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Monday, 26 September 2016

What did Hubble see around Europa?

I was right! 
Well - sort of: I guessed that NASA's much touted 'surprising  find at Europa' would be about further evidence of water plumes over Europa, Jupiter's ocean and ice covered moon, and it was. It's more evidence of an internal ocean, which is great. Even better, it suggests a way to sample what's in that ocean without needing to drill through thousands of meters of rock hard ice.

Above: A cutaway of  th possible vents, warm ice  blobs, and the internal ocean of Europa

What I didn't get right was that this wasn't a discovery from a new Hubble image. This discovery was made by going over images of Europa from 2014, with two independent teams using new software and analytical techniques to tease the signature of the water plumes out of the data. Each used an different method, but both hit the same conclusion: The plumes are saline water. As Bill Sparks, from the the Space Telescope Science Institute in Baltimore puts it:
“When we calculate in a completely different way the amount of material that would be needed to create these … features... it’s pretty similar to what Roth and his team found. The estimates for the mass are similar, the estimates for the height of the plumes are similar.  The latitude of two of the plume candidates we see corresponds to their earlier work,” 
Like any scientific discovery this one will need independent checking, and lots of arguing about on the internet*. We should all keep a pinch of doubt in mind about it until then. But it's a great boost for hopes of exploring Europa, and it's ocean: The case has never been more compelling. For a bit more detail I'll point you to the press relese here, the paper here, and pass you over to the NASA Goddard video:  


  

*It's amazing how some people will happily believe aliens frequently come to Earth and steal our underwear while texting the Lizardmen and Illuminati, but will balk at the idea of a team of scientists teasing new information from old data with upgraded software.
 

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Thursday, 22 September 2016

What Has NASA Seen At Europa?

Above: Europa, courtesy of NASA. The brown stripes are thought to be zones where upwelling ice is carrying material up from the ocean.

NASA has teased the world by announcing a press conference today about a 'surprising find' made regarding Europa. 

So what's the big buzz about? 

Europa is the second moon out from Jupiter and one of a handful of worlds known to have a substantial ocean. That makes it one of the best places to look for present day extraterrestrial life - but there's a catch: Europa’s ocean is ice covered, moonwide. The depth of the ice is unknown, but the optimistic models suggest its thousands of meters deep. 

So it's a cosmic middle finger: Here's what space explorers were always looking for, and they get stopped by the last few kilometres to the prize. 

But in 2013 Hubble picked up something potentially game changing: A plume of water vapour over Europa's pole. 
That suggests that the ocean sometimes breaks through the ice, as it does at Saturn's (much more distant) moon Enceladus. Right now a lot of space fans are hoping the news is more plumes.... But is it? 

Lets take a look at the details that have been released for the conference:
NASA will host a teleconference at 2 p.m. EDT Monday, Sept. 26, to present new findings from images captured by the agency’s Hubble Space Telescope of Jupiter’s icy moon, Europa. Astronomers will present results from a unique Europa observing campaign that resulted in surprising evidence of activity that may be related to the presence of a subsurface ocean on Europa. Participants in the teleconference will be:

•Paul Hertz, director of the Astrophysics Division at NASA Headquarters in Washington

•William Sparks, astronomer with the Space Telescope Science Institute in Baltimore

•Britney Schmidt, assistant professor at the School of Earth and Atmospheric Sciences at Georgia Institute of Technology in Atlanta

•Jennifer Wiseman, senior Hubble project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland 
What can we get from that?

Well...
  • Paul Hertz is Director of the Astrophysics Division in the Science Mission Directorate at NASA in March 2012. He's head honcho of research programs and missions 
  • Dr. Britney Schmidt's research interests are astrobiology, icy shell and ocean dynamics of moons, and the evolution of water-rich asteroids and other small bodies  
  • Dr. Jennifer Wiseman is a senior astrophysicist at the NASA Goddard Space Flight Center, where she serves as the Senior Project Scientist for the Hubble Space Telescope. 
  • Bill Sparks is part of the Astrobiology institute, and the deputy division head for the Instruments Division and is a member of the Advanced Camera for Surveys Instrument Definition Team (ACS IDT). His most recent research project involves using polarised light to detect chiral molecules.
We have two astrobiologists, one with an interest in Europa, the other a camera expert with an interest in characterising molecules using spectrometry. We also have two high ups involved with Hubble.

