View Full Version : NASA Study Summary: "Definition of Experimental Tests- Manned Mars Excursion Module"
23rd May 2011, 07:08 AM
Here's an interesting study from the late 60's- detailing the MEM, or Mars Excursion Module. This was essentially an Apollo capsule upscaled to 31.5 foot diameter, and totally reworked on the inside to incorporate a small ascent module with staged tanks in the upper center portion of the vehicle, surrounded by landing fuel tanks and equipment around a toroidal living area and laboratory for Mars surface operations. The vehicle had a single high-thrust landing engine under the heatshield in the center of the vehicle. Deorbit burn to Mars entry was by a solid motor retropack (similar to how Mercury capsules retroed back to reentry) which was jettisoned prior to entry interface. After Mars entry, the vehicle would jettison its heat shield and either deploy a ballute or supersonic parachutes to slow down, then jettison those and switch over to propulsive descent and landing, with a 2 minute hover capability. Landing was via six build in landing legs which conformed to the shape of the underside of the capsule. Crew size was for four men, for either 4 or 30 days. Upon Mars departure, the crew entered the small ascent cabin in the upper portion of the MEM, which then blasted off from the lower portion which was left behind, with the living space, lab, equipment, etc. The ascent stage would burn through its first stage propellant tanks, which would jettison as they emptied, and switch over to its second stage propellant tanks (using the same engine-- only the tanks were jettisoned like the ET). The vehicle would enter Mars orbit and return the crew to the awaiting transit spacecraft for return to Earth, and the ascent stage would be jettisoned. The MEM remained unmanned during its transit to Mars, as the crew were housed in the transit spacecraft.
This study outlines a series of test flights, to simulate the heat shield and abort conditions at Mars using Earth's extreme upper atmosphere to simulate the low density Mars atmosphere, and booster rockets to lift the MEM to those regions and accelerate it to the requisite speeds to simulate the Mars entry conditions of the specific tests. Test vehicles, depending on the nature of the test, ranged from uprated Saturn I's, to two-stage Skylab style Saturn V's (launched manned and unmanned) to Saturn S-IC first stages from Saturn V used as a single stage vehicle to launch the MEM to high altitude suborbital tests, to a new SRM powered "Super Little Joe II" designed not to the 154 inch diameter Apollo Command Module, but to the 31.5 foot diameter MEM... sort of an "uber Little Joe", which would have been launched out of White Sands. Both unmanned and manned landing tests would have been conducted at White Sands, with the MEM landing propulsively under its own power (if the heat shield were designed to Earth entry standards, which was the recommendation) and also there was a plan for a possible "all up" test mission rehearsal landing the MEM on the moon. There was also a possible plan to do a half scale MEM using an Apollo module, which would be almost perfectly half-scale, adapted to simulate the functions of the MEM (but of course its internal layout would have been markedly different....) this would have been launched unmanned by a single Saturn V to Trans-Mars Injection, and the Service Module would have provided Mars Orbit Insertion propulsive braking. The modified Apollo "MEM half scale" vehicle would have then separated from the SM, and entered Mars atmosphere and performed EDL just as the MEM was designed to do. After a suitable surface stay, the vehicle would then fire its half scale ascent stage back to orbit. Such a mission would be an excellent design for a Mars sample return, if we still had the Saturn V around to launch it! :mad:
Anyway, it's an interesting idea-- too bad it never happened. If it had, history might have recorded the first Mars landing in 1982 instead of *maybe sorta someday perhaps hopefully might kinda think about it study and make plans to maybe do it* in about 30 years or so FROM NOW...
Later! OL JR :)
23rd May 2011, 07:15 AM
Pic one is showing the planned mission phases and profile...
Pic two is showing the MEM operations profile after arrival in Mars orbit, with EDL, surface ops, and return to Mars orbit, and rendezvous and docking with the Earth Transit spacecraft...
Pic three is showing the layout of the preferred MEM design based on the OML of the Apollo capsule...
Pic four is showing the engine design options for the descent and ascent engines for MEM-- either the plug nozzle aerospike (recommended) or the regular bell nozzle engine.
Pic five is another pic of the MEM design...
