The thread for space cadets!

[hobbsyoyo]

I was all hyped for actually finding liquid water but nope. They found stuff that looked like there may have been water. Granted the evidence is really strong and that it was very recent that there was water, but I'm not happy until they actually see it on the ground.

They've actually seen it flowing on the surface for years now but couldn't definitively say it was water with high certainty until now. But they pretty much always knew it was flowing liquid water from the moment it was spotted.

Spoiler images of flowing water on Mars :

Any kind of experiment to detect life (whatever that means) in situ? I dont know, maybe mass spectrometry to detect proteins or other compounds characteristic of life. i know mass spectrometers have used before in some probes.

The tried this with the Viking landers and one of the experiments actually got a positive indication for life. Unfortunately, there was a lot of controversy over what the positive indication actually meant. Life entails extremely complicated chemistry and unfortunately a lot of that chemistry can be mimicked by non-biological processes.

So to design a test that can both accurately identify something as life exclusively and also have the test be rugged enough to survive deep-space transit is very difficult to do. Further, our efforts are hampered in other ways -

*We only know of life on Earth so any conceivable test we could design would necessarily be calibrated to find that kind of life. We could actually have already found lots of signs of life on Mars or other planets but missed them as they could be so radically different from what we are looking for.

*Our robots will always be extremely limited in what they can do by default. The more complex a robot is, the more likely it will break and the more expensive it is. So the kinds of experiments that a robot can perform on Mars pale in comparison to what a field biologist or geologist could perform. Now of course, human exploration isn't just expensive - it's exorbitantly expensive compared to a robot. However, once you have invested the funding and logistics to get to Mars in the first place, the added cost of supplying proper tools to hunt for life would be minuscule in comparison to the overall mission. In other words, it costs way more to send people than robots but if we sent people, we'd probably know for sure if there was life on Mars in a few weeks at most - assuming there is in fact life. It's impossible to definitively prove a negative.

 

[MagisterCultuum]

If we sent humans to Mars we would know there was life on Mars as soon as there was confirmation that they arrived, without any further tests, as humans are life and would be there then. Even if they died upon impact we could surmise some of the bacteria from their bodies would survive for at least a little while.

 

[hobbsyoyo]

Forgot to add that the Curiousity follow rover to be launched in 2020 is designed to look directly for life (Curiosity itself actually is not) but I'm not familiar enough with the experiment designs of that rover to comment.

 

[Thorgalaeg]

Probably some experiment looking for characteristic molecules, based on what we understand for life, in other words: terrestrial life.

We only know of life on Earth so any conceivable test we could design would necessarily be calibrated to find that kind of life. We could actually have already found lots of signs of life on Mars or other planets but missed them as they could be so radically different from what we are looking for.

Which leads to the "what is indeed life?" question. I wonder if we could recognize extraterrestrial life even having it in front of our nose. Or even terrestrial life. I mean, is a forest alive? or a city? or even a car?

 

[hobbsyoyo]

Right they tried something similar with Viking and it didn't work - or at least they couldn't agree that what they had found was life. That was using the best science of the time and though surely we could do better, I'm not convinced that we could design a single test without faults. It's really only when you run lots of tests and look at lots of samples that you can be sure and it's really hard to do that with a lander or rover.

*The viking tests added nutrients to soil samples and then the air in the sample chambers was chemically sniffed to see if the nutrients had been metabolized. The tests indicated that metabolism had occurred but was later thought to have been just a false positive. Likewise, a separate test on the viking landers has been tagged as a false negative in light of more recent evidence. So it's all up in the air and none of the landers sent since then have been equipped to answer the questions raised by Viking.

 

[illram]

Is there some sort of imaging/laser or other type of thing we can do with a super duper powerful satellite to detect life or signs of life at really tiny levels?

 

[hobbsyoyo]

Not really. The best we can presently do is pick up macro-level signs of life like excess methane production (also recently found on Mars). The problem then is that it's really, really difficult to definitely prove biological origin of said evidence (they are having a raging debate over the Methane right now as a matter of fact).

The other problem is back to the 'what is life' question. There are some proposals to search for photosynthesis on a large scale on extrasolar planets (when we build telescopes capable of doing this - which isn't a given, look at the situation in Hawaii with Keck) but that presupposes that all life depends on Earth-like photosynthesis in the first place.

