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U.S. astronauts are climbing back into space capsules. Here's howthey've improved over the past 50 years



 
 
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  #11  
Old September 23rd 17, 09:54 AM posted to sci.space.policy
Anthony Frost
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Posts: 253
Default U.S. astronauts are climbing back into space capsules. Here's how they've improved over the past 50 years

In message
Jeff Findley wrote:

This has changed somewhat recently. Reportedly SpaceX is the one who
shelved development of Dragon V2 vertical landing. The reasons for this
aren't terribly clear, but there are hints from SpaceX that this is
because they've decided to change the (Mars) landing mode of their
(eventual) Mars vehicle.


Also apparently NASA weren't happy about cargo flights being used for
testing powered landings.

Also, SpaceX is supposed to have a press briefing about the changes in
their Mars program sometime this fall. Hopefully we'll get more
information then which will allow us to "connect the dots".


Elon is giving another presentation at IAC in Adelaide on the 29th,
cyrrently due to start talking at 04:30 UTC. Speculation is for a
not-quite-so-BFR that can be built in existing SpaceX facilities and
which won't require major strengthening of HLC-39A.

Anthony

  #12  
Old September 23rd 17, 12:45 PM posted to sci.space.policy
Jeff Findley[_6_]
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Posts: 2,307
Default U.S. astronauts are climbing back into space capsules. Here's how they've improved over the past 50 years

In article , says...

In message
Jeff Findley wrote:

This has changed somewhat recently. Reportedly SpaceX is the one who
shelved development of Dragon V2 vertical landing. The reasons for this
aren't terribly clear, but there are hints from SpaceX that this is
because they've decided to change the (Mars) landing mode of their
(eventual) Mars vehicle.


Also apparently NASA weren't happy about cargo flights being used for
testing powered landings.

Also, SpaceX is supposed to have a press briefing about the changes in
their Mars program sometime this fall. Hopefully we'll get more
information then which will allow us to "connect the dots".


Elon is giving another presentation at IAC in Adelaide on the 29th,
cyrrently due to start talking at 04:30 UTC. Speculation is for a
not-quite-so-BFR that can be built in existing SpaceX facilities and
which won't require major strengthening of HLC-39A.


Yes, the rumors are flying. I've heard that the not quite so big BFR
would fly exclusively out of Texas, not LC-39A, but that doesn't seem
likely. I would think with this new vehicle SpaceX would want to court
things like cargo launches to NASA's proposed lunar orbiting station.
If so, NASA would likely be more comfortable with KSC launches.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.
  #13  
Old September 23rd 17, 06:33 PM posted to sci.space.policy
Fred J. McCall[_3_]
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Posts: 10,018
Default U.S. astronauts are climbing back into space capsules. Here's how they've improved over the past 50 years

Anthony Frost wrote:

In message
Jeff Findley wrote:

This has changed somewhat recently. Reportedly SpaceX is the one who
shelved development of Dragon V2 vertical landing. The reasons for this
aren't terribly clear, but there are hints from SpaceX that this is
because they've decided to change the (Mars) landing mode of their
(eventual) Mars vehicle.


Also apparently NASA weren't happy about cargo flights being used for
testing powered landings.


Why would they care? They get their cargo on the way up, not the way
down. I think it's funny that NASA lets astronauts ride on Soyuz,
which relies on power at landing on dirt for them to survive, yet is
being obstructionist to safety certify Dragon V2 for fully powered
landings on dirt.


--
"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
  #14  
Old September 23rd 17, 06:36 PM posted to sci.space.policy
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default U.S. astronauts are climbing back into space capsules. Here's how they've improved over the past 50 years

Jeff Findley wrote:

In article , says...

In message
Jeff Findley wrote:

This has changed somewhat recently. Reportedly SpaceX is the one who
shelved development of Dragon V2 vertical landing. The reasons for this
aren't terribly clear, but there are hints from SpaceX that this is
because they've decided to change the (Mars) landing mode of their
(eventual) Mars vehicle.


Also apparently NASA weren't happy about cargo flights being used for
testing powered landings.

