News We probably won't be going to Mars anytime soon.

[PhantomCruiser]

I myself don't believe that the problem is "insurmountable", I think rather that the motivation (and funding) to work towards a solution is currently not there. Nice article though.

 

[Urwumpe]

Generally speaking, it will be simpler with near-term technology (including technologies, that have such a low technological risk, that they can be made operational in the next 20 years), to include additional mass for adequate shielding at a low mission DV, than to increase the mission DV and reduce the travel time with lower shielding requirements.

The sweet spot will likely be somewhere around slightly less optimal shielding and slightly faster travel, but shielding mass scales better than propellant mass there.

 

[MaverickSawyer]

Personally, I doubt that the U.S. will take the lead in a mission to Mars due to political and managerial issues at NASA.

Anyways, back on topic: Radiation? Pfft. You'd be safer taking a trip to Mars than being an airline pilot, if you ask me.
Shielding? We've hit on it: Strongbox for CMEs, lightweight hull to reduce scattering. Makes sense from a weight perspective too.
Cancer? For a shot at glory and the history books, people have taken even higher odd of death with pleasure. Cancer's fixable to an extent already. Death is permanent. Why should we stop people from having at least a chance to go based off a raised chance of a largely fixable illness?

 

[Urwumpe]

Personally, I doubt that the U.S. will take the lead in a mission to Mars due to political and managerial issues at NASA.

This can change from one day to the other. A few new faces, a different political climate, some wind in NASAs solar sails from favorable media coverage and all that we think we know about NASA is different.

Money is less important there than simply be on a roll. If you are successful, people will want to be known as somebody who funded and supported you, for standing a bit in your light.

 

[PhantomCruiser]

One of the downfalls of NASA being a government entity. New faces=new direction like you say. We were talking about this a few weeks ago at work. One guy sees no purpose in manned spaceflight, and his point about doing a lot of things robotically is valid. But once I pointed out a dozen (or so) things we've learned about human physiology that we owe to NASA (and Roscosmos too I guess) he started to understand the manned point of view.

For radiation shielding, I think we'll work it out. But it'll happen. Progress in that area will make my job easier too. I get less radiation exposure per year than most of the general population, and I work at a nuclear plant (what is inside the bottle can't get out (normally) and what's outside can't get in either). I spend most of my time inside a concrete box, separated from the zoomies by time, distance and shielding. Improvements in shielding will help in more areas than spaceflight and nuclear power too.

For Mars travel, I think if we were properly motivated, we could be there in 50 years (semi-permanant research station). Once there we start burrowing under the soil, and take advantage of the lava tubes. Those who undertake the trip will be well aware of the dangers involved.

 

[T.Neo]

Why should we stop people from having at least a chance to go based off a raised chance of a largely fixable illness?

How fixable cancer is depends on a number of factors, and it certainly isn't desirable to get cancer in the first place. Still, I think you raise a good point- one option for mitigating the problem would be to include very good healthcare coverage for Mars astronauts, that would include regular screenings to detect illness as soon as possible.

we could be there in 50 years

In 50 years, I will be beyond retirement age.

 

[PhantomCruiser]

I'll be 95. I plan on sticking around that long though (I plan on seeing Halley's Comet again). I seriously would like to see a manned Mars mission, but I think it's out of my time-frame (so to speak).

 

[csanders]

I'll be 95. I plan on sticking around that long though (I plan on seeing Halley's Comet again).

If you do, it will end up being cloudy.

