KSP Rocket Probe: Mun

[ihtoit]

We're a bit short on computer processors (and decent radio gear), so we're having to fire off rockets and hope for the best.

THE CHALLENGE:

Fire a three-stage probe at Mun. Hard landing or orbital insertion ideal, passive slingshot flyby is good.

THE REAL CHALLENGE:

No burns above 100km ASL of either Kerbin or Mun (assume the Munar relay is a walkie talkie and has a REALLY short range!). Yes, this does mean that if your Munar periapse is higher than 100km you won't be allowed to fire your third stage.

Rules:

- Probe core challenge: Kerbals not necessary for this challenge

- Any structural or powerplant part allowed. For this challenge and purpose, shrouds and procedural fairing ejection does not count as staging.

- NO MECHJEB. PERIOD. ALL flight manoeuvres MUST be done manually.

- First stage burn MUST be a combined (ie single burn) launch/Kerbin orbital insertion. No burn-coast-burn to orbit on the first stage, folks!

- Second stage burn MUST be the Munar transfer burn.

- Third stage burn may be either: Free return, orbital insertion, or Minmus transfer burn. Any third stage burn MUST occur BEFORE Munar periapse

- Engine staging MUST occur after EACH burn (yes, that's all three. I don't want to see attached engines/tanks on any Minmus flybys!).

- NO RCS or Infiniglide

- NO welding or unbreakable joints

- NO gravity hack

- NO infinite fuel

Scoring (relevant screenshot proofs please):

The Bottle Rocket Award: Use all your fuel in each stage

The Roger Ramjet Award: Make a successful Kerbin orbital insertion

The Buck Rogers Award: Make a successful Munar encounter

The Flandro Award: Fly by Mun *and* Minmus (named for Gary Flandro, who first conceived of the planetary Grand Tour at JPL)

The Lunik Award: Insert into Munar equatorial orbit (inclination less than 30 degrees) (named for Lunik 10, the first artificial Lunar satellite)

The Clementine Award: Successfully insert into polar Munar orbit (inclination greater than 70 degrees) (named for the Lunar mapping program launched by BMDO/NASA)

The Shackleton Award: Achieve the Clementine Award challenge, with the addition of a kethane scanner and show scanning progress after at least two full orbits (named for the private company planning to exploit rumoured ice deposits on Lunar poles).

The Luna Award: impact probe on Munar surface without using the third stage. (named for Luna 2, the first manmade Lunar impacter)

The Jade Bunny Award: Perform a Munar lithobrake without breaking anything off (ie a survivable hard landing) (named for the Chinese Lunar mission that's... sort of in the air right now)

The Lunokhod Award: Land a rover on Mun via lithobrake maneuvre and show controlled traversal (named for the first robotic rover to land on the Moon)

The Venera Award: Achieve the Flandro Award, with the addition of a survivable lithobrake on Minmus (named for the Russian Venus probes 1961-1984).

The Anaxagoras Award: Make free-return flyby around Mun and return to Kerbin (named for the Greek philosopher who reasoned that the Sun and the Moon were both giant spherical rocks) (yes this is possible! Watch Apollo 13 to see how they did it).

The Apollo Award: Achieve the Anaxagoras Award challenge and make a safe landing on Kerbin (named for the aforementioned Apollo 13 mission where the capsule and astronauts were retrieved less than an hour after splashdown).

*I'm open to adding new awards, please put your suggestions on a postcard...

**I know there are some award combinations that are physically impossible (ie Flandro and Clementine, Flandro and Shackleton, Flandro and Jade Bunny...), that's deliberate.

Missions:

ihtoit (Challenge proof w/video): Roger Ramjet, Buck Rogers awards

Xeldrak: Roger Ramjet, Buck Rogers, Anaxagoras, and Apollo awards.

UpsilonAerospace (w/video): Roger Ramjet, Buck Rogers, Anaxagoras (which you almost didn't get for splitting your S2 burn), and Apollo awards (notwithstanding the use of the third stage to slow terminal descent!)

Edited February 18, 2014 by ihtoit

[Captain Sierra]

I'm gonna be the first and throw up the "dam near impossible' flag. you're asking for a Kerbin SSTO which does not cut it's engines from launch to stable orbit WITH a payload of several tons, likely at least 10.

