Shooting Gallery

30th June 1908: A huge explosion flattens over 800 square miles of Siberian forest in the remote region of the Podkamennaya Tunguska River. In the absence of detailed information, wild theories abound – it might have been a miniature black hole, perhaps even an alien spacecraft in difficulties. However, the general view is that it was an asteroid or comet fragment entering the Earth’s atmosphere and bursting in mid air, possibly a piece of Encke’s Comet; witness accounts mention repeated sounds like artillery, which perhaps means that Siberia was under bombardment by a series of separate fragments.

13th August 1930: There are reports of three large explosions in the Brazilian rain forest near the Peruvian border – local inhabitants talk of burning trees and a widespread ash cloud. Observatory records suggest that these were caused by one or more asteroid impacts coinciding with the peak of the annual Perseid meteor shower.

2nd February, 1932: Explorer and intelligence officer St. John Philby (father of double agent Kim Philby) discovers pieces of meteoric iron littering the remote Arabian desert in the Empty Quarter or “Rub’ al Khali”. Later, three impact craters are found in the sand at Wabar, which suggests that an asteroid exploded in mid-air over the Arabian Peninsula (with the force of a 16-kiloton nuclear weapon, approximately), maybe as recently as 1891.

16th July, 1994: The first of many fragments of comet Shoemaker-Levy 9 crash into Jupiter, the comet having been captured by the gas giant’s gravity in the 1960s or ’70s and fallen victim to Jupiter’s crushing tidal forces. Over the next few days, big pieces of comet slam into the planet’s atmosphere one after the other, creating vast dark spots which are clearly visible by telescope from Earth. The largest of these pieces (fragment G), impacting on 18th July, smashes with a force equivalent to 6,000,000 megatons.

15th February, 2013: A meteor explodes high over the Urals in Russia, creating a massive fireball, damaging buildings in six cities across the region and injuring over a thousand people (mainly cuts caused by shattering window glass). This happens 16 hours before asteroid 2012DA14 is due to pass by Earth; NASA tells us, however, that the two events are not related, the trajectories of the two objects being very different.

The meteor that lit up the skies over Chelyabinsk last week exploded with a force of nearly 500 kilotons and is estimated to have had a diameter of up to an estimated 56 feet. However, near-earth asteroid 2012DA14 which skimmed past us the same day has a diameter of around 160 feet and would have made a correspondingly bigger bang, had it collided with Earth instead – it would not have been in the Shoemaker-Levy class (thankfully!) but might have done considerably more than create smoke trails and smash windows.

To those who say that global warming is the greatest long-term threat to the human race, I think we might have to agree to disagree. In the Solar System’s great meteoric shooting gallery – going by a century’s worth of occasional impacts and near misses – it seems we have been relatively fortunate. So far, anyway.

Some useful links:

Wikipedia on the Tunguska Event:
http://en.wikipedia.org/wiki/Tunguska_event
Article on the Armagh Observatory website about the Brazilian meteors of 1930:
http://star.arm.ac.uk/impact-hazard/Brazil.html
Wikipedia on Wabar impact craters:
http://en.wikipedia.org/wiki/Wabar_craters
Wikipedia on Shoemaker-Levy 9:
http://en.wikipedia.org/wiki/Comet_Shoemaker-Levy_9
Wikipedia on the Russian meteor event of 2013:
http://en.wikipedia.org/wiki/2013_Russian_meteor_event

Return to the Moon

Like some huge, dusty old attic above our heads, the Moon has been unvisited by humans ever since the crew of Apollo 17 departed from the lunar surface exactly 40 years ago last Friday – 13th December 1972. You can go to see their command module (“America”) at the Lyndon B Johnson Space Center in Houston, Texas, and if you were on the Moon now, you could also go and see their electrically-powered rover, which is still where the crew parked it at “Station 8″ in Cochise Crater four decades ago, in the spectacular Taurus-Littrow valley, which lies on the south-eastern edge of the Mare Serenitatis. Eugene Cernan and Harrison “Jack” Schmitt were the last men to walk on the Moon, and no-one’s been back since.

However, all that may be about to change. Alan Stern, CEO of new company Golden Spike, announced on 6th December that he is aiming to offer a private manned Moon expedition by 2020, at a cost of $1.5 billion. It’s a tall order, and a price tag that would better suit a national government than a wealthy individual; with that sort of sum, you could build a new airport.

