Aldrin's Cyclers

EarthWolf · 2005-03-25 07:18:31

Hello,

I remember reading a Popular Science magazine article about five years ago that described Buzz Aldrin's idea of interplanetary cycler spacecraft making perpetual figure-eight orbits between Mars and Earth. What benefits would there be to such a spacecraft?

Cordially,

EarthWolf

Grypd · 2005-03-25 10:42:22

The main benefits is that the cycler can allow crews to only have to take the supplies they need to survive the voyage and the shuttlecraft that gets them from Earth to cycler and from cycler to Mars. The infrastructure and space to allow the crew to move around will already be on the cycler. And it is not just to Mars that cyclers are good for as there orbits allow a mission to anywhere that the cycler is going.

Another advantage to cyclers is that they can be added to and can be made very big. So if you have a need to send a lot of people and equipment then cyclers are the best way. But then again it will cost a lot of money to develop them and unless we do plan colonisation I dont believe we will go this way.

Hop · 2005-03-28 16:50:34

If it's like the Aldrin cyclers I've seen, it's an ellipse, not a figure eight. Habs capable of keeping passengers healthy for seven months are large and expensive. It's hard to lift these out of earth's (or Mars') gravity well. With Aldrin's proposal these large habs (which Aldrin and Oberg call castles) fly by Earth or Mars each synodic period (about 2 1/7 years) and large habs don't need to be lifted from planetary gravity wells each trip.
Smaller crafter (Oberg and Aldrin call these taxis) ferry passengers from castles to planet. These Taxi could be much smaller since they only need sustain passengers for a few weeks instead of seven months.

There are other possible cyclers besides Aldrin's. If there's an interest I will talk about these.

Austin Stanley · 2005-03-28 17:13:05

One thing that worries me about Aldrin's Cyclers is the abort mode for the Taxi's if they miss their redevous. Most designs I have seen call for dispisable high energy chemical stages to reach the necessary delta-V to catchup up to the cycler. But what if for some reason they miss, it's not exactly an easy operation by any means. The taxi may lack the means to return their crew to Earth or even Earth orbit.

Hop · 2005-03-28 18:04:10

One thing that worries me about Aldrin's Cyclers is the abort mode for the Taxi's if they miss their redevous. Most designs I have seen call for dispisable high energy chemical stages to reach the necessary delta-V to catchup up to the cycler. But what if for some reason they miss, it's not exactly an easy operation by any means. The taxi may lack the means to return their crew to Earth or even Earth orbit.

It's even scarier for the Mars taxi trip. The Aldrin path is almost 90 degrees to the Martian path. The delta vee between Mars and castle is 12 km/sec. So if you don't make it to Mars, you're up the creek with no paddle. This is my major objection to the Aldrin cyclers. Other cyclers have much nicer delta vees.

RobS · 2005-03-28 19:55:29

This is a reason I much prefer "semicyclers," vehicles that stop in very high orbit at each end. If one used the L1 point between the Earth and moon, a taxi could take people up there quickly and easily in three days for a delta-v of 3.5 km/sec. The cycler could wait there, and it can go to Mars in six months for a delta-v of about 1.4 km/sec (0.3 km/sec to fly past earth deep in the gravity well, and 1.1 km/sec to achieve escape velocity plus the extra to fly past Mars quickly). Since the launch window from L1 to Mars via Earth is open a dew days every month during the few months of the synodic period when the planets are aligning, you don't have the severe time constraint on your taxi launch. At the other end, you'd aerobrake or perform Mars orbit insertion into a 24.6 "one sol" elliptical orbit (something like 500 km by 33,000 km). This orbit allows a return to Earth for about 1.6 km/sec (it takes about 5.4 km/sec to reach from the Martian surface). Since it has a very high apoapsis, it's easy to perform a plane change to get the orbit aligned for trans-Earth injection. And of course these semicyclers arrive at their destinations at reasonable sppeds; they could use aerocapture to get into the right orbit, with minor orbital corrections later.

-- RobS

Yeah, it's my posting 1,000!

SpaceNut · 2005-03-29 06:38:08

I guess the only thing I might add would be how could one off set the fuel costs for each slow down such that the only fuel consumed would be to speed back up for the L1 location.