 

[Admiral_Ritt]

OTHER MARS hazzards. Mars is much closer to the debris of the asteroid belt

Mars gravity well attracks several large impacting meterors per year.
These are impacts visilble from mars orbiting
spacecraft. Mars recon cameras only see impactors of the size of gumballs and up. But rest assured that if a 1mm sized
meteorite hit you it would slice through you like the finest stilleto. and get this, MARS CRAPPY ATMOSPHERE will not
slow them much. It is calculated that mars experiences 10 times more metorite impact as the earth because of this 'atmosphere'.
MARS IS JUST A CRAPPY PLACE TO GO TO

So step on over here, and join in trying to push for a trip to TITAN's surface
The only hazzard on the surface is extreme cold. Put on some polar exploration gear a heating element and air supply and you're good. No
space suit required. (you may require 5 min of decompression time cause
of the 02-N2 air supply mix)

No cosmic rays, no CME showers, very few meteorites make to the
surface at Titan has 1500 mb Atmospheric pressure which is tall and thick.
You want to carve a cave into mountain ?, just bring a torch with a long
boom type nozzle. Plus Hydrocarbons and ICE allow you to build any
kind of structure you want. N2 allows you to grow food.

 

[Urwumpe]

OTHER MARS hazzards. Mars is much closer to the debris of the asteroid belt

Mars gravity well attracks several large impacting meterors per year.
These are impacts visilble from mars orbiting
spacecraft. Mars recon cameras only see impactors of the size of gumballs and up. But rest assured that if a 1mm sized
meteorite hit you it would slice through you like the finest stilleto. and get this, MARS CRAPPY ATMOSPHERE will not
slow them much. It is calculated that mars experiences 10 times more metorite impact as the earth because of this 'atmosphere'.
MARS IS JUST A CRAPPY PLACE TO GO TO

Thats mostly wrong.

http://arxiv.org/abs/1212.3273

What Mars has more often than Earth, is MegaTon type impacts.

The Mars atmosphere would slow the 1 mm sized pebble down to very slow speeds. No danger.

Mars isn't crappy. It is much closer, much safer too reach and we can reach it without gravity assist at Jupiter, which would be more harmful than a few dozen Mars missions, radiation-wise

 

[Admiral_Ritt]

I was off on the 1mm power, it's more like the energy of a firecracker.

However a iron meteor .25 cu cm in size (BB size)
Entering Mars at a steep angle.

coming in at 18,000 Mph = 6,000 Joules. W/0 atmospheric braking.

So on the surface of mars you are hoping that 7 Mb of atmosphere will slow this meteor considerably below the energy of a Ak47 bullet which has about 1400 Joules.

I would still prefer to make my martian home inside a nice rugged cave.
Might be a good idea to make your mars buggy's roof out of kevlar and deployed with a pitched angle

 

[Urwumpe]

So on the surface of mars you are hoping that 7 Mb of atmosphere will slow this meteor considerably below the energy of a Ak47 bullet which has about 1400 Joules.

Density is important, not pressure. The Mars atmosphere is colder and denser at the same pressure as Earths atmosphere.

The density at the surface is 0.02 kg/m³, dropping with a scale height of 11 km.

Means your iron bullet meteorite will have a terminal velocity of 108.97 m/s, at 2 g mass = 12 J kinetic energy.

 

[thepenguin]

The curies kept working with radioactive materials even after their fingers were burned from the radiation. They probably didn't understand what they were dealing with fully, but they must have known the radiation burns weren't good. Chances are that we can find some astronauts dedicated enough to go, regardless of the risks. We try to shield them as much as we can, but out there it's hard to block it all. Space will never be fully save, just like air travel and submarines.

 

[Urwumpe]

The curies kept working with radioactive materials even after their fingers were burned from the radiation. They probably didn't understand what they were dealing with fully, but they must have known the radiation burns weren't good.

actually, they already had a very good grasp what happened to them... and did it anyway, for the science. :facepalm:

Pierre Curie and Henry Becquerel published the first scientific paper on radiation illness in 1901, 5 years before his death in a traffic accident

 

[Admiral_Ritt]

terminal velocity

Mass .002 Kg
Surface Area = .000025 cu meters
Drag coefficient for Sphere .1
Density at surface .02 Kg/M3
Gravity .38 g

Terminal Veloctiy 546 m/s
Typical muzzle Speed of Ak47 715 m/s

So tell how is this Not dangerous.