Also, SpaceX is supposed to have a press briefing about the changes in
their Mars program sometime this fall. Hopefully we'll get more
information then which will allow us to "connect the dots".


Elon is giving another presentation at IAC in Adelaide on the 29th,
cyrrently due to start talking at 04:30 UTC. Speculation is for a
not-quite-so-BFR that can be built in existing SpaceX facilities and
which won't require major strengthening of HLC-39A.


Yes, the rumors are flying. I've heard that the not quite so big BFR
would fly exclusively out of Texas, not LC-39A, but that doesn't seem
likely. I would think with this new vehicle SpaceX would want to court
things like cargo launches to NASA's proposed lunar orbiting station.
If so, NASA would likely be more comfortable with KSC launches.


Why would SpaceX want to use BFR with its huge cargo capacity for
cargo launches to lunar orbit? Falcon Heavy is more than adequate for
that. However, any real Mars program other than small scientific
visits and 'flags and footprints' needs a bigger rocket.


--
"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
  #15  
Old September 24th 17, 02:17 AM posted to sci.space.policy
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default U.S. astronauts are climbing back into space capsules. Here's how they've improved over the past 50 years

JF Mezei wrote:

On 2017-09-23 13:33, Fred J. McCall wrote:

down. I think it's funny that NASA lets astronauts ride on Soyuz,
which relies on power at landing on dirt for them to survive, yet is
being obstructionist to safety certify Dragon V2 for fully powered
landings on dirt.


A rare instance where I agree with you.

But being devil's advocate: At the time NASA started to purchase seats
on Soyuz, it had already proven itself and it ability to land. Also,
they had no choice since Soyuz was also the escape pod in case of emergency.

And during post Columbia stand down and after permanent shutdown of
Shuttle, NASA had no choice either.


True, but doesn't address the issue. Why not let SpaceX prove powered
landing?


Had SpaceX insited on doing land landings for dragon from the get go,
NASA's reaction might have been to not bring back important cargo until
after a few flights when the capsule had proven itself.


Just how much cargo do you think comes back down? Most cargo vehicles
are used to dispose of trash by doing uncontrolled reentries.


But because the option to land on water remained available, NASA saw
this as a much simpler way to get commercial cargo going, and once this
happens, it is easier to just insist on it continuing.


True, but what about all the flights that aren't bringing anything
back? Why obstruct development?


Note: for researchers, landing on land has HUGE advantages as they can
get to experiments much faster.


To some extent, but not all that much.


Question: for a "newbie" company like Space-X, and considering the USA
does not have vast areas of undevelopped land that is flat and easy to
land on, how difficult is it to fairly precicely target a landing site
and what are the implications if re-entry isn't perfect (as has happened
on Soyuz a few times) ?


If you're coming down under power (as opposed to Soyuz which comes
down on parachutes and just uses power to 'soften' the landing enough
to be survivable), you're not going to 'miss' by more than a handful
of meters.


--
"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
  #16  
Old September 24th 17, 01:32 PM posted to sci.space.policy
Jeff Findley[_6_]
external usenet poster
 
Posts: 2,307
Default U.S. astronauts are climbing back into space capsules. Here's how they've improved over the past 50 years

In article ,
says...

Anthony Frost wrote:

In message
Jeff Findley wrote:

This has changed somewhat recently. Reportedly SpaceX is the one who
shelved development of Dragon V2 vertical landing. The reasons for this
aren't terribly clear, but there are hints from SpaceX that this is
because they've decided to change the (Mars) landing mode of their
(eventual) Mars vehicle.


Also apparently NASA weren't happy about cargo flights being used for
testing powered landings.


Why would they care? They get their cargo on the way up, not the way
down.


Because Dragon is the only way that NASA can get things like EMUs back
to earth for refurbishment. There have been articles on how few
functioning EMUs are left. Sorry for the word-wrap on the cites:

NASA is running out of space suits and it?s years away from having new
ones ready
https://www.theverge.com/2017/4/27/1...ut-space-suit-
development-deep-space

NASA Won't Have New Spacesuits For Years - Despite $200 Million
Investment
https://www.forbes.com/sites/bridain.../nasa-running-
out-of-spacesuits/

I think it's funny that NASA lets astronauts ride on Soyuz,
which relies on power at landing on dirt for them to survive, yet is
being obstructionist to safety certify Dragon V2 for fully powered
landings on dirt.