Could unfurling a solar sail act sort of like a breaking device? Sure the size would be huge to make large changes in volocity but would it work for the return path to Earth.

RobS · 2005-03-29 15:04:22

I'm not sure what you are asking. A solar sail to speed up or slow down a large craft for humans would be impossibly large for near-term technology (say, 20 square kilometers). If you want to go from interplanetary space to L1, you'd aerocapture by flying through the upper atmosphere, slowing the ship down by about 1 km/sec (coming from Mars on a six-month trajectory). It's a pretty small aerobraking maneuver. That would put you in an elliptical orbit around the earth that goes almost to the moon. Then you'd perform a delta-v burn of about 0.5 km/sec to circularize the orbit at the distance of L1. If you flew to the moon, captured into an elliptical orbit around the moon that reaches to L1, then circularized the orbit from there, the delta-v is less (0.1-0.2 km/sec, I think). It may also be possible to capture into a high lunar orbit and then to fly to L1 for relatively little fuel.

-- RobS

Ian Flint · 2005-03-30 15:26:53

Rob,
You use this highly elliptical orbit in your novel for embarcadero station. Have you addressed the problem of aerobraking too shallow and not achieving orbit? What would your back up plans be in this scenario?

dicktice · 2005-03-30 17:04:41

How about emergency robotic high-gee ships, launched from Mars, or LMO (sort of like a Space "Coastguard" Rescue Service).

RobS · 2005-03-30 17:58:02

I know next to nothing about aerobraking and I have no idea whether it is easier to aerobrake into circular orbits or elliptical ones. I assume that the less delta-v an aerobraking maneuver has to perform, the better. If that is true, elliptical orbits are best, because they involve less delta-v.

I also assume that aerobraking can be made highly precise and predictable. Apparently both MER rovers were dropped into the Martian atmosphere within a hundred meters or so of target. If that is the case, a staffed vehicle with GPS positioning and a Mars orbit or Mars-ground mission control should be highly reliable and exact, unless some sort of Apollo-13 style accident happens within an hour or so of atmospheric encounter.

Does anyone know whether this is right?

-- RobS

Austin Stanley · 2005-03-31 04:22:07

How about emergency robotic high-gee ships, launched from Mars, or LMO (sort of like a Space "Coastguard" Rescue Service).

Catching up to a "taxi" headed out to deep space is going to be very difficult. The rescue vessle would have to have not only greater delta-V than the orginal taxi, but enough to stop and return to base. There is generaly no free return orbit for these trajectories, or if they do exist they are of very long duration. Needless to say that this would require not only a signifigant amount of thrust, but also alot of propellent. And it doesn't avoid the problem of redevous either. Better IMO to either avoid these high speed redevous all together, or have the abort option built into the taxi craft itself, which is going to increase it mass signifigantly.

Apparently both MER rovers were dropped into the Martian atmosphere within a hundred meters or so of target. If that is the case, a staffed vehicle with GPS positioning and a Mars orbit or Mars-ground mission control should be highly reliable and exact, unless some sort of Apollo-13 style accident happens within an hour or so of atmospheric encounter.

I would only point out that the rovers aerocaptured directly onto the planet rather than aerobreaking into an orbit and then landing.

Ian Flint · 2005-03-31 07:40:02

I know next to nothing about aerobraking and I have no idea whether it is easier to aerobrake into circular orbits or elliptical ones. I assume that the less delta-v an aerobraking maneuver has to perform, the better. If that is true, elliptical orbits are best, because they involve less delta-v.

All I know is that in 'Case for Mars' Zubrin mentioned that a low circular orbit would be safer than a high elliptical one. Breaking into the lower orbit would burn off more velocity than a high one, so if there were any problems it would have more room for error.
Remeber in KSRs trilogy, one craft had to pull up at the last moment and skipped past the planet because it didn't shed enough velocity.
That's about all I know.

RobS · 2005-03-31 17:58:13

I'll look over Zubrin's comments again tonight. I know GCN worries a lot about the reliability of aerobraking and aerocapture. It seems to me it should be as safe as using engines once the technology is mature. The problem is that right now the technology is not mature; we have only used heat shields for direct landing on the Martian surface, not aerocapture into orbit.

