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Wednesday 26 April 2017

We apologise for the delay...

Normally I'd have a new post out today, but thanks to a combination of the flu and a teething baby to look after... get the idea. I'll be back asap with something fascinating (there's lots out there - the nebula above and below are some damn beautiful examples) but for right now I need to use what focus I've got wisely. Until then here's Neil Degrasse Tyson:

See you all next week (with any luck):

John Freeman

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Monday 24 April 2017

Answers for Authors: How could we make Venus habitable?

Above: Fraser Cain of Universe Today talks us through it.

Human colonisation of Venus doesn't sound too smart on paper. Terraforming Venus – a world that is much closer to Earth in size, surface gravity, and location than almost any other – is a much harder proposition than terraforming a sun blasted airless desert like Mercury or our Moon. 


Mainly because of what is already there – Venus’ atmosphere. The surface is drowned under a CO2 atmosphere so thick and hot it's almost more like a boiling ocean, and turns the planet into a badly maintained suburb of hell. The pressure is over 90 atmospheres, and the temperature tops 450 degrees Celsius everywhere except the mountaintops – on which heavy metals, rather than H2O, snow out as a glittering coating

Above: The barren rocks of Venus today, beneath the hazy sky and pressure cooker atmosphere.

To add to the worrisome brochure reading for a colonist, it rains sulphuric acid. 

If people are ever to live there we need to renovate, but to do that we’d need to remove that sweltering atmosphere. Here are a few of the ideas most often tossed about: 

1: Drop thousands of huge asteroids onto Venus.
It’s the brute force and ignorance approach – smash huge asteroids hundreds of kilometres wide into Venus until the atmosphere is blasted away into space. Brute force and ignorance has a lot of charm in some situations, but in this one it’s stunted by the Venusian gravity: Nearly as strong as Earth’s, it means that it would take thousands of such huge impacts to eject enough atmosphere. Worse, the ejected atmosphere would remain in the vicinity of Venus’ orbit, so that same high gravity might well just re-absorb it. Lastly there’s the inconvenient fact that either wed have to space the asteroid strikes so widely that the whole process took hundreds of thousands of years, or so many huge asteroid strikes in quick succession would turn Venus surface into a lava ocean, like the new born Earth had – a lava ocean that would generate lots of hot gas, replenishing the lost atmosphere. 

Send in the Willis

2: Drop massive amounts of calcium and magnesium from space.
A more realistic alternative is to use chemistry on a massive scale to turn Venus’ atmospheric gas into something else. One idea - less mad than dropping huge asteroids but still pretty mind bending in scale - is that the atmosphere could be reacted with refined magnesium and calcium, turning it into carbonate rock. Using calcium and magnesium we’d need more than twice the weight of the giant asteroid Vesta of each.

Above: The giant asteroid Vesta. A whole lotta rock.
3: Drop huge amounts of hydrogen into the atmosphere.
The atmosphere could also be reacted with hydrogen, via an aerosol of iron in the atmosphere, turning it into graphite and water. The attraction of this approach is that it delivers a worldwide ocean to Venus (roughly 10% the volume of Earth’s) at the same time the atmosphere thins. If we used the hydrogen approach we’d need mass mine hydrogen from the water ice of one of the icy moons of Jupiter or Saturn. Still, this would make a more workable approach than the giant asteroid strikes, unless anyone’s especially fond of living on a ball of lava. 

And no one wants to live on a ball of molten lava. 

Aside from Darth Vader (minor spoiler for Star Wars: Rogue 1 there, sorry). 

Vader, Sauron, Voldemort...I can't help but think there's an Ikea 'dark lord's castle' flatpack all these guys are all just modifying slightly.

