View source for Mars Excursion Module

{{short description|Proposed NASA spacecraft}}
The '''Mars Excursion Module''' ('''MEM''') was a spacecraft proposed by [[NASA]] in the 1960s for use in a [[human mission to Mars]], and this can refer to any number of studies by corporations and spaceflight centers for Mars landers. However, primarily a MEM referred to a combination of a Manned Mars lander, short-stay surface habitat, and Mars ascent stage. Variations on a MEM included spacecraft designs like an uncrewed Mars surface cargo delivery, and there was a MEM lander that combined a communications center, living habitat, and laboratory.<ref name="nasa.gov">{{cite web |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660021498.pdf |title=An Initial Concept of a Manned Mars Excursion Vehicle for a Tenuous Mars Atmosphere |last=Woodcock |first=G. R. |date=7 June 1966 |website=NASA |access-date=22 September 2018}}</ref>

A MEM formed part of [[Mars orbit rendezvous]] (MOR) and flyby-rendezvous mission profiles studied at NASA's [[Manned Spacecraft Center]] in the 1960s.<ref name="portree2001">{{cite book |pages=15–18 |chapter=Chapter 3: Empire and After |first=David S. F. |last=Portree |title=Humans to Mars: Fifty Years of Mission Planning, 1950–2000 |series=NASA Monographs in Aerospace History Series |number=21 |date=February 2001 |publisher=[[National Aeronautics and Space Administration]] |url=https://history.nasa.gov/monograph21/Chapter%203_low.pdf |access-date=18 July 2014}}</ref> A Mars Excursion Module would have been a combination of a Mars lander, short-stay surface habitat, and ascent vehicle; the ascent stage performed the rendezvous. One design for a MEM would have been used for a 40-day stay on the Martian surface in the flyby-rendezvous mission profile or for a 10- to 40-day stay in the MOR profiles.<ref name="portree2001"/> There was also a descent-only uncrewed MEM for delivering cargo, like a rover to the surface of Mars.<ref name="wired12">{{Cite magazine |url=https://www.wired.com/2012/10/origin-of-the-apollo-shaped-manned-mars-lander-1966/ |title=Origin of the Apollo-shaped Manned Mars Lander (1966) |date=25 October 2012 |magazine=[[Wired (magazine)|Wired]] |access-date=4 March 2018}}</ref> Another MEM cargo lander variant would deliver a nuclear reactor to support the surface operations, and there was another with a communications, living quarters and lab in one landing-only MEM unit.<ref name="nasa.gov"/>

== Proposals ==

=== Philco Aeronutronic MEM ===
[[File:Mars Excursion Module.jpg|thumb|Philco Aeronutronic MEM]]
In the early 1960s, NASA contracted [[Philco|Philco Corporation]] to design a Mars Excursion Module for a Mars mission for the early 1970s.<ref name="nasa.gov1">{{cite web |url=https://solarsystem.nasa.gov/docs/Thompson%20Mars%20Cargo%20Entry.pdf |title=Design of an Entry System for Cargo Delivery to Mars |last1=Thompson |first1=Robert|last2=Cliatt|first2=Larry|last3=Gruber|first3=Chris|last4=Steinfeldt|first4=Bradley|last5=Sebastian|first5=Tommy|last6=Wilson|first6=Jamie|display-authors=3|date=23 June 2007 |website=NASA |access-date=22 September 2018 |url-status=dead |archive-url=https://web.archive.org/web/20161222084440/https://solarsystem.nasa.gov/docs/Thompson%20Mars%20Cargo%20Entry.pdf |archive-date=22 December 2016}}</ref> The basic requirements were for a crew of two, one US ton of science hardware, and to support 40 days of surface operation on Mars.<ref name="nasa.gov1" /> 

In 1964, [[Philco Aeronutronic]] proposed a [[lifting body]] MEM, approximately {{Convert|30|ft}} long and {{Convert|33|ft}} wide at the tail, which would carry three astronauts. The hull would have consisted of [[columbium]] and [[List of alloys#Alloys of nickel|nickel alloy]]. The MEM's descent stage would have served as the launch pad for liftoff of the ascent stage, as with the [[Apollo Lunar Module]].<ref name="portree2001" />

=== Ames-TRW MEM ===
Another MEM from this period was the [[Ames Research Center|Ames]] contracted [[TRW Inc.|TRW]] MEM, a design which weighed 11.4 metric tons but was designed for Mars atmosphere which had 10% of Earth's density.<ref name="auto1">{{cite web |url=http://astronautix.com/t/trwmars.html |archive-url=https://web.archive.org/web/20161228043347/http://astronautix.com/t/trwmars.html |url-status=dead |archive-date=December 28, 2016 |title=TRW Mars |website=Astronautix.com |accessdate=22 September 2018}}</ref> The TRW MEM would support 10 days on the surface.<ref name="auto1" />

=== Project Deimos MEM ===
[[File:Project Deimos - Mars Surface Base.jpg|thumb|Project Deimos MEM on the surface]]
[[File:Project Deimos - MEM and Rombus docking.jpg|thumb|Project Deimos MEM ascent stage and the [[ROMBUS]] spacecraft dock in space]]
Project Deimos was a Mars expedition concept proposed by [[Philip Bono]] in 1964, utilizing the [[ROMBUS]] single-stage-to-orbit booster.<ref name="astronautix.com">{{cite web |title=Project Deimos |url=http://www.astronautix.com/p/projectdeimos.html |url-status=dead |archive-url=https://web.archive.org/web/20161227234230/http://astronautix.com/p/projectdeimos.html |archive-date=December 27, 2016 |accessdate=22 September 2018 |website=Astronautix}}</ref> This booster, refueled in Earth orbit, would serve as the propulsion system for the round trip to Mars.

