Author Topic: Massive Mars RoverDome  (Read 4538 times)

Offline Aussie_Space_Nut

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Massive Mars RoverDome
« on: 11/12/2016 11:19 pm »
I've been following the discussion on Geodesic Domes etc. in the SpaxeX Mars section and a very valid point is made, I believe, that the bigger the dome (volume) the more likely it will float away!

Another point is that solar radiation and solar storms do not come in line of sight from the sun. Robotbeat says solar radiation can come from any angle as the radiation itself as it travels out from the sun spirals etc. So just building your dome in a permanently shaded spot on Mars does no good regarding protection from damaging solar radiation.

Both of these are major show stoppers in one sense. But can we turn them around?

What about a massive domed rover, with as many feet of regolith on top to provide excellent radiation protection, but big enough (volume of air) to almost float away.

It could move around the surface of Mars, perhaps even fly around, science/habitat building could be done directly under it, mostly protected from radiation by the RoverDome above.

Think of how big some of the ships are here on Earth at 1g and imagine how big they could be on Mars at 0.38g.

:-)

Offline Robotbeat

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Re: Massive Mars RoverDome
« Reply #1 on: 11/12/2016 11:30 pm »
Solar radiation is effectively shielded by the Mars atmosphere. Still have GCR to deal with, but it's not too bad at low altitude.

If you built against a tall vertical wall of rock, you'd almost halve your GCR dose. Should be below 100mSv/year then, good enough.
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Offline meekGee

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Re: Massive Mars RoverDome
« Reply #2 on: 11/12/2016 11:34 pm »
I've been following the discussion on Geodesic Domes etc. in the SpaxeX Mars section and a very valid point is made, I believe, that the bigger the dome (volume) the more likely it will float away!

Another point is that solar radiation and solar storms do not come in line of sight from the sun. Robotbeat says solar radiation can come from any angle as the radiation itself as it travels out from the sun spirals etc. So just building your dome in a permanently shaded spot on Mars does no good regarding protection from damaging solar radiation.

Both of these are major show stoppers in one sense. But can we turn them around?

What about a massive domed rover, with as many feet of regolith on top to provide excellent radiation protection, but big enough (volume of air) to almost float away.

It could move around the surface of Mars, perhaps even fly around, science/habitat building could be done directly under it, mostly protected from radiation by the RoverDome above.

Think of how big some of the ships are here on Earth at 1g and imagine how big they could be on Mars at 0.38g.

:-)

Just one clarification - not "float away"...  Rather, we have to contend with the structural joint along the perimeter since if it fails, the top part of the dome will shoot up and that would be a bad day.
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Offline Aussie_Space_Nut

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Re: Massive Mars RoverDome
« Reply #3 on: 11/13/2016 12:04 am »
Solar radiation is effectively shielded by the Mars atmosphere. Still have GCR to deal with, but it's not too bad at low altitude.

If you built against a tall vertical wall of rock, you'd almost halve your GCR dose. Should be below 100mSv/year then, good enough.

Ok so that's a good thing with respect to the DomeRover, less regolith required on top.

I've been following the discussion on Geodesic Domes etc. in the SpaxeX Mars section and a very valid point is made, I believe, that the bigger the dome (volume) the more likely it will float away!

Another point is that solar radiation and solar storms do not come in line of sight from the sun. Robotbeat says solar radiation can come from any angle as the radiation itself as it travels out from the sun spirals etc. So just building your dome in a permanently shaded spot on Mars does no good regarding protection from damaging solar radiation.

Both of these are major show stoppers in one sense. But can we turn them around?

What about a massive domed rover, with as many feet of regolith on top to provide excellent radiation protection, but big enough (volume of air) to almost float away.

It could move around the surface of Mars, perhaps even fly around, science/habitat building could be done directly under it, mostly protected from radiation by the RoverDome above.

Think of how big some of the ships are here on Earth at 1g and imagine how big they could be on Mars at 0.38g.