Really the best thing we could do is send a single biologist with a bunch of microscopes and gear and he'd find life pretty darn quick if it was there (and if it is somewhere on Mars, it's likely to be everywhere in my opinion).

I'm not sure how fast/accurate/powerful the microscopes on Curiosity are currently but I assume they aren't the best compared to what the average scientist has access to. Then again, I would think they are good enough that if there were microorganisms crawling around on the samples, the microscopes would have already picked them up. Or maybe not. I'm not well versed in the imagers/microscopes.

 

[illram]

I've always subscribed to the idea that there are probably various kinds of life based on something unlike our own biochemistry... I mean we might create a new life form ourselves made out of silicon computer chips very shortly. But I feel like scientifically with the limited scope of tools currently available to us, can't we only really search for life like our own? I.e. unless a giant fish decides to just swim past our view in a methane lake on Titan, the limited utility of automated probes probably limits us to more rudimentary things like analyzing soil samples from Martian salt water deposits or flying through water vapor jets spewing from Enceladus, and looking for what we can scientifically verify... i.e. life like us. Am I off base in this assumption?

 

[hobbsyoyo]

No you are totally correct and I 100% agree with you. I'm sorry if I came off otherwise - I am just trying to shed light on the fact that the search for life is infinitely clouded by the vast unknown.

Unfortunately we have very limited tools and an even more limited perspective from which to perform our search and this makes it even more difficult than it already is. Just landing something as large as Curiosity on Mars was almost as big a technical leap forward as the Apollo program, for example.*** Searching for life on top of that is enormously challenging.

***Maybe even more so. Landing anything on Mars is really that hard - there's a reason why so many missions there have failed. It's also a great example of how the technology of rocket science these days is as much about the software as the hardware because without excellent software, it would have been impossible altogether.

 

[uppi]

Any kind of experiment to detect life (whatever that means) in situ? I dont know, maybe mass spectrometry to detect proteins or other compounds characteristic of life. i know mass spectrometers have used before in some probes.

I don't think mass spectrometers are the right tool for that. The problem is that they only give you the mass of a molecule and if that mass is high enough, it could be anything. For example, if you detect something with mass 113 u, it could be an amino acid, but it could also be just an Indium atom, or one of many other combinations that add up to 113 u.

I would probably go for an infrared/Raman spectrometer that measures vibrational (and maybe rotational) lines. Because there are so many of those, you get a unique fingerprint for each molecule. The only problem would be if it is an unknown molecule, because then it could take forever until someone synthesizes the molecule with exactly that fingerprint.

I'm not sure how fast/accurate/powerful the microscopes on Curiosity are currently but I assume they aren't the best compared to what the average scientist has access to. Then again, I would think they are good enough that if there were microorganisms crawling around on the samples, the microscopes would have already picked them up. Or maybe not. I'm not well versed in the imagers/microscopes.

I was going to answer that it is easy to build microscopes that could image bacteria and Curiosity should have one. But then I looked it up, and the only thing I found was the MAHLI camera with a resolution up to 15 micrometers per pixel. That is so crappy for a microscope that I would hesitate to actually call it a microscope and bacteria would have to be pretty big to be seen by that.

If there is anything crawling around on Mars, sending a microscope there to detect it should be pretty easy (well, easy on a getting something to Mars scale).

 

[Thorgalaeg]

I don't think mass spectrometers are the right tool for that. The problem is that they only give you the mass of a molecule and if that mass is high enough, it could be anything. For example, if you detect something with mass 113 u, it could be an amino acid, but it could also be just an Indium atom, or one of many other combinations that add up to 113 u.

I would probably go for an infrared/Raman spectrometer that measures vibrational (and maybe rotational) lines. Because there are so many of those, you get a unique fingerprint for each molecule. The only problem would be if it is an unknown molecule, because then it could take forever until someone synthesizes the molecule with exactly that fingerprint.

I have worked with MS (a long time ago i admit) and AFAIR molecules break down in a certain characteristic way. you do not obtain a single peak of a given mass and charge but a set of peaks which can be called a fingerprint too.

