Space Bus - What's with the space bus idea?

Ian · 2002-02-11 18:46:21

Buzz Aldrin told the Inquirer about the Space Bus Idea.

What's with the Space bus idea of it oribiting the sun and then going to Mars that Buzz Aldrin proposed that I heard about?

Phobos · 2002-02-11 19:26:20

Some people propose cutting the costs of getting to Mars by putting a ship in a permanent orbit around the Sun that would swing by Mars every six months or so. I like the idea personally, it seems like it should be cheaper than always building new spacecraft for the long voyage.

Bill White · 2002-02-12 16:47:41

Combine the idea of an L-5 city in space with the Aldrin free return cycler. Add modules every time you swing past Earth and earn revenue by carrying passengers and supplies to Mars.

Living modules are spun up using tether technology to simulate gravity and you use solar ion propulsion and solar sails to adjust your orbit as needed. Use your water supply as the radiation shield.

Why would anyone want to build a city at a LaGrange point (sitting essentially stationary in space) when that exact same city could be built in a free return cycling orbit between Earth and Mars - or Mars and various points in the asteroid belt.

A motto for such a city: "L5? Not! We maintain momentum!"

Josh Cryer · 2002-02-12 22:47:56

Heh, I like it.

Is it possible to have more than one? (In opposing orbits, etc.)

Bill White · 2002-02-13 11:42:14

Look at this link for more information:

http://www.spacedaily.com/news/tourism-02b.html

This article claims Purdue University is working on the complex trajectory calculations needed to determine feasible orbits. Apparently, there are a large number of possible orbits with various advantages and disadvantages, but the math is very, very difficult.

Nonetheless, if someone were to accept the relative advantages and disadvantages of the various possible trajectories, it seems there are more orbital options than humanity could possibly build in the foreseeable future.

In other words, there seems to be enough room to build as many cyclers as we can possibly build and occupy.

And, if *any* such cyclers were built, a Phobos based "fueling depot" would have enormous commercial value.

Shaun Barrett · 2002-02-13 19:56:53

I believe Buzz Aldrin has been working on these "cyclers" for 10 years or more. I guess with his detailed knowledge of celestial mechanics, it was what you might expect of him. Back in the 60s, he was known as Dr Rendezvous because of his work on the mathematics and practical problems of docking spacecraft in orbit; an essential precursor to the moon missions (for obvious reasons).
Buzz Aldrin was somewhat overshadowed on Apollo 11 by all the hoopla surrounding Neil Armstrong's first footprint on the moon. But, since that time, and despite some serious personal problems including a struggle with alcohol and depression, he has made enormous contributions to the cause of manned spaceflight; the "cycler" idea being a good case in point.
Unfortunately, though, a fleet of "cyclers" would cost a great deal of money. Without a major find of something on Mars to fire the imagination of the public and, consequently, the politicians, it seems unlikely these oceanliners of the sky will ever get off the drawing board; at least not in the forseeable future.
Sorry to sound so negative. I hope I'm completely wrong about it. In the meantime, I hope I've helped to elevate Buzz Aldrin, in your minds, to the position I believe he deserves. He has been a voice in the wilderness for a long time now and I am one of his staunchest admirers.

RobS · 2002-02-14 01:57:06

If you hunt around on various web sites you can find bits of additional information. Aldrin's talking about building the cyclers out of space shuttle external tanks. With two or three tanks a cycler could transport up to fifty people to Mars. The idea is to use small, light-weight "taxi" craft to go from low earth orbit to the cycler and then from the cycler to Mars at the other end. The cycler would have the housing, radiation shielding, and other heavy weight items, which would have to be boosted into space only once.

Different cycler configurations have been proposed. The basic idea seems to be based on a two year orbit around the sun, basically the free return trajectory that Mars Direct proposes (which goes to Mars in 6 months, then swings further out and returns to Earth orbit 2 years later). One cycler would pass Earth, then Mars six months later; another would pass Mars, then Earth six months later.

The problem is that one can't go to Mars every 24 months, but every 26 months. So the cycler has to return to Earth orbit every 26 months. But it returns to Earth orbit at the spot where it left, and in 26 months the Earth is now two months farther along in its orbit. This means when the cycler gets to Mars, Mars's gravity has to bend the trajectory so that the cycler returns to Earth orbit at the spot where Earth will be the next time someone wants to fly to Mars. This is called rotating the line of apsides (the line that connects perihelion and aphelion; one always encounters Earth at perihelion). Mars does not have a strong enough gravitational well to do this all the time (it can do it when the planet is at aphelion, I think, but not perihelion, or maybe vice versa). That means the cycler has to have a rocket engine on board to complete the rotation of the line of apsides. Most likely this would be an ion engine, since the cycler would have a lot of power and the cruise back to Earth, being 18-20 months, is a long cruise when the craft is unmanned.

For the cycler going in the other direction there is less of a problem. After passing the earth, the cycler returns to Mars when Mars is at the spot in its orbit for a flight to Earth, about 20 months later. That involves rotating the line of apsides, but Earth has strong enough gravity to do it.

Other possibilities: three cyclers following a more complicated path, so different ones are available for the outbound and inbound legs; and semicyclers, which stop and go into very high elliptical orbits around one planet or the other (or stop at a Lagrange point) until needed to fly in the other direction.

