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aftercolumbia
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« on: June 25, 2006, 08:57:25 PM »

I've started the characterization of Mars Challenger, ACP's entry into the MarsDrive Consortium, but I have not selected a configuration or booster yet.  The front runners are

a) far too tentative to bother posting at this point
b) proprietary: I want to get a head start on developing my ideas before letting the competition see them

The contest rules are here: http://marsdrive.com/files/MDC_MSR_ISRU.pdf

I will say that I have selected the standard Sabatier cycle oxymethane propellant combination, the favorite of Martian ISRU concepts, but I'm also going to look up ethylene as a possible alternative fuel.  It would be a surprise if it passes muster in its production processes and performances.

Right now the MSR entry is my primary timegrabber, and the other projects are currently on hold (as much as is possible without leaving OMDP in the lurch.)

Terry Wilson
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aftercolumbia
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« Reply #1 on: September 25, 2006, 01:59:43 PM »

Mars Challenger's Abstract is complete and submitted.  Further posts will conflict with earlier ones on mass numbers and other details.  Check the dates ot the posts, whichever one is the latest is precedent.  If it wins, development will probably resume in January, so those posts dated earlier than the end of November will apply to the contest submission.

Anyway, the Abstract:

Mars Challenger is After Columbia Project's entry into the MarsDrive Contest.  Mars In-Situ Resource Utilization (ISRU) was originally conceived by Dr. Robert in 1989 by putting together three chemical reactions in a relationship capable of producing oxymethane propellants using seed hydrogen brought from Earth and Martian carbon dioxide.

The dominant element is the return booster and its accompanying fuel plant capable of compressing locally acquired carbon dioxide for use in a Sabatier propellant reactor, which produces methane for fuel.  Water from this reaction is stored in hover propulsion system tanks until the first of the ascent tanks is empty and available for the liquid oxygen resulting from electrolyzing the water, which also recovers the hydrogen for recycling.  The relatively undeveloped closed hydrogen loop and direct carbon dioxide pyrolysis reactions have been rejected. This increases the liquid hydrogen seed requirement to nearly equal the total volume of the propellants to be used for the return ascent ( 9.066% by mass.)  The extra hydrogen is required to capture additional oxygen from the Martian air.  Excess methane, containing the hydrogen premium, is vented early during the ISRU phase while there is no room for it.  This applicability of this simplified technique is probably unique to the scale of a sample return mission and inefficient for piloted mission designs.

Mars Challenger uses two vehicles, the Judith Booster and Christa Rover, which are launched together on a common booster and cruise stage, but are landed separately on Mars near each other in Marte Vallis, where there are Amazonian era water channels.  The dual lander approach bypasses the current technological limitations of large landers while still offering the simplicity of a single launch from Earth.

Solar power is used throughout, with a small amount of nuclear material in heating units, Christa's scientific spectrometers, and the control sample sterilizers for its laboratory style experiments.  The already controversial radioisotope heat sources needed for nuclear power would heat Judith's ascent tanks, causing seed hydrogen to be lost.

Wherever possible, qualified technologies and off the shelf or derived hardware will be used to keep development and testing costs to a minimum.  Most of the landing system employed for Mars Exploration Rovers is used for Christa.  For Judith, a new arrangement of existing parts has resulted in an unexpected increase in landing performance as compared to previous missions.  Unfortunately, the long term storage of the seed liquid hydrogen has presented challenges requiring expensive new development, forcing the author to conclude that a sample return mission of any scale is not feasible on a Discovery Program budget, and unlikely on a New Frontiers budget.  This paper shows that Mars Challenger is feasible on a six year schedule and a US$1 billion class budget typical of flagship robotic missions.
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aftercolumbia
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« Reply #2 on: September 25, 2006, 02:20:38 PM »

Atlas V 541 has been tentatively selected as the launch vehicle.  Launch mass is 4323kg, and limitations, as I had predicted from the start, are not related to launch vehicle performance.  The stack is 5.5m high, winding up just a little too big for the 5m Short fairing.  The estimated center of gravity (which is centered, since I dropped managed energy) is just a little bit outside the curve for the B-type 1154mm clamp band.  Hopefully that turns out better (I haven't mass modelled it at all, it is currently wild-guessed at 3.5m)

The cruise configuration mass breakdown is:

Cruise stage: 1496kg
Propulsion system: 225kg
Main Adapter: 200kg
Equipment Deck: 380kg
Solar Power: 131kg
Christa Separation system: 30kg
Can Separation System: 30kg
Judith Separation System: 30kg
Christa Can: 450kg

Judith Lander: 1900kg
Christa Lander: 827kg (sound familiar? Check MER Press Kit.)

