Real Life Minmus Mission

[Jodo42]

Suppose for the sake of argument that an object proportionally similar in terms of physical and orbital characteristics to Minmus orbited Earth as a natural satellite. What would a real life mission to it look like? How would such missions differ from the Apollo or Surveyor programs?

Some things for consideration:

Orbiting at an altitude of around 1370Mm, Minmus takes around a month to reach via a standard Hohmann transfer. The Moon takes 3 days to reach.

-Surface gravity on Minmus is .491m/s^2, or .05g. The Moon's is 1.6m/s^2, or .17g.

-dV from low Minmus orbit to its surface is about 1000m/s. dv from low lunar orbit to its surface is about 1900m/s.

Some topics for discussion:

-Could Minmus fit in our current understanding of the Solar and Earth systems' formations? Would missions to it provide significant scientific insight? What would we learn by going to Minmus that we would not from going to the Moon? If not, how would Minmus have to be different to be more realistic? How would this impact the remaining questions?

-What is Minmus composed of?

-When would missions to Minmus have taken place? Before or after the lunar missions? Would they have been manned?

-Identify challenges unique to a Minmus mission, both for manned and unmanned missions. How would/could they be overcome?

-Are there any unique advantages of a Minmus mission, as opposed to lunar missions? Could Minmus be used for as a staging ground for other missions?

Some potentially useful resources:

Minmus' wikia page

dV information for 10x Kerbol (similar to irl scales)

Have at it.

Edited October 18, 2015 by Jodo42

[Gaarst]

First thing to take into account is that Minmus's density is 29.2 g/cm³, this is denser than any known element at standard pressure and temperature (Osmium the densest element is at 22.6 g/cm³).

But suppose Minmus exists as it is in the Earth system, with the same mass and radius.

About manned missions:

470 Mm is only slightly further than the Moon (380 Mm) and the surface gravity is several times smaller than the Moon's. So I think it would be easier to get to Minmus than to get to the Moon. We will probably have been there before going to the Moon, as even though insertion burn would be greater, the lander would need to be a lot smaller, and less powerful.

Permanent human occupation, if it happened, would most likely take place on Minmus due to its weaker gravity, as it would be easier to take materials or humans to its surface. Its ice layer could also easily provide water for its inhabitants.

The greater distance to Minmus would actually be a good thing for space travel: after going to the Moon, our only option for manned flights is Mars. With Minmus at this position, there actually would be an intermediate destination before Mars. It would be easier to test vessels or general interplanetary technologies. Assuming space conquest happened at the rythm it did in real life, I think we would probably have sent humans to Minmus, and we would be more advanced in our Martian programs, at least technologically and biologically.

Also, due to this proximity of orbits between the Moon and Minmus, the latter's the great distance from Minmus to the Earth, Minmus' orbit would most likely be unstable. It would risk being ejected from Earth orbit anytime.

Assuming Minmus would be made of extremely dense ice, then the most plausible scenario for its origin would be that Minmus was once two very large comet from the outer solar system. They somehow impacted each other and fused, making this extremely large comet (60km radius). Its orbit would have been modified and after several gravity assists by Jupiter or Saturn it would have ended up being captured by Earth.

If you take a 10x radius for Minmus (600km), then it is trickier as bodies this size are essentially made of rock, and form by accretion (with the exception of the Moon). That would make Minmus somewhat between Enceladus and Ceres, though surface features would be very different. Minmus would then be made of rock covered by a thick ice layer.

The large flat surfaces of Minmus could have been caused by an impact ejecting a part of Minmus' ice layer, and leaving the rocky interior exposed.

A plausible scenario for its formation would be that it was originally formed as a moon of Jupiter or Saturn. For some reason, Minmus formed very closed to its parent planet or another moon. This unstable orbit would have thrown Minmus extremely close to its planet, tidal forcces ripping off a part of its ice layer, and was then ejected to a solar orbit. Then, it stayed on an unstable orbit, was disrupted by Jupiter and eventually captured by Earth.

Another scenario for Minmus' formation would be similar to Ceres': a protoplanet that never got large enough to be a proper planet. Either formed in the Kuiper belt, or somewhere between Mars and Jupiter, it would have been captured by Earth like the scenari above.

