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Tom Kalbfus

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Registered: 2006-08-16

Posts: 4,401

Human Missions to Mercury

I think the hardest part about sending humans to Mercury is the spaceship that gets you there. Before you tell me that Mercury is hot enough on its surface to melt lead, I must remind you that that is true only of its day side, the night side is a different story. A two stage lander could land on the night side of the planet, and there is some hardware that might even assist in this. Remember Pathfinder? Pathfinder had rockets which slowed it down to a few tens of meters above the surface, and it was then released and bounced on a cushion of air bags surrounding a tetrahedral structure which then unfolded into a triangle once safely down, a similar thing could be dropped onto the surface of Mercury, it would then act as a homing beacon for a manned lander and then self-illuminate so the lander can land on it in the dark.

Once on the surface, a large drill drills into Mercury's surface and radiator fins are deployed, the lander then runs on underground heat. For while the surface of Mercury gets quite low at night, if you go deep underground the temperature should get quite hot if it is near the equator, one can use the difference in temperature to generate electricity abd power the spacecraft while it sits on the surface, and on top floodlights would illuminate the ground around the lander I all directions so astronauts can get a good view and collect samples. The space suits the astronauts would use would be similar to Mars space suits, as there is hardly any difference between the surface pressure of Mars and the vacuum of space., probably each spacesuit would come equipped with a "miners light" on top of the suit's helmet, and the astronaut would carry a handheld flash light as well. the vacuum of space would insulate the suited astronaut quite well, though the bottoms of the boots would have to be thickly padded with insulation.

Unlike as astronaut walking on the daylight surface of the Moon, an astronaut walking on the night side of Mercury would get an excellent view of a starry sky, and would not need a glare shield over his face mask. under floodlights and flashlights, the astronaut's face would be quite visible to other astronauts and to cameras sending pictures back to Earth.

A day on Mercury is 176 Earth days, half that amount is spend in darkness, and with a very slight axial tilt, Each day is about the same length. I see no reason for humans to be on the surface during the day. 88 days of darkness is enough to get the mission accomplished. The synodic period is about 115 days, so the astronauts can depart about 115 days after they arrive.

Last edited by Tom Kalbfus (2015-02-16 23:17:25)

RobS

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From: South Bend, IN

Registered: 2002-01-15

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Re: Human Missions to Mercury

The best place to land on Mercury is the poles, where there are extensive ice deposits in permanently shaded areas and where there is perpetual sunlight on peaks. I'm not sure you can get enough energy from temperature differences because the day-night cycle is very long. But one could conduct numerous short expeditions from the poles. I suspect daytime conditions would be so extreme, one would not want to be out in them.

Tom Kalbfus

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Registered: 2006-08-16

Posts: 4,401

Re: Human Missions to Mercury

Depends on how deeply you drill. You are aware that if you go far enough under ground at 45 degrees latitude on Earth, the temperature stays a constant 50 degrees F all year round. Probably underground on Mercury the average temperature is a lot higher than that, The Rock above acts as insulation so the surface rock cools more quickly after the Sun sets, but if you go deep under ground, the rock stays hot at the average temperature for Mercury at that latitude. Also the equator is the best place to place mass drivers. Mercury's equator is about lined up with the plane of its orbit, if you launch rocks at the right velocity, they can reach the Earth from Mercury. One way to power the mass drivers is to tap the subsurface heat after sunset, the cold night will provide the temperature difference, and allow for the operation of superconducting magnets. The mass drivers would stay dormant under shade during day.

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,433

Re: Human Missions to Mercury

The loops of fluid in the dug hole could indeed create power via steam and or other methods depending on the working fluid once it is deep enough as done with geothermal heat pumps and other such devices. To keep a surface area habitat cool one needs to have a system that circumnavigates around the planet to the cold regions of the planet such that it becomes the radiator for the heat build up running underground so as to keep it from obsorbing heat along the run until it gets to the area that is cold. As for a material that can surviv the surface temperatures I would look to the shuttle style tile and insulation that is used in a furnace to aid in isolating the crew from all the heat.
So what would be the sites preload tonnage and how long can we wait to develope the site before we lose the initial investment before man can go?