By the way, the orbit I assume for Embarcadero Station in my novel is straight from the NASA Design Reference Mission. But I don't recall whether the DRM assumed a Mars Orbit Injection burn or aerocapture.

-- RobS

Chazbro38 · 2005-04-03 22:41:45

Since any "Cycler" would probably have to have a nuclear power source anyway I think an array of ion drives or a medium sized VASIMIR should be attached in order to maintain a reasonably high Delta-V during transit and also for any required trajectory shaping that might be required. When the cycle arrived in the vicinity of mars a landing module with an Aeroshell could be employed so that it could either aerobrake into orbit or into a direct decent trajectory. The same mathod could be used as the cycle approached earth and in that way the cycler never bleeds off all that much energy as it interacts between the gravity fields of either Earth or Mars.

Charles

BWhite · 2005-04-03 23:15:54

One thing that worries me about Aldrin's Cyclers is the abort mode for the Taxi's if they miss their redevous. Most designs I have seen call for dispisable high energy chemical stages to reach the necessary delta-V to catchup up to the cycler. But what if for some reason they miss, it's not exactly an easy operation by any means. The taxi may lack the means to return their crew to Earth or even Earth orbit.
It's even scarier for the Mars taxi trip. The Aldrin path is almost 90 degrees to the Martian path. The delta vee between Mars and castle is 12 km/sec. So if you don't make it to Mars, you're up the creek with no paddle. This is my major objection to the Aldrin cyclers. Other cyclers have much nicer delta vees.

What about using tethers deployed from the cycler to accelerate the taxi? Loiter the taxi on a relatively low energy orbit that merely intersects the trajectory of the cycler.

Deploy multiple and very long tethers (50 - 100 km?) in front of the cycler, or at right angles to the cycler's movement. Given the low mass of the tether, a very small engine could manuever the tether tip fairly easily.

Snag the taxi (and then solve an enormous shock loading problem!) then reel in the taxi.

= = =

Loiter your crew taxi at a La Grange point or fly the taxi on an orbit that quickly returns back to Earth or Mars but which comes within 50km (or 100km or maybe closer) of where (and when!) the fast moving cycler will pass.

Use slack in the tethers to give additional time to assure a solid redundant connection BEFORE the tethers draw taut. If attachment begins as the cycler continues to approach the taxi, slack would increase for a while, allowing a manueverable tether tip to simplify hooking up. Attach securely with multiple tethers and wait for the gee-forces.

Carefully planned "rope tricks" might well ease the shock loading by spreading it out - - also if the cycler attachment points spooled their tethers on large drums, let the taxi play out the tether using the inertia of the spinning drum to dissapate the shock loads.

A Bigelow style (gossamer or inflatable) 6 person taxi with one heck of a hard point keel to anchor the attachment points might be surprisingingly low in mass, which makes the tether technology all the easier.

= = =

The cycler will lose momentum which would need to be recovered by ion drive, solar sails or whatever. Lots and lots of math!

So Hop right on it! (Sorry for the pun)

= = =

A chemical kick stage to be fired after the tether loads up can also be used to mitigate the shock loading. Suppose the chemical stage is only 50% of what is needed to match velocities. It would still reduce the tether loads substantially.

Edited By BWhite on 1112591881

Hop · 2005-04-04 00:17:34

Since any "Cycler" would probably have to have a nuclear power source anyway I think an array of ion drives or a medium sized VASIMIR should be attached in order to maintain a reasonably high Delta-V during transit and also for any required trajectory shaping that might be required. When the cycle arrived in the vicinity of mars a landing module with an Aeroshell could be employed so that it could either aerobrake into orbit or into a direct decent trajectory. The same mathod could be used as the cycle approached earth and in that way the cycler never bleeds off all that much energy as it interacts between the gravity fields of either Earth or Mars.
Charles

Trajectory shaping will be required.

Aldrin (and Niehoff) cyclers exploit the fact that 15 earth years is very nearly 8 Mars years. But "very nearly" isn't the same as "exactly" so the cycler will drift from the rendesvous points as time goes on. This can be corrected by rotating the line of apsides. Which makes it necessary to change trajectory.

