Mars Bound Spacecraft Example

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The in-situ solution would means finding nitrates to mine. You can't just
use electricity to convert dirt to fuel.

No one is suggesting that. So that's a complete strawman.

The same for cracking water. The efficiencies and materials just don't
exist.

Water doesn’t exist on Mars? That would be news to the scientists studying
Mars.

But even then, you don't need that. You need the existing atmosphere and
some H2.

https://en.wikipedia.org/wiki/Sabatier_reaction
https://en.wikipedia.org/wiki/In_sit...ce_utilization


Putting a power source on mars to make hydrogen and oxygen liquids has a
price tag.

Yes, but you need a power source already for your landing team. You land
your lander and power source before hand and make your fuel.

Once you have full tanks, THEN you send your landing team.


I do not believe gas could be found by hole drilling. Mars never went
thru the exotic flora history of Earth.

No one is suggesting that



Although I do like the concept of artificial crust vents.

The reason for basic silicon elemental existence is not well understood.
Sol evolution sciences are bullcrap. This question begs the question of why
life?


Both the above are irrelevant.

Finding uranium would be the most fruitful attack. Natural enrichment
levels of natural uranium on earth can be used in a true critical core.
Reduce the spacing between fuelrods to increase the U-235 space density to
the right U-235 state. Then use a moderator that is more efficient than
water. The small rod spacing causes the level of moderation for
criticality. So just go prompt critical using liquid hydrogen moderation.
The mandate for delayed neutron control is just an issue of ease of core
neutron population control. It tends to self disassemble nicely. But how
to harness this system?

Again, way to complicated.

--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

In article om,
says...

On 2016-02-20 20:37, Fred J. McCall wrote:

It seems obvious. The atmosphere reaches high enough to cause orbital
decay but doesn't get thick enough fast enough to slow any reasonable
sized craft down enough for parachutes to get a safe landing. A chute
big enough to slow you down enough to get a safe landing at surface
pressures gets ripped off because you don't get ENOUGH aerobraking. So
you either need a series of parachutes of increasing size (not
practical, as they'd just take up too much space) or you need some
other way to get slowed down.

Yet, NASA has landed craft on Mars before using parachutes.

But not parachutes alone. Airbags were needed on smaller craft and
rocket engines on larger. The problem comes in when you try to scale up
to manned spacecraft sizes.

And considering Mars' atmosphere does not densify rapidly, one set of
parachutes could last a fair amount of time before their drag is too
much for their strength.

I guess it comes down to a formula of weight of parachutes vs fuel for
equavalent delta-V produced.

And final descent of the larger Mars probes have all been done with
rocket engines (e.g. the complex sky crane approach).

Jeff
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All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
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Inflate a large transhab like structure, and let it doing the decellration....

pehahaps you it as living area on mars, by partially reinflating it.

In article ,
says...

Inflate a large transhab like structure, and let it doing the decellration....

Repeating this doesn't make it posible.

pehahaps you it as living area on mars, by partially reinflating it.

Things that are different, just aren't the same. An inflatable heat
shield for a hypersonic reentry is not constructed *at all* in the same
way that an inflatable habitat is constructed. The many layers for MMOD
protection, in particular, would certainly not stand up to a hypersonic
reentry.

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.

On the natural uranium reactor concept. Making nested cylindrical fuel cans, i.e a coaxial geometry allows a huge increase of 235 atom density relative to the normal fuel rods. The coaxial liquid hydrogen moderator has spacing sufficient. It is a simple parametric theory. Trial and error core geometry parameter/sizing design until it goes prompt critical. Success is a hand grenade sized core disassembly. or larger as designed.

In article om,
says...

On 2016-02-21 13:48, Jeff Findley wrote:

Things that are different, just aren't the same. An inflatable heat
shield for a hypersonic reentry is not constructed *at all* in the same
way that an inflatable habitat is constructed. The many layers for MMOD
protection, in particular, would certainly not stand up to a hypersonic
reentry.


I am not Eisntein, and I understood his suggestion properly. Just
because he mentioned "transhab" didn't mean it was expected to use the
exact same material for the baloon.