Tom Kalbfus

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Registered: 2006-08-16

Posts: 4,401

Re: Human Missions to Mercury

One thing to survive the heat is simply to shade it from the Sun. Mercury is basically a vacuum world, so you can store heat sensitive equipment on stilts under shades that are high off the ground. Vacuum is a good insulator so long as you can keep sunlight off of it. Basically I imagine a string of mining camps or bases all along the equator and astronauts move from one to another, the taps stay deep in the ground the radiators fold up when the Sun rises and reflective shades are deployed. A more permantly occupied base is at the poles in shadowy craters, but you don't want human activity to be confined to those poles only. There is a lot of stuff to mine on Mercury. Mass drivers on the night side can fling ore into space. I don't think they can be flung all the way directly to Earth mainly because the planet rotates slowly, it might be more practical to fling ore into ore catchers in orbit around Mercury and then use solar sails to ferry the ore to where its needed. I think we really need to fully develop Solar Sail technology to fully exploit Mercury, you need large delta-Vs to get to mercury, but you don't need high thrust to mass ratios to get there and back, just basically off the planet into low Earth orbit and landing stuff onto it as well. I think Cyclers might be more practical on the Earth to Mercury route than the Earth to Mars one, as Mercury has an orbital period of one quarter of an Earth year, and planetary alignment with Earth occurs rather frequently. A cycling spaceship will get a lot of use. It would be slowly accelerate with Solar Sail, and the Solar Sail would adjust its orbit so it continually goes from Earth to Mercury and from Mercury to Earth. The astronauts themselves would be accelerated in Orion capsules to match velocities with the cyclers. I think the heat shield of an Orion capsule would have to be fairly robust for atmospheric reentry in Earth's atmosphere I'm not sure what g-load the astronauts would be facing. Solar Sails tend to be slow, so you use them for unmanned payloads, so cyclers are already in their established orbits, and astronaut launches in an SLS and is accelerated to meet the cycler and it passes the Earth, most of the fuel would be expended just making the velocity change to meet up with the cycler. A mercury orbiter/lander would also be docked with the Cycler, it would detach and use to propellant to match velocity with Mercury and then land on the dark side of the planet's surface.

Tom Kalbfus

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Registered: 2006-08-16

Posts: 4,401

Re: Human Missions to Mercury

Look at the picture of the crater at the South pole. This is a mosaic image of Mercury detailing the polar regions, notice the dark crater right at the south pole! That would be an excellent place to put a manned base. Notice the bottom of the crater never receives sunlight, the walls of the crater should protect against solar flares as well, and Mercury has very little axial tilt.

JCO

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Registered: 2015-01-22

Posts: 35

Re: Human Missions to Mercury

Most of the discussion has been about avoiding heat. Heat is relatively easy problem compared to radiation. Mercury has a magnetosphere like Earth. That means that cosmic radiation rains down constantly on both day and night side. Not only are the solar winds over 6 times more powerful in Mercury's orbit but it has no atmosphere to shield anyone on the surface. With the amount of radiation it is exposed to it is likely the entire surface of Mercury itself emits harmful levels of radiation. The only manned mission I could imagine is is one that directed robotic operation on the surface from Mercury's L2 point with the Sun. This would only be true if this did provide enough protection from most of the Sun's radiation.

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,433

Re: Human Missions to Mercury

With any Mercury occupation thou the astronauts will take up root below ground and will not see any of these harmful radiation types.

The poles do look like a perfect place to take up root and get some real data....

Tom Kalbfus

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Registered: 2006-08-16

Posts: 4,401

Re: Human Missions to Mercury

Magnetic fields tend to concentrate radiation at the poles, that is charged particles. Mercury's magnetic field is weak however, about 1% of Earth's, the radiation environment is probably not as lethal as Jupiter's.

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,433

Re: Human Missions to Mercury

The space requirement for each astronaut to keep sane does not change from one destination to the next but the more we do have for the longest of journeies would help.