My guess (and it's definitely only a guess) is that Hubble has used a background star to back light the space around Europa and found evidence of more plumes. In fact Jupiter and Ganymede were predicted to occult a 7th-magnitude star on April 12, but Europa was not. Perhaps a plume did? 
As an outside possibility, I wonder if Bill Sparks' latest project on detecting chiral molecules - often regarded as a biomarker - has anything to do with this?

Or it could be that Hubble has spotted a discarded pizza box orbiting Europa, and everyone at NASA is having a breakdown... but one way or another we'll find out tonight!



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Tuesday, 20 September 2016

The Universe in 101 words: How does a supernova build a neutron star?


Supernova are complicated. The star doesn’t just explode, like a primadonna asked to do the dishes: First the core stops producing energy – unfortunate, as that energy was supporting the star against gravity - and the star collapses. That superheats the unused fuel around the core, igniting all of it at once. 

And, well, adios neighbourhood. 

The dead core is surrounded by the explosion, and gets squeezed so hard the nuclei of the atoms in it join together. The resulting 20km ball of fused nuclei is the neutron star – so dense and magnetic it warps space, time, and re-writes the laws of chemistry. 



Above: NASA introduces us to spinning neutron stars....

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Friday, 16 September 2016

The Universe in 101 words: Alcubierre's Warp drive...

Above: A SpaceX spaceship leaves Earth behind.
Here’s a loophole: Strictly, the rules say ‘no exceeding light speed, as compared to local space’. 

Alcubierre’s engine would exploit that loophole by forcing space in front of itself to rapidly contract, and space behind to rapidly expand - so things behind move away at FTL rates, and the things in front approach at FTL rates... 

...but the ship stays (locally) still. 

It's like parking a new car on a super-strong travellator that's disguised as road, under a speed camera**: Speed with the travellator, then… 

“Officer, that camera’s broken! This car can’t have been speeding, its mileage is zero.” 
  
 **In other words: It’d be very, very, hard to pull off. 


 

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Thursday, 15 September 2016

The Universe in 101 words: The Lightspeed Barrier

The Enterprise: Inspiring physicists to look for loopholes.

Nothing goes faster than lightspeed. Why? 

It’s because of something noticed over a hundred years ago: Lightspeed measures as 299,792km/sec, whether you’re stationary or doing 299,791km/sec. Every experiment shows it always measures the same. 

Weird, but triple checked as true. 

The explanation? If someones's speed is close to 299,792km/sec, compared to yours, time appears* to run slower for them. That's not all: 

• They get shorter.
• They get heavier. 

Close to 299,792km/sec these effects get incredibly strong – and slowing of time slows any acceleration. Things very near lightspeed appear frozen, squashed, and super heavy. They can't accelerate. 

Going faster will mean cheating… 

*I'm saying 'appears', because to them you're the one that's slow and squashed.

Above: For some more details here's Fraser Cain of UniverseToday.

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Wednesday, 14 September 2016

The Universe in 101 words: There are rocks and metals older than the world...


Most people know that shooting stars are meteorites – rocks arriving from space, hitting Earth’s atmosphere. When those rocks reach the ground some are picked up, clues found inside them, and their stories revealed. 

Those stories are… astounding: Many of these rocks are parts of worlds destroyed billions of years ago - worlds with internal heat, water flowing underground, and the carbon chemistry that could lead to life. Some are from surviving worlds, like Mars or the Moon, and tell stories of ancient atmospheres, or long dried waters

Exploring those worlds is as hard as picking up fallen rocks… 

...OK, you probably need a laboratoy too.

Above: Imperial College scientists explain how we use meteorites to learn about other worlds..

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Tuesday, 13 September 2016

The Universe in 101 words: A Balloon/Rocket Hybrid?


Is there a better way into space than rockets? 

For a long time huge ideas like space elevators or space cannons have been touted as the rockets successor. Much like a manned Mars mission.... the world always seems to be ten years away from really starting work on them. 

But what if the answer is simpler? What if it's a giant ladder balloons? A company called Bloostar has a truly unique (read: Fairly weird looking) design for balloon/rocket hybrid. It could float to 20 km altitude before flying the rest of the way like a rocket – here’s their video: 


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