4: Freeze the atmosphere out: 
This is actually a way that falls between terraforming Venus and simply colonising its atmosphere: Cool it with sunshades. Once it drops below a certain point the atmospheric CO2 would start to snow out as crystals that could then be scooped up and shipped off world. There are two ways we could freeze Venus enough to do this: Orbiting sunshades, or with sunshades floating in the upper atmosphere. 
If we based our reflectors in space they’d have to be big – and by big I mean really, stupidly, huge: The best place to site such a reflector would be the point where the Sun’s gravity and Venus gravity cancel out… but it would need to be four times wider than Venus itself
It’s the second option that would give the crossover with more near term colonisation – there would need to be an enormous number of sunshades floating in the Venusian atmosphere, and some of them could actually be floating cities. Keeping them aloft wouldn’t be a problem, as breathable air would be a lifting gas on Venus. We’d only need to coat the upper surface with a high reflectivity layer, and they'd fit right in with the countless floating reflectors we'd need to fill the atmosphere with.

Sunshades are also one approach to Venus' other big problem: It's day, which is 243 times longer than Earth's. A series of orbiting or floating sunshades and mirrors could artificially create a more Earth-like day-night cycle. They would also ease the temperature difference between the day and night sides, which would drive extreme weather patterns. That said, it's been suggested that the long Venusian day would stimulate thick cloud cover on the day-side, increasing the planet's reflectivity and helping regulate it's temperature.

Above: An artists impression of a huge floating city in the atmosphere of Venus.

The time scale for all of these ideas is looong – thousands of years – but eventually the atmosphere would thin. Water and organic molecules to support life could be imported from the outer solar system. What would our new Venus be like?

Exactly what we got would depend on how we'd gone about terraforming it, but a few key differences would be:
  • The Sun rises in the west and sets in the east
  • One day is 117 Earth days long - so daytime temperatures near the equator will climb ferociously high, and night time ones will be able to get bitterly cold
  • There's no moon in the sky, but Mercury shines as a brilliant evening / morning star, and the Earth and moon are an incredibly bright point of light in the night time sky.
  • Venus has no axial tilt to speak of - so there are no seasons.
So, even terraformed, Venus would still be an alien world. Will anyone ever call it home? Only time (probably lots of it) will tell...

Above: An artists impression of a terraformed Venus

Monday 17 April 2017

The Universe in 101 words: The ocean of Enceladus

Above:Saturn, core of a system of moons and rings like the solar system in miniature.

Our solar system is, well, awash with ocean worlds*. And, thanks to the Cassini mission, we've gotten to know one: Enceladus, 500km wide moon of Saturn

So what's it like?

Dark - the ocean's covered in 20km of ice - but maybe not totally black: There's volcanic activity on the ocean floor, like the white smoker vents of Earth, so there'd be the dim  glow of volcanism. More importantly the salty, alkaline, water contains organic chemicals and hydrogen - food for possible micro-life.

Cassini's mission is nearly over - but its now hard to imagine not eventually returning to Enceladus....

*Sorry, couldn't help myself.

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Above: The icy surface of Enceladus.

Wednesday 12 April 2017

What's NASA's mystery discovery?

Above: A diagram of Europa's ice protected ocean.
What's NASA's big announcement about? True, I could just wait until Thursday when they'll, y'know, announce it. But where's the fun in that?

Well... looking over the list of  who'll be there, and the press call...

NASA to Reveal New Discoveries in News Conference on Oceans Beyond Earth

NASA is exploring the ocean worlds in our solar system as part of our search for life outside of Earth.
NASA will discuss new results about ocean worlds in our solar system from the agency’s Cassini spacecraft and the Hubble Space Telescope during a news briefing 2 p.m. EDT on Thursday, April 13. The event, to be held at the James Webb Auditorium at NASA Headquarters in Washington, will include remote participation from experts across the country.
The briefing will be broadcast live on NASA Television and the agency's website.
These new discoveries will help inform future ocean world exploration -- including NASA’s upcoming Europa Clipper mission planned for launch in the 2020s -- and the broader search for life beyond Earth.
The news briefing participants will be:
  • Thomas Zurbuchen, associate administrator, Science Mission Directorate at NASA Headquarters in Washington 
  • Jim Green, director, Planetary Science Division at NASA Headquarters
  • Mary Voytek, astrobiology senior scientist at NASA Headquarters
  • Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California
  • Hunter Waite, Cassini Ion and Neutral Mass Spectrometer team lead at the Southwest Research Institute (SwRI) in San Antonio
  • Chris Glein, Cassini INMS team associate at SwRI
  • William Sparks, astronomer with the Space Telescope Science Institute in Baltimore
A question-and-answer session will take place during the event with reporters on site and by phone. Members of the public also can ask questions during the briefing using #AskNASA. money is on this relating to one of the ocean moons orbiting Jupiter or Saturn. Jupiter's best known ocean world is Europa, and Saturn's is called Enceladus. Both have ice covered oceans, and both are known or suspected to vent some of their ocean water into space from time to time. Both oceans are thought to be some of the best locations to look for alien life - much better than Mars' deserts, although much harder to reach.

