Earth-Mars Cycler Orbits

[Siliconaut]

I was doing some looking into hyberbolic trasfers between planets and by luck came up with this document here.

https://engineering.purdue.edu/peop...06GuidanceStrategyforHyperbolicRendezvous.pdf

Which discusses the idea of Earth-Mars/Mars-Earth cycler ships. I remember reading about this before in science fiction novel about 4 cycler stations that orbit in such a way than can perform fly by free returns to lap between martian and earth orbit regularly.

This way small taxi ships from earth could fly up and meet with the cycler ship and be carried to mars and detached while the cycler ship flies by mars and free returns to earth.

This document gave much information but seriously I'm not an orbital mechanics guy I'm out of my league here on where to even begin to calculate the proper math to set something like this up in orbiter and some helpful links and suggestions would be appreciated.

 

[Columbia42]

Haven't read the document yet so I'm just speaking off the top of my head here but it seems to me that when the cycler ship flies by Earth or Mars it will be going too fast for an orbital ship to dock to it.

 

[RGClark]

There are several articles on the plan here:

Aldrin Mars Cycler.
http://buzzaldrin.com/space-vision/rocket_science/aldrin-mars-cycler/


Bob Clark

 

[Jarvitä]

Haven't read the document yet so I'm just speaking off the top of my head here but it seems to me that when the cycler ship flies by Earth or Mars it will be going too fast for an orbital ship to dock to it.

Exactly. This doesn't save any fuel, as insertion and ejection burns are still required at either end.

 

[Wishbone]

The idea is to save on loitering in Mars and Earth orbit waiting for the window. Besides an obvious reduction in fleet size, this gives another great advantage: if you're propelled by cryogenic fuels, you won't waste much return trip fuel to boiloff in Mars orbit.

EDIT: SCRATCH THAT! The actual idea is not that simple. The Cycler would waste NO FUEL for capture etc., but the orbital taxi would rendezvous at hyperbolic speeds. The reliability requirements are somewhat staggering, though.

EDIT #2: The PDF file cited above is a must-read.

EDIT #3: Re: for calculating the orbit of the cycler you can use Arrowstar's Trajectory Optimization Tool (available at OHM) and IMFD. Since I'm busy building the nuclear rocket to send folks to Mars I sincerely hope the maestro of interplanetary transfers (flytandem) will help us out with the numbers

Re: intercept from a waiting 200x200 orbit around Mars - I haven't tried that before in other craft than Polyot ASAT vehicle, and I can tell you high-speed intercepts and rendezvous are great fun, but also a great risk.

 

[C3PO]

Exactly. This doesn't save any fuel, as insertion and ejection burns are still required at either end.

The idea is to accelerate the HAB module only once.

You save energy by lowering the mass of the "taxi" that does the hyperbolic rendezvous. You still need the same DV though.

 

[Siliconaut]

Re: intercept from a waiting 200x200 orbit around Mars - I haven't tried that before in other craft than Polyot ASAT vehicle, and I can tell you high-speed intercepts and rendezvous are great fun, but also a great risk.

Pff? Risk? It's orbiter. I crash, zip off into interstellar space, burn up in various atmospheres, and thanks to Ummu and UCGO generally leave the scarred chunks and Oxygen deprived bodies of crew in various orbits.

I think I can handle this.

 

[flytandem]

This reminds me a little bit of the thread :
http://www.orbiter-forum.com/showthread.php?t=19628
It has 2 ships that would be in effect the supply ships doing flyby's at Mars and the third ship is a crew ship. The crew ship is docked with one supply ship for the trip to Mars and undocks to land at Mars just as it gets to Mars. That supply ship continues on back to Earth with nobody aboard. Then the crew waits and explores for 3 weeks on Mars to hop back into a parking orbit to wait on the second supply ship to do its flyby. The rendezvous is a hyperbolic one meaning the crew does an eject for Earth burn just as the supply ship is arriving for its flyby. It reminds me a bit of a batton handoff in a track and field race.

The fun part was that the supply ship that arrived 3 weeks later for the crew to ride back to Earth in, actually left Earth 1 day before the crew and its outward supply ship left Earth. The idea was the make sure the returning leg supply ship was properly on its way before committing the crew to its outward journey. It takes a slightly different trajectory which allows leaving 1 day early but arriving Mars 3 weeks late.

The other fun part was to make the round trip journey of shorter duration by doing a Venus sling on the way to Mars.