As per good challenge etiquette, show us this is possible before you ask the same of others.

[ihtoit]

very easy without even resorting to a video capture: by keeping to terminal velocity curves, it's entirely doable.

By keeping to Vterm., you are always at or very near your apoapse, and gravity turning at the correct pitch throughout so by the time you hit orbital altitude you should be vectoring on the horizon, at the correct speed.

Terminal velocities are given in the table here, about 1/3 down the page. You should be thrusting to Vterm. from launch, and to maintain velocity at 32000m to orbit (where you're not actually speeding up but raising your periapse, your vertical momentum carrying you to orbital apoapse). Funnily enough, fuel optimal ascents involve a single long burn (what I call a "lawn dart ascent"). Burn-coast-burn ascents are wasteful.

Edited February 16, 2014 by ihtoit

[MarvinKitFox]

So, you have good enough radio comms to fine-tune your throttle level and gravity turn all the way up, but you are not allowed to switch engine off, then on again because of bad comms?

Inconsistent rule!

[Northstar1989]

I'm gonna be the first and throw up the "dam near impossible' flag. you're asking for a Kerbin SSTO which does not cut it's engines from launch to stable orbit WITH a payload of several tons, likely at least 10.

As per good challenge etiquette, show us this is possible before you ask the same of others.

It *CAN* be done- but the mass ratios are frankly insane.

I built a SSTO fuel tanker a while back that carried a larger payload to what would be needed for the Munar probe (around 18 tons of fuel- you could definitely do the free-return and most of the others with a 9-ton total upper two stages), but the thing weighed over 1.25 MEGATONS on the launchpad, and used plasmodynamic thrusters for frankly insane ISP (over 1000). It also required over 20 MINUTES of burn-time (game-time, longer with lag), as its TWR was so low out of the atmosphere with only the plasmodynamic thrusters still running so as not to burn up the fuel that was the intended cargo (hey, nobody said the engines all have to burn out at the same time)- and that was with MechJeb to take away the tedium; it would be VERY painful to do manually...

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I don't suggest anybody try this at home unless a melting computer is their idea of a good time (I was so worried about the laptop overheating I opened the windows in winter, disabled all unnecessary computer processes, and turned off the heat in the room...) So, I don't really want to launch that again- especially since my laptop's fan hasn't been working so well lately...

For scale, the black and white tank is 5 meters in diameter (the bottom tank is a super-stretchy StretchyTank). Since you would only need 9 or 10 tons for the upper stages (especially if you use 3rd-stage ion drives and a tiny probe), you could probably do it with something scaled down to about 1/2 the size- but at over 600 tons without normal staging, that would still be painful... Keep in mind that thing *just barely* limped into Low Kerbin Orbit with its payload.

You could also do it with an Orion, no problem (this was a real-life technology pioneered by the US Air Force, but never actually utilized due to the Nuclear Test Ban Treaty)- although I wouldn't suggest trying to land again after liftoff with a drive that releases thermonuclear warheads at pulsed intervals underneath...

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Anyways, OP, show that it can be (*reasonably*) done before asking others to meet a challenge. Those comments were right- it's just common courtesy.

Regards,

Northstar

Edited February 16, 2014 by Northstar1989

[BagelRabbit]

I think that you guys are overthinking this a little.

I will probably use the craft in this video as a start. It's a 720-gallon-of-fuel SSTO that can carry a very small payload, and while this video shows the craft not following all of the rules (too high a Kerbin orbit! Two burns!) it should definitely be able to accomplish this challenge with fuel to spare. The payload, after all, managed to brake to Munar orbit with over half of its fuel left.

Am I missing something?

[ihtoit]

So, you have good enough radio comms to fine-tune your throttle level and gravity turn all the way up, but you are not allowed to switch engine off, then on again because of bad comms?

Inconsistent rule!

how is it inconsistent?

[Xeldrak]

Is it possible that you did not completely understand what a free return trajectory is? Because there is no need for a third stage to "use for free return". That's why it's "free".

Still, here is my entry, the Münar Probe One (MPO):

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As you can see, I never touched my third stage.