Since the Cassini mission, which has spent a good amount of time studying the water being vented from Enceladus, is going into it's final phase I'm betting on some discovery about the nature of Enceladus ocean, and the mysterious process that keeps it warm and liquid. Possibly something to do with the chemistry of the sea water, since Cassini flew through the plumes leaking from it not too long ago. 

I may be right (or not) but stay tuned for more news...

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Above: Enceladus.

Monday 10 April 2017

Video roundup: Three amazing events in space for 2017

True, there are a lot more than three amazing things going on in, and relating to, space this year. But here are three of the biggest - both anticipated, and that have already happened...

1: Cassini ends it's mission to the Saturn system, spectacularly...

2: The Event Horizon Telescope may take the first ever pictures of the giant black hole in the centre of our galaxy...

3: Lastly we have the first ever re-launch and landing of a re-usable rocket. This has been accomplished by American firm SpaceX, and other ambitious 'new space' companies, like Amazon founder Jeff Bezos' Blue Origin, aren't far behind...

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Thursday 6 April 2017

What's so important about re-usable rockets?

Above: The view from the tail of a SpaceX rocket, as it leaves Earth for the GEO belt of satellites.

Getting to space, through Earth's thick atmosphere and gravity... that's hard work. To do it we use massively powerful, massively expensive, rockets. Which get used once, and then allowed to crash or burn up in Earth's atmosphere.

Why? We wouldn't drive like that, throwing away a car after every trip, so why fly into space that way?

The truth is it all comes down to money: To reach space you have to fly so fast, and so high, that bringing the rocket back to Earth in fit state for re-use means building a much stronger rocket, and giving it more fuel. For the amount of industry there is in space the expense in building a re-usable, rocket just didn't seem worth it.

Until the turn of the millennium, when a change in viewpoint started to grow in the space industry: What if that expensive re-usable rocket was the thing that was missing to stimulate bigger economic growth in space? At the same time there were revolutions in space flight that fed into this:

  • In unmanned space flight there was a steady rise in miniaturisation. Miniature space craft sophisticated enough to carry out meaningful missions at a fraanction of the cost of a full sized satellites, like the well known cubesats, became more and more common.
  • In manned spaceflight the idea of private manned missions - known colloquially as space tourism - has been growing.

Both are being taken as signals that there could be more opportunities in space, opportunities a low cost route up there could realise.
Which is where companies like SpaceX, and their successful re-flight of an already flown booster, come in. SpaceX aren't the only ones with a novel idea for a cheap launcher  - but as the pictures and video of last week's launch (available here) show, they probably have the most spectacular...

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Monday 3 April 2017

The Universe in 101 words: Cosmic Inflation

Above: The web of matter formed by the Univers's expansion.

After the big bang the Universe expanded hugely. But… not the way you think: The objects making up the universe didn’t fly apart through space. Space itself expanded, stretching like warm dough.

That opens a loophole in the laws of physics: Objects rapidly get further apart – yet, as it’s space that is moving, everything also stands still. They can even ‘move’ faster than light, without breaking the lightspeed limit – and, for a tiny moment, the Universe expanded like that. Physicists call it ‘inflation’. 

Getting a headache? Imagine life for the families who have a theoretical physicist at the dinner table...

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