Goodnight, Phoenix

NASA’s Pheonix lander, which touched down on Mars in late May, has stopped responding:

If you are reading this, then my mission is probably over.

This final entry is one that I asked be posted after my mission team announces they’ve lost contact with me. Today is that day and I must say good-bye, but I do it in triumph and not in grief.

In its five months it photographed water-ice on the surface of Mars, took pictures at close to atomic-level detail, and detected, three kilometres above, the first extra-terresterial snowfall. It was a cool little machine. It’s hoped Phoenix may live up to its namesake after the Martian winter, but it’s unlikely.

As I’ve said before, there’s no other place I’d rather be than here. My mission lasted five months instead of three, and I’m content knowing that I worked hard and accomplished great things during that time. My work here is done, but I leave behind a legacy of images and data.

In that sense, you haven’t heard the end of me. Scientists will be releasing findings based on my data for months, possibly years, to come and today’s children will read of my discoveries in their textbooks. Engineers will use my experience during landing and surface operations to aid in designing future robotic missions.

Well done, Phoenix. Someone’ll be along to dust you off, one day. And it shouldn’t be forgotten that 2004 rovers Spirit and Opportunity are still going.

View satellites in Google Earth

A new Google Earth plugin lets you view all the orbiting satellites currently tracked by the US military. Doesn’t sound very exciting, right? It’s more interesting than you’d think – mainly because the sheer number is almost unbelievable. It’s like a Cylon armada. Clicking on them displays their use and status, and lots are inactive. You can track their orbits, too. If nothing appears, it’s geostationary1, but most have far more complex tracks than you’d think – particularly those further out. Astronomy Cast explaned the reasons behind the strange paths in ‘Getting around the solar system‘, although I’ve apparently forgotten most of it already (I hate that).

  1. apart from the Ryman satellite, which is geostationery []

Keeping up with the cosmologists

If I could alter my brain and adapt to one particular profession, high on my list would be a cosmologist. It’s just such a cool time to be alive, in terms of space probes confirming or disproving theories, and the universe throwing curve balls at every step. Unfortunately the maths is way beyond my capability1, but I’ve been roughly following the field for years and years. I find that it’s important to actually keep up with developments, as things are rapidly changing. For example, the last couple of years have seen large changes in the understanding of dark matter and dark energy.

Dark matter is matter that only indicates its existence through its gravitational effect on other matter – it’s not detectable in any other way. But another interpretation of this is that our understanding of gravity is wrong. This was still an option when I took an Open University cosmology course a few years back, but recent observations pretty much killed that theory.

Dark energy is the mysterious force causing the acceleration of the universe to increase, and analyses of the movements of massive-scale galaxy clusters have shown they move exactly as predicted by current theories of gravity – if dark energy were also a flaw in our understanding, it’d be detectable at those levels2.

We’re figuring this all out right now. That is cool. The best I can do is stand at the sidelines and catch what I can, which is why I like Astronomy Cast so much – I can follow recent developments without great amounts of effort on my part, which suits me just fine 🙂 Today’s episode caught me out – I thought I roughly understood the concept of the shape of the universe, but their recent episode on the topic caused many WTF moments. I’m a little out of date. It turns out that the WMAP probe has found the universe is likely to be totally flat – no matter how big a triangle you draw in space, the angles will always add up to 180 – but, this requires fine-tuning to an insane degree, as a difference of 1 in 447 sextillion in densities during the big bang would have created a non-flat universe. So there’s got to be either a) some new physics out there or b) a bajillion big bangs, and we have to be in one of them. Wow!

Wish I could be a cosmologist. Can’t, though, but I’ll try to keep up – I’d hate to be alive and miss it all.

  1. took the maths A-level twice and got worse, baby []
  2. at least, I’m pretty sure this was the study, I can’t find a link right now though []

Google Sky

Google today released an update to Google Earth which adds the night sky, complete with images of galaxies and nebulae, as well as planetary motion, wikipedia links and constellations. A cheezeball video on the GE website introduces the basics (update: much much much better video here). This sounded most exciting, so I downloaded the update.

It is, initially, underwhelming.