:-)

Just one clarification - not "float away"...  Rather, we have to contend with the structural joint along the perimeter since if it fails, the top part of the dome will shoot up and that would be a bad day.

Valid point for the structure of a fixed dome.

What would the volume required for the DomeRover to almost float be? Given that volume goes up by the cube is there a crossover point where the size of a floating DomeRover falls within the bounds of what can actually be manufactured? Volume of air/tonne of structure at a given sweetspot.

Offline Jcc

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Re: Massive Mars RoverDome
« Reply #4 on: 11/13/2016 12:27 am »
Solar radiation is effectively shielded by the Mars atmosphere. Still have GCR to deal with, but it's not too bad at low altitude.

If you built against a tall vertical wall of rock, you'd almost halve your GCR dose. Should be below 100mSv/year then, good enough.

Ok so that's a good thing with respect to the DomeRover, less regolith required on top.

I've been following the discussion on Geodesic Domes etc. in the SpaxeX Mars section and a very valid point is made, I believe, that the bigger the dome (volume) the more likely it will float away!

Another point is that solar radiation and solar storms do not come in line of sight from the sun. Robotbeat says solar radiation can come from any angle as the radiation itself as it travels out from the sun spirals etc. So just building your dome in a permanently shaded spot on Mars does no good regarding protection from damaging solar radiation.

Both of these are major show stoppers in one sense. But can we turn them around?

What about a massive domed rover, with as many feet of regolith on top to provide excellent radiation protection, but big enough (volume of air) to almost float away.

It could move around the surface of Mars, perhaps even fly around, science/habitat building could be done directly under it, mostly protected from radiation by the RoverDome above.

Think of how big some of the ships are here on Earth at 1g and imagine how big they could be on Mars at 0.38g.

:-)

Just one clarification - not "float away"...  Rather, we have to contend with the structural joint along the perimeter since if it fails, the top part of the dome will shoot up and that would be a bad day.

Valid point for the structure of a fixed dome.

What would the volume required for the DomeRover to almost float be? Given that volume goes up by the cube is there a crossover point where the size of a floating DomeRover falls within the bounds of what can actually be manufactured? Volume of air/tonne of structure at a given sweetspot.

The entire habitation will not "float", it, including the air inside it will weigh considerably more than the Mars atmosphere that it displaces, even if you filled it entirely with hydrogen. Begin pressurized, the dome could pop off if it is made of light materials and not anchored well enough.

Offline Aussie_Space_Nut

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Re: Massive Mars RoverDome
« Reply #5 on: 11/13/2016 12:37 am »
Ok. So the pressure of the air inside the fixed dome, small pressure maybe but over a vast area, causes the dome side to pull up whatever is anchoring it down.

Has nothing to do with it floating. Just a pressure vessel failing.

Offline meekGee

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Re: Massive Mars RoverDome
« Reply #6 on: 11/13/2016 12:51 am »
Ok. So the pressure of the air inside the fixed dome, small pressure maybe but over a vast area, causes the dome side to pull up whatever is anchoring it down.

Has nothing to do with it floating. Just a pressure vessel failing.

Exactly, and with the assumption that the perimeter line is the weakest spot.  Hence some of the talk about half-buried full spheres, or some two-diameter shapes.
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Offline LMT

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Re: Massive Mars RoverDome
« Reply #7 on: 11/13/2016 01:00 am »
Solar radiation is effectively shielded by the Mars atmosphere. Still have GCR to deal with, but it's not too bad at low altitude.

Not accurate.  See McGirl et al. 2016 for recent model and physically meaningful results.  Solar flares and GCRs will combine to disqualify crews from multi-synod missions unless the radiation is shielded via technically aggressive and/or mass-intensive efforts.  Also the dangers of HZE particles remain largely unknown; the shielding requirement, likewise.