If a cycler can rotate its line of apsides with only planetary gravity assists, then it's known as a "ballistic cycler". But even ballistic cyclers need to shape their trajectory to pass within the correct distance of the planet to turn the line of apsides by the desired angle. So a cycler _will_ need some way to change velocity whether it's ballistic or not.

The Aldrin cyclers are not ballistic. They'll need heavy duty burns to rotate their line of apsides even with planetary gravity assists.

I believe the Niehoff cyclers (1.5 year and 1.25 year orbits) are ballistic. These orbits are much closer to the minimum energy Hohmann transfer orbit than is the 2+ year orbit of the Aldrin cycler. Consequently they pass by Mars and Earth much slower than Aldrin cyclers (this is much nicer for the cycler to planet taxis, also). With a lower Vinfinity, the hyperbola's turning angle can be greater (the turning angle can be controlled by how far the hyperbola's periapsis is from the planet).

BWhite mentions the use of tethers to impart momentum to taxis. I've played around with cycler mass-drivers to help send the taxis on their way. Either of these would change the cycler's momentum and make course correction necessary as White notes.

Ion engines may be a good way to do this. The continuous thrust trajectories are not the conics I've become accustomed to, so, sorry, I can't do the math on those.

BWhite · 2005-04-04 08:21:22

BWhite mentions the use of tethers to impart momentum to taxis. I've played around with cycler mass-drivers to help send the taxis on their way. Either of these would change the cycler's momentum and make course correction necessary as White notes.
Ion engines may be a good way to do this. The continuous thrust trajectories are not the conics I've become accustomed to, so, sorry, I can't do the math on those.

Simple solar thermal might be a low tech solution to provide continuous thrust during the extended transits betweeen Mars and Earth.

The math detail is waay over my head however the idea that some fancy computers could "play billiards" and design trajectories to place cyclers at specific points in space (& time) seems conceptually easy enough.

= = =

Perhaps in a few centuries we will attach tethers to large numbers of inner solar system asteroids and by use of ultra high powered computational methods allow spacecraft to "swing" from asteroid to asteroid using momentum transfers. Vessels travelling in different directions can replenish momentum borrowed from these objects.

Fuel efficient travel.

Heh! - - Who "owns" the right to use the momentum possessed by this or that NEO?

RobS · 2005-04-04 10:48:07

Perhaps in a few centuries we will attach tethers to large numbers of inner solar system asteroids and by use of ultra high powered computational methods allow spacecraft to "swing" from asteroid to asteroid using momentum transfers. Vessels travelling in different directions can replenish momentum borrowed from these objects.

I love it! Let's call this the "Tarzan propulsion system"! Better than going from tree to tree. . . . I guess the question them will be, can we equip enough "trees" with "vines" for it to work!

This is a cool idea. If you want to send a spacecraft to Jupiter or a more distant destination, you'll need a tether on a highly elliptical object, such as a comet. The tethers will have to be pretty strong and reliable, though.

-- RobS

BWhite · 2005-04-04 10:59:43

Perhaps in a few centuries we will attach tethers to large numbers of inner solar system asteroids and by use of ultra high powered computational methods allow spacecraft to "swing" from asteroid to asteroid using momentum transfers. Vessels travelling in different directions can replenish momentum borrowed from these objects.
I love it! Let's call this the "Tarzan propulsion system"! Better than going from tree to tree. . . . I guess the questin them will be, can we equip enough "trees" with "vines" for it to work!
-- RobS

George of the Jungle was my image.

RobS, I know you enjoy writing fiction. Think about some of the lingo that inhabitants of a cycler city might develop. For example, imagine a cycling "castle" with a few thousand inhabitants:

"Hi guy, haven't seen you in a while. What's going on?"

"Not much, just 'taining mo'"

'taining mo' = maintaining momentum which would be one of the ongoing critical issues for the city.

At Aldrin CIty, Martin Lo's papers are taught in junior high.

= = =

I have long believed L5 cities are a fairly daft idea except as small outposts. Get those suckers moving in free return orbits and build them as big or bigger than any L5 fantasy city.

publiusr · 2005-04-08 13:54:30

Buzz advocates the use of External Tanks, as well as Gene Meyers:

http://www.spaceislandgroup.com]www.spaceislandgroup.com

This infrastructure will be lost if we go to EELV.