The positions of the objects base themselves around your location in Google Earth, so I set it to my address and hit the ‘sky’ button. I saw black, with lines and coloured dots. Not as beautiful as I was hoping. There is no artificial horizon, so you start essentially floating in the middle of a black sphere. A myriad of constellation lines and names takes up much of the screen. I guess some people are interested in arbitrary groups of stars; I’m not. Thankfully, they can be easily turned off in a Layer panel similar to Google Earth’s.

Slightly disappointed, I played around with the layers. ‘Planets in Motion’ adds a slider, which when dragged shows the movement of the planets over the next three months. This was kinda fun. My search for Saturn failed, so I scrolled around manually until I spotted it, and zoomed in.

Google Sky screenshotAt which point: wow.

Once you start to zoom, GS downloads higher-resolution images in the same way as GE. And what images! Starry Night and other astronomy programs can map the stars, but don’t use real photographs, and it makes a hell of a difference. I haven’t tested it fully, but they seem to cover most, if not all, of the sky. The milky-way is a patchwork of glowing dust. The ring around Polaris is a bit weird, but everything else seems to be very high-quality. Hubble images are correctly located – check out the orion and horsehead nebulae (searching for stars / other objects seems to work better than planets). And you can keep zooming and zooming and zooming.

There is nothing like looking at images of billions and billions of stars. It’s astonishing.

The red and blue dots represent interesting sights: the Messier objects are included, all with associated information, along with the 12000-object New General Catalog and Yale Bright Star catalog. Between them these pick out the most interesting items in the sky, and each click brings fresh wonder.

The only obvious omission is the artificial horizon. Perhaps they’re concerned about competing with commercial products such as Starry Night. But Picasa is free and possibly the best image-manager out there, regardless of price, so this seems unlikely. Hopefully they’ll add one later – being able to view an easy-to-understand map of the sky above your head would be wonderful.

Google’s massive database means there’s huge potential here. I want to zoom in on Mars and see the Spirit and Odyssey photos. I want to see moon craters, comets and the real-time position of the international space station. I want to be able to switch to infra-red.

Don’t let the initial impressions put you off. Search for ‘ultra deep field’, and you’ll see objects which were exposed at the rate of one photon per minute. This is light from over 13 billion years ago, when the universe had barely begun. This is an amazing thing to release for free, and worth spending time with.

Update: From the discussion forum:

We had the horizon in during beta testing and the testers recommended
removing it because it was very confusing. Instead, you go somewhere
on Earth and then click SKY and see what is overhead.

We could consider bringing the horizon back, but it was confusing.

We really want Sky and Earth integrated….someday

The ecliptic could be added. We will think about it!

That’s a shame…Hopefully enough people are complaining about it that it’ll be back. The same post pointed out that CTRL-L will display the sphere’s grid, which makes the view a little more comprehensible, but is unfortunately bright red…

Three-and-a-bit Interesting Thursday Things

Via BA, a scale image of all known planetary bodies with a diameter of over 200 miles. It’s fascinating. I knew there were moons larger than Mercury, but Ganymede’s not all that much smaller than Mars. I’d be annoyed if I were that big and still called a moon.

In 1986, in a remote area of Cameroon, 1800 people in a circle of 12-mile radius abruptly fell over and died. Scientists investigated, and after a year’s research realised measures were needed to prevent it happening again. Neatorama has the full story.

And, why eBooks are better than, er, Books, when it comes to bathtime. Read the various bookshop blogs and you’d think eBooks were the worst idea since marmite, but I’m happy to discover there are blogs who think otherwise. Andrew Marr, too. Booksquare – it of the wonderful header illustration – thinks the iPhone might be a major step forward

Happy Birthday to Opportunity

Happy Birthday to Opportunity, the Mars rover which landed safely three years ago today. I was sitting in a York car park when I heard the news, and had to cheer. Despite the design aim of 90 sols (Mars days), it’s still going 1000 sols later, and has travelled 6.1 miles. Brilliant. Far from becoming decrepid in its old age, it’s actually getting smarter due to software upgrades.

OpportunitySol1036PancamL257View2 Soil closeup


Is there anything cooler than space probes?

