0.16 craft files will work.

It looks a lot like what olex is using (if you know it, what's the Delta-V on your craft?)

Anyhow, some pics below of testing my prototype...

In the VAB

Landing under chutes

Success

To orbit again

[AncientAstronaut]

You realize you can just go from Mun to Minmus and it's the same idea. I tried it a few times and nailed it. I'm ready for planets.

[nhnifong]

Why are all the support struts on the same side?

[olex]

You realize you can just go from Mun to Minmus and it's the same idea. I tried it a few times and nailed it. I'm ready for planets.

It's the same idea, but vastly different amounts of delta-V are required. With transferring from Mun to Minmus and back, you can learn the technique, but not prepare your ship.

if you know it, what's the Delta-V on your craft?

I've since redesigned the interplanetary stage slightly, and measured its delta-V to be ~1.7km/s. The return stage should be similar, however not measured, plus there is a lot of delta-V in the lander stage (enough to put it into LKO). Also, in an 80km LKO the initial launcher stage has some unexpended fuel left, that could be used to boost the interplanetary stage - need to see exactly how much delta-V is in there, too.

[DEADBEEF]

Why are all the support struts on the same side?

On mine?

Mainly just for aesthetics so it looks like a proper launch tower.

[EpsilonSigma]

You realize you can just go from Mun to Minmus and it's the same idea. I tried it a few times and nailed it. I'm ready for planets.

The Mun and Minmus are pretty small in comparison to a planet, and have no atmosphere. A mission from Home to Minmus to Mun and back home again will use, as usual, more fuel leaving the atmosphere found at "home". Provided you have a powerful enough engine you can jump between Minmus and Mun more or less as many times as you like.

Getting between atmospheric planets where takeoff is a lot harder is...well...harder. Besides, it's a lot larger distance and one initial trajectory mistake won't just mean a million meters out, but more like a trillion.

[nhnifong]

On mine?

Mainly just for aesthetics so it looks like a proper launch tower.

Doesn't it fall over?

[DjVip3rStrike]

I thought there was going to be gravity and air density changes in 0.17? Anyway it shouldnt be too hard as you can just slingshot past the mun or minimus.

[what-the]

I have done this in what I would call a small rocket.

Album of pictures

[Thobewill10]

A ship capable of successfully flying this mission profile should be fully capable of reaching and returning from any landable destination within the Kerbol system in 0.17, since to my knowledge no landable bodies will have denser atmospheres or stronger gravity than Kerbin.

Unfortunately, that does not hold for Eve, which will have a surface gravity 1.7 times Kerbin gravity and a far thicker atmosphere.

[Exclipse]

I do not think this test proves much for any ship in terms of interplanetary travel. It ignores possible factors, such as the Sun's gravity, possibility of larger planets with higher gravity than Kerbin, not to mention planet surfaces and atmosphere... You assume alot saying Kerbin will still have the toughest gravity and thickest atmos.

However I think if you can do the following with stock KSP... regards from me.

Travel from Kerbin land on Mun. Leave Mun travel to within 10,000,000 of the Sun. Travel back, land on Kerbin, take off without restarting or refueling, land on Minmus, and then travel back and land on Kerbin.

Think you should be good for most of the planets then...

Except maybe the one planet that is so close to the Sun it is barely visible