Will it happen, though? The Cold War is over and developed economies are strapped for cash; few nations would have the appetite and the resources to return to the Moon a mere eight years from now. So the timeline might be unrealistic. But it is encouraging that someone is thinking about going back up there. Somebody’s going to have to, sooner or later. the Moon is not just a dusty (and dangerous!) old attic above our heads. It is – or could be – a vital resource and staging post on our journey to the bigger skies of the Solar System, with all the potential wealth that it contains. The Golden Spike company is named after the symbolic spike driven in 1869 to link the Central Pacific and Union Pacific railroads in the United States to form the First Continental Railroad; if its namesake is successful, this may mark the next step in an equally ambitious and grand venture ending – centuries hence, who knows? – in the stars.

Another news item recently was of course the death of Sir Patrick Moore, the famous amateur astronomer, on Sunday 9th December, which was a week ago today. I have some fond memories of staying up very late in the 1970s to watch his programme “The Sky at Night”, and learn of meteor showers, the occasional comet and which constellations were prominent at the time of year – it was like a news bulletin for those interested in such arcane things. Following the programme, I’d sometimes be out in the back garden after midnight trying to identify star clusters or wander – via a heavy pair of binoculars – among the mountains of the Moon. This was when my interest in space was kindled – Patrick Moore’s enthusiasm for the subject was infectious and I’m sure played a big part – along with all the science fiction I was reading at the time – in getting me started. He will be sadly missed.

Some useful links:
An article in Wired magazine about the Golden Spike announcement:
http://www.wired.co.uk/news/archive/2012-12/07/golden-spike-plans
Sky at Night, on the BBC:
http://www.bbc.co.uk/programmes/b006mk7h

The (very small) starship Voyager

Just a brief trip to outer space, before I post links to the next lengthy climate transcript. In the news this week, the people at NASA JPL announced (actually not – see my update!) that they believe Voyager 1 is about to leave the solar system, 35 years after its launch in 1977, and after having had thrilling close encounters with Jupiter and Saturn along the way. This being the vast wilderness of space, there is no obvious frontier which marks out the limits of the solar system, but the JPL people have picked up an increase in the amount of cosmic rays hitting the probe, which suggest it is crossing the borderland or “Heliosheath”, where the solar wind pushes up against the cosmic radiation from the rest of the universe, about 16 – 18 billion kilometres away.

What will happen to it now? And how long will we be able to keep in touch with it? The answer to the second question hinges on how much electrical power Voyager has access to, as it crosses the deep, dark gulf between worlds. The probe is powered by three RTGs (radioisotope thermoelectric generators) fuelled by plutonium-238, which of course is in limited supply and must be husbanded very carefully. And what it’s doing is gradually shutting down some of its more power-intensive activities in order to maintain others for as long as possible. That will last until about 2025, after which time the spacecraft will no longer be able to power any single instrument and Voyager will be drifting, inert and basically, dead.

I was curious to find out where it is heading. Anywhere famous, perhaps? There are actually two Voyagers, as you will know, and according to NASA Voyager 2 will pass within about 4.3 light years of Sirius, which is, of course, a very prominent and bright local star, well known to us from prehistoric times. This will take place around 296,000 years from now. Voyager 1, on the other hand, is heading towards AC+79 3888, otherwise known as Gliese 445, a very dim and unremarkable red dwarf in the unfashionable constellation of Cameleopardalis. It will pass by Gliese 445 in about 40,000 years, but what also might be surprising is that Gliese 445 itself is approaching the solar system much faster than Voyager 1 is moving in the other direction – it’s 17.6 light years away, at present, but will be only about 3.45 light years away from us, 400 centuries from now. Such is the unnervingly dynamic nature of stars, as they buzz like bees around the galactic hive.

So, what will happen to Voyagers 1 and 2, after that? Maybe they will drift forever in the dark spaces of the galaxy, until the end of time. Maybe one day humans will go out and retrieve them (or, even better, send a robot) and they will be exhibited in a museum, if they still have these in the 40th century (and I hope they will, as I think museums are a very good thing in any epoch.)

In the 1979 movie Star Trek: The Motion Picture, a Voyager probe has been discovered by sentient machines, who transform it into a gigantic and threatening spacecraft (renamed “V’ger”), which then starts to make its way back towards Earth and is only stopped by the brave people aboard the Enterprise, armed with their superior wits and sparkly late-1970s special effects. However, Trekkies will be aware that the probe in question was actually Voyager 6, and so the events of the movie clearly take place in an alternative timeline and dimension to this one, where I am writing this blog and where Voyagers 3, 4 5 and 6 were never built.

But maybe the basic premise of the film is correct, and someone – or something – else will find our little metal emissaries to the stars. And if they do, will it be good or bad news for Earth? I wonder.

