A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Space Science » Policy
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

Entry/Egress from BFS on Mars



 
 
Thread Tools Display Modes
  #1  
Old September 21st 19, 05:25 PM posted to sci.space.policy
Rocket Man[_2_]
external usenet poster
 
Posts: 8
Default Entry/Egress from BFS on Mars


"JF Mezei" wrote in message
...
At KSC, they'll have a nice tower, elevator, and air conditioned arm to
bring people between the tower and the BFS/Starship.


What about when it lands on Mars? Do they just open the door high up,
and unroll a rope ladder to the ground and hope that ladder stays on so
they can one day climb back onto the ship? Just curious if a flexible
ladder over such a long distance would be viable?

If they need attach points for latter at regular intervals, would such
present aerodynamic challenges for take off/Landing or be small enough
to be a no brainer? (for re-entry, such attach points would conduct
heat to the structure under heat shield would they not?

I assume there would be a floor for cargo with its own hatch, and arm
that can be extended out and a winch to lowr pallets to the ground?


I wondered about the same thing. What if the elevator breaks down when
they're on the surface. How are they going to climb back up into the
habitable section? Are there emergency stairsteps in the side of the rocket?


  #2  
Old September 21st 19, 08:33 PM posted to sci.space.policy
Alain Fournier[_3_]
external usenet poster
 
Posts: 548
Default Entry/Egress from BFS on Mars

On Sep/21/2019 at 12:25, Rocket Man wrote :
"JF Mezei" wrote in message
...
At KSC, they'll have a nice tower, elevator, and air conditioned arm to
bring people between the tower and the BFS/Starship.


What about when it lands on Mars? Do they just open the door high up,
and unroll a rope ladder to the ground and hope that ladder stays on so
they can one day climb back onto the ship? Just curious if a flexible
ladder over such a long distance would be viable?

If they need attach points for latter at regular intervals, would such
present aerodynamic challenges for take off/Landing or be small enough
to be a no brainer? (for re-entry, such attach points would conduct
heat to the structure under heat shield would they not?

I assume there would be a floor for cargo with its own hatch, and arm
that can be extended out and a winch to lowr pallets to the ground?


I wondered about the same thing. What if the elevator breaks down when
they're on the surface. How are they going to climb back up into the
habitable section? Are there emergency stairsteps in the side of the rocket?


That's a very minor problem to solve. But the thing is, there are many
such minor and a little less minor problems to solve before they can
send humans to Mars. SpaceX seems to be solving the main issue of
building a suitable rocket. But I don't see much going on about all the
other things. Oh, some people will talk about designing space suits for
Mars, and things like that. But talk is cheap. I'm not aware of anyone
working on actually making a space suit for Mars.

My hope is that after the SpaceX presentation next week in Boca Chica, a
human mission to Mars will start looking quite real enough that serious
work will start on all those little things. Still, I think that at some
point, SpaceX will have a vehicle ready to send humans to Mars, but an
actual mission will have to wait until some relatively minor details are
worked out.


Alain Fournier
  #3  
Old September 22nd 19, 09:56 AM posted to sci.space.policy
Niklas Holsti
external usenet poster
 
Posts: 168
Default Entry/Egress from BFS on Mars

On 19-09-22 09:51 , JF Mezei wrote:
On 2019-09-21 15:33, Alain Fournier wrote:

That's a very minor problem to solve.


And there were many suggestions posted, when this thread originally
appeared.

Having a ladder stick out of fuselage isn't "minor" when you have to
consider entry aerodynamics.


So don't do it. Have two or more doors and cranes for redundancy. Leave
some crew on board at all times to be on hand to solve problems.

And remember that SpaceX plans to send at least two ships at a time to
Mars, so there is a spare ship, even.

This may be a "minor" aspect in the big picture, but consider for
instance if they require to have some permanent recessed hook below
doors to which a ladder can be attached. That area can't have
"transpiorational" cooling [...]

Same thing with the doors, whether human or cargo. Will they get
transpiration cooling? [...]


Put the doors on the lee side, where it seems heat shielding is much easier.

--
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
. @ .
  #4  
Old September 23rd 19, 01:08 AM posted to sci.space.policy
Greg \(Strider\) Moore
external usenet poster
 
Posts: 752
Default Entry/Egress from BFS on Mars

"Niklas Holsti" wrote in message ...

On 19-09-22 09:51 , JF Mezei wrote:
On 2019-09-21 15:33, Alain Fournier wrote:

That's a very minor problem to solve.


