Space News: Asteroids revealed, NASA missions fail

Brian G Turner

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1. Asteroids - they all look the same to me...

NASA's OSIRIS-REx mission to the near-Earth asteroid Bennu is almost in position - and it's latest photo reveals that Bennu looks remarkably similar to the asteroid Ryugu, which the Japanese mission is currently in orbit around. Check the image above for a comparison to both.

According to Phil Plait at Bad Astronomy, basic physics has shaped both: Hey Bennu, have we met? I never forget an asteroid.

That’s no coincidence! Both are small, with very weak gravity. Both are also rubble piles: Not solid, monolithic objects but instead like bags of rocks held together by their own gravity. Billions of years of slow-speed collisions have essentially shattered them in place.

The important bit here is that both rotate relatively rapidly. Bennu spins once every 4.3 hours, and Ryugu once every 7.6 hours. That means that a rock sitting on the surface feels a weak pull downward toward the center due to gravity, but also a weak centrifugal force outward, away from the spin axis of the asteroid. These combine such that the equator feels like it’s downhill.

2. Kepler fails, Dawn ends, no word from Opportunity

It's been a bad couple of week's for NASA.

The Kepler telescope, which was already running years past it's end date - it's mission to find planets around other stars - is finally confirmed to have run out of fuel: Kepler telescope dead after finding thousands of worlds and NASA retires Kepler Space Telescope

It's not the only one - the Dawn mission, which saw NASA successfully put a spacecraft in orbit around two asteroids between Mars and Jupiter, has also run out of fuel, and will be left to remain in orbit around Ceres: Dawn mission to asteroid belt comes to end

There's still no word back from the Opportunity rover on Mars, which found itself facing a planet-wide dust storm. However, NASA has yet to give up on the mission: NASA will keep trying to contact stalled Mars rover Opportunity

All three missions have been massive successes that ran well past the time they were designed for - but it's still sad to see a string ending around the same time.


3. Our hungry galaxy

Burp! The Milky Way ate another galaxy. Except this latest merger event probably happened about 10 billion years ago: The Milky Way ate another galaxy, and we can still see the undigested bits

It's now reasonably certain that a number of smaller galaxies have already merged with our Milky Way - and it continues to surprise us. An announcement this week suggested one of the oldest possible stars has also been found within it: Scientist finds elusive star with origins close to Big Bang


4. 'Oumaumau click bait goes viral

A research team working on solar sails for Harvard suggested the possibility that 'Oumaumau - our first proven extra-solar visitor, spotted last year - showed similar properties to a solar sail.

The claim wasn't peer-reviewed and seemed like an obvious click-bait promotion.

However, it does underline one of the particular mysteries of 'Oumaumau - it's apparent acceleration away from our solar system. Some scientists think this was due to gas venting, presuming that 'Oumaumau was a comet - but no comet debris was ever observed.

Phil Plait gives the run-down on this: Is 'Oumuamua an interstellar spaceship? I'm still going with 'no.'

Curiously, I think another article published this week could offer a clue: New insights on comet tails are blowing in the solar wind. Though no-one's apparently made a connection , it might be more plausible to suggest 'Oumaumau contained ferrous-magnetic metals - which might have been given a small kick by our Sun's magnetic field, and therefore explain the change in acceleration. The jury remains out.


5. Bright black holes

Astronomers think they have images of black holes merging in other galaxies Astronomers find pairs of black holes at the centers of merging galaxies




6. Panspermia rocks!

A recent study looked at how life may have travelled between planets - specifically in the Trappist system, famous for its 7 big planets: Sharing life with the planets next door

Warning: some people may be alarmed by the mention of Panspermia! :D


BONUS! Dinosaurs had colourful eggs: Jurassic world 'more colourful than thought'
 

Robert Zwilling

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A great series of articles, plenty of good thoughtful ideas to mull through the week. The last thought in the last article is a funny side note for me, "Astrobiologists need to ensure that they are not limiting life to what's already known..." That only brings a smile, could someone who was studying the idea of life transferring between close planets when we know we get hit by stuff from Mars from time to time, push the human first philosophy that far out so as to think that only our kind of life is capable of hitching a ride. I suppose stranger things have happened.

White dinosaur eggs might have been the first instant breakfast for a table of five to go extinct, instead of over easy, it was easy pickins.

I'd like to see a picture of the Milky Way that pictured the stars by their basic components so we could see all the trailing results of the different collisions. Like their are two types of constellations, one set made of individual stars and the other, big and small streams of a former galaxies. The big one featured in the article is all around us but smaller ones are probably just splashes of color here or there. The star location map done in colors, red closest, yellow farthest comes out backwards for me, my eyes are putting on the optical delusion I see on computer screens where the red is perceived as being behind the yellow, though I normally only see red and doing it. The center line is an open rip that goes all the way through the picture to the far side.

No matter what is driving the Oumaumau guy, it's very cool, not slowing down but speeding up as it leaves. The impression is apparently it's not hanging around. Seen it, done it, been there. The idea that magnetic material gave it a boost around the sun is intriguing. Would something like that add to our orbit. If it is solar sailing even by natural shape whose to say it hasn't picked up stuff along the way the same way drifting stuff in the ocean can carry an assortment of life from one side of the ocean to the other picking up stragglers all along the way.
 

Brian G Turner

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I think the asteroids one could be very important for our SF writers. All too often asteroids are simply thought of as giant rocks - but it's clear that some are piles of rubble shaped like D&D dice. :)
 

Robert Zwilling

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Most asteroids seen so far don't have geometric shapes like the current 3 mentioned in the 2 articles. Elongated or normal blob type structures seem to be the norm, like stuff broken off of something. Would geometric shaped asteroids be growing like crystals. Are the asteroids we see normally decreasing in size by losing bits and pieces while these three are collecting material.
 

Dave

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There is probably a story based upon the similarity to dice. That, and Einstein's letter to Max Born in 1926. “Quantum theory yields much, but it hardly brings us close to the Old One’s secrets. I, in any case, am convinced He does not play dice with the universe.”
 
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4. 'Oumaumau click bait goes viral

Curiously, I think another article published this week could offer a clue: New insights on comet tails are blowing in the solar wind. Though no-one's apparently made a connection , it might be more plausible to suggest 'Oumaumau contained ferrous-magnetic metals - which might have been given a small kick by our Sun's magnetic field, and therefore explain the change in acceleration. The jury remains out.
If it does contain ferrous magnetic metals that doesn't preclude that this is a propulsion "system".

I'm not saying this is an extra-solar visitor BUT if it is an extra solar visitor, then surely this sort of accelerated propulsion which essentially just uses external magnetic energy would be a very efficient way to do it.

I would imagine something whereby a return trip might be a few thousand years and might use magnetic and gravitational energy for acceleration and maneuvers.

For all we know Oumaumau might actually be the home world for an intelligent microbial life - or it might contain data banks and an entire digital civilisation.

Who knows?

I really do like these little science round ups you do Brian - I mean I already read most of the articles but it's nice to see another perspective.
 

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