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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.

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...

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Above: An artists impression of a terraformed Venus

Wednesday, 19 April 2017

Opinion: Does space belong to the robots?

Above: An astronaut floats by the window of the International Space Station, an enduring image of spaceflight with immense power to inspire.

It's the space nerd argument that never dies: Should space exploration be the province of right stuff astronauts, or of humanity's tougher servants, robots?

If you're going to set science and exploration as your goals and do a cold hearted benefit/risk & cost analysis.... sorry human spaceflight fans, it's the robots for almost every destination

True, humans have advantages over robots: We can work independently, think on our feet, negotiate our way through tricky terrain and unexpected situations. But space exploration costs, and all human advantages tend to fall rather flat in the face of a simple fact: Robots are much cheaper and much, much more disposable. So much so that, even taking into account human's advantages, on most worlds sending a human being, and getting the risks to them down to acceptable levels, costs so much that we'd still get more science done by spending the money on lots of robots instead.


The risk/benefit argument's a narrow viewpoint, and misses something crucial: Space exploration is not simply about doing science and exploration as efficiently and safely as possible. Space is an endeavour bound up in things like national pride, public enthusiasm, and what it contributes to our culture. Those are things that need a human face - and there are some humans who are much more comfortable with risks than most od us. 

Look at it like this: Russia landed a lot of successful robots on the Moon. But history doesn't remember Russia as the winners of the Moon race because they had a better cost to benefit ratio from their probes and rovers - it remembers America as the winners, because they managed to send people. 

And the risks to those people were so great that the U.S. president had a speech ready to go for if they died.

When the science and pure exploration rests on the shoulders of all the other, more emotional and human, aspects of space exploration... it seems pretty clear that loosing the manned aspect if spaceflight would have a pretty damaging knock on effect on the unmanned side.

Today there are still more factors to consider: Newspace companies are working to reduce the cost of putting humans in space (SpaceX are even planning their own Moonshot), and at the same time advances in AI and robotics are making our droids more versatile. But I don't see that race as ever having a definitive winner - both robots and humans look set to keep their places in space for a good long while.

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Above: Apollo was motivated by politics, but still did reams of good science.

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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Wednesday, 29 March 2017

The Universe in 101 words: What's the Big Rip?

Above: A map of the web of galaxies and galaxy clusters that make our local universe.

It sounds like a fart joke. 

But this fart could end the Universe:

The expansion of the Universe is accelerating, powered by ‘dark energy’. If dark energy stays constant it will eventually pull the galaxy clusters apart – but the gravity holding the galaxies themselves together wont be overwhelmed. 

There's another scenario however, if dark energy grows with time...

The expansion of space will accelerate, until gravity can't hold the Milky Way together.

Then the Solar System will fly apart, leaving Earth alone in the darkness. 

Finally, Earth would disintegrate - down to its atoms.

That's the Big Rip.

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One by one the stars would disappear from view....

Monday, 27 March 2017

The Universe In 101 Words: Rogue Black Hole Ahead!

Bad day? Any inhabitants of the galaxy pictured are getting a worse one. A black hole the size of a solar system is barrelling through it at 2000 km/s - far faster than any space ship.

How? Huge black holes result from smaller holes merging. This merger gave off massive gravitational waves, equivalent to 100 million supernova - hurling the monster hole through space.

Worlds caught in its path wouldn't see darkness approaching though - the hole's dragging clouds of superheated gas along. Instead the sky would get brighter and hotter until the very rocks boiled.

Not much better IMHO...

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Wednesday, 22 March 2017

Answers for students: What are ray diagrams?

Part of a series in which I answer some of the fundamental physics questions students of all ages ask me.

What is light? Mostly you'll hear that light travels in waves. And that's true*. But it also comes in particles, called photons. And then, to make it more confusing, people talk about 'rays' of light.

Who the hell is Ray, and  what does he have to with lasers? Can he be trusted with one?

And what does he know about the missing Death Star plans!!!?

Well, I've got bad news for you: Like Death Stars, rays aren't real.... but if we're trying to calculate the path light takes, especially when we get to things like diffraction and refraction, accurately drawing waves themselves quickly gets difficult - it's all just too complicated. 
To simplify this we use ray diagrams: These aren't meant to indicate that light is made up of rays, it's just a convenient way of showing the direction of a group of waves. 

To turn a wave diagram into a ray diagram is simple: Draw a line at right angles from the line of the wave, pointing in the direction the waves is going. Like so:
This is the 'ray' associated with that wave. If the the wave front is very broad, add some more. If the wave front is curved draw your ray at right angles to the tangent of the wave, and do it at several points, like so:

...which gives you a ray diagram like this:

...and that's all a ray diagram is, a way of showing the direction of motion of the waves!

*Light can also be a particle, and can morph from particle to wave... but that way lies quantum mechanics, and I've had enough headaches today.

