View Single Post
  #9  
Old April 18th 17, 01:20 AM posted to sci.space.policy
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default SLS launches likely delayed

JF Mezei wrote:

On 2017-04-17 13:07, Fred J. McCall wrote:

That article had a link to a NASA web page which describes its concept
for Mars. That page does not paint Orion/SLS as sending man to Mars.


Then you must not have read it very carefully. You think they're
going to get there on the wings of butterflies, perhaps?



I was refering to this:
https://www.nasa.gov/feature/deep-sp...t-destinations


(It was linked to in the artciel your refered to).


I know what you were referring to.


It calls ISS-2 "Deep Space Gateway".


No, it doesn't, since ISS and the Deep Space Gateway are about as
similar as the White House and an outhouse.


##
build a crew tended spaceport in lunar orbit within the first few
missions that would serve as a gateway to deep space
##

##
For those destinations farther into the solar system, including Mars,
NASA envisions a deep space transport spacecraft. This spacecraft would
be a reusable vehicle that uses electric and chemical propulsion and
would be specifically designed for crewed missions to destinations such
as Mars. The transport would take crew out to their destination, return
them back to the gateway, where it can be serviced and sent out again.
##


Well, that seems to answer your question, doesn't it? So why were you
asking, again? Bait and switch, anyone? Wasn't Orion (I keep calling
that thing 'Ares' for some reason) advertised as needed to go beyond
the Moon? They're going to 'service' their transit vehicle using
space walks?


It odesn't mention SLS used to get to mars, it mentions its cargo
capacity to that Deep Space Gateway.


So no need for Orion, then, and SLS can and should be replaced by a
cheaper launcher (like SpaceX Super Heavy or Blue Origin New Glenn).

This is the typical NASA plan; be all things to all people so that
it's a lousy plan for almost everything. Put your interplanetary way
station in lunar orbit, even though that makes little sense, just so
you get something to let you change directions and do 'Moon First' in
case someone changes their mind. You have no decent capability to
check out or repair your Mars vehicle (which is only a glimmer in
someone's eye for additional funding right now), since it is always on
orbit. That means it will get flown until something in the engine(s)
goes 'poof' and you lose a mission. NASA used to say a Mars ship
should have thermal nuclear propulsion and I'm pretty sure their
reference mission still says that, but this thing is "electric and
chemical". And it better be mostly chemical, or your transfer orbit
is just going to be too slow. They presumably also need some way to
get down from Mars orbit to the service, since you certainly aren't
going to land this thing on Mars - which means you need to haul enough
fuel to Mars for the whole trip.

At least their Orion plus Hab plan had some small hope of actually
getting people to Mars. This thing will never get built.


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw