Think it's doable with a single FH and F9. These will total to about 87
metric tons to LEO. Give the Orbital ATK Cygnus capsule life support to be
used as a lunar lander crew module. This is about 2 tons. Use the storable
propellant upper stage EPS of the Ariane 5
<http://www.esa.int/Our_Activities/Space_Transportation/Launch_vehicles/Storable_Propellant_Stage_EPS>
for the propulsive module of the lunar lander. This will be about 11 tons.
Use the Dragon 2 for the command module role, a la the Apollo
architecture. That's about 8 tons, with the Superdracos fuel included. Use
another Ariane 5 EPS stage as the propulsive module to insert the stack
into lunar orbit a la the service module of the Apollo architecture once it
is already sent to TLI(trans lunar insertion). That's another 11 tons. Then
the total mass so far that needs to be sent to TLI is 2 + 11 + 8 +11 = 32
tons.
But you also need, following the Apollo architecture, to be able to send
the Dragon 2 out of lunar orbit back to Earth for the return trip. I was
thinking of using the Superdracos to provide the propulsion for this but I
don't think the ca. 1.3 tons of Superdracos propellant planned to be
carried by the Dragon 2 will provide sufficient delta-v for this. Might
need ca. 1.5 tons additional propellant which can be carried in the Dragons
trunk section. But if you are going to carry additional propellant in the
trunk section you might want to dispense with that extra Ariane 5 EPS stage
serving as the service module and just use the Superdracos both for
entering and exiting lunar orbit. You would need then ca. 10 tons extra
propellant in the trunk also for the entering lunar orbit. The mass for
this propulsion for entering and exiting lunar orbit would be about the
same either way, so call the total amount of mass to be sent to TLI 33.5
tons.
Now use the rule-of-thumb that an efficient hydrolox upper stage a la the
Centaur can send a payload mass equal to it's propellant load to escape
velocity. So you would need a hydrolox stage of ca. 33.5 tons propellant
size to send this stack to TLI. The dry mass of such a Centaur-like
hydrolox stage is about 1/10th that of the propellant mass, so about 3.4
tons. Then you would need to send a total mass of about 33.5 + 33.5 + 3.4 =
70.5 tons to LEO, well less than the 87 tons total possible for the FH + F9
together to LEO.
There are a few ways to make up this hydrolox stage using existing
components. You could use the Delta IV Heavy's hydrolox upper stage. You
could use two Centaurs, at ca. 20 tons propellant load each. Or you could
use one Centaur and one Ariane 5 cryogenic upper stage, which is about half
size to the Centaur.
Bob Clark
On Thu, Feb 8, 2018 at 7:51 AM, Bill Bruner <bill@xxxxxxxxxx> wrote:
The wild card here is the President's strong desire to return to the Moon
sooner, rather than later. The *only* way to do that at the beginning of
the second term (with substantial progress in the first) is with FH.
To modify Henry V.'s grand bargain, here is how the Administration can cut
this Gordian knot:
1. Immediately make the policy decision to return to the Moon permanently,
starting with a FH centric architecture, by the early 20s.
2. Transition from SLS at Marshall to FH-compatible lunar lander and DSG
contracts, while significantly expanding the nuclear thermal propulsion
work they're already doing there
<https://www.nasa.gov/centers/marshall/news/news/releases/2017/nasa-contracts-with-bwxt-nuclear-energy-to-advance-nuclear-thermal-propulsion-technology.html>.
The strategic defense work is coming, but the architecture is yet
undefined, so it is probably too early to use it as part of this deal -
plus any new MDA work would be at SMDC, not Marshall - resulting in
politically problematic layoffs at MSFC.
3. Work with the Hill and industry to come up with an intentional plan to
transition Station to the private sector by the end of the second term
rather than "cancelling" it.
Within the current NASA topline, this would a) get us back to the Moon
sooner b) free up SLS and Station money to do something useful c) build a
gateway to the rest of the Solar System and d) put us on a pathway to a
serious interplanetary drive.
Bill Bruner
New Frontier Aerospace
bill@xxxxxxxxxx
925-456-4553 <(925)%20456-4553>
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On Wed, Feb 7, 2018 at 9:22 PM, Henry Vanderbilt <
hvanderbilt@xxxxxxxxxxxxxx> wrote:
On 2/7/2018 8:16 PM, Henry Spencer wrote:
It will take time for a substantial heavylift market to develop.
Time, or a high-volume government customer. Say, a serious human
deep-space exploration program that actually wanted to accomplish something
interesting for the ~$4G/year that's the likely max politically-practical
funding.
Henry V