Mars Bound Spacecraft Example

"bob haller" wrote in message
...
sadly the reportm i saw said that even a tiny debris impact on a
spacewalking astronaut will incenerate the person and the suits interior

Incinerate? In the vacuum of space?

And since there's at least one possible case of an orbital debris impact, I
sort of discount your fear-mongering.

Could it happen, sure. Something puncturing the helmet is probably the worse
(in the few suit penetrations I can think of the skin basically got sucked
into the tiny hole, sealing it and the astronaut ended up with a hickey.

In the helmet, a hole would be harder to plug.


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

On 19/02/2016 2:33 PM, Greg (Strider) Moore wrote:
"Sylvia Else" wrote in message ...

On 18/02/2016 10:23 AM, wrote:

I tried to figure the basic parameters. My first fallacy was to
require the Earth/Moon/Mars landing craft capacity. The Moon and
rare atmosphere Mars need identical rocket descent.

The atmosphere of Mars is thin, true enough, but it can still provide
a useful deceleration, and parachutes are still effective. I'd be
surprised if a manned lander wasn't designed around that, making it
substantially different from a lunar lander.

Sylvia.

You may want to check out the most recent Air & Space magazine. It's not
quite that easy.

And especially for larger, more massive craft.

It's one reason they used the "sky crane" for Curiosity.

Curiosity used both atmospheric drag and a parachute.

Sylvia.

"Sylvia Else" wrote in message ...

On 19/02/2016 2:33 PM, Greg (Strider) Moore wrote:
"Sylvia Else" wrote in message ...

On 18/02/2016 10:23 AM, wrote:

I tried to figure the basic parameters. My first fallacy was to
require the Earth/Moon/Mars landing craft capacity. The Moon and
rare atmosphere Mars need identical rocket descent.

The atmosphere of Mars is thin, true enough, but it can still provide
a useful deceleration, and parachutes are still effective. I'd be
surprised if a manned lander wasn't designed around that, making it
substantially different from a lunar lander.

Sylvia.

You may want to check out the most recent Air & Space magazine. It's not
quite that easy.

And especially for larger, more massive craft.

It's one reason they used the "sky crane" for Curiosity.

Curiosity used both atmospheric drag and a parachute.


AND rockets. It's also at about the limit of what we think we can currently
do with parachutes.


Sylvia.

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

I forgot. What is the lowest altitude for orbiting Mars. It might be classified?

Ascent to 10 mile high orbit. Mate with a transfer module in orbit there to complete the trip to the transit craft. Carry fuel for direct to transit craft modality, mate with fuel/booster transfer module, allow emergency descent of transit craft orbit to 10 miles.

Not carrying fuel to ground saves fuel! The boost to Mars from Earth will not contain high Mars ascender fuel load.

It is rather complex theory. I need help.

My ideas might prove useful in earth application. Wireguided HV powerlines for 4 miles.

wrote in message
...

I forgot. What is the lowest altitude for orbiting Mars. It might be
classified?


Probably not. It's really a matter of how fast you want your orbit to
decay. Mars has a pretty thing atmosphere, so its lowest possible orbit is
certainly lower than Earth's.

That said, Mons Olympus is 22km (16mi) high. So if you're orbiting that low,
you might end up lithobraking.


Ascent to 10 mile high orbit. Mate with a transfer module in orbit there
to complete the trip to the transit craft. Carry fuel for direct to transit
craft modality, mate with fuel/booster transfer module, allow emergency
descent of transit craft orbit to 10 miles.


The problem isn't altitude. It's speed. You have to get going fast enough
to mate to your orbiting craft.


Not carrying fuel to ground saves fuel! The boost to Mars from Earth will
not contain high Mars ascender fuel load.


Which is why most plans these days rely on in-situ fuel making. Make your
fuel ON Mars.


It is rather complex theory. I need help.

My ideas might prove useful in earth application. Wireguided HV powerlines
for 4 miles.

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

On Feb/19/2016 3:41 PM, Greg (Strider) Moore wrote :
wrote in message
...

I forgot. What is the lowest altitude for orbiting Mars. It might be
classified?


Probably not. It's really a matter of how fast you want your orbit to
decay. Mars has a pretty thing atmosphere, so its lowest possible orbit
is certainly lower than Earth's.

That said, Mons Olympus is 22km (16mi) high. So if you're orbiting that
low, you might end up lithobraking.