Some interesting links:
NASA JPL’s main Voyager page: http://voyager.jpl.nasa.gov/
Interstellar mission overview: http://voyager.jpl.nasa.gov/mission/interstellar.html
Spacecraft lifetime: http://voyager.jpl.nasa.gov/spacecraft/spacecraftlife.html

UPDATE

After all that, I just realised that the NASA people haven’t actually made any official announcements yet. But they will, soon. Or they might do. Or something like that.

The Passing of a Quiet Hero

It was saddening to hear of the death of Neil Armstrong on Saturday, at 82 and following complications after heart surgery. He was a genuine hero – unassuming, quiet, never seeking the limelight – yet he was the one who piloted the Apollo 11 Lunar Module to a safe landing on the Moon on 20th July 1969, with a sensor telling the astronauts they were low on fuel and in conditions where an error could easily have led to certain death.

Later this century, when much of the Moon will have probably become a vast industrial park, I think at least one acre or so of regolith should be kept as it was when the Eagle landed there on that long-ago July day, as a memorial to Armstrong and the other Apollo astronauts. It ought to be on every serious visitor’s itinerary when they touch down on Luna, perhaps on their way to far more remote destinations.

Neil Armstrong was the first human to set foot on another world. He was thus – and will be, forever – unique. RIP.

The Spaceplane – Still Early Days

One of my childhood treasures is a slim book called Inside Information on Space Travel, which was published in 1970 and has cutaway diagrams of various spacecraft, from Sputnik 1 forward in time – via Black Arrow, communications satellites and Apollo – to the Space Shuttle (or a rather oddly-shaped Shuttle as it was envisaged in those days, before it became a reality.) The final page has a picture of a futuristic, sleek-looking spacecraft, accompanied by the following text:

WHAT OF THE FUTURE? A space liner like this will shuttle passengers between earth and orbiting space stations in the late 1970′s. It will be a combination of aircraft and space ship and will be able to take-off and return to land-based space ports.

Maybe there is an alternative dimension where space liners actually did start to operate in the late 1970s, but not in this particular universe, sadly. However, spaceplanes are on the drawing board and a technology that might power them was tested to destruction again last week. A scramjet could propel a vehicle up into Earth orbit, as an air-breathing engine of this kind is theoretically capable of providing the sheer power needed to climb up and out of the planet’s gravity well, and the U.S. military carried out its latest attempt to fly a prototype, over the sea off Southern California last Tuesday.

This trial, like the others before it, ended in failure, when the machine – the hypersonic X-51A “Waverider” – crashed into the ocean, due to a faulty control fin, before the scramjet engine could even be ignited. So it’s really still early days, and we won’t be able to ride in comfort up to space or across to a distant continent in one of those, to the music of Johann Strauss’s Blue Danube waltz (one of my favourite moments from 2001: A Space Odyssey) for some years yet.

Spaceplanes are taking shape, though – on paper and on computer screens. One promising (and British!) example is the Skylon, which is a hydrogen powered spaceplane that could take off from a conventional runway; the SABRE engine powering this vehicle would be an air-breather, technically not a scramjet but a kind of jet/rocket combination.

The Skylon remains a wonderful idea, but at the moment only the military appear to be actually building and testing anything similar, and their motivation, as you’d imagine, has to do with war and the capability of delivering some sort of explosive payload anywhere on the planet within minutes of launching.

However, military technology has a habit of trickling down to the rest of us, given time. The jet engine is an example of this, of course – swiftly developed during World War II (although the concept and early development of the jet engine pre-dates the war), but now powering civilian airliners across the globe, 24/7. And so is the internet. Eventually, something of the sort will be available for the likes of you and me – and even if there is no space station for us to rendezvous with, there’s always the promise of being able to hop from London over to Sydney, or Tokyo or Honolulu in a couple of hours. It would probably be very expensive but you might even be able to commute!

Earth Declares War on N165

On Mars this weekend, the Curiosity rover gets a first chance to try out its ChemCam (Chemistry and Camera) imaging system, which includes a powerful laser – over a period of 10 seconds or so, it will fire off about 30 shots at a designated sitting target, which is located three metres away. This target has been given the imaginative name of N165, and is an otherwise rather unexceptional, small, roughly triangular-looking Martian rock, about 7.5 centimetres wide. The flashes of light generated by the mini laser strikes will then be analysed by Curiosity’s spectrometer, to see what N165 is composed of.

The laser is, of course, a very familiar device, and ubiquitous these days. The first one was built in the 1960s, but before then, in the 1950s, scientists had already developed its older cousin the maser – from “Microwave Amplification by Stimulated Emission of Radiation” – which amplifies microwaves rather than visible light (an early term for the laser was “optical maser”, in fact.)