 

[hobbsyoyo]

I was going to answer that it is easy to build microscopes that could image bacteria and Curiosity should have one. But then I looked it up, and the only thing I found was the MAHLI camera with a resolution up to 15 micrometers per pixel. That is so crappy for a microscope that I would hesitate to actually call it a microscope and bacteria would have to be pretty big to be seen by that.

If there is anything crawling around on Mars, sending a microscope there to detect it should be pretty easy (well, easy on a getting something to Mars scale).

I assume that this is because it's probably really hard to properly ruggedize a microscope capable of better resolution. Also, I assume preparing samples for examination gets harder as the resolution increases. I think right now they just put the microscope/camera right up to a rock that they want to look at but that won't necessarily be good enough for something of even higher resolution. But I could be wrong.

 

[uppi]

I assume that this is because it's probably really hard to properly ruggedize a microscope capable of better resolution. Also, I assume preparing samples for examination gets harder as the resolution increases. I think right now they just put the microscope/camera right up to a rock that they want to look at but that won't necessarily be good enough for something of even higher resolution. But I could be wrong.

Not really. You can get a reasonable microscope with quite simple optics. A single wavelength microscope with a numerical aperture of 0.5 (resolution well below 1 micrometer) can be built from two lenses (and if you really want, even just one will suffice). The camera objectives on Curiosity are much more complicated than that. An achromatic design is going to be a bit more complicated, but I still see no reason it could not be ruggedized. Obviously, a NA > 1 oil-immersion objective is not going to work, but a relatively simple design should be sufficient to see bacteria if there are any.

Sample preparation might be a bigger problem, because you need precise positioning of the sample with respect to the objective, but even on Mars you should be able to do that if you put some thought into it.

One problem would be, that if you see bacteria or anything else crawling around, it might be quite hard to tell, if they are a species from earth that hitchhiked or something that can be actually found on Mars.

 

[hobbsyoyo]

Then the question is - why hasn't this been done yet? (Serious question - I don't know other than to say it must be really hard)

To be fair, I don't think a single lander/rover since Viking have had the goal of actually detecting life. They were really sent to see if life could have existed or possibly if it could exist given the environment now, as well as doing a bunch of geological research. While all of that sounds like searching directly for life, it really isn't. But still I can't help but wonder if it is easy to build and ruggedize such a simple imager why it hasn't been done yet?

 

[illram]

One problem would be, that if you see bacteria or anything else crawling around, it might be quite hard to tell, if they are a species from earth that hitchhiked or something that can be actually found on Mars.

I imagine this would be the primary problem. If you cannot be sure what you are seeing is the genuine article or just a stowaway, it's wasted space isn't it?

 

[hobbsyoyo]

Is there such thing as a simple and compact gene sequencer?

 

[ori]

not yet, though there are some interesting things coming up - personally I am partial to this one. Its just still so error prone that its hardly usable.

 

[Valka D'Ur]

...is a forest alive?

Considering that forests are made of living organisms that interact with each other, I should think so.

 

[hobbsyoyo]

I think you missed the forest for the trees at that!

 

[hobbsyoyo]

Earth's Gravitational Pull Cracks Open the Moon

Earth's gravitational pull is massaging the moon, opening up faults in the lunar crust, researchers say.

Just as the moon's gravitational pull causes seas and lakes to rise and fall as tides on Earth, the Earth exerts tidal forces on the moon. Scientists have known this for a while, but now they've found that Earth's pull actually opens up faults on the moon.

"We know the close relationship between the Earth and the moon goes back to their origins, but what a surprise [it was] to find the Earth is still helping to shape the moon," study lead author Thomas Watters, a planetary scientist at the Smithsonian Institution's National Air and Space Museum in Washington, D.C., told Space.com

Follow the link for more from the article.


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The Most Mysterious Star in Our Galaxy

Excerpt:

Jason Wright, an astronomer from Penn State University, is set to publish an alternative interpretation of the light pattern. SETI researchers have long suggested that we might be able to detect distant extraterrestrial civilizations, by looking for enormous technological artifacts orbiting other stars. Wright and his co-authors say the unusual star’s light pattern is consistent with a “swarm of megastructures,” perhaps stellar-light collectors, technology designed to catch energy from the star.

The link has the full article.