Judith Landed Net Payload: 1232.9kg (includes the landing propellant tanks that get used for ISRU)
Christa Landed Net Payload: 420.0kg

Chapter 1: Introduction
Chapter 2: Launch and Cruise
Chapter 3: Landers
Chapter 4: Christa Rover
Chapter 5: Judith Booster
Chapter 6: Propellant Production
(includes care of hydrogen seed during cruise phase)
Chapter 7: Science and Planetary Protection
Chapter 8: Going Concern
(design analyses current point, expected changes for next iteration, operational organization, expected technical challenges.)

Mars Challenger's current design is frozen.  Even if pending analyses prove that it does not work, the current version will appear in the contest submission paper.

Chapter 1-3 is finished
Chapters 4 and 5 are undergoing revision
Chapter 6 is under development
Chapter 7 is aligned but not started
Chapter 8 is in the 'doodle' phase

Subsections currently in Chapters 1-5 will wind up in 8; Chapter 4 has content that will wind up in Chapter 7, while Chapter 5 has content that will wind up in Chapter 6.

I look forward to bringing it here.
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aftercolumbia
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« Reply #3 on: November 02, 2006, 08:21:28 PM »

New tweaked abstract:

Mars Challenger: Two Landers, One Mission: Mars Sample Return
 
Terry Wilson
After Columbia Project
 
Abstract
 
Mars Challenger is a sample return mission concept using In-Situ Resource Utilization (ISRU); After Columbia Project's entry into the MarsDrive Contest.  ISRU was originally conceived by Dr. Robert Zubrin in 1989 for a piloted mission plan entitled Mars Direct by putting together three industrial chemical reactions in a relationship capable of producing oxymethane propellants using seed hydrogen brought from Earth with locally acquired carbon dioxide.  Mars Challenger uses two elements, the Judith Booster and Christa Rover, which are launched together on a common launch vehicle and cruise stage, but are landed separately on Mars near each other in the Marte Vallis region, where there are recent Amazonian era water channels and the small possibility of discovering current life.
 
The dominant element is the Judith Booster and its accompanying fuel plant capable of compressing locally acquired carbon dioxide for use in a Sabatier propellant reactor.  Water from this reaction is then electrolysed to recover the hydrogen for recycling, and the oxygen for the propellant oxidizer.  Mars Challenger eliminates the least critical and most difficult of the three reactions used by Mars Direct.  This increases the liquid hydrogen seed requirement to exceed the total volume of the propellants which will be used for the return ascent.  The extra hydrogen is required to provide for generation of additional water from the Sabatier reactor, which is then electrolysed for the oxygen captured from the Martian air by the Sabatier reactor.  Excess methane, containing the hydrogen premium, is vented.  This applicability of this technique is probably unique to the scale of a sample return mission and inefficient for piloted mission designs.
 
The Christa Rover, which is landed up to several kilometres away from Judith uses its suite of scientific instruments on route to the booster to examine sites and select samples.
 
For reasons of cost and politics, both craft are electrically powered by solar arrays, with a small amount of nuclear radioisotope material in heating units, Christa's scientific spectrometers, and the control sample sterilizers for its laboratory style experiments.
 
Proven technologies and off the shelf or derived hardware will be used throughout to keep development and qualification costs to a minimum, however several technologies must be converted from terrestrial equivalents into flight hardware, and the protecting the mission's biological integrity is expensive in any case.  For example, the development of hydrogen compatible ascent tanks must be done from scratch.  The author is convinced that this mission can be accomplished for $800 million on a six year schedule.
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aftercolumbia
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« Reply #4 on: February 26, 2007, 01:22:00 PM »

Mars Challenger is online at http://aftercolumbia.tripod.com (remember to turn on your pop-up blocker!!)

Abstract: http://aftercolumbia.tripod.com/id14.html
Full Report (1.56MB): http://aftercolumbia.tripod.com
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« Reply #5 on: April 23, 2007, 12:07:44 AM »

This is truly brilliant. You are definitely onto something big. I can see that a lot of thought has gone into this to make it a sound idea.  I hope you keep us informed as you continue.
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aftercolumbia
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« Reply #6 on: April 23, 2007, 07:38:39 PM »

Thanks, Mars Challenger is complete and was sent in near the end of February.

I was working on Symtex, but put that on hold for something I feel is more important to get done first: the MarsDrive Baseline Mission.  There isn't (officially at least) a contest to do this, and I'm hoping rather to spur a team effort to develop a plan to send humans to Mars which is both more feasible and higher fidelity than any plan that has flown before (on paper or in Orbiter of course.)

The thread on the MarsDrive Mission is here:
http://marsdrive.com/phpBB2/viewtopic.php?t=312
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