If Stephen Hawking was looking for evidence that alien species are ultimately bad news for a planet, this would appear to be the proverbial smoking gun. Or smoking rock at any rate.
NASA scientists have provided tantalising evidence that Earth's oceans may have originated in space, supplied by water-packed asteroids which deposited their loads in terminal collisions with our ancient planet. Observations of 24 Themis - which at roughly 190 km (120 miles) wide is the largest of the Themis asteroid family …
The definition difference between a comet and an asteroid is that an asteroid orbits the sun (or some other planetary body) in a near constant orbit whilst a comet streaks through the galaxy on a highly ellitpical orbit
Comets tend to be a mixture of ice and rock because they spend so much time a long way from the sun and so most of the time they're too far away for their ice to be melted. When they are close ot the sun, the ice melts (and hence you get a comets tail), but a lot refreezes and other chemical reactions take place as it flys away from the sun and so this changes the chemistry of the ice on the comet.
The significance of this find is that, an asteroid in a stable orbit has been discovered to have surface ice at a distance believed to be so close to the sun that all surface ice should have sublimated away. This means it must have a resevoir or similar of ice/water that would be the same resevoir it had billions of years ago when the Earth was still young...
Finally we might get to drink the original brew that caused cells to decide life could be a good party! Lets hope the hangover isnt too bad...
"The definition difference between a comet and an asteroid is that an asteroid orbits the sun (or some other planetary body) in a near constant orbit whilst a comet streaks through the galaxy on a highly ellitpical orbit"
Although it's true enough that comets have highly elliptical orbits, there are plenty of short term and long term comets that don't do any streaking through the galaxy. Comet Halley, for instance, has an aphelion of 35.1 AU, little more than the distance at which Neptune orbits the sun.
If I recall correctly (or theoretically) comets are mostly in stable orbits very far from the sun (theorised Oort / Kuiper objects) whose stable orbits become perturbed more easily by extrasolar system influence (collisions, passing stars, supernovae) than inner solar system "belt" objects. Indeed some do get perturbed *away* from the solar system but then so do other comets from extra-solarsystem solar systems (if you see). Some, indeed a small minority of comets will "streak through the galaxy on a highly ellitpical orbit", most will either be in a stable "invisible" orbit or highly eliptical orbits within the solar system.
Anyway, Carl Sagan reckoned all water on Earth could be attributable to comets in "Comet" (1985), but then he didn't have observational proof.
"a comet streaks through the galaxy on a highly ellitpical orbit" not really. Streaks through *the solar system* would be better. Still it could have been worse. I recently got involved in a discussion where a couple of people didn't know the difference between a meteor and a comet.
The difference tends to be that when you see a meteor streak through the sky you live to tell someone about it :D
Last time I looked, the asteroid belt was further out than the orbit of Mars. So going to the asteroids to get a cup of tea on the way is rather like stopping off at Wooley Edge services on the M1 in the middle of your journey from London to Birmingham. And I'm not sure whether the quality of the tea would be any better either.
"water ice left over from the solar system's origin 4.6 billion years ago"
So it would seem that water formed in the birth of the solar system. The sun is, after all, made of hydrogen and the birth of the solar system created oxygen, so it had to happen.
The water came from the sun, at the dawn of the solar system.
"Themis asteroid family lying between the orbits of Jupiter and Mars"
"Themis is an ideal target for Barack Obama's audacious plan to land on an asteroid, and thirsty astronauts could enjoy a refreshing cup of space water before heading off to Mars."
Not if the first statement is true. When flying from Earth you reach Mars before Jupiter and therefore also before any asteroids between Mars and Jupiter. So going to Themis enroute to Mars would be like going to Glasgow when travelling from London to Newcastle.
I hope NASA's grasp of basic astronomy is better than the author's.
Imagine heading for Mars (orbiting the Sun at a different rate and distance to both ourselves and the asteroids) via an asteroid.
It would be like going to Glasgow when conditions to do so were more favourable than heading straight to where Newcastle is once every 686-odd days, then waiting for Newcastle to come round to where you'd prefer it to be?
What they generally are looking for are amino acids, proteins, enzymes, etc. Not life per se, but really important to the formation of living things. I believe the common theory has held for a while now that asteroids and comets seeded the early earth with water and the "raw materials" for life.
The problem is that research I saw last year demonstrated that all the water on earth had been here since VERY early, estimates around 100m years into the lifespan. Not sure all that shows up from just asteroids based on the shortened timeline, even if it's a possibility from water production perspective.
Would you consider Octane to be a life form? No? But Octane is a carbon based organic material. Still your right we dont consider it alive - we all know theres a big difference....
But carbon based organic materials are usually considered a requirement for life developing, hence why this place looks interesting - water and carbon-based organic materials! The good stuff!
Expect a headline tomorrow from the Sun saying Life found on Themis...
Life is well beyond organic. Organic, in chemistry, simply refers to virtually any compound containing carbon, though there are some exceptions. This means Methane qualifies, however. Honestly, rather than being an admission of extraterrestrial life it is simply a redundant statement; organic materials (by our definition) are carbon-based materials. It is rather like saying hydrogen-based water.
"When flying from Earth you reach Mars before Jupiter and therefore also before any asteroids between Mars and Jupiter. So going to Themis enroute to Mars would be like going to Glasgow when travelling from London to Newcastle."
Yes, but what if there was no service station at Newcastle? Refuelling at Glasgow ready for the return trip might be your only option.
Don't these people know anything?? Everybody who has ever watched any kind of space/sci-fi will know that asteroids were used as ice prisons for bacteria/life forms that nearly destroyed the beings that put them there.
To go defrosting asteroids at random is suicide! Don't do it Obama!!!
Think about it.
Water vapourises off an asteroid. Where does it go? There ain't no winds in space.
It just sits there, bound by gravity to the asteroid. At some point the molecules swing into the shadow of the asteroid, where it's very cold, and water condenses back onto the asteroid. Hey, it could even rain for a while, depending on the temperature range, but soon it'll be 240-odd below.
Then the asteroid swings round again and we see the ice reflection. Of course the ice gets hotter, and then the water boils off. The cycle repeats. Simples!
Why has this obvious and boring explanation been ignored in favour of a much less likely vision....?
No particular reason why all that water would land only on Earth; the same objects must have carried water to other bodies as well, along with organic molecules, so pre-life chemistry might be discovered on other planets (or moons) where water was present. And those other bodies have had about the same amount of time to evolve life as on Earth, possibly under favorable conditions at some period.
It seems likely that given their need to retain funding and promote future missions, NASA probably shared these findings with the White House before released to the general public, which could explain Obama's thinking to shift the next target from our moon.
Idea has been around for years NASA, years,
Basically it snows in space.
(I am going a little beyond the SCT people here, in fact they are going to deny this.)
The solar wind currently at 393.3 km/sec and a density of 3.2 protons/cm3 strips a bit of our atmosphere off as it goes past.
That and other crap are driven out there and not on any kind of orbital path.
Gets out far enough and it freezes clumps and falls back.
Gets close to the sun, sublimates and gets driven out again.
Nice continuous process that keeps our planet wet.
As I said, the Small Comet people think I am wrong.
You could haul on over to their website for the explanation as to why that didn't work for the moon or mars.
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