Get your ass to the moon (CFE-style)
In designing an architecture for lunar flight, we face a difficult choice: do we take the easy way back to the moon in exchange for an unsustainable lunar effort, or do we take the hard way back to the moon so we can build a sustainable lunar colony? Project Apollo falls into the former category, and so does the current Project Constellation. I would like to see Project Constellation evolve into the latter, so I can see a sustained human presence on the moon in my lifetime.
Tom Cuddihy, Rand Simberg and Ken Murphy have been pointing out the need for a space platform at the L1 Lagrange point, an argument I am in total agreement with. While lunar-orbit rendezvous worked for Apollo and "Plan Griffin," the needs of a sizable colony dictate the use of a point whose position does not change relative to the positions of the earth and moon. If people need to get back to earth in a hurry, L1 is the way to do it. Example: if a person becomes ill or injured on the lunar surface, they could be sent to an L1 space station to be stabilized, then sent to earth for extensive medical treatment. Direct return from the moon to earth would get that person home fastest, but it comes at the expense of propellant. Lunar orbit rendezvous would require a precise rendezvous with a lunar orbiting CEV or space station, and would probably take longer to accomplish than an L1 rendezvous.
As a first whack at a lunar architecture, I propose the "CFE Plan" for human lunar return. It consists of five elements: the "Delta-Atlas" booster, the crewed CEV, the Lunar Surface Access Module, the Earth Departure Stage, and the L1 Space Platform (L1SP.)
My CEV would be a biconic capsule, capable of reentry in earth's atmosphere upon return from Mars. It would carry enough propellant (either internally or in an expendible service module) for a return to earth from L1. It would be reusable to the maximum practical degree. The CEV and its crew would be launched on a single-core Delta-Atlas.
On the first mission, the CEV would rendezvous with the EDS and L1SP in low earth orbit. The EDS and L1SP would be launched just prior to the CEV, on board a triple-core Delta-Atlas. After rendezvous, the EDS would fire its engines, deliver the stack to L1, and perform necessary propulsive braking maneuvers.
The purpose of the initial mission is for a human crew to test out the L1SP (which would essentially serve as a "mini-Mir" at L1) in both its inhabited and untended modes. Assuming all goes well, L1SP would be left at L1 and the CEV would return to earth.
For the second mission, the stack in LEO would consist of the CEV, LSAM, and EDS. The single-stage LSAM would use liquid oxygen as its oxidizer (and either hydrogen or methane as a fuel) so it could refuel with oxygen from oxidizer production plants on the lunar surface. The EDS would deliver CEV #2 and LSAM to L1SP. When all systems on the LSAM were checked out, it would be "go" for landing on the moon.
While the initial LSAM would be discarded, it would establish the oxygen production plant used to refuel future LSAM's. Hydrogen could be produced on the moon if water ice persists, but it will likely have to be sent from low earth orbit via ion rockets. Likewise, all aspects of the CFE Plan are modular and can be upgraded in the future. The Delta-Atlas can be replaced by a future RLV. L1SP can be built up beyond the bare-bones space station that will be launched on the initial mission. Modules for a lunar surface base could be checked out at L1 before being delivered to the surface on modified LSAM's. Enlarged, multi-stage LSAM's for direct return from the moon to the earth could also be pre-positioned at the lunar base.
Note that the CFE plan is very short on numbers and specifics. If I find the time and motivation, I may attempt to flesh the plan out. Nevertheless, it represents a concept of operations that should guide future lunar colonization.
Tom Cuddihy, Rand Simberg and Ken Murphy have been pointing out the need for a space platform at the L1 Lagrange point, an argument I am in total agreement with. While lunar-orbit rendezvous worked for Apollo and "Plan Griffin," the needs of a sizable colony dictate the use of a point whose position does not change relative to the positions of the earth and moon. If people need to get back to earth in a hurry, L1 is the way to do it. Example: if a person becomes ill or injured on the lunar surface, they could be sent to an L1 space station to be stabilized, then sent to earth for extensive medical treatment. Direct return from the moon to earth would get that person home fastest, but it comes at the expense of propellant. Lunar orbit rendezvous would require a precise rendezvous with a lunar orbiting CEV or space station, and would probably take longer to accomplish than an L1 rendezvous.
As a first whack at a lunar architecture, I propose the "CFE Plan" for human lunar return. It consists of five elements: the "Delta-Atlas" booster, the crewed CEV, the Lunar Surface Access Module, the Earth Departure Stage, and the L1 Space Platform (L1SP.)
My CEV would be a biconic capsule, capable of reentry in earth's atmosphere upon return from Mars. It would carry enough propellant (either internally or in an expendible service module) for a return to earth from L1. It would be reusable to the maximum practical degree. The CEV and its crew would be launched on a single-core Delta-Atlas.
On the first mission, the CEV would rendezvous with the EDS and L1SP in low earth orbit. The EDS and L1SP would be launched just prior to the CEV, on board a triple-core Delta-Atlas. After rendezvous, the EDS would fire its engines, deliver the stack to L1, and perform necessary propulsive braking maneuvers.
The purpose of the initial mission is for a human crew to test out the L1SP (which would essentially serve as a "mini-Mir" at L1) in both its inhabited and untended modes. Assuming all goes well, L1SP would be left at L1 and the CEV would return to earth.
For the second mission, the stack in LEO would consist of the CEV, LSAM, and EDS. The single-stage LSAM would use liquid oxygen as its oxidizer (and either hydrogen or methane as a fuel) so it could refuel with oxygen from oxidizer production plants on the lunar surface. The EDS would deliver CEV #2 and LSAM to L1SP. When all systems on the LSAM were checked out, it would be "go" for landing on the moon.
While the initial LSAM would be discarded, it would establish the oxygen production plant used to refuel future LSAM's. Hydrogen could be produced on the moon if water ice persists, but it will likely have to be sent from low earth orbit via ion rockets. Likewise, all aspects of the CFE Plan are modular and can be upgraded in the future. The Delta-Atlas can be replaced by a future RLV. L1SP can be built up beyond the bare-bones space station that will be launched on the initial mission. Modules for a lunar surface base could be checked out at L1 before being delivered to the surface on modified LSAM's. Enlarged, multi-stage LSAM's for direct return from the moon to the earth could also be pre-positioned at the lunar base.
Note that the CFE plan is very short on numbers and specifics. If I find the time and motivation, I may attempt to flesh the plan out. Nevertheless, it represents a concept of operations that should guide future lunar colonization.
posted by Mr. X at
5:38 PM
