Exploring the Unknown: Selected Documents in ... - The Black Vault

Exploring the Unknown 497
4. Impulses
hydrogen-oxygen
storable propellants
420 sec
300 sec
These figures and estimates are considered reasonable and consistent
with those used in the concurrent Nova studies. With this information we can
now match the previously discussed vehicles and rendezvous concepts.
II.
II.
2. Mission Vehicle Matching
2. a: Earth Rendezvous Only.
On the basis of the preceding paragraph, the following weights at
different stages of the mission pertain to the case of rendezvous in earth orbit
only (based on H202 performance):
[4]
Weight returned to vicinity of earth
Lunar take-off weight
Weight landed on moon
Weight in escape trajectory
Weight in earth orbit
12, 500 pounds
28, 800 pounds
31, 000 pounds
73, 000 pounds
210, 000 pounds
These weights indicate that five C-2’s or two C-3’s are required in order
to accomplish the mission.
II.
2. b: Lunar Rendezvous.
A concept in which a rendezvous is made in lunar orbit only or together
with earth orbit rendezvous possesses basic advantages in terms of energy
management and thus launch vehicle requirements. This approach involves
placing the complete spacecraft in orbit about the moon at a rela tively low
altitude. One or two of the three-man crew then descends to the lunar surface
in a special capsule which detaches from the spacecraft. Upon leaving the lunar
surface, the capsule performs a rendezvous with that portion of the spacecraft
which remained in lunar orbit. The lunar capsule is, of course, left behind on the
return trip of the spacecraft to earth. A variation on this approach involves two
lunar landing capsules, one of which remains with the “mother” ship and can be
used for rescue operations on the lunar surface.
The basic advantage of the system is that the propellant required for the
lunar landing and take-off is reduced which in turn translates into a reduction
in the amount of weight which must be put into an escape tra jectory. The escape
weight saving achieved is related to the fraction of the spacecraft weight which
is retained in lunar orbit. The actual weight saving which can be realistically
achieved by this method can only be determined after detailed consideration
of the design and integration of the complete spacecraft. Calculations suggest,
however, that the amount of weight which must be put into an escape trajectory
for a given reentry vehicle weight might be reduced by a factor of two by use of