 

[RGClark]

The idea is to save on loitering in Mars and Earth orbit waiting for the window. Besides an obvious reduction in fleet size, this gives another great advantage: if you're propelled by cryogenic fuels, you won't waste much return trip fuel to boiloff in Mars orbit.
EDIT: SCRATCH THAT! The actual idea is not that simple. The Cycler would waste NO FUEL for capture etc., but the orbital taxi would rendezvous at hyperbolic speeds. The reliability requirements are somewhat staggering, though.
EDIT #2: The PDF file cited above is a must-read.
EDIT #3: Re: for calculating the orbit of the cycler you can use Arrowstar's Trajectory Optimization Tool (available at OHM) and IMFD. Since I'm busy building the nuclear rocket to send folks to Mars I sincerely hope the maestro of interplanetary transfers (flytandem) will help us out with the numbers
Re: intercept from a waiting 200x200 orbit around Mars - I haven't tried that before in other craft than Polyot ASAT vehicle, and I can tell you high-speed intercepts and rendezvous are great fun, but also a great risk.

I wonder if this can be used to make a "cycler" between Earth and an asteroid. I'm interested in the idea of asteroid mining and want to minimize the cost of bringing the minerals back to Earth.


Bob Clark

 

[Wishbone]

Since gravity assist is done at Earth flybys only, why not? Caveat: my ballistic knowledge is ... well... ballistic, YMMV. The construction of cycler orbits is discussed here: http://www.troymcconaghy.com/storage/AIAA_2002-4420.pdf

However, must warn you that those minerals may be not worth the flight.

 

[Siliconaut]

Okay I really started to think about this more and conceptualize a rough idea of the mission and wanted to see if I"m on the right track.

According to the purdue PDF They show these example windows for the cycler missions.


Earth Mars

Yr DOL dV Per DOA dV Per

2009 11/27/2009 6.19 37,600 09/10/2011 3.05 23,900
2011 12/14/2011 4.33 32,600 10/29/2013 2.93 28,600


Okay.

So lets say I'm in my hypothetical DGIV that I want to put into a cycler orbit. Lets make everything simple, Rinc of 0 degrees on Mars, etc.

So I fire up IMFD and plug in for a transfer orbit to Mars with a Date of Arrival for 9/10/2011 and then insert into that trajectory.

Now I know there is probably a better way now but the way I learned to do slingshots is old way from when IMFD slingshot tool didn't work and I never tried to tool after learning this way from IMFD author.

Basically once I get into Mars SOI I plot a course for Earth using Mars as the source and make a correction burn to fly by mars at the mission specified Periapsis of 23,900.

The question is.. what is the date of arrival at earth so that the process can be repeated?

How many average flight days are there between each periapsis?

Apologies in advance, I'm just an enthusiast with about 9th grade math education so TIA for patience.

 

[flytandem]

Not sure what you are all looking for but I hopped into a DG and fired up TransX and looked for a way to eject to Mars then sling back to Earth with hopes of doing additional slings to Mars Earth etc. Found a 2-cycle round trip (Earth eject to Mars then sling to Earth sling to Mars sling to Earth). 2 round trips takes 4 years. Here is the scenario all set for a 090 heading launch...

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[Siliconaut]

I did it! At least for an outbound Aldrin cycler.

Thanks Tandem. My skills with TransX are about nill I need to practice with it.

The mistake that I at least made was in believing that the cycler slings directly back to Earth.

Here's an outline for the classic Aldrin cycler:http://buzzaldrin.com/files/pdf/200...Strategies_for_Continuous_Mars_Habitation.pdf

1)Launch from Earth Orbit on 2/21/2016

2)Normal Transfer to Mars: TOF 146-47 Days, arrival on 7/17/2016

3)Apparently at this point, instead of a direct slingshot back to Earth. The cycler will orbit far outside of Mars' orbit near the asteroid belt in a long slow loop around the sun for an MCC at the apoapsis of the cycler orbit(near the asteroid belt) sometime around 06/06/2017.

So after zipping by Mars I let the ship continue on until it reached apoapsis and then using IMFD I plugged in a MCC using the DG as the source and Earth as the target for arrival at the specified mission date of 4/11/2018.

4)Worked like a charm showed up at earth on 4/11. Once I reached Earth SOI I set the source back to Earth and set up a gravity assist from earth back to mars to repeat the process, although I ended the scenario here I'm going to try to see how many cycles I can get.

I'll update as necessary.

Now if I can figure out the parameters for inbound aldrin cyclers..

EDIT:Launching from a 200x200km parking orbit to meet with the cycler as it flies by looks like a daunting task. The cycler moves by at an amazing velocity relative to mars.