GCNRevenger · 2005-04-09 20:04:37

Buzz Aldrin is not a space engineer, and his opinion doesn't make the Space Island kooks any less totally insane.

Losing the KSC infrastructure may not be a bad thing since it is so expensive.

srmeaney · 2005-04-09 22:31:53

The transfer window will still be too small for the needs of colonization. It will need to be 'load the super transport and haul two years of heavy lift in one window'.

publiusr · 2005-04-13 14:56:38

Buzz Aldrin is not a space engineer, and his opinion doesn't make the Space Island kooks any less totally insane.
Losing the KSC infrastructure may not be a bad thing since it is so expensive.

How about Mark Wades opinion?
http://www.astronautix.com/craft/stsati … sation.htm

NASA studied several concepts in the 1980's using the 'wet workshop' approach to the capacious External Tank carried into orbit with every shuttle flight. Despite the incredible logic of this, NASA management never pursued it seriously - seeing it as an irresistable low-cost alternative to their own large modular space station plans.

Or the opinion of Mark Holderman at Johnson?

So having the 39 series pads with the ABANDON IN PLACE placards on them "may not be a bad thing?"

Only a kook like you wants to wreck our architecture.

GCNRevenger · 2005-04-13 16:14:12

Thats correct, I am discounting their poor judgement. The Shuttle main tank is not suited to being any sort of space station hull, and building it in such a fasion (armor, insulation, hatches, etc) that it would be would make it too heavy to lift to orbit.

NASA never persued it seriously because it isn't a serious idea, its nonsense. Good call NASA.

"So having the 39 series pads with the ABANDON IN PLACE placards on them "may not be a bad thing?"

Only a kook like you wants to wreck our architecture."

Not at all, I would be quite happy if Pad-39 closed tomorrow and the Smithsonian took custody of the Orbiters this week. Our "arcitecture" has been so horribly expensive for the last thirty years and it has been the millstone around our necks, keeping us from going anywhere or doing anything. Getting rid of the Shuttle Army is nessesarry, and if NASA can't do that willingly, then NASA should not be permitted to fly Shuttle Derived either. If that means starting over from scratch when we need a heavy lifter, so be it, its a do-or-die situation.

New Mars Forums

Announcement

#1 2005-03-25 07:18:31

Re: Aldrin's Cyclers

#2 2005-03-25 10:42:22

Re: Aldrin's Cyclers

#3 2005-03-28 16:50:34

Re: Aldrin's Cyclers

#4 2005-03-28 17:13:05

Re: Aldrin's Cyclers

#5 2005-03-28 18:04:10

Re: Aldrin's Cyclers

#6 2005-03-28 19:55:29

Re: Aldrin's Cyclers

#7 2005-03-29 06:38:08

Re: Aldrin's Cyclers

#8 2005-03-29 15:04:22

Re: Aldrin's Cyclers

#9 2005-03-30 15:26:53

Re: Aldrin's Cyclers

#10 2005-03-30 17:04:41

Re: Aldrin's Cyclers

#11 2005-03-30 17:58:02

Re: Aldrin's Cyclers

#12 2005-03-31 04:22:07

Re: Aldrin's Cyclers

#13 2005-03-31 07:40:02

Re: Aldrin's Cyclers

#14 2005-03-31 17:58:13

Re: Aldrin's Cyclers

#15 2005-04-03 22:41:45

Re: Aldrin's Cyclers

#16 2005-04-03 23:15:54

Re: Aldrin's Cyclers

#17 2005-04-04 00:17:34

Re: Aldrin's Cyclers

#18 2005-04-04 08:21:22

Re: Aldrin's Cyclers

#19 2005-04-04 10:48:07

Re: Aldrin's Cyclers

#20 2005-04-04 10:59:43

Re: Aldrin's Cyclers

#21 2005-04-08 13:54:30

Re: Aldrin's Cyclers

#22 2005-04-09 20:04:37

Re: Aldrin's Cyclers

#23 2005-04-09 22:31:53

Re: Aldrin's Cyclers

#24 2005-04-13 14:56:38

Re: Aldrin's Cyclers

#25 2005-04-13 16:14:12

Re: Aldrin's Cyclers

Board footer