 

[Shifty]

So step on over here, and join in trying to push for a trip to TITAN's surface The only hazzard on the surface is extreme cold. Put on some polar exploration gear a heating element and air supply and you're good. Nospace suit required. (you may require 5 min of decompression time cause of the 02-N2 air supply mix)

No cosmic rays, no CME showers, very few meteorites make to the
surface at Titan has 1500 mb Atmospheric pressure which is tall and thick.
You want to carve a cave into mountain ?, just bring a torch with a long
boom type nozzle. Plus Hydrocarbons and ICE allow you to build any
kind of structure you want. N2 allows you to grow food.

Titan would be miserable. 6-7 years on a spacecraft one way to get there. Average temperature of -180C. Cloud cover so thick you'd never be able to see stars or the Sun or even Saturn. It may be true that Titan would be the easiest extra-terrestrial body in the solar system to establish long-term semi-independent habitation using ISRU, but it would be absolutely miserable.

 

[Urwumpe]

terminal velocity

Mass .002 Kg
Surface Area = .000025 cu meters
Drag coefficient for Sphere .1
Density at surface .02 Kg/M3
Gravity .38 g

Terminal Veloctiy 546 m/s
Typical muzzle Speed of Ak47 715 m/s

So tell how is this Not dangerous.

The drag coefficient for a sphere is not 0.1, but 0.5* - 0.1 is already a stream lined body. A meteorite will have a much higher value then 0.5.

Also, the surface area is not 0.000025 cubic meters. It is 0.0184 square meters as quick estimate (volume^(2/3)) and 0.003298 m² when using a sphere as model.

So, no surprise your terminal velocity is much higher.

* varies strongly with reynold number, but has a large long plateau around 0.5 for Earth and Mars Atmosphere: http://www.grc.nasa.gov/WWW/k-12/airplane/dragsphere.html

 

[Admiral_Ritt]

Numbers Stand correction indicated.
I am making a small simplification that volume of the sphere equals
the volume of the cube, the result are still pretty valid.


for 1/4 of cu in meteor (okay it's a sphere but close enough)
Mass .002 Kg
Surfa Area = .000025 SQ meters (5mm x 5mm) = 25 (1000mm x 1000mm)/25
coefficient for Sphere .1
Density at surface .02 Kg/M3
Gravity .38 g

Terminal Veloctiy 546 m/s
Typical muzzle Speed of Ak47 715 m/s

THE NUMBERS STAND ....but it is SQ meters for area above
as you pointed out

. Further more
for 1 mm size iron particle.


Mass .0000078 Kg
Surface area .0000001 M2
Drag coef .1
Medium density .02 Kg/m3
Gravity .38

Terminal velocity 539 M/S


Just dont try to tell me that it's like getting hit by a wiffle ball.

 

[Urwumpe]

Again, you calculate with 1/5th of the drag force (lower Cd than Reynolds number permits) and 1/100th of the area, a much higher density, etc.

You simplify things in the wrong direction. Also I think your formula is wrong, which did you use?

With your unrealistic numbers, I just get 385 m/s² But at such a speed, the reynolds number would already be too low for your claimed drag.

http://www.grc.nasa.gov/WWW/k-12/airplane/dragsphere.html

The drag is NOT the optimal lowest - that you can have only for a single special "velocity/altitude" combination, only for perfectly smooth spheres (what meteors are never), and that combination can even be unreachable for some sphere sizes.

 

[RGClark]

OTHER MARS hazzards. Mars is much closer to the debris of the asteroid belt.
Mars gravity well attracks several large impacting meterors per year.
These are impacts visilble from mars orbiting
spacecraft. Mars recon cameras only see impactors of the size of gumballs and up. But rest assured that if a 1mm sized
meteorite hit you it would slice through you like the finest stilleto. and get this, MARS CRAPPY ATMOSPHERE will not
slow them much. It is calculated that mars experiences 10 times more metorite impact as the earth because of this 'atmosphere'.
MARS IS JUST A CRAPPY PLACE TO GO TO
...

Comet ISON's closest approach to Mars is coming up soon. That should be interesting.

Bob Clark