That's the rumor. Another rumor says Dragon V2 propulsive landings are
being dropped because SpaceX is going to be changing its landing mode
for Mars missions. I'm not sure how much stock I put in that, but we'll
just have to wait and see. SpaceX isn't afraid to change directions
when something isn't working out or when another more promising approach
surfaces.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.
  #18  
Old September 24th 17, 01:43 PM posted to sci.space.policy
Jeff Findley[_6_]
external usenet poster
 
Posts: 2,307
Default U.S. astronauts are climbing back into space capsules. Here's how they've improved over the past 50 years

In article ,
says...

JF Mezei wrote:

On 2017-09-23 13:33, Fred J. McCall wrote:

down. I think it's funny that NASA lets astronauts ride on Soyuz,
which relies on power at landing on dirt for them to survive, yet is
being obstructionist to safety certify Dragon V2 for fully powered
landings on dirt.


A rare instance where I agree with you.

But being devil's advocate: At the time NASA started to purchase seats
on Soyuz, it had already proven itself and it ability to land. Also,
they had no choice since Soyuz was also the escape pod in case of emergency.

And during post Columbia stand down and after permanent shutdown of
Shuttle, NASA had no choice either.


True, but doesn't address the issue. Why not let SpaceX prove powered
landing?


Higher (perceived) risk for returning payloads. NASA doesn't want
valuable commodities like EMUs being turned into garbage upon high speed
impact with land. On the other hand, splash-downs have been used by all
other US capsules with only a handful of notable "anomalies", so
management is more comfortable with what they (think) they know.


Had SpaceX insited on doing land landings for dragon from the get go,
NASA's reaction might have been to not bring back important cargo until
after a few flights when the capsule had proven itself.


Just how much cargo do you think comes back down? Most cargo vehicles
are used to dispose of trash by doing uncontrolled reentries.


Absolutely true, which means that cargo which *must* come back to earth,
like EMUs, can *only* come back on Dragon. No other cargo craft
departing ISS has this capability besides Dragon.

Perhaps in a few years we'll see Dreamchaser returning cargo on the old
shuttle runway at KSC, but they're far from orbital flight. They're
just now resuming (space shuttle Enterprise style) test flights.


But because the option to land on water remained available, NASA saw
this as a much simpler way to get commercial cargo going, and once this
happens, it is easier to just insist on it continuing.


True, but what about all the flights that aren't bringing anything
back? Why obstruct development?


Because there are payloads which absolutely need to be returned intact.
With the space shuttle, this was a given capability with the MPLMs.
Post space shuttle, only Dragon has this capability, so it's a quite
valuable capability.


Note: for researchers, landing on land has HUGE advantages as they can
get to experiments much faster.


To some extent, but not all that much.


Agreed. Due to schedule constraints (astronaut time is a precious
commodity), most completed experiments surely end up in storage for
weeks or months before being returned on a Dragon.

Question: for a "newbie" company like Space-X, and considering the

USA
does not have vast areas of undevelopped land that is flat and easy to
land on, how difficult is it to fairly precicely target a landing site
and what are the implications if re-entry isn't perfect (as has happened
on Soyuz a few times) ?


If you're coming down under power (as opposed to Soyuz which comes
down on parachutes and just uses power to 'soften' the landing enough
to be survivable), you're not going to 'miss' by more than a handful
of meters.


Agreed. Dragon capsule is designed to provide lift, so it can steer
itself during descent, even when the Super Dracos aren't firing. This
is quite similar to Falcon 9 first stage landings where the Merlin
engines only fire briefly for boost back, reentry, and landing. The
most recent Falcon 9 first stage landings have literally all been right
in the center of the X. Their landing accuracy appears to be within
mere meters of the center of the landing pad.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.
  #19  
Old September 24th 17, 09:34 PM posted to sci.space.policy
Jeff Findley[_6_]
external usenet poster
 
Posts: 2,307
Default U.S. astronauts are climbing back into space capsules. Here's how they've improved over the past 50 years

In article om,
says...

