>>12803818>>12803821>>12803822Boeing’s Mars plan was actually very neat. Everything was reusable except for the Mars Excursion Module. The basic plan was:
1) Three Solar Electric tugs are launched to the Earth Moon L2.
2) The Mars habitat is launched to the EML2, where it docks with one tug
3) The Mars Ascent/Descent vehicle is launched to the EML2, where it docks to the second tug
4) The two tugs depart the EML2 and fly out to Mars.
5) The tugs deposit the landers before flying past mars. The two landers aerocapture into mars orbit.
6) The habitat lands on the surface, while the Ascent/Descent vehicle stays in low mars orbit.
7) The two tugs return to the EML2.
8) A crew habitat is launched to the EML2 and docks with the third tug. A crew is launched right after and they dock with the Tug/Hab, making a “Mars Transfer Vehicle”
9) The MTV boosts out to mars. It then brakes into Mars orbit. The crew rendezvous with the waiting Ascent/Descent vehicle.
10) The Ascent/Descent vehicle brakes and lands next to the habitat. The crew get out and spend 300 or so days on Mars. When their trip is complete, they board the ascent vehicle, and its upper stages detach from the descent platform and it flies into orbit.
11) The crew dock with the waiting Mars Transfer Vehicle and enter it again. They say “goodbye” to the Ascent/Descent vehicle before undocking from it. The MTV then burns its ion engines to head back home.
12) The MTV brakes into the EML2. The crew board their Orion and return home.
13) Two refueling trips fill up the first two Tugs. Two more launches carry a second hab and a second Ascent/Descent vehicle.
14) Eventually, a a refueling trip docks with the MTV (now sitting at the EML2 and unmanned). After this, the second mars crew is launched to the EML2, to begin the second Mars mission.
SOURCE:
https://www.nasaspaceflight.com/2013/01/boeing-outlines-technology-crewed-mars-missions/Also, pic related is the space tug.
