asterroc: (Astro - H-alpha)
1) They've cried wolf enough times at this point that I'm always skeptical about every new announcement.

2) This is yet more indirect evidence - they've found visual evidence of changing patterns that could look like streams, and in the same areas spectra give the chemical "fingerprints" of assorted salts (not table salt, NaCl, but chemically similar) which as far as we know can only form in water.

To me, if the evidence is indirect, we will need a lot more of it than if we actually saw liquid H2O flowing and used spectra to confirm it was water. Right now we have circumstantial evidence of things that look like stream beds (but could be caused by other liquid solvents, or a remote chance they're caused by wind), and we a number of chemicals which as far as we know can only form in water (not only these salts, but also the hematite blueberries from a few years back). However the hypothesis "this can only form in water" is one of those things we can never actually prove true, just eliminate more and more untrue possibilities.

So to me as a watcher of all this, it's just a waiting game. If there really is liquid water, then little pieces of evidence like this (and the hematite blueberries) will continue to build up until at some point the molehill has become a mountain and it'll be generally accepted by all planetary astronomers (and then all astronomers, and then the world) that yes, there's liquid water on Mars.

3) Water is a key building block for life, so the next question is "is there life on Mars?" Assuming this liquid water exists, it is transient - it's seasonal, appearing only in local summer. If it's transient liquid water, I will need to see some pretty solid evidence to believe that there is current single-cellular life. If it's persistent liquid water I will switch over entirely and I will assume that there's single-cellular life until proven otherwise. Even if it didn't evolve on Mars, we've sent missions there and it's impossible to sterilize everything completely, plus bits of Earth have been knocked off from impacts and landed on Mars so it might've been seeded with Earth life millennia ago. If it's possible to sustain some form of life on Mars, I guarantee you that it's there.

Originally posted on Dreamwidth. comment count unavailable comments there. Comment here or there.
asterroc: (Astro - H-alpha)
Post copypasted from Tumblr b/c I'm just that excited.

OMFG I’m so excited! New Horizons flew by Pluto about 2.5 hours ago. It’s going to remain pointed at Pluto for another 5 hours or so to get as much data as possible, and then the craft is going to slew around and spit back all the images and other data to Earth, and then it’s going to take another 5 hours for the signal to get here.

Among the amazing discoveries so far, we already have that Pluto is larger than previously thought. We knew that Eris was the most massive Kuiper Belt Object - mass is easy to get when an object has moons, and Pluto has five (Charon, Nix, Hydra, Styx, Kerberos) and Eris one (Dysnomia).

Read more... )

How exciting is that!?

Originally posted on Dreamwidth. comment count unavailable comments there. Comment here or there.
NASA's big press release today was that a new form of DNA was discovered in a type of bacteria living in Mono Lake, California. DNA usually requires phosphorus to hold together the different "rungs" of the "ladder". On the periodic table of the elements, phosphorus falls directly above arsenic, meaning they have the same number of electrons in their outer shells, and therefore act similarly in forming molecules. This is the very reason that arsenic is well-known as a poison: it is easily incorporated into human (or animal, or plant) chemistry, it replaces the phosphorus, but it does a crappier job than phosphorus and even though it can form similar molecules they easily fall apart.

Apparently this bacterium has not only overcome that - there are many bacteria that can live in an arsenic-rich environment - but it even uses that fact. This bacterium can apparently switch between using phosphorus, and using arsenic, depending upon which is available in its environment.

NASA press release

A very slightly more technical article, including a description of tests used to determine that the arsenic is actually incorporated into the DNA.

And a couple blog posts, one from a science writer Ed Yong, one from astronomer-turned-science-writer Phil Plait.



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