You'll note that one of the Orion or CST100 will use inflatable
structure to increase drag during re-entry. So this isn't totally out of
whack in terms of ideas.

This is not true. These capsules can deploy airbags to cushion the
final landing forces. But, this is not at all the same as a heat shield
for reentry (things that are different, just aren't the same).

in "2010", they used aerobraking, and then disposed of the inflated
balloons.

That is fiction. This is "real life".

What if they did that for Mars re-entry and detached the ballons just
before touch down when retro rockets provide the smooth landing ? The
balloons would bounce on the bound and hopefully wouldn't end up too far
away, and be patriated to become pressurized habitable volume.

Nope, not going to happen. This isn't McGuyver, or The Martian. Again,
things that are different, just aren't the same.



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.

On Wednesday, February 17, 2016 at 10:02:59 AM UTC-5, wrote:
I was thinking about actual design of the hardware. The inflatable hull has a debris limit in earth orbit. Old spacecraft pieces cloud the orbits. These pieces will in general not challenge the steel hulls. This is because of the rather low relative velocities.

On a path to Mars the issue is ultra high speed impacts. It just may be that if the event causes a inflatable hull breech it would also cause a steel hull breech. Negating the advantage of steel over fabric hull selection.. A hybrid use is allowed therefor.

SO I submit the large revolving classical artificial gravity section made of fabric. This is in addition to the smaller steel portions. Use brute force design and place sensors over the hull to detect holes. A sensor every square four inches. The issue is how to then gain access to place a patch.

This simply means use something like army cots to sleep on. Everything on the walk way is to be hand moveable for effortless patching. Make it a rather garden like gravity park.

The center has ladders to climb up into at instrumentation overhead.

In general a station in the steel command module is to be manned 24 hours a earth day.

A nuclear battery system of several 10's of kilowatts is a good target power source value.

SO the basic parameters are not challenging for the transit spacecraft. And the hard part is the lander.

The moon mission plans also require landers. A common design would help hugely. A basic lander? Earth, moon, Mars capable. In general there are two modalities of landing. One for the couple of astronauts and one for cargo. Moving humans is a fairly small endeavor. While cargo includes takeoff craft.

The lander for the astronauts can be two way. While cargo can be also. What modality is required?

Land cargo always. This is why passenger aircraft carry cargo. It is free.

Taking of with no cargo? This is nontrivial system theory. The cargo to return to earth needs to be clarified and used in the lander design. It is a critical value. Shuffling cargo in the human craft with out occupants is free once more. Auto control human/cargo dual design.

I would submitted that the size of several astronauts should suffice for all return to earth cargo.

The question becomes travel and land and return or travel and occupy a Mars base module for a while. Here is where the fabric colony shines.

All in all design the cargo capacity of the lander plus astronauts as capable of self carriage of a real Mars fabric module. Carry one-way. Simple space in lander is required for the module. But it never returns.

The system concepts lead I hope to a design. Space is cheap in a lander.. Low density cargo weighs small with large volume.

I hope the concepts make some sense. Just use the cargo density as a critical concept.

hey were going to send humans to the moon and return them safely, back when the space program was struggling to orbit anything.

we will all have communicators and call anyone from anywhere. ahh that star trek stuff. totally impossible

In article om,
says...

On 2016-02-21 16:56, Jeff Findley wrote:

This is not true. These capsules can deploy airbags to cushion the
final landing forces. But, this is not at all the same as a heat shield
for reentry (things that are different, just aren't the same).

From NASA tweets, I had been given impression that the inflatable system
was designed to act as air brake to greatly widen the circumference at
base of capsule during re-entry (likely after the hot phase but was
never specified by NASA)

So I never researched it more than that. Doing a google does seem to
confirm it is nothing more than a landing cushion and a means to keep
capsule upright in water.

So essentially useless dead weight

Cushioning a landing is important, but not the hardest part of landing a
manned vehicle on Mars.

