Encyclopedia Astronautica

American manned spacecraft module. Study 1968. Re-entry at extreme velocities from manned interplanetary missions..

The Earth Entry module was a unique biconic design by NASA Langley and Boeing, capable of returning six crew and a metric ton of samples safely to earth from interplanetary missions at re-entry velocities of up to 18 km/sec.

Use of the EEM allowed the mass of propellants for a rocket-powered earth braking maneuver at the end of a planetary mission to be dispensed with, which reduced mission mass substantially. But it was a risky maneuver, and Von Braun's mission profile of a year later returned to rocket braking as allowing more room for error. Mass of the EEM would vary according to the amount of ablative material applied, tailored to individual missions. It would be as high as 7900 kg for returns at 18.3 km/sec from Mars opposition missions, or as low as 6300 kg for returns at 11.6 km/sec from Venus orbiter missions. After burning off between 1100 kg and 2700 kg of ablative heat shield material, the capsule would have slowed to subsonic speed. Parachutes would deploy and flotation bags would cushion the impact of a water landing.


Crew Size: 6. Orbital Storage: 1,100 days.

AKA: Earth Entry Module.
Gross mass: 7,900 kg (17,400 lb).
Height: 5.60 m (18.30 ft).
Diameter: 3.20 m (10.40 ft).

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Associated Countries
Associated Spacecraft
  • IMIS 1968 American manned Mars expedition. Study 1968. In January 1968 Boeing issued a report that was the result of a 14 month study on manned Mars missions. More...

See also
Associated Manufacturers and Agencies
  • NASA Langley American agency overseeing development of rockets and spacecraft. Langley, USA. More...
  • Boeing American manufacturer of rockets, spacecraft, and rocket engines. Boeing Aerospace, Seattle, USA. More...

  • Baker, Larry L, "Manned Interplanetary Spacecraft", Northwest Professional Engineer, Summer/Fall 1968.

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