Monday, 20 March 2017

4 Crazy ways of getting into space - that might actually get built:

The Rocket-Balloon*:

Above: The rocket stage of a rocket-balloon (called the Bloostar) pulls away from its balloon stage.

The idea of crossbreeding a balloon with a rocket sounds like madness doomed to end in a fiery explosion on a spectacular youtube video.

But the idea has been around since the 1950's. To get to space a rocket must first punch through the Earth's atmosphere, which eats up a lot of extra fuel. So why not float the rocket to the top of the atmosphere on a balloon?

Well, partly because that makes the rocket incredibly hard to steer, and partly because a rocket big enough to launch a useful satellite would need a balloon that was unfeasibly huge. One snapped cable and someone could be getting a fully fuelled space rocket through the roof of their house.

This, of course, hasn't stopped people doing it: Sub-orbital sounding rockets, carrying simple and lightweight sensor packages, were launched in the 1950's

And that was as far as the rocket-balloon got, until the turn of the millennium when miniaturisation started to work its way into satellite technology. Today a useful space satellite can be small enough to hold in you hand, and the rocket needed to put it into orbit can be not much bigger than a 1950's sounding rocket. The Spanish company Zerotoinfinity have developed a commercial rocket-balloon launcher for small satellites called the Bloostar, and have just had a successful test firing at altitude - commercial flights could start as soon as next year.

Space cannons:

Above: A rare image of the HARP space cannon firing. Bits of this behemoth gun can be found rusting on the island of Barbados today.

H.G Wells wrote about a cannon big enough to blast a projectile into space, and all the way to the Moon. 

Which is insane, right? I mean, such a cannon would need to be many times the size of the biggest naval cannons, and the shock waves from it would shake buildings apart...

...Enter the US military.

In the 1960s the US army and Canadian ballistics expert Gerald Bull led a project that built, tested, and fired space cannons, sending sensor packages and test payloads well above Earth's atmosphere and into space. Despite their success, the project was scuppered by the space explorer's old nemesis, politics. 

From there the story takes a much darker turn: Gerald Bull turned to advanced weapons manufacture to keep funding his research - sort of like a reversed Tony Stark - and ended up facing a professional assassin in a hotel corridor

You can read the full, tragic, story here.

Ride a laser beam up the rear:

Above: An infographic explaining one variant of the 'lightcraft' idea.

Space travel is fairly risky to start with, so you'd think that shooting a high powered laser at a spaceship while it flew wouldn't be a good idea. I work with industrial cutting lasers professionally, so I can confirm that it's a very bad idea - I've seen how little respect a powerful laser has for solid steel.

It's such a bad idea that it's actually the basis of some novel anti-missile weapons.

But... a rocket, a long tube of highly flammable stuff with an explosion at one end, ain't that safe either hombres. So how do you turn a laser into a rocket?

You attach a curved mirror to the base of your rocket, and fire a powerful laser  at it. The mirror focuses the laser light to a point just beneath the rocket, which forces the air there to rapidly expand, producing thrust. If you need it to work in space, you can have the rocket expel material into the laser's focus.

The huge advantage of this is that the rocket is fuel free - the electricity for the laser can be taken from the national grid even. The down side is that you are, as I mentioned, shooting a powerful laser at your spaceship. 

Surprising, then, that people have very seriously looked at a laser propelled manned vehicle.

The technology is still a very long way from being mature, but it might do a lot more than just launch satellites. Laser based tractor beams are one of the technologies space agencies are seriously looking at to defend Earth from a major asteroid strike.

Climb a magic rope: 

Above: A car climbing a space elevator cable.

Rope is wonderful stuff, but most ropes aren't so wonderful that they'll get you into space. 

That could change, however: where most people would shrug and go 'eh, rope's just rope' scientists and engineers went 'we shall build a rope all the way into space'! 

Because... well, because a great many of us are a wee bit crazy.

Even so, the basic 'climbing rope to space' idea has spawned a host of daringly edge-of-what's-possible high-tech-rope based ways into space.
  • Probably the best known is the brain melting space elevator, a cable car into space thousands of kilometres long, anchored at one end to a huge geostationary satellite  and to a mega-mega skyscraper on the ground end. But there are other equally zany designs for ropes into space.
  • The rotating orbital tether: This is a big, spinning, bit of high strength space rope. As it whirls around the lower end grazes the upper atmosphere, striking just deep enough for a sub orbital spacecraft (like Virgin Galactic's SpaceShipTwo) to hook on to it and be flung into deep space.
  • Endo atmospheric tethers: This tether is run behind a high altitude aircraft, and grabs a small, lightweight, launch vehicle. The tether, and the difference in momentum between the big heavy plane and the lightweight launcher propels it to hypersonic speeds.
All crazy as a spoon... yet space agencies have been quietly working on tether technologies for decades...

* Yes there's a condom joke there if you're determined to find it. I'm not, but feel free.