Mars has a bigger scale height than Earth. Meaning that its atmosphere
gets thinner at a slower rate than that of Earth. If I recall correctly
the two have same pressure at about 100 km. That is about the lowest
practical orbit for Earth and would therefore be likewise for Mars. If
you have a higher orbit around Mars, the pressure is actually higher
than what it would be at a similar altitude around Earth and therefore
the orbit would decay faster than around Earth.

You will experience severe aero-braking before experiencing lithobraking
even at Mons Olympus.

Ascent to 10 mile high orbit. Mate with a transfer module in orbit
there to complete the trip to the transit craft. Carry fuel for direct
to transit craft modality, mate with fuel/booster transfer module,
allow emergency descent of transit craft orbit to 10 miles.

You can't orbit 10 mile high orbit around Mars.

The problem isn't altitude. It's speed. You have to get going fast
enough to mate to your orbiting craft.

Yes.


Alain Fournier

"Alain Fournier" wrote in message ...

On Feb/19/2016 3:41 PM, Greg (Strider) Moore wrote :
wrote in message
That said, Mons Olympus is 22km (16mi) high. So if you're orbiting that
low, you might end up lithobraking.

Mars has a bigger scale height than Earth. Meaning that its atmosphere
gets thinner at a slower rate than that of Earth. If I recall correctly
the two have same pressure at about 100 km. That is about the lowest
practical orbit for Earth and would therefore be likewise for Mars. If
you have a higher orbit around Mars, the pressure is actually higher
than what it would be at a similar altitude around Earth and therefore
the orbit would decay faster than around Earth.

You may be right. I honestly can't recall.


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

The in-situ solution would means finding nitrates to mine. You can't just use electricity to convert dirt to fuel. The same for cracking water. The efficiencies and materials just don't exist.

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

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

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?

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?

On Feb/20/2016 12:05 AM, Fred J. McCall wrote :
"Greg \(Strider\) Moore" wrote:

"Alain Fournier" wrote in message ...

On Feb/19/2016 3:41 PM, Greg (Strider) Moore wrote :
wrote in message
That said, Mons Olympus is 22km (16mi) high. So if you're orbiting that
low, you might end up lithobraking.

Mars has a bigger scale height than Earth. Meaning that its atmosphere
gets thinner at a slower rate than that of Earth. If I recall correctly
the two have same pressure at about 100 km. That is about the lowest
practical orbit for Earth and would therefore be likewise for Mars. If
you have a higher orbit around Mars, the pressure is actually higher
than what it would be at a similar altitude around Earth and therefore
the orbit would decay faster than around Earth.

You may be right. I honestly can't recall.


There is some altitude where air pressure at Mars and air pressure at
Earth will be the same. Below that altitude Earth atmosphere will be
thicker. Above that altitude Mars altitude will be thicker.

This is why aerobraking into parachutes doesn't work very well on
Mars.

Aerobraking into parachutes is difficult on Mars. But I'm not sure of
your reasoning here. It is the "This is why" part I don't understand.

The greater scale height for the Martian atmosphere makes aerobraking
easier. The problem is simply that you don't have enough atmosphere and
you run into the ground too early. Parachutes are most effective at
pressures above the ground level pressure on Mars. If Mars had a smaller
scale height but the same amount of gas in its atmosphere aerobraking
into parachutes would just be harder. For instance if you would replace
the CO2 in Mars' atmosphere by something heavier like radon (okay you
would have to heat up Mars a little to keep it gaseous but this is just
a thought experiment), the scale height would go down and it would be
harder to aerobrake at Mars because you would have a much thinner layer
to do your aerobraking.


Alain Fournier

On Feb/20/2016 8:17 AM, wrote :
The in-situ solution would means finding nitrates to mine. You can't just use electricity to convert dirt to fuel. The same for cracking water. The efficiencies and materials just don't exist.

Why nitrates?

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

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

Methane can be found in other places than on Earth where there never was
"exotic flora history". But that is mostly irrelevant. You can crack the
CO2 into CO and O2 and that will make you a useful fuel. You can also
harvest water from the atmosphere, you split it into H2 and O2 and you
now have more conventional rocket fuel.

This has been studied a lot. You can look at:
https://en.wikipedia.org/wiki/In_sit...ce_utilization
If you do a web search you will find numerous other interesting sites.


Alain Fournier