Assuming Minmus was indeed formed in the outer solar system (either orbiting a gas giant or in the Kuiper belt), studying it could provide precious information about this part of the solar system. In our system we need to send probes to comets or in orbit of the gas giants to get such information. It would be much easier to land probes or rovers on Minmus, and bring back samples, and huge amounts of data.

Edited October 18, 2015 by Gaarst
Edited post according to Jodo's correction

[Jodo42]

Sorry, I completely blew the orbital altitude. I believe it's now correct.

[Gaarst]

Corrected my post accordingly.

[Frozen_Heart]

I suspect that human spaceflight would be much more advanced and developed if there was a Minmus like body in the real solar system.

Its distance would allow it to be a stepping stone to full interplanetary missions and would mean that the technologies needed could be perfected much easier. Additionally its very low gravity and large amounts of water ice would mean it is the perfect place to put a surface base or to mine.

I suspect we would have gone after the moon missions, as it would require additional things such as a habitat module for the crew to live in.

[SargeRho]

Near Earth Asteroids are easier to reach than the surface of the Moon, and we haven't gone to those yet, so I'm not sure if a 'Realmus' would have much of an impact on manned space flight to be honest.

[Findthepin1]

Even if it is easier to reach Minmus than the Moon, I think that we still would have gone to the Moon. The Moon is a big rock in the sky and Minmus is a little green dot. People would consider the Moon a much more significant object for this reason, and reaching Minmus wouldn't really make people awed because we can't easily see the place with the event.

[peadar1987]

At this orbital radius, Minmus would lie at the very edge of earth's Hill Sphere, and its orbit would be very unstable. You'd want to visit it quickly before gravitational perturbations from other objects (most notably our own moon, but also the sun and other solar system objects) threw it off into space.

[ChrisSpace]

Minmus would be a perfect 'halfway' point between the Moon and Mars. So this means that if it was real, when Apollo 11 landed on the moon in 1969 the Soviet Union could have raised the bar higher (literally) and the space race could go much further.

[RA3236]

Okay a few ideas:

1. No matter what, Minmus would have been ripped apart more than a billion years ago, not by Earth, but the moon giving it a boost so it exited Earths SOI and melted as it approached the Sun or shot towards the outer solar system.

2. EVEN if that didn't happen, there's more chance it will crash into Earth as its orbit was changed constantly by the Moon and orbital decay.

3. If that didn't happen, then when the Americans landed on the moon, Minmus would be the Soviets next target.

4. Collisions with NEOs would cause mass extinctions on Earth as the debris from them would be deorbited. Furthermore, Minmus would be cratered.

5. We wouldn't be alive because of 4.

Just my guess.

[KerikBalm]

For #1 and #2

I seem to remember somebody once did a N-body simulation of the solar system from KSP.

Val got ejected from the Jool system.

Some time later, bop got ejected.... everything else appeared to be more or less stable

Although maybe thats stable on the order or thousands of years... billions? I don't know

Minmus can't be water ice, or it would sublimate away like a comet.

#3) I think that's sort of the point of this thread, it would be a lot more reachable than Mars

#4) I don't think it would do much to the mass extinction rate given its distance and small mass. If our moon doesn't do that, a rescalled +real minmus wouldn't do it.

#5) I don't think 4 would be a problem.

If #2 happened and the perapsis was brough down to earth, the impact would be an extinction event. If it was ejected, it may collide again, and extinction event, or maybe it forms a resounance, or is further boosted by close passes, and cleared outward (perhaps by Jupiter)

- - - Updated - - -

Here's val going bye-bye very fast:

and the rest of the system:

[Findthepin1]

Our moon does do that

[PB666]

What you are considering is a Hohmann of maximum efficiency. If minmus was an earth moon and earth were kerbin (obviousl an object at 50 million meter from earth is only 50,000 km, only a quarter of the distance to our moon) is that the orbital velocity of minums is so slow that the last quarter of the transfer takes most of the time, while efficient, if you wanted to waste a couple 100 dv you could markedly speed up the transfer. in the case of leaving kerbin you start out at 2900 with zero radial velocity, this builds to a max around 1500 m/s radial and slows quickly to a few 100. If you can double or triple the radial velocity crossing minmus orbit that very slow leg approaching minmus can be spead up, trimming up to 1/3 rd off the time of flight off.