Designing a cycler system is made much more complicated by the fact that Mars has such an elliptical orbit. It's closest encounter to Earth every 26 months varies from 34 million to 60 million miles. That means sometimes the Cycler goes between them in something like 112 days out of the 2-year orbit and other times more like 220 days, and that means Mars is in a different position relative to Earth. If Mars had a circular orbit, the problem would be much simpler (maybe we should move it).

You can find this out by searching through Google or another engine on "interplanetary cyclers" or "semicyclers."

Bill White · 2002-02-14 11:15:12

RobS:

Can you do us a favor and post the title of a textbook or a web link or other resource which we can study at home to better grasp the orbital mechanics at issue here?

Has anyone ever published an interactive CD-Rom for teaching the basics of orbital mechanics?

Also, while searching at the Purdue University website I found an article suggesting that the January 2014 Earth-Mars launch window does include a free return trajectory option and the article also seemed to say that the next few launch windows after that did not include a readily available free return trajectory.

Perhaps a schedule or table of available launch windows would be an interesting feature to add to the New Mars website.

Bill White · 2002-02-14 11:29:35

Shaun writes:

<< Unfortunately, though, a fleet of "cyclers" would cost a great deal of money. Without a major find of something on Mars to fire the imagination of the public and, consequently, the politicians, it seems unlikely these oceanliners of the sky will ever get off the drawing board; at least not in the forseeable future. >>

Shaun would seem to be correct, of course.

However, despite KSR's caution about the use of metaphor (see his interview with the New Mars staff) indulge me for a moment and consider Zubrin's frequent comparison of the settlement of Mars with the 19th century settlement of the American West.

Historically, who became the most wealthy from the 19th century settlement of the American West?

Not the poor folks trekking west in their wagons. No, it was the railroad companies. Whoever comes to own a fleet of cyclers will be the 21st century equivalent of the 19th century railway companies. While there is a very real chicken/egg dilemma, anyone who wanted to build cyclers would have a strong financial incentive to subsidize early settlement, looking to recoup that investment if settlement thereafter took off.

The first trillionaire will be made in space and he/she may very well be a cycler baron.

RobS · 2002-02-19 01:45:17

Alas, I don't have a source about orbital mechanics. I don't know much about it myself. But I have figured out that the cycler's orbit can't come back to earth easily when the oppositions occur when Mars is near perihelion. Consider that the July 26, 2018 opposition (when Mars is just 58 million kilometers away) is followed by the Oct. 13, 2020 opposition. A spacecraft leaving earth on May 26 (you leave two months before opposition for a six month flight) would have to leave Earth again on August 13, 2020. But a two-year free return trajectory would get it back to Earth on May 26 instead. Mars can't rotate the re-encounter with Earth by 2.5 months, which is 2.5/12 *360 = 75 degrees.

On the other hand, consider the oppositions of Dec. 8, 2022; Jan. 15, 2025; Feb. 20, 2027; March 24, 2029. Mars has to push the cycler ahead in its orbit only about 1.25 months or 1.25/12 * 360 = 37 degrees. Much easier.

Zubrin notes that magsail and other exotic technologies will fix the problem, and a small ion engine and 50 kilowatts of power might be enough to fix the problem, too. So could a stage full of fuel made on Phobos.

-- RobS

Dustin Freeman · 2002-02-25 18:04:54

If you've checked the news lately, it seems that more and more loaded people are wanted to go into space (Lance Bass being the most recent contender). Imagine the money that could be made off people going on 2-year vacations, or even retirement. This has already been discussed for Earth orbit. But since we're going to throw a hunk of metal up there, why not give it a bit more delta-V so it can be put in a cycler orbit. eehhh?
The premanent occupants would get great views of two worlds, and the people who are taking the one-way trip would be able to live in the economy-class apartements!

Mark S · 2002-04-11 13:32:35

First off, I just want to say that Buzz Aldrin still has "the right stuff." His promotion of flyback boosters and Mars cyclers just might lead to another golden age of exploration.

The best part about the cycler idea is that it provides an infrastructure for continuous trips to Mars. Although I like Mars Direct or something similar for an initial Mars mission, cyclers will keep the people and cargo moving between earth and Mars. If we stay the "Mars Direct" route, we will just end up with another Apollo dead end.

And the cycler doesn't have to be expensive. In one scenario, a shuttle can carry it's ET to orbit and then snare it with the Canadarm. Astronauts would then outfit the empty ET with life support systems, electrical systems, and all the amenities a cycler should have. A second flight can add a nuclear reactor and plasma engines for the cycler's course corrections.

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#1 2002-02-11 18:46:21

Re: Space Bus - What's with the space bus idea?

#2 2002-02-11 19:26:20

Re: Space Bus - What's with the space bus idea?

#3 2002-02-12 16:47:41

Re: Space Bus - What's with the space bus idea?

#4 2002-02-12 22:47:56

Re: Space Bus - What's with the space bus idea?

#5 2002-02-13 11:42:14

Re: Space Bus - What's with the space bus idea?

#6 2002-02-13 19:56:53

Re: Space Bus - What's with the space bus idea?

#7 2002-02-14 01:57:06

Re: Space Bus - What's with the space bus idea?

#8 2002-02-14 11:15:12

Re: Space Bus - What's with the space bus idea?

#9 2002-02-14 11:29:35

Re: Space Bus - What's with the space bus idea?

#10 2002-02-19 01:45:17

Re: Space Bus - What's with the space bus idea?

#11 2002-02-25 18:04:54

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#12 2002-04-11 13:32:35

Re: Space Bus - What's with the space bus idea?

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