Research which is helpful is along these lines:

Inflatable Re-entry Vehicle Experiment - NASA
http://www.nasa.gov/pdf/378699main_NASAFacts-IRVE.pdf

http://www.nasa.gov/home/hqnews/2012...-3_Launch.html

NASA Explores Inflatable Spacecraft Technology
Sat, 01/03/2015 - 12:40pm by Brock Vergakis, The Associated Press
http://www.manufacturing.net/news/20...es-inflatable-
spacecraft-technology

NASA studies inflatable heat shield for Mars landing
Larger spacecraft needed for voyage to Red Planet requires new
technology
The Associated Press Posted: Jan 03, 2015 5:28 PM ET Last Updated: Jan
05, 2015 11:49 AM ET
http://www.cbc.ca/news/technology/na...e-heat-shield-
for-mars-landing-1.2889075

This article has some nice drawings. Note that none the shape of the
inflatable heat shield. It is shaped nothing like an inflatable HAB
module. And if you read the article, it's not built like one either.

http://www.gizmag.com/nasa-irve-3-in...-system/22974/

Side question: how different is Mars re-entry in terms of heating/plasma ?

Do temperatures rise to about the same as when re-entring in Earth ?
More ? less ?

Does composition of Mars artmosphere make a difference with regards to
the need for shield ? With less O2, is there less oxidation/burning of
the shield or is that irrelevant because it is only the temperature that
matters ?

The big problem is the fact that the Martian atmosphere is so thin.
Because of this, you need a really big heat shield. This is why NASA
has been so interested in inflatable heat shields. They allow for a
very large diameter heat shield that is not limited so much by the
diameter of the payload shroud used to launch it.

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.

On Feb/21/2016 6:26 PM, JF Mezei wrote :

Does composition of Mars artmosphere make a difference with regards to
the need for shield ? With less O2, is there less oxidation/burning of
the shield or is that irrelevant because it is only the temperature that
matters ?

The composition of the atmosphere does have a small effect but that
isn't important. The important points are that re-entry speeds are
slower at Mars compared to Earth and the atmosphere is much thinner near
the ground.

Mars escape velocity is slightly more than 5 km/s. That is less than
speeds at LEO. And you don't have to shed all that 5 km/s at once. You
can get captured, lower your orbit to low Mars orbit in a few passes.
You are then at about 3.4 km/s, which is much less than the 8 km/s of LEO.

Compared to Earth re-entry, the first phase of re-entry at Mars are
easy. It is still hard and dangerous, only less so than for Earth. But
aero-dynamic drag will only slow you down so much at Mars. The last
phase of re-entry is more complicated at Mars. You can go very fast in a
10 millibar atmosphere. You have to be careful not to hit the ground
real hard.


Alain Fournier

On Thursday, February 18, 2016 at 4:02:59 AM UTC+13, wrote:
I was thinking about actual design of the hardware. The inflatable hull has a debris limit in earth orbit. Old spacecraft pieces cloud the orbits. These pieces will in general not challenge the steel hulls. This is because of the rather low relative velocities.

On a path to Mars the issue is ultra high speed impacts. It just may be that if the event causes a inflatable hull breech it would also cause a steel hull breech. Negating the advantage of steel over fabric hull selection.. A hybrid use is allowed therefor.

SO I submit the large revolving classical artificial gravity section made of fabric. This is in addition to the smaller steel portions. Use brute force design and place sensors over the hull to detect holes. A sensor every square four inches. The issue is how to then gain access to place a patch.

This simply means use something like army cots to sleep on. Everything on the walk way is to be hand moveable for effortless patching. Make it a rather garden like gravity park.

The center has ladders to climb up into at instrumentation overhead.

In general a station in the steel command module is to be manned 24 hours a earth day.

A nuclear battery system of several 10's of kilowatts is a good target power source value.

SO the basic parameters are not challenging for the transit spacecraft. And the hard part is the lander.

The moon mission plans also require landers. A common design would help hugely. A basic lander? Earth, moon, Mars capable. In general there are two modalities of landing. One for the couple of astronauts and one for cargo. Moving humans is a fairly small endeavor. While cargo includes takeoff craft.

The lander for the astronauts can be two way. While cargo can be also. What modality is required?

Land cargo always. This is why passenger aircraft carry cargo. It is free.

Taking of with no cargo? This is nontrivial system theory. The cargo to return to earth needs to be clarified and used in the lander design. It is a critical value. Shuffling cargo in the human craft with out occupants is free once more. Auto control human/cargo dual design.