I claim the the Anaxagoras and the Apollo award.

[ihtoit]

heh... ok, here comes a

showing me launching a <11t rocket to stable Kerbin orbit in one burn (it would have been circular but I racked up the throttle too early), then staging and burning for Munar encounter/flyby after just ONE orbit. Powerplant on that first stage is a Luvodicus Super Atomic, stage TWR is about 2.8 at full throttle.

Note that my transfer burn was basically done blind (after making sure I was at least pointed in the right direction with a manoeuvre node), if I had tried at this beyond proving that SBTO is not only possible but sensible, I could easily make Munar orbit.

Refer to leaderboard for awards gained.

PS: Xeldrak, great flight - again, see the OP for your awards. A free return can use the third stage or not, it's the decision of the flight controller. Apollo 13 used a farside burn to slow down (otherwise it would have just kept on going and escaped to solar orbit)

Edited February 17, 2014 by ihtoit

[BagelRabbit]

I've gotten it to work with a tiny little 100% stock rocket called the Munshot Mini. It has three stages, and is capable of achieving all of the awards except for the ones that would involve additional parts, including the rover one or the Kethane one.

It weighs 11.4 tons on the launch pad. The second and third stages combined have a mass of 0.81 tons.

I know there are some dubious things shown in the video I made (Almost turning the first-stage engines off, multiple second-stage burns to get a free-return trajectory) but overall, this flight shows that it can be done with a really small craft. (If you want me to redo the flight for competition legality, I would be happy to do so.)

Enjoy!

[ihtoit]

yep, good first stage burn there, second stage burn... I'm gonna have to disqualify, but I'm feeling generous this morning, following awards stand.

[Northstar1989]

I think that you guys are overthinking this a little.

I will probably use the craft in this video as a start. It's a 720-gallon-of-fuel SSTO that can carry a very small payload, and while this video shows the craft not following all of the rules (too high a Kerbin orbit! Two burns!) it should definitely be able to accomplish this challenge with fuel to spare. The payload, after all, managed to brake to Munar orbit with over half of its fuel left.

Am I missing something?

As you yourself said, the payload is VERY small. My point is that to get a large enough payload (>10 ton PAYLOAD) to orbit for a Munar landing AND return with only a single stage requires an initial rocket on the scale of the behemoth in my previous post.

[Northstar1989]

Is it possible that you did not completely understand what a free return trajectory is? Because there is no need for a third stage to "use for free return". That's why it's "free".

Still, here is my entry, the Münar Probe One (MPO):

http://imgur.com/a/W8cKc

As you can see, I never touched my third stage.

I claim the the Anaxagoras and the Apollo award.

Another TINY payload. That probe would be incapable or Munar landing AND return...

EDIT:

On reading the rules more carefully, I don't see any actual requirement for return of the probe. That makes a lot more of the awards possible- but still requires a tiny payload fraction...

Edited February 21, 2014 by Northstar1989

[Northstar1989]

Anyways...

I'm going to challenge your preconceptions a little, and ask: well what about using a mountaintop launchpad?

That was from the mountains west of KSC, where I set up that launchpad by means of hauling components using *THIS* mega-helicopter- shown here during an initial supply mission to set up the mountaintop base up (I did cheat a little, and edited in additional Rocketparts using TAC fuel Balancer after the initial setup, to avoid having to continuously run out new helicopter supply missions every time I wanted to launch an additional rocket- which would just be tedious and no fun)

Even a 4600 meter launch like this (over 15,000 feet) significantly reduces the Delta-V requirements to orbit: rockets experience less drag, have less altitude to climb, and can launch with a higher TWR than 2 (normally the optimal launch TWR) without losing more Delta-V to drag than they benefit from reduced gravity-losses.

It would make it entirely more feasible to complete the challenge with a reasonable-sized rocket (even if using a tiny payload).

Regards,

Northstar

Edited February 21, 2014 by Northstar1989

[ihtoit]

oh, brilliant... actually, since you have the proof of concept right here, how about you put up a challenge to build and deploy a mobile launcher capable of flinging a mun mission?

EDIT: I did it - with a twist >:]

Edited February 21, 2014 by ihtoit