The mission involved separate Mars landers for surface exploration. The Mars-bound vehicle was designed to weigh approximately 3.97 million kg in a 323 km parking orbit, with a [[trans-Mars injection]] (TMI) burn scheduled for May 1986. After a 200-day journey, the ROMBUS would enter a 555 km orbit around Mars, with a reduced mass of 984.75 tons after jettisoning empty fuel tanks.

A 25-metric ton Mars Excursion Module (MEM) would land a crew of three astronauts on the Martian surface for a 20-day mission. The crew would return to the mother craft via a Mars ascent vehicle, which would then initiate the return journey to Earth after a 280-day stay in Mars orbit. The total mission duration was 830 days, with the ROMBUS spacecraft landing back on Earth 330 days after departing Mars.

=== Marshall Space Flight Center MEM ===
[[File:Marshall Space Flight Center MEM.webp|thumb|Marshall Space Flight Center MEM]]
The watershed moment for mission planning was July 1965, when [[Mariner 4|Mariner IV]] returned more accurate atmospheric data about Mars.<ref name="wired12" /> This ruled out many of the lifting body and glider designs that were being considered based on estimates of a thicker [[Atmosphere of Mars|Mars atmosphere]] than revealed by Mariner IV.<ref name="wired12" />

Gordon Woodcock at the NASA [[Marshall Space Flight Center|Marshal Space Flight Center]] worked on the basis of a thinner Mars atmosphere (0.5 percent of Earth's), and developed design for a MEM (a more Apollo-like "gumdrop" style design), and also a pure-lander variant that would deliver a pressurized crewed Mars rover called Molab.<ref name="wired12" />

=== Space Task Group MEM ===
A Mars Excursion Module was discussed as a possibility in the [[Space Task Group]] Report of 1969, with a development decision required in [[Fiscal year|FY 1974]] for a 1981 Mars mission or in FY 1978 for a 1986 mission.<ref>{{cite web |date=September 1969 |title=Report of the Space Task Group, 1969 |url=http://www.hq.nasa.gov/office/pao/History/taskgrp.html |accessdate=10 July 2014 |website=NASA |archive-date=14 January 2016 |archive-url=https://web.archive.org/web/20160114031850/http://www.hq.nasa.gov/office/pao/History/taskgrp.html |url-status=dead }}</ref>

==Cultural impact==
* "[[The Time Tunnel#Episodes|One Way To The Moon]]", a 1966 episode of ''[[The Time Tunnel]]'', featured a Mars Excursion Module launched in 1978.<ref>{{cite episode |last=Welch |first=William |title=One Way To The Moon |series=[[The Time Tunnel]] |season=1 |number=2 |date=16 September 1966 |network=[[American Broadcasting Company]]}}</ref> Mars Excursion Modules are also featured in [[Stephen Baxter (author)|Stephen Baxter]]'s novel ''[[Voyage (novel)|Voyage]]'', an [[alternate history]] of space exploration in which NASA astronauts land on Mars in 1986 in a MEM named "''Challenger''"<ref>{{cite book |first=Stephen |last=Baxter |authorlink=Stephen Baxter (author) |title=[[Voyage (novel)|Voyage]] |publisher=[[HarperPrism]] |location=[[New York, N.Y.]] |year=1996 |isbn=0-06-105258-2}}</ref> which was based on a [[North American Rockwell]] design proposal.
* The 1975 Year Two ''[[Space: 1999]]'' episode "[[The Taybor]]" features a spacecraft, the SS ''Emporium'', modeled by Martin Bower, which was clearly inspired to the MEM. The spaceship, symbolizing innovation (just like the MEM), was the first spacecraft in the series which could reach [[Faster-than-light|FTL]] [[Velocity|velocities]] thanks to an [[Extraterrestrial life|extraterrestrial]] "[[Hyperspace|Jump Drive]]".
* It is probable that the MEM inspired the Ares program Mars Ascent Vehicle (MAV) and Mars Descent Vehicle (MDV) in [[Andy Weir]]'s 2011 novel ''[[The Martian (Weir novel)|The Martian]]'' (later adapted into [[The Martian (film)|a theatrical film]]).

==See also==
*[[Lander (spacecraft)]]
*[[Manned Mars rover]]
*[[Mars habitat]]
*[[Mars suit]]

== References ==
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{{Reflist}}

==External links==
{{Commons category}}
*[https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660021498.pdf An Initial Concept Of A Manned Mars Excursion Vehicle For A Tenuous Mars Atmosphere] (1966)

{{Human missions to Mars}}

<!--- Categories --->
[[Category:Crewed spacecraft]]
[[Category:Human missions to Mars]]