More to come! OL JR :)
23rd May 2011, 07:30 AM
Pic one is an alternative design based on a lifting body... it would consist of a half-cone shaped lifting body which would enter, slow down, be jettisoned, and then unfold its landing legs and ignite its descent engine which would be behind the nose of the lifting body at entry. The vehicle would then descend and land, and the living areas and lab would unfold from the "upper" end where they had been housed in the wider end of the lifting body and would be deployed near the ground level for surface ops after landing. Upon leaving Mars, the central ascent stage at the top (rear of the lifting body during entry) would lift off from the top of the lander and ascend back into orbit much like the Apollo-shaped MEM. The conical outline shows the approximate outer appearance of the vehicle at Mars entry, and the "unfolded" landed outline shows its appearance on the Martian surface...
Pic two is a proposed heat shield qualification test, using a Saturn V first stage (S-IC) to loft the MEM suborbitally to speed and altitudes to simulate a Martian atmospheric entry...
Pic three is a ballute qualifications test at White Sands, using a 33 foot diameter "uber Little Joe II" to loft the MEM boilerplate to sufficient altitude and speed to perform the high speed deployment of the ballute for deceleration tests...
Pic four is an unmanned abort test for the MEM from KSC, flown by a two-stage Saturn V (S-IC/S-II). The MEM would separate from the Saturn V suborbitally to simulate the Mars entry and then simulate the ascent stage abort from the descent stage boilerplate, performing a turnaround manuever and ascent to orbit. Of course, the MEM ascent stage had insufficient propellant to achieve EARTH orbit, so it would reenter and disintegrate at the conclusion of the test...
Pic five is the "all up" unmanned orbital soak, entry, and landing test. The MEM would be placed in orbit by a two-stage Saturn V, where it would remain inside a protective shroud for 200 days (to simulate the Mars transit time in deep space). After 200 days, it would be fired up and perform a reentry (assuming the heat shield was designed to Earth entry standards, which was the recommendation in the report, despite making the heat shield somewhat heavier, it removed a great deal of uncertainty from the vehicle design and also made weight gain and heat loading problems of the final vehicle easily handled by the Earth-capable heat shield) followed by ballute or supersonic parachute deployment and deceleration, followed by the propulsive descent, short hover, and landing at White Sands...
More to come! OL JR :)
23rd May 2011, 08:09 AM
Pic one is the MANNED version of the same unmanned EDL test shown in the last pic of the last post. It would have been launched on a two stage Saturn V, with the MEM in a shroud, with an Apollo CSM atop it (not particularly likely-- the vehicle could have been checked out in orbit by telemetry; no need for a manned vehicle for this part of the test). The CSM would transpose and dock with the MEM in its shroud and perform a checkout, and presumably after a few days, undock and deorbit and return to Earth. The MEM would cold soak in orbit for 200 days, then be docked with by another crew in an Apollo CSM launched on a Saturn IB, and checked out again and prepared for EDL. Two of the CSM's crew would return the MEM to Earth, landing at White Sands as the unmanned test did. The third crewman would return to Earth to a standard splashdown in the Apollo CM. If it was necessary to have the full four-crew complement aboard the MEM, an Apollo logistics vehicle (converted to fly 4-6 astronauts) would be used instead of the stock Apollo CSM, leaving one or two crew to return to Earth in the logistics vehicle. There was little justification for this test, let alone the two launches it required, except possible to gain "real life" experience flying the MEM, instead of just simulator time... but it would be VERY expensive training!
Pic two is a mission profile of a propulsion test-- essentially an "Apollo 9" mission of the MEM... a two stage Saturn V launches the MEM and crew capsule into orbit for checkout, then the Apollo returns, leaving the MEM for a 200 day cold soak in space to simulate the Mars transit time. (As before there is little justification for the manned checkout of the vehicle before the 200 day cold soak, so was quite unlikely to have ever happened-- there would be considerable expenses involved in qualifying the Saturn V to fly in a two stage configuration with essentially a new payload shroud with a manned Apollo CSM on top-- expenses that would have been VERY difficult to justify...) After 200 days, a Saturn IB launches a second CSM to meet up and dock with the MEM and perform a checkout, along with deorbit motor, descent stage engine, and ascent stage engine propulsion tests, and a rendezvous and docking as the vehicle would with the Earth Transit spacecraft in Mars orbit, but instead here docking back with the CSM. The crew would then return to Earth in the CSM, abandoning the spent MEM in Earth orbit.
