This is why manned missions to Mars need to happen.

Nope. We have more of those metals than Mercury and Venus and we're the farther away. (Hell the largest deposits of Iridium are in the Kuiper Belt objects and the assorted asteroids.)

I had a chat with some physicists, and they say that this is not possible due to 2nd law of thermodynamics.

^ Stars seem to do it.

Building stars seem challenging.

Otto did it in Spider-man two.

As in "getting them controllable and outputting more energy than you put in". Stars I believe are not exactly controllable.

edited 11th Jul '12 4:40:14 PM by IraTheSquire

Above a certain mass yes. But in nuclear physics the lower limit for nuclear fusion is two atoms. (Or four if you go the protium route.)

The question is, what is the level of mass needed to achieve ignition above two atoms but below the weight of a star? That's what we're trying to find out.

Er, it's the the level of mass that's the problem: it's the temperature required to get the nucleii close enough for the Strong force to overcome the electrostatic repelling force (which from memory is ~180 million celcius).

Is this a derail?

Re Rare metals, etc. The issue isnt how valuable or rare they are. The issue is how much it would cost to go get them vs. how much you could sell them for. No way would you make back expenses, unless completely automated, but I didnt think that was what you were arguing for.

And why do you think we couldn't design probes to find life? We certainly could, we just haven't made that a priority.

Limited mobility, limited flexibility, limited tools, slow moving, less "aware" of things such as sound, terrain or something moving in the sands.

Not to mention we might be looking for life using the wrong definition and standards to look for. Say we found life on Mars, what's to say it isn't utterly and completely alien to all our known "laws" of biology? A probe might not be capable of detecting life even if it was right in front of them because it's looking at all the wrong things using the Earth model of life when it's actually staring right at the Mars model of life and failing to recognize it.

Humans on the other hand might notice something scanners won't such as bizarre coloration or a pattern indicating something else and take it in for further testing such as putting a sample under a microscope. Thus a human can notice the Mars model of life far earlier than simple EM band scanners and tools could.

Humans can move faster than a mile a day, for sure, but we can transport so many more probes than humans to Mars for the same price (about 100x I would guess) that it makes no sense to send humans down to the surface. They couldn't possibly cover enough terrain in the time they would have there (a few months?) to make it worth it.

As for detection of non-standard life- why would humans be more likely to detect something completely alien? All probes do is collect data- they are much better at that than any human being- being more precise, more meticulous and possessing enhancements like microscopes and infra-red sensors, etc. Once the collect the data, it would get sent back to Earth for analysis. That would be true even if humans were included in the expedition.

Really, what can a human do that a probe + digital uplink to Earth cant do better for less money?

"Hey Charlie, you see that mesa over yonder? Race ya to it!"

Spontaneity and flexibility that's what. Also we're more aware. Peripheral vision is sensitive to motion, cameras are not. People's brains can notice patterns in the soil, rocks or terrain, cameras do not without extensive analysis.

Thirdly what bullshit figure are you pulling out of your ass to say 100 rovers can be sent for the price of 1 manned? Adjusted for inflation the Apollo manned landings on the Moon were cheaper than Spirit and Opportunity. And we had to invent new technologies and make shit up as we went to get there!

The number I have seen being thrown around was a trillion dollars. I dont have the link right now, have to find it tomorrow.

Edit-

OK, so it turns out to be extremely difficult to estimate the cost of an hypothetical project this huge, and price figures are all over the map. This article contains references to estimates that range from $14 billion (Russian Space Agency) to $500 billion (NASA). [scroll down to "Cost Estimations in Existing Publications] The Apollo program cost about $125 billion in today's dollars.

The Mars Rover Mission, including their extension past the initial 9 day missions, come in at just under a billion each.

Rovers designed to search for life in a systematic way might cost more than the Rovers did, but even if we double the cost and go with a low estimate for the manned mission, say $100 billion, that's still 50 rovers for each manned mission.

So I wasn't that far off.

This article, by a skeptic, explain the challenges that face a future manned mission really well, although he doesn't come up with a cost estimate.

In the interest of fairness, this article attempts to tabulate the arguments for both sides of the debate, with references. I strongly encourage everyone with an interest in this topic to read it.

Bottom line, there is good reason to presume that unmanned exploration will be significantly less expensive than a manned one. So the question is, are the benefits of sending people worth the extra cost and risk?

edited 12th Jul '12 7:08:28 PM by DeMarquis