Mars Cyclers

Tom Kalbfus · 2016-03-30 07:23:02

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Suppose we went with this Cycler as our next space station. I like this configuration, because it spins for gravity, not a whole lot of gravity, maybe a Martian gravity, maybe less. The point is, we use the space to grow crops with robots controlled remotely from Earth. The Mars to Earth transfer time is 146 days, that means that the remaining time of the Cycler's orbit period is 633 days. the astronauts are onboard for the journey from Mars to Earth. That means we have 633 days to grow food for them. Now the arms of this space station spin slowly to get a sense of up and down. We need the gravity for the plants so the dirt stays down, and we can move robotic vehicles across the growing areas so they can pick crops, can them or freeze them. So it turns out that we have 4.3 growing days for every day the astronauts stay onboard this space station. Since this particular model seems powered by a nuclear reactor, I suppose the nuclear fuel itself is of negligible mass compared to the station, it can probably be brought up with the astronauts, it doesn't really get radioactive until it is used in a reactor!

RobS · 2016-03-30 07:33:52

Nice design, Tom.

It is still not clear whether cyclers are a good idea. They usually can't be used every opposition, and can't be used for both directions, so you need at least two, maybe more. That's the downside. The advantages are: they can be made big and heavy so as to reduce radiation exposure and provide a lot of room. But it is not yet clear that the radiation exposure is a serious issue and it may be possible to reduce the exposure or effects other ways. They also do not require a lot of propellant, so you can get a lot of mass going back and forth and only transfer the astronauts and their capsule from gravity well to gravity well. But if Space X lowers the cost of launching propellant to Earth orbit as much as they may manage to do, the propellant cost will no longer be a huge issue. And there is still the issue of making sure you depart for the cycler at exactly the right second and don't have a propulsion problem on the way.

Tom Kalbfus · 2016-03-30 09:58:58

RobS wrote:

Nice design, Tom.
It is still not clear whether cyclers are a good idea. They usually can't be used every opposition, and can't be used for both directions, so you need at least two, maybe more. That's the downside. The advantages are: they can be made big and heavy so as to reduce radiation exposure and provide a lot of room. But it is not yet clear that the radiation exposure is a serious issue and it may be possible to reduce the exposure or effects other ways. They also do not require a lot of propellant, so you can get a lot of mass going back and forth and only transfer the astronauts and their capsule from gravity well to gravity well. But if Space X lowers the cost of launching propellant to Earth orbit as much as they may manage to do, the propellant cost will no longer be a huge issue. And there is still the issue of making sure you depart for the cycler at exactly the right second and don't have a propulsion problem on the way.

I think a cycler would be best used on the return leg of the journey to start. Presumably the astronauts would be bringing the "House" they are going to live in on Mars on the outbound journey, That hab will have all the supplies they need for the outbound leg and for the duration of their stay on Mars. To get back to Earth, there is a separate Earth Return Vehicle, that lands on the surface of Mars with empty fuel tanks and with a nuclear reactor and stored onboard fuel it manufactures methane for its engines to return to Earth, the problem is, onboard the ERV, quarters will be tight, and they supplies they will need for the return leg, will take away from the payload of the rocks and soil samples from Mars that they may want to return to Earth for further studies, if you reduce the supplies for the astronauts to a minimum, then all the ERV has to do is bring the astronauts, and rock and dirt samples to the Cycler, the Cycler has the supplies to sustain the crew for the return to Earth. the Mars rocks stay in the Orion Capsule, the ERV then seperates from the Cycler when it gets close to Earth, and then fires its engines for a reentry trajectory into Earth's atmosphere, the capsule separated from the rest of the ERV and uses its heat shield to survive reentry and its parachutes to slow it down for a soft landing with astronauts and rock and soil samples from Mars.

Later on when their are permanent bases on Mars, the astronauts won't be bring habs with them, so another Cycler would be added for the outbound journey to Mars, and a simple lander will land the astronauts on Mars. The lander could be another ERV with empty fuel tanks, that way it will be available to the next crew for a return to Earth.

Last edited by Tom Kalbfus (2016-03-30 10:01:04)

SpaceNut · 2016-03-30 17:05:17

Hey Tom was there another topic yesterday that you started out with some of the same content that I posted to or was I only dreaming....

In the first image there is delta V values, are these catch up values or are these the needed changes to keep the cycler on time for rendevous?

Is there an article for it....

I did like the mars artificial gravity cycler design it was simular to the one I posted in another topic but this unit has an additional x member with 2 more pods for a large area of gravity to be present for crew to use.