And there were many suggestions posted, when this thread originally
appeared.

Having a ladder stick out of fuselage isn't "minor" when you have to
consider entry aerodynamics.


So don't do it. Have two or more doors and cranes for redundancy. Leave
some crew on board at all times to be on hand to solve problems.


This is almost certainly how they will do it. If for some reason they want
everyone on the surface, simply rig a crane with a rope before you leave.
Even worst case, you can build a haul system so on astronaut can lift
another up to the door.

As Niklas points out there are multiple solutions that can easily solve
this.


And remember that SpaceX plans to send at least two ships at a time to
Mars, so there is a spare ship, even.

This may be a "minor" aspect in the big picture, but consider for
instance if they require to have some permanent recessed hook below
doors to which a ladder can be attached. That area can't have
"transpiorational" cooling [...]

Same thing with the doors, whether human or cargo. Will they get
transpiration cooling? [...]


Put the doors on the lee side, where it seems heat shielding is much
easier.


Ayup.

--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net
IT Disaster Response -
https://www.amazon.com/Disaster-Resp...dp/1484221834/

  #5  
Old September 23rd 19, 12:47 PM posted to sci.space.policy
Jeff Findley[_6_]
external usenet poster
 
Posts: 2,307
Default Entry/Egress from BFS on Mars

In article ,
says...

On 2019-09-22 20:08, Greg (Strider) Moore wrote:

As Niklas points out there are multiple solutions that can easily solve
this.



Many solutions yes. But leaving this to the last minute may result in
your trying to fit a simple solution into a ship that was not planned to
handle it and require some serious engineering changes.


Agree to disagree here. Any solution is going to be constrained by the
structure and tank design. They're not going to make major changes to
the design that would do something like change the tank geometry.

Consider the function of lowering cargo pallets to ground. If you will
have some rail deploy out the door and then a crane be able to lift
cargo pallet from cargo floor, move to the outside and lower pallet
down, then that rail needs to have structural attach point that designed
at the right location. So when designing the structure of Starship, you
need to think of that. Not only to have structural elements where a rail
would need to be attached, but also to live without strucrtural elements
going through door frames.


That's a minor thing compared to, say, the structure needed to support
the winglets/flaps on the spacecraft. The loads on those during an
earth reentry are *very* high compared to rails/cranes/ladders/etc.
needed on Mars to lower cargo and crew to the surface (and back up
again).

And there is also the issue of testing pressurized doors that are larger
than humans have ever built (which are truly airtight and safe). Unless
they do CBM hatch sized doors for both human and cargo exits.


I'm pretty sure that the doors used for test facilities at NASA
installations would beg to differ. Especially those in Ohio. This
really isn't that hard of a problem. That's just straightforward
mechanical engineering.

If manned vs cargo Starships will have totally seperate setructures,


This is extremely doubtful. Everything from the base up to the top of
the propellant tanks would be essentially the same. Minor differences
might be introduced, but keeping them as close to the same as possible
means commonality which reduces production and maintenance costs.

then SpaceX can start to work on the cargo version now and only worry
about the doors needed to release satellites in orbit.


Obviously cargo Starship will be the first. They're not launching crew
in it on the first flight like the shuttle did. We very nearly lost
STS-1 and its crew on Columbia's first flight. That's a mistake no one
will repeat.

But when it
stats work on the manned version, it really needs to start planning ALL
the details of anything that would replace normal skin of ship as well
as punch large enough holes to force discontinuity in structural elements.


The upper portion of the Starships will necessarily be different
internally. But structurally, I have a feeling that these beasts will
be overbuilt by aerospace standards. Having a large factor of safety is
a "good thing" enabled by in orbit refueling.

So really early on in the ship's design, they need to think about
this.


Sure, internally. But being a private company means we're not privy to
such details unless Elon Musk himself decides otherwise.

This idle speculation is largely irrelevant given that Elon Musk is
giving us an update in a matter of days. Just wait a bit and I'm sure
he'll answer some of these questions.

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.
  #6  
Old September 24th 19, 12:29 PM posted to sci.space.policy
Jeff Findley[_6_]
external usenet poster
 
Posts: 2,307
Default Entry/Egress from BFS on Mars

In article ,
says...

On 2019-09-23 07:47, Jeff Findley wrote:

Agree to disagree here. Any solution is going to be constrained by the
structure and tank design. They're not going to make major changes to
the design that would do something like change the tank geometry.