Offline Aussie_Space_Nut

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Re: Massive Mars RoverDome
« Reply #8 on: 11/13/2016 01:04 am »
So by the time we get to an Earth like atmosphere on Mars and my DomeRover can float, it won't be needed anymore. Sigh. One more idea headed for the scrapheap. :-)

Offline MikeAtkinson

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Re: Massive Mars RoverDome
« Reply #9 on: 11/13/2016 06:44 am »
Solar radiation is effectively shielded by the Mars atmosphere. Still have GCR to deal with, but it's not too bad at low altitude.

Not accurate.  See McGirl et al. 2016 for recent model and physically meaningful results. 

If you read that (table 4) you will see that a SPE will give about 1% of career average dose at datum height (0.88 cSv), assuming no special shielding. The 1989 SPE is the largest since 1976, average per year are an order of magnitude smaller, it is averages we need to be concerned about for long duration stays.

Add a storm room for the most intense SPE which occur every decade or so and they are of no particular concern.

Offline LMT

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Re: Massive Mars RoverDome
« Reply #10 on: 11/14/2016 12:49 am »
Chronic

Add a storm room...

No, that doesn't solve the dosage problem, and your interpretation mangles the authors' findings, badly.  GCRs produce the higher surface dosage in the study, and GCRs don't flare.  They persist.  That's what the authors mean by the word, "chronic". 

Net net:  for multi-synod missions, your "storm room" has to become the hab. 
« Last Edit: 12/14/2016 06:37 pm by LMT »

Offline Robotbeat

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Re: Massive Mars RoverDome
« Reply #11 on: 11/14/2016 01:26 am »
Chronic

Add a storm room...

No, that doesn't solve the dosage problem, and your interpretation mangles the authors' findings, badly.  GCRs produce the higher surface dosage in the study, and GCRs don't flare.  They persist.  That's what the authors mean by the word, "chronic". 

Net net:  for multi-synod missions, your "storm room" has to become the hab.
Um, but the original reason you posted that study is to counter my claim that solar radiation really doesn't matter on Mars. A claim which the study actually supports! Table 4. The worst flare in decades, and it is 0.6cSv. That's it! Averaged over decades, that's like 0.1% of your total dose, maybe less. Other storms would be similarly reduced in intensity. Solar radiation (other than maybe UV, though not as bad as deep space) simply doesn't matter. It's about GCR, as you said and as I also originally said.
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To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline LMT

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Re: Massive Mars RoverDome
« Reply #12 on: 11/18/2016 06:16 pm »
Chronic

Add a storm room...

No, that doesn't solve the dosage problem, and your interpretation mangles the authors' findings, badly.  GCRs produce the higher surface dosage in the study, and GCRs don't flare.  They persist.  That's what the authors mean by the word, "chronic". 

Net net:  for multi-synod missions, your "storm room" has to become the hab.
Um, but the original reason you posted that study is to counter my claim that solar radiation really doesn't matter on Mars. A claim which the study actually supports! Table 4. The worst flare in decades, and it is 0.6cSv. That's it! Averaged over decades, that's like 0.1% of your total dose, maybe less. Other storms would be similarly reduced in intensity. Solar radiation (other than maybe UV, though not as bad as deep space) simply doesn't matter. It's about GCR, as you said and as I also originally said.

?  Odd.  No, I mentioned the study, to someone else, because it's relevant.  It's not about you.

To say "solar radiation simply doesn't matter" is not accurate.  The usual and my stated concern is with the high-energy cosmic ray flux, which obviously is not shielded by the martian atmosphere.  And that's why for example that new study finds that a single brief flare increases a woman's effective dose by up to 1/30 of career limit, despite the shielding expected from hab metal and planetary body.  There's no good reason to accept that dosage, especially on multi-synod missions where career limit is the unwanted knock on the door.  Hence the need for protection -- meters of dense protection -- from the flares, and also from chronic GCRs of course. 
« Last Edit: 12/14/2016 06:09 pm by LMT »

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