So we would need to solve for the building blocks to send up for modular assembly of such a cycler station. Then once we pin down the size of each piece we would then need to select a launcher to loft it to the assembly zone in orbit or we would need to mass and size restrict the blocks for a specific launch vehicle.

Tom Kalbfus · 2016-03-31 00:28:15

SpaceNut wrote:

Hey Tom was there another topic yesterday that you started out with some of the same content that I posted to or was I only dreaming....

I took the information from this article:
https://en.wikipedia.org/wiki/Mars_cycler
Posted it in this thread about space stations:
http://newmars.com/forums/viewtopic.php?id=7224&p=3
I view a cycler as a space station in orbit around the Sun, it needs an engine to get there, but after that, the reactor simply powers the space station. The design I posted has four cylindrical pods which spin around the axis of the space station, since the station spins, I think it is simpler to power it with a nuclear reactor rather than trying to counter rotate solar panels and make them face the Sun. the actual nuclear fuel is compact and low mass compared to the station, and can be brought up with each crew easily enough. The rocket that gets it into that orbit is a nuclear rocket and after the propellant is spent, the nuclear fuel can continue to power the space station.

In the first image there is delta V values, are these catch up values or are these the needed changes to keep the cycler on time for rendevous?
Is there an article for it....
I did like the mars artificial gravity cycler design it was simular to the one I posted in another topic but this unit has an additional x member with 2 more pods for a large area of gravity to be present for crew to use.
So we would need to solve for the building blocks to send up for modular assembly of such a cycler station. Then once we pin down the size of each piece we would then need to select a launcher to loft it to the assembly zone in orbit or we would need to mass and size restrict the blocks for a specific launch vehicle.

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th?&id=OIP.M842b31da06ba19dfa22795874e284960o0&w=299&h=193&c=0&pid=1.9&rs=0&p=0&r=0
Here are a few.

SpaceNut · 2016-03-31 19:21:53

Thanks I was not dreaming, thats good....

The cycler still needs fuel for engine firing in order to do course corrections and for controlling entering mars and exist from the gravity slightshot with the same going for the earth end of this path around the planets.

Nice side mount Shuttle derived vehicle (SDV) but Nasa choose to go away from that to just using modified shuttle parts....

Tom Kalbfus · 2016-03-31 22:27:27

Yeah, must be an old image from the 1990s. The cycler could use inflatable modules for extra space and to create extra growing areas for the food crops. Plants can also produce oxygen, and for most of their journey, the habs would be unoccupied, the excess oxygen from the plants could be liquefied and stored in tanks, while the food could be harvested by robots, operated remotely from Earth, in much the same manner as the Curiosity rover on Mars is operated. Plants don't move much, so this should work out fine. It should also be fairly easy to freeze the harvested vegetables, and keep them frozen until astronauts arrive to consume the food. Also human waste as well as exhaled carbon dioxide can be stored and recycled through plant action, and turned back into food, plant matter and oxygen for the next crew to use the Cycler. The mass of the food, plants, air, and water remain more or less constant, the astronauts bring themselves, their rocks from Mars and consume the food, drink the water, eliminate, and then they leave with themselves and the Mars rocks they collected for departure to Earth, and all that waste and carbondioxide gets turned by into food by the on board farms for the next crew.

kbd512 · 2016-04-01 19:39:01

We could certainly use cyclers for cargo delivery, but I think the necessity for cyclers is far off into the future when we have a colony on Mars.

Regarding in-space nuclear propulsion, I think the most realistic concept on the horizon is the MSNW fusion rocket. A fusion rocket can widen launch windows (specific impulse is much higher than can be obtained using solid core fission reactors), increase payload mass (most practical and probable use), or get humans to Mars really fast (the propellant expended for super fast transits makes payload fraction unfavorable, but it's workable). The combination of high thrust, high specific impulse, low power requirements (relatively speaking, 150kWe in space is still a lot of power), low thermal dissipation requirements (certainly no higher than a fission reactor that produces 150kWe), and low total mass (50%+ payload fraction with a transit time of two weeks is spectacular compared to what we currently have).

Tom Kalbfus · 2016-04-01 23:10:17

Well actually cargo is inert, so it doesn't need a cycler. The best way to think of a Cycler is as a hab in space, it is the same thing as the hab on Mars in principle, only it stays in space, its purpose is to keep the astronauts alive during the journey, while minimizing the life support cargo that needs to be accelerated and decelerated. Without a Cycler, the Earth Return Vehicle is going to have to store life support for the returning astronauts, that takes up payload which could otherwise be Mars rock samples returning to Earth.

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Mars Cyclers

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