One of the obvious applications of course, for this emerging technology was as a beam weapon, but – perhaps fortunately – this has not really happened yet, outside the realm of SF and James Bond. This idea can be traced back to the fiction of H.G. Wells, whose Martians wielded a horribly effective Heat Ray after they landed in Surrey, in his 1898 novel The War of the Worlds. Here is the moment when a group of men approach the landing site, hoping to communicate with the visitors from another world:

Beyond the pit stood the little wedge of people with the white flag at its apex, arrested by these phenomena, a little knot of small vertical black shapes upon the black ground. As the green smoke arose, their faces flashed out pallid green, and faded again as it vanished. Then slowly the hissing passed into a humming, into a long, loud, droning noise. Slowly a humped shape rose out of the pit, and the ghost of a beam of light seemed to flicker out from it.

Forthwith flashes of actual flame, a bright glare leaping from one to another, sprang from the scattered group of men. It was as if some invisible jet impinged upon them and flashed into white flame. It was as if each man were suddenly and momentarily turned to fire.

Then, by the light of their own destruction, I saw them staggering and falling, and their supporters turning to run.

If there is microbial life on Mars, and if a deputation of tiny Martians have assembled today on N165, preparing to communicate with this giant visitor from another world, it would be a very odd and ironic – if highly unlikely – twist on the classic tale.

UPDATE

Well, the laser firing seems to have gone well (hopefully with no microscopic Martian pacifists being killed), and now Curiosity has gone for its first drive. We can see tyre tracks!

Curiosity

Next Monday – with a bit of luck – the latest Mars rover mission will land on the red planet without mishap and begin its battery of scientific experiments. NASA’s Mars Science Laboratory, otherwise known as Curiosity, is due to touch down inside the giant Gale crater, which lies on the Martian equator, and once the rover gets itself into gear, it will trundle off to investigate a great mountain of debris in the crater which was named Mount Sharp but is now officially called Aeolis Mons.

Walter Frederick Gale, by the way, was a 19th century Australian astronomer and Mars observer, who like Percival Lowell thought he was able to see canals on the planet’s surface. Robert P Sharp was a geologist who worked for NASA, and the Aeolis quadrangle is one of the 30 subdivisions of the Martian surface, named after Aeolia, the floating island home of Aeolus, the ancient Greek god of the winds.

I find Curiosity a very pleasing and apt name for this mission. I hope that Aeolus will smile on this latest venture, and that the rover will survive the landing and set out, like a nuclear-powered robotic Mini Cooper, to solve a few more of the red planet’s mysteries – CosmOnline has a good article about the mission here.

Perhaps in future centuries they will build a museum for all the brave little machines we have sent to explore the deserts of Mars – they could call it the Hall of the Rovers. Or maybe each one will remain at its last resting place when the batteries finally ran out, and become the centre of its own miniature museum – each one a shrine to the perpetually ingenious and inquisitive human spirit.

Mystery Space Vehicle Returns

In another piece of space news, a mysterious US military shuttle returned from orbit at the weekend, after having been up there for about 15 months, without many people being aware of it! It’s an unmanned Boeing X-37B robotic vehicle and has a compact and appropriately rather sinister, drone-like appearance. And nobody outside the US military knows much more than that. What was it doing up in space for a whole year? Dunno. What was its payload? No idea. What sort of mission was this? Classified. And that’s about it, really.

UPDATE

Here’s an article which has a useful summary of recent space shuttle activity.

Spacewoman from China

Some recent space news – the Chinese have sent their first woman into orbit. Liu Yang is one of a team of three who went up in their Shenzhou 9 launch vehicle and docked successfully on Monday with the orbiting Tiangong 1 spacelab. Does she have the right stuff? According to the Guardian, state news agency Xinhua describes her as a wife, good cook and a “proficient home maker”. Fine attributes maybe, but little clue as to her actual qualities as an astronaut. Other sources, however, mention that when flying an Air Force cargo plane, Liu Yang was able to bring it down in one piece after serious engine damage caused by collision with a flock of pigeons. Now that’s more like it.

Thumbs Up

An encouraging article in Popular Mechanics by veteran astronaut Tom Jones, with some positive feedback for SpaceX and Dragon.

ISS astronauts were impressed with Dragon as a potential transport ship, finding its roomy interior clean and inviting. The mission’s success may build support in Congress for NASA’s dual approach to human spaceflight: fly cargo and crew to low Earth orbit on commercial rockets, built and operated privately, and with those savings focus on deep-space travel with the government’s Orion spacecraft, intended to reach the Moon, lunar orbit outposts, and nearby asteroids. Orion’s first unmanned test flight is planned for 2014.