EDIT:As planned this orbit requires very little fuel. I flown it a few times it now and each time I'm getting a little better requiring less drastic correction burns each time.

Once I've got this down it'll be time to moving on to figuring out how to dock with a ship zipping by at 9.3 km/s

Final Edit:Well on the 3rd go around at Earth I accidentally entered the wrong value into the approach program and slammed into the Earth atmosphere at a respectable 14 km/s.. I suppose I left a light show over half the Pacific Ocean.

 

[Siliconaut]

Here's a scenario that has a DG on an outbound cycler trajectory.

BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 57440.0829016408
END_ENVIRONMENT

BEGIN_FOCUS
  Ship DG-01
END_FOCUS

BEGIN_CAMERA
  TARGET DG-01
  MODE Cockpit
  FOV 60.00
END_CAMERA

BEGIN_HUD
  TYPE Surface
END_HUD

BEGIN_MFD Left
  TYPE Orbit
  PROJ Ship
  FRAME Equator
  REF Sun
  TARGET Mars
END_MFD

BEGIN_MFD Right
  TYPE User
  MODE Interplanetary
  Scenario Old2
  MapMFD V5
  Reference Auto
  Target none
  Center GravityRef
  Data 0 1 1e-006 1 0 0 0 0 1 0 0 0
  MassLimit 1e+020
  CMode 0
  Config 1 1 1 1 0 0
  ExtMode 0
  Periapis none
  END 
  CorMFD V4
  Reference Sun
  Target Mars
  Source DG-01
  ActiveProg 1 1
  DataA 0 3 0 0 0 0
  DataB 1 1 57440.08289859809 0 0 4.682316281155947 0 57579.40000000018 0
  DVProg 0 0 0 1
  AdvConf 0 0 1 0 0
  Guidance 0
  END 
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  Reference Auto
  Data 0 1 3 0 1 57440.0799293566 10
  Guidance 0
  END 
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  Reference Auto
  Target none
  Source none
  DataA 0 0 120000 0.10821 0.366519 1 1 57440.0799293566 57440.0799293566 0
  DataB 0 3 0 1 0 1
  END 
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  Reference Auto
  Source none
  Data 0 1 1 3 0 1 57440.0799293566 0
  END 
  LaunchMFD V4
  Target None
  Data 0 1 1 3 0 1 0
  END 
  CF1_DataA 0 0
  CF1_DataB 57440.0799293566 10 120000 2 20 150000
  CF1_SecTgt 
  mfdShare -1
  mfdProgram 2
END_MFD

BEGIN_PANEL
END_PANEL

BEGIN_SHIPS
DG-01:Deltaglider
  STATUS Orbiting Sun
  RPOS -131560287906.54 -69041221.35 67725771647.91
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  AROT -134.04 -71.59 120.45
  AFCMODE 7
  PRPLEVEL 0:1.000000 1:1.000000
  NAVFREQ 0 0 0 0
  XPDR 0
  AAP 0:0 0:0 0:0
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BEGIN_uap
END

 

[Siliconaut]

Well I've been refining this idea into a massive scenario that is turning out to be a lot of fun.

I took a Longshot freighter and outfitted it with Station Building Blocks into a massive aldrin cycling station complete with centrifuge, etc. and started by placing one on and inbound and an outbound trajectory. Thanks to these document here which have entire plans that are easy to plug into IMFD and attain these orbits.

http://buzzaldrin.com/files/pdf/200...sportation_Plan_for_Mars_Cycling_Concepts.pdf

https://engineering.purdue.edu/peop...icles/1993/CyclerOrbitbetweenEarthandMars.pdf

These two documents are must reads if you want to set up these sorts of scenarios IMO.

Anyway, I have a question as what is the best way to getting the space taxi to the station within mission parameters, which is 12-24 hours? It's a pretty hefty task. I've pulled it off a few times, but it took me several months of game time to get the taxi into position to dock and I spent so much time doing that i wasn't able to attend to the MCC necessary to keep the orbit and it wound up throwing the station off the orbit.

So it's essential to dock with the cycler as quickly as possible.

Can anyone contribute a possible mission profile of sorts about the best way to climb from 200x200 parking orbit to the passing cycler station in less than 24 hours?

Also does anyone know of the existence of an MFD that converts dates to MJD?

 

[Malky]

Not an MFD, but in utils folder in orbiter instalation you've got date.exe application to do this.

 

[boogabooga]

Notice the year after the date of the last post...