I would submitted that the size of several astronauts should suffice for all return to earth cargo.

The question becomes travel and land and return or travel and occupy a Mars base module for a while. Here is where the fabric colony shines.

All in all design the cargo capacity of the lander plus astronauts as capable of self carriage of a real Mars fabric module. Carry one-way. Simple space in lander is required for the module. But it never returns.

The system concepts lead I hope to a design. Space is cheap in a lander.. Low density cargo weighs small with large volume.

I hope the concepts make some sense. Just use the cargo density as a critical concept.

http://goo.gl/25ZmJE

The odds of getting hit by anything is very low for the 279 days it takes for a minimum energy transfer orbit to Mars.

10^(-5) m is 10 microns - you'll likely get hit with a few dozen of those accordinmg to these statistics. At 2.3 g/cc and 9.6 km/sec this particle contains 15.2 microjoules. At 12 megajoules per kg vaporisation energy we have a 10 micron diameter particle producing a 140 micron diameter hole.

Such holes, even if they were 10x larger involving 1,000x as much energy, would be of no real concern since they could easily be covered over with a a thick version of Duct Tape.

This idea goes way back in time, and the details were worked out 56 years ago!

Langley researchers got to work examining the feasibility of various space station configurations in 1960, they soon agreed that the most promising design was a self- deploying inflatable space station. Thanks to their Echo II experience, Langley engineers already knew first hand that a folded station packed snugly inside a rocket would be protected during the rough ride through the atmosphere. That's not to say the Langley space station office didn't consider other concepts. They did. Among the non-inflatable concepts considered were designs for orbiting cylinders, and for a cylinder attached to a terminal booster stage, but these were rejected as dynamically unstable because they tended to roll at the slightest disturbance.

A version of Lockheed's elongated modular concept was turned down because it required the launch of several boosters to place all the elements into orbit, and proposals for Ferris wheels in space were rejected because of Coriolis effects. While the Langley space station team had sound technical reasons for doubting the feasibility of these proposals, it perhaps wasn't surprising they favored the inflatable option because the technology was developed at Langley! The concept also happened to make good engineering sense because the inflatable option meant a light payload and, with hundreds of kilograms of propellant required to put just one kilogram of payload into orbit, any plan that lightened the payload was a winner.

A rotating space station will produce the feeling of gravity because the rotation drives any object inside the station towards the hull. This "pull", or centrifugal force, is a manifestation of objects inside the station trying to travel in a straight line due to inertia. From the perspective of astronauts rotating with the station, artificial gravity behaves similarly to normal gravity, but there are side effects, one of which is the Coriolis effect, which gives an apparent force that acts on objects that move relative to a rotating reference frame. This force acts at right angles to the motion and the rotation axis, and tends to curve the motion in the opposite sense to the station's spin. If an astronaut inside a rotating station moves towards or away from the axis of rota- tion, they will feel a force pushing them towards or away from the direction of spin. These forces act on the inner ear and can cause nausea and disorientation. Slower spin rates (less than two revolutions per minute) reduce the Coriolis force and its effects, but rates above seven revolutions per minute cause significant problems.

https://www.youtube.com/watch?v=1wJQ5UrAsIY
https://goo.gl/7oa39I

The first idea for an inflatable station was the Erectable Torus Manned Space Laboratory, developed by the Langley space station team led by Paul Hill and Emanuel Schnitzer with the help of Goodyear. Their idea was a flat inflatable unitized torus about seven meters in diameter. Since it was unitized, all its elements were part of a single structure that could be carried to orbit on one booster, which was a major selling point. All NASA needed to do was fold the station into a compact payload. The Langley space station team was so enthusiastic about its inflatable torus that they made a presentation on the design to a national meeting of the American Rocket Society. In the months following their presenta- tion, Langley built and tested models of the Erectable Torus Manned Space Laboratory, including a full-scale research model constructed by Goodyear. This was the same size as the centrifuge in the fictional discovery of the 1968 movie, 2001: A Space Odyssey.

Development of the concept appeared promising, but the design had its drawbacks.