Liquid water flowing on Mars

Generally, if somebody describes planetary activity as ‘recent’ they mean on geological timescales: a few hundred thousand years or so. So the BBC headline announcing ‘recent’ water flow on Mars perhaps sounds less impressive than when you discover it means in the last seven years. Although not conclusive, comparisons of two photographs taken seven years apart strongly suggest water flow in the intervening period. The team leader called the possibility of liquid water ‘high, but not extremely high’, although some are apparently calling it ‘a squirting gun’. It seems increasingly likely that there’s water not far under the surface, and it escapes occasionally in flash floods then immediately boils in the low atmospheric pressure. Two immediate thoughts:

  • On Earth at least, where there’s water there’s life.
  • A base on Mars just became much more feasible.

The evidence comes from a photograph taken by the Mars Global Surveyor, but unfortunately the probe was so surprised at the discovery that it promptly died. Not bad for a ten year old machine, though. The newly-arrived Mars Reconnaissance Orbiter, with its amazing 1-2 meter-per-pixel resolution camera, will presumably be asked to take a closer look.

The best coverage, as ever, comes from Bad Astronomy.

The problem of scale

Learning anything about physics always involves grappling with the problem of scale. Whether incredibly small or ridiculously large, the human brain hasn’t evolved to cope with the kind of extreme number necessary for investigation into nature’s workings. Science writers do their best to think up real-world analogies, but the nature of the number makes this extremely difficult to do.

If you created a scale model of the solar system in which the sun was a metre wide, Earth would be just under 1cm across, 100m away; Jupiter would be 10cm across, 560m away; Pluto would be just over 1.6mm across, 4.5km (2.8 miles) in the distance. This is already getting hard to grasp – the sheer amount of empty space boggles the mind. Outside of the solar system, the nearest star – Alpha Centaurai – would be 29km (18 miles) away. The centre of the milky way? 188,340,398 kilometres away – on our scale model it would be placed about a fifth of the way between Mars and Jupiter. Current estimates are that there exist around 100 billion galaxies within the visible universe.

Time’s just as bad. The best analogy I’ve heard came from Richard Dawkins: if you stretch out your arm and use the distance from the centre of your body to your fingertip to represent the time since the formation of Earth, brushing the edge of your fingernail would wipe away the dust representing the entire period of man’s existence.

At the other end of the size scale are atoms and molecules. The average small glass of water contains about 225 cubic centimetres of water. This works out at 7,525,000,000,000,000,000,000,000 molecules of water. This is far larger than the number of sand grains in the Sahara, and probably more than there are on the entire planet.

Richard Feynman came up with a good analogy for representing the size of an atom: if you enlarged an apple to the size of the Earth, the atoms would be roughly the size of the original apple. What’s amazing is that we can directly view atoms, in some cases, using electron microscopes. But that’s only half of it, because atoms themselves are almost completely empty, to a staggering degree. This website is a scale model of a hydrogen atom (on most computer monitors). Electrons and protons are close enough in size that they can be visualised in reference to each other, but the distance between them cannot. Make the electron the size of a pixel, and the proton about 1000 pixels across, and there’s still eleven miles of emptiness between the two.

The most insane analogy I ever read was from string theorist Brian Greene, when talking about the relative sizes of the theoretical strings which comprise all matter. He says that a string is to an atom as a tree is to the known universe. Unsurprisingly, nobody’s yet come up with a way to verify the existence of something so small.

Large numbers are sometimes useful for debunkage. Homeopathic ‘remedies’ supposedly increase in potency as they are diluted. A relatively standard amount of dilution is ’30C’, which means that the amount of ‘remedy’ is to reduced 1 in 100, thirty times over. When you figure it out (I’m going by what somebody tells me on this one, since I keep messing up the calculations) this is equivalent to placing one cubic centimetre of substance into a sphere of water with a radius of 800 light years, stirring until randomly distributed, then taking a cupful. It’s highly unlikely there’ll even be one molecule of the original substance in the cup, and that’s amongst the aforementioned 7 million billion billion molecules. And there are other remedies which claim potencies of 200C.

Hopefully the maths in the above stands up to scrutiny – let me know if I’ve made any silly mistakes! For some reason these numbers are astonishing me even more than usual, today.