Archive for ESA

Not Now, Voyager

Posted in The Universe and Stuff with tags , , , , , , on July 10, 2011 by telescoper

Last week I found myself a bit perplexed by the frenzy of twitter angst surrounding the last ever launch of the Space Shuttle. It’s not the first time something like this has happened. I’ve often felt like there must be something wrong with me for not getting agitated over such things. After Altantis returns to Earth in a couple of weeks’ time she will be taken out of service and, for the foreseeable future, America will no longer have the ability to put humans into orbit. This does mark the end of an era, of course, but is it really something to get all upset about?

I find myself agreeing with the Guardian editorial, which I’ve taken the liberty of copying here:

Fewer than 600 people have been admitted an exclusive club: space travel. Now, with the last flight of the space shuttle under way, the membership list is harder to join than ever. When Yuri Gagarin orbited the earth, half a century ago, and when astronauts landed on the moon eight years later, it would have been inconceivable to think of a time when manned space flight began to slip from the present to the past. But America, at least for the moment, no longer has the capacity to send people into space. In terms of national pride, this may be a failure. In terms of scientific advancement, it may not matter that much at all. Deep space exploration – using robot probes – is a very different and more useful thing than the expensive and unreliable effort to send human beings into low earth orbit, no further from Cape Canaveral than New York. The shuttle has been an icon of its age, but its human passengers – however brave and skilled – have made their flights as much to show the world what America could do as for any particular and necessary purpose. Even the International Space Station, extraordinary though it is, could operate without a human presence, its experiments automated. The only good argument for sending people into space is the simple daring of it – the need, as Star Trek used to claim, “to boldly go where no man has gone before”. Visit Mars, by all means – but there is little to be gained by sending astronauts to orbit this planet, not all that far above our heads.

For me, the most remarkable thing about the Space Shuttle is how matter-of-fact it has become. It’s rather like Concorde, which was an engineering marvel that people would drop everything and gawp at when it  first appeared, but which soon became a part of everyday life. Technology is inevitably like that – what seemed remarkable twenty years ago is now pretty commonplace.

I had similar feelings a couple of  years ago, when Planck and Herschel were launched. Of course I was extremely nervous then , because many of my colleagues had invested so much time and effort in these missions. However, watching the behaviour of the mission control staff at ESA during the launch it struck me how routine it all was for them. It’s a great achievement, I think, to take something so complex and turn it into an everyday operation.

Incidentally, it always strikes me as curious that people use the phrase “rocket science” to define something incredibly difficult. In fact rocket science is extremely simple: the energy source is one of the simplest chemical reactions possible, and the path of the rocket is a straightforward consequence of Newton’s laws of motion. It’s turning this simple science into working technology where the difficulties lie, and it’s a powerful testament to the brilliance of the engineers working in the space programme that workable solutions have been found and implemented in working systems.

So now the era of the Shuttle has passed, what next? Should America (and Europe, for that matter) be aiming to send people to Mars? Should manned spaceflight resume at all?

Different people will answer these questions in different ways. Speaking purely from a scientific point of view I would say that manned space exploration just isn’t cost effective. But going to Mars isn’t really about science; going to the Moon wasn’t either. It’s partly an issue of national pride – note how loss of the Shuttle programme has effectively ended America’s dominance in space, and how keenly that has been felt by many US commentators.

Others argue that manned space flight inspires people to become scientists, and should be done for that reason. I can’t speak for anyone but myself, and I’m sure there will be many who disagree with me, but it wasn’t the Apollo missions that inspired me to become a scientist. When I was a kid I found the footage of people jumping around on the Moon rather boring, to be honest. What inspired me was the excellent science education I received at School. And just think how many physics teachers you could train for the cost of, e.g. the ESA Aurora program

Another argument is “because it’s there” or, as Walt Whitman put it,

THE untold want, by life and land ne’er granted,
Now, Voyager, sail thou forth, to seek and find.

As a species we have an urge to set challenges for ourselves, whether by asking difficult questions, by designing and building difficult devices, or by attempting difficult journeys – sometimes all three! This is our nature and we shouldn’t shy away from it. But we should also recognize that “going there” is just one of the ways in which we can explore the cosmos. Modern telescopes can see almost to the visible edge of the Universe, the Large Hadron Collider can probe scales much smaller than the nucleus of an atom. I worry sometimes that the political lobbying for manned space flight often seems to be arguing that it should be funded by taking money from other, more fundamental, scientific investigations. Astronomers and particle physcisists are explorers too, and they also inspire. