“A variety of Artificial Gravity/Mars Transfer Vehicle (AG/MTV) concepts were developed by the Martin Marietta Astronautics Group for NASA’s Mars Exploration Case Studies in 1988 to 1989. Each of these concepts used a large diameter (~39 to 46 m) aerobrake (AB) with a low lift to drag (L/D) ratio of ~0.2 for Mars Orbit Capture (MOC). These large ABs required assembly in LEO before being outfitted with habitation, auxiliary Photo-Voltaic Array (PVA) power and chemical propulsion system elements within their protective envelope. By rotating the AB about its central axis at different spin rates and mounting the habitat modules near the outer perimeter of the AB to increase the rotation radius, a range of centrifugal forces can be generated for the crew during the transit out to Mars and back…
However, initial concepts had several drawbacks, to include being very large, requiring significant orbital assembly for the AB and overall vehicle, with large Initial Mass in Low Earth Orbit (IMLEO) requirements. Additionally, problems of the five different concepts developed ranged from incompatible internal arrangements of varying habitation modules, the required movement of major pressurized mechanical joints, large propellant consumption to start/stop a tethered combination along with associated dynamic control problems & possible critical mechanical failures, even the possibility of crew isolation from systems enclosed within the AB e.g., Mars Descent/Ascent Vehicle (MDAV).
To avoid the deficiencies of those concepts, Martin Marietta proposed ‘Concept 6’, an AG/MTV design that used chemical propulsion and carried twin cylindrical Space Station Freedom (SSF) habitation modules whose long axes were oriented perpendicular to the longitudinal spin axis of the MTV—referred to as the Dumbbell B configuration. The hab modules were connected to a central logistics and docking hub by two pressurized tunnels each ~12.5 m long. Each hab module—designed to accommodate two to three crewmembers—had excess capacity so that either could serve as a safe-haven for the entire crew in case of an emergency. Attached to the Sun-facing side of each tunnel and hab module were ~30 and 75 m2, respectively, of PVAs producing ~26 kWₑ of electrical power for the spacecraft’s various systems. Once fully assembled, the rotation radius from the center of the logistics module to the floor of each hab module was ~17 m allowing centrifugal acceleration levels ranging from 0.38-g to 0.68-g for vehicle spin rates of 4.5 to 6 rpm. At a slightly higher spin rate of 7.25 rpm, 1-g could be achieved. The pressurized logistics hub also provided a shirt-sleeve environment and anytime crew access to the MDAV docked to the front of the vehicle.
The aft end Mars Orbit Capture Stage (MOCS) and forward Trans-Earth Injection Stages (TEIS) used four ~25 thousand-pound thrust liquid oxygen/liquid hydrogen (LOX/LH₂) RL10B-2 engines with an Iₛₚ of ~460 s. The MOCS also functioned as the TMI stage using propellant supplied from six surrounding drop tanks jettisoned in pairs as they are drained. The vehicle IMLEO at TMI was ~710.8 t.”
The above, at/per:
ntrs.nasa.gov/api/citations/20160014801/downloads/2016001...
The second paragraph consists of my paraphrasing, the rest is direct copy/paste.
The two capsules docked to the ‘top’ SSF habitation module are referred to as Earth Crew Capsule Vehicles (ECCV).
Who knew?!?
Did YOU!?!
I didn’t!!!
While I’ve never paid close attention to artificial gravity considerations with regard to a Mars Transfer Vehicle, I know I’ve NEVER seen this distinctive “dumbbell” design!
FINALLY, as if ALL of the linked to above/below, wasn’t enough…which it should be frankly, this beautiful work is by Martin Marietta artist Robert S. Murray. I like the clever framing of the AG/MTV by an obliquely viewed Arsia Mons (below) & Pavonis Mons (above), capped off by the tenuous upper atmosphere layer of haze visible on the Martian limb…nice, very nice.
A WIN:
www.paintingsbyrobertsmurray.com/about-me.html
Credit: “Paintings by Robert S. Murray” website
midcurrent.com/art/robert-s-murray/
Credit: “MIDCURRENT” website