But the designe of the structure above the tanks (the usable space) will
matter and this is where careful planning can make things such as
ladder/doors easy to implement vs extremely big headache that requires
redrawing the upper structure.

And if the structures above the tank might differ betwene the cargo and
manned versions (and I would venture a 3rd model that is used as a fuel
tanker). then you ant to make sure the "baseline" structure around the
Starchip tanks/engines can support/interface with the variable structure
above.


The above is largely nonsense because you keep failing to distinguish
between the areas that have large loads versus areas that are almost
insignificant. Leave these details to the mechanical engineers at
SpaceX. They know their stuff. For nearly three decades I have been
writing CAE software for a living and get to interact with customers at
Beta Test every year that do just this sort analyses every day. I know
what they do with our software because I've seen their models first hand
and talked to them about how they use the software and how we can make
it better. And last I checked, SpaceX using our software to do their
CAE analysis.

Disclaimer: All statements above regarding CAE software do not reflect
those of my employer. They are all my personal opinions and should be
taken as such.

At any rate, you're hand-waving here. We don't yet know the details.
wait for the update.

That's a minor thing compared to, say, the structure needed to support
the winglets/flaps on the spacecraft.


Not so minor if the structural elements needed to support those winglets
blocks the way for a door. As well, if the cargo version with the huge
doors will be in vacuum, that also means planning around lack fo air as
coolant for components. So they would need to likely plan for water or
ammonia loops or whateer is felt is needed. And BTW, how would the
manned version dump excess heat during a 6 months mission? Would it
deploy radiators, solar arrays during the trip and neatly fold them back
for re0-entry in Mars and back on Earth? If they fail to retract and
close doors, that could be a show stopper for re-entry in Earth's
atmosphere.

It is easy to stick an engine below a glorified grain silo. But when you
start to factor in all the various things that "break" a clean smooth
outer skin with doors etc, things become more complex.


You're waving your hands even faster here, but again we don't know the
details. Wait for the update.

I'm pretty sure that the doors used for test facilities at NASA
installations would beg to differ. Especially those in Ohio.


Do these dooors have to maintain perfect seal for perhaps 2 years? (6
month trip each way, plus a year stay on Mars). NASA can paliate for
small leaks by having compressors deal with any leaks in/out of the
pressure chamber.


This is incorrect. Any small leak in a large vacuum chamber ruins the
vacuum that needs to be achieved.

Also, there is the small matter of weight. Those very large opressure
vessels are very heavy, not exactly what they want on a spaceship.


Spaceships have had doors with seals in the past. Again, this is a
simple mechanical engineering problem to solve.

BTW, how did Dragon V1 deal with a CBM hatch at the top during
re-entry?


They shut the door and it reenters. It's on the "cooler" side of things
and made of aluminum which distributes the heat very well.

did crewmembers attach some sort of blanket over it before closing the
station side CBM and releasing Dragon? Ir was the CBM hatch coated with
heat shield material?


No blankets or anything. They just shut the hatch and secured it. Go
watch the undocking videos on YouTube.

Obviously cargo Starship will be the first.


Considering that investor who was promised a ride to the Moon on an
early flight, I wonder if SpaceX can realy delay the manned Starship
till Cargo one is all done. (Unless they really ride the Cargo Starship
with a Dragon V2.0 perched on top instead of the nose)


They're different copies of the vehicle. Why would one have to be done
before starting work on the other? Makes no sense. Large teams of
people can work on more than one thing at a time whether that's design,
test, fabrication, operations, maintenance, and etc.

This idle speculation is largely irrelevant given that Elon Musk is
giving us an update in a matter of days.


And exactly because of that that discussing various issues before that
presentation makes one look at what will and especially will not be
said during his presenation. Avoided subjects just as important as those
that are mentioned.


Meh.

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.
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Shapes of Mars entry aeroshells? Mr Jim History 2 April 14th 07 05:22 AM
Egress into space of the ISS expedition 9 crew Jacques van Oene Space Station 0 June 28th 04 10:39 AM
Hopefully Mars rover will be destroyed on entry into crater Dogma Questioner History 7 June 9th 04 02:27 PM
Mars,Moon,Eart re entry a pop quiz Lynndel Humphreys Technology 2 January 17th 04 12:40 AM
Mars,Moon,Eart re entry a pop quiz Lynndel Humphreys Space Shuttle 0 January 15th 04 06:24 PM


All times are GMT +1. The time now is 12:26 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.