Langley engineers built a three-meter-diameter elastically scaled model of the torus. By the time the model became operational in 1961
..
While still pursuing the inflatable torus concept, the Langley group also explored other ideas. In the summer of 1961, it entered into a six-month contract with North American Aviation for a feasibility study of an advanced modular space station concept, which also incorporated inflatable technology.. While rigid in structure, this advanced station could still be automatically erected in space. The idea was to put together six rigid modules connected by inflatable spokes or passageways to a central non-rotating hub. The 22.8 meter diameter structure would be assembled on the ground, packaged into a snug launch configuration, and launched into space. To ruggedize it against micrometeorites, the rigid sections of the rotating hexagon airlock doors could be sealed when any threat arose to the integrity of the interconnecting inflatable sections. The structure was designed to rotate, making it possible for astronauts to take advantage of artificial gravity, which space station designers of the day believed was an absolute must for any long-term stay. Incidentally, the 22.8-meter-diameter size was selected because it provided the minimal rotational radius needed to generate the 1 G required for the station's living areas.
As the Langley engineers continued to investigate the potential of a rotating hexagon, they became increasingly confident they were on the right track.. The only problem was finding a launch vehicle capable of lofting the 77,500-kilogram structure into orbit.

The solution was von Braun's Saturn, so a team of Langley researchers tried to figure out how to mate their space station to the Saturn's top stage. After working with a number of dynamic scale models, they refined a system of mechanical hinges enabling the six interconnected modules of the hexagon to fold into one compact mass. Tests confirmed the arrangement could be carried aloft in one piece and, once on orbit, actuators located at the joints between the modules would deploy the folded structure. The cost for the space station project was US$100 million. At the time, this was too much for NASA, which only had sufficient funding to finish Mercury and US$29 million for Apollo. Also, NASA wasn't even sure it needed a space station, because Apollo entailed only a circumlunar mission, with the possibility of building a space station as a byproduct of the Earth-orbit phase. Such uncertainty is par for the course in the aerospace industry, but it put Langley in a difficult situation. Since some sort of space station was still possible in the Apollo era, the basic technology had to be ready, so Langley continued their research. On May 19th, 1961, six days before President Kennedy's lunar landing speech, Loftin updated the US House Committee on Science and Astronautics on Langley's manned space station work. He passed around a series of pictures show- ing Langley's concepts for the inflatable torus and the rotating hexagon, before summarizing Langley's assessment of the status of the space station. The politicians were somewhat flummoxed, many of them not understanding what a manned space station was all about or how it might be used.
Six days after Loftin's appearance, President Kennedy stunned the world--including NASA--with his lunar landing speech. For 14 months following Kennedy's speech, NASA debated various mission modes. Many in NASA were certain the mission architecture would involve Earth-orbit rendezvous, which would require the lunar spacecraft to be assembled from components put into orbit by two or more Saturn rockets. This plan would therefore involve the development of orbital capabilities that might translate into a space station. With this in mind, the Langley team continued to explore the problems facing the design and operation of a space station. One continuing issue was how to protect astronauts from micrometeorite strikes, because big hits, especially those striking the inflatable torus, could prove disastrous. In an attempt to solve the problem, structure experts at Langley and Ames searched for a wall structure that offered the greatest protection for the least weight. They settled on a sandwiched structure with an inner and outer wall--a precursor to the layered structure that was later used in TransHab. Developed by North American, the outer wall was a meteorite shield comprising aluminum, backed by a poly- urethane plastic filler that overlaid a bonded aluminum honeycomb sandwich. The wall seemed rugged enough to do the job, but no one really knew because there was no way to simulate micrometeorite strikes in any ground facility. For the inner wall, Langley's engineers decided nylon-neoprene, Dacron-silicone, saran, Mylar, polypropylene, Teflon, and other flexible and heat-absorbing materials could do the job. What made these materials attractive was their ability to withstand a hard vacuum, electromagnetic and particle radiation, and large temperature changes. At a symposium in July 1962, the Langley team presented summary progress reports on their space station research, concluding that the rotating hexagon was superior to the inflatable torus. The inflatable concept was still a possibility.