On 2017-09-24 08:43, Jeff Findley wrote:

itself during descent, even when the Super Dracos aren't firing. This
is quite similar to Falcon 9 first stage landings where the Merlin
engines only fire briefly for boost back, reentry, and landing.



And how many stage 1s were lost before SpaceX got it right?


The aerodynamics of Dragon are easier and well known at this point.
Dragon V2 isn't much different aerodynamically from the current cargo
Dragon.

For the initial test flights for Dragon, NASA should have let SpaceX try
landings on land. SpaceX could have debugged it and gotten something
trustworthy by the time they switched to "production" flights.


Propulsive landings nixed from SpaceX?s Dragon spaceship
July 19, 2017 Stephen Clark
https://spaceflightnow.com/2017/07/1...gs-nixed-from-
spacexs-dragon-spaceship/

From above article:

"The reason we decided not to pursue (powered landings) heavily
is it would have taken a tremendous amount of effort to qualify
that for safety, particularly for crew transport," Musk said.
"And then there was a time when I thought that the Dragon
approach to landing on Mars, where you've got a base heat shield
and side-mounted thrusters, would be the right way to land on
Mars, but now I'm pretty confident that is not the right way,
and that there's a far better approach."

So, since it's not as important to Mars as SpaceX once thought it was,
it's just not worth the effort to qualify it for manned landings. This
was a management/engineering trade-off and appears to be SpaceX's call,
not NASA's.

In terms of landing accuracy, can landing from a full orbit altitude be
as accurate as landing after a 3 minute flight where speed during
re-entry is much lower so minute deviations in angles etc have far
lesser impact?


Yes. Dragon flies a lifting reentry and therefore has some cross-range
capability. This was also true of both Gemini and Apollo (and Russian
Soyuz and Chinese Shenzhou).

I know that guidance can bring a ship over the "X". But running out of
fuel before you land doesn't let guidance do much, and unless you do
like Batman and land on a mattress factory, the landing will be rather
harsh if you run out of fuel.


After the deorbit burn, the fuel remaining in the reaction control
system is only used to maintain the proper attitude. The "lift" of the
craft is provided by aerodynamics and an offset center of gravity.
There would be little worry about "running out of fuel". And if that
were the case (e.g. a launch abort), then the plan was for Dragon V2 to
land using parachutes, not propulsion.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.
  #20  
Old September 25th 17, 12:16 AM posted to sci.space.policy
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default U.S. astronauts are climbing back into space capsules. Here's how they've improved over the past 50 years

Jeff Findley wrote:

In article ,
says...

Anthony Frost wrote:

In message
Jeff Findley wrote:

This has changed somewhat recently. Reportedly SpaceX is the one who
shelved development of Dragon V2 vertical landing. The reasons for this
aren't terribly clear, but there are hints from SpaceX that this is
because they've decided to change the (Mars) landing mode of their
(eventual) Mars vehicle.

Also apparently NASA weren't happy about cargo flights being used for
testing powered landings.


Why would they care? They get their cargo on the way up, not the way
down.


Because Dragon is the only way that NASA can get things like EMUs back
to earth for refurbishment. There have been articles on how few
functioning EMUs are left. Sorry for the word-wrap on the cites:


But most flights aren't carrying those (or anything else) back down.
So why is NASA apparently being obstructionist about landing the
'empties' propulsively?


I think it's funny that NASA lets astronauts ride on Soyuz,
which relies on power at landing on dirt for them to survive, yet is
being obstructionist to safety certify Dragon V2 for fully powered
landings on dirt.


That's the rumor. Another rumor says Dragon V2 propulsive landings are
being dropped because SpaceX is going to be changing its landing mode
for Mars missions. I'm not sure how much stock I put in that, but we'll
just have to wait and see. SpaceX isn't afraid to change directions
when something isn't working out or when another more promising approach
surfaces.


Well, they could get smaller by removing the outer ring of engines.
That would reduce thrust to 1/4 of the original concept, which is
about four times what a Falcon Heavy delivers. But is that big enough
to support a real Mars colony?


--
"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
 




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