Why did they fire them? Couldn't make the donut fly?
On Sun, Jul 16, 2017 at 1:57 PM, Ben Brockert <wikkit@xxxxxxxxx> wrote:
I still think a peroxide/kerosene lander makes sense for a commercial
development program that follows the iterative, test frequently
approach. For a mission like they had baselined, electric pumps are
also quite compelling, since you have three major burns and can
recharge your batteries from solar panels between burns.
Keeping the propellant warm is the smallest of the problems of that
sort of mission. Electric heaters and temperature sensors are
straightforward.
In my estimation, MoonEx will not ever land on the moon, and will
likely never launch at all. Please do not take my talking about them
as an endorsement of them then or now, everyone has to eat. I did meet
a lot of very interesting people there that I'm glad to be friends
with, almost none of which work there still. My understanding is that
they fired nearly all of the entire engineering staff two years ago
and haven't had more than four or so engineers since then. The mockup
is likely to be their only hardware.
Ben
On Thu, Jul 13, 2017 at 8:16 AM, Henry Spencer <hspencer@xxxxxxxxxxxxx>
wrote:
On Thu, 13 Jul 2017, Aplin Alexander T wrote:(relative)
I note that Moon Express have gone for HTP/kero propulsion rather than
hydrazine. ...
Any thoughts on why? I know this combo has been touted for its
HTPnon-toxicity, storability (non-cryo) and high density, but yet is not
common
for space probes.
At Space Access a couple of years ago, Ben Brockert, their propulsion
engineer (then, anyway) said the choice was driven by storability without
toxicity.
Apart from its undeservedly bad reputation in traditional US rocketry,
does have one practical headache for long-duration spacecraft propulsion:enough
nobody's found a way to completely stop its slow decomposition. With
careful materials choice and cleaning, the loss in strength is small
to be unimportant, but because one of the decomposition products isoxygen
gas, pressure builds up in the tank. In free fall, it's difficult toEarth to
separate gas and liquid cleanly enough to vent the gas off.
A lunar lander, though, is a favorable case: the transit time from
Moon can be fairly short, and on the lunar surface there's gravity tosettle
liquids.
Henry