Pic three is using the MEM for a manned lunar landing and ascent. The MEM would be launched to the moon using a Saturn V (presumably in some kind of bizarre hammerhead configuration, since the MEM was 31.5 feet in diameter and the S-IVB was only 21.6 feet diameter-- the plan is quite vague here, and also was quite vague about the delta V requirements and the weight of the MEM compared to the regular Apollo lunar stack). The MEM would be outfitted with a "propulsion module" (again quite vague here, but it's shown with something like an enlarged Apollo SM attached to it-- though I can hardly believe it would be cost-effective to upscale the Apollo SM for this single mission-- I could see them adapting an standard (slightly modified) Apollo SM to the underside of the much larger MEM, to provide the Lunar Orbit Insertion propulsion (and perhaps even part of the Trans-Lunar Injection propulsion-- the plan was quite vague on the weights and how this would exactly be accomplished!) The MEM would be dropped into LLO by the propulsion module, which would then be jettisoned. At a later point (perhaps after the 200 day cold soak so often used) a crew, launched by Saturn V in an Apollo CSM, would arrive in LLO and dock with the MEM, transfer the crew, undock, and descend to land on the lunar surface. After an "appropriate stay" the MEM ascent stage would then return the crew to LLO, where they would dock with the CSM, transfer back aboard, and jettison the spent MEM ascent stage, and return to Earth. The delta V requirements for landing the MEM on the moon were somewhat different than landing on Mars, due to the fact that there was no atmosphere to provide thermal entry braking and then ballute/parachute braking prior to powered descent, so the MEM would have to use the first stage propellant in the ascent vehicle as well as all the descent stage propellant to land on the moon. This would require modifications (plumbing) to allow the ascent modules first stage propellant tanks to transfer their propellant to the descent stage engine. This was an interesting idea, and could provide a lunar habitat in the MEM for four men for 30 days, which could have been extended with only two men aboard (presumably one would be left in the CSM as with Apollo for safety). No mention was made of the "appropriate stay" duration on the lunar surface, however. It's interesting in that it also leaves behind an mostly-intact surface habitat (the MEM lab/living quarters) and the relevant support equipment (life support, supplies, fuel cells, batteries, etc.) that could possibly be reused by future crews landed in smaller LM type vehicles, using the spent MEM descent stage facilities as a sort of 'base camp' supplemented by supplies brought in their LM.
Pic four is an "all up" test flight of the entire Mars spacecraft/MEM stack-- in highly elliptical Earth orbit. The spacecraft and MEM would be "launched" from Earth orbit into a highly elliptical Earth orbit out near the moon, where it would remain orbiting from the lunar vicinity to near Earth and out again for the 200 days necessary to simulate the Mars transit time. The Trans-Mars spacecraft would then perform the aerobraking or propulsive braking necessary to enter Mars orbit (in this case return to LEO). At this point, half the crew would enter the MEM, check it out and prepare for departure, undock, and perform the EDL through the Earth's atmosphere, landing at White Sands as the previous unmanned (and manned if it had been performed) test had done. The other half of the crew would remain in the Trans-Earth spacecraft, which would then boost itself back into a highly elliptical Earth orbit, simulating the Trans-Earth Injection burn from Low Mars Orbit after the MEM's mission was completed and the crew had docked and returned to the spacecraft from the MEM ascent stage, and discarded it in LMO. The crew would then sit out another 200 day (or so) "return flight" to Earth, transiting from the lunar vacinity to near Earth in the highly elliptical orbit for the requisite time, until time for the return to Earth in the Earth Reentry Module. The crew would jettison the Trans-Mars spacecraft at high velocity to simulate a flyby Earth reentry at high speed to a standard ocean splashdown, presumably, much like Apollo.
Pic five is the half-scale MEM unmanned test vehicle, capable of being launched to Mars for a half-scale EDL test on a single Saturn V-- essentially an unmanned reworked Apollo, with the CM reworked into a scale model of the MEM, sent to Mars by Saturn V, and braked into Mars orbit and deorbited to Martian EDL by the SM, which would then be discarded. The scale model MEM would then land like the full size version, and then after successfully landing, at some point fire off a scale model of the ascent stage back to Martian orbit. This would make an interesting method of performing a Mars Sample Return mission, if we still had Apollo and Saturn V, or if it had been done...
That's it for this one! OL JR :)
26th May 2011, 07:46 AM
Ever read 'Voyage' by Stephen Baxter?
I think you'd enjoy it...especially after reading this.
26th May 2011, 05:54 PM
Ever read 'Voyage' by Stephen Baxter?
I think you'd enjoy it...especially after reading this.
No, but I've heard of it...
Have to look for it at Half Price Books next time I'm in there... that or Amazon.... LOL:)
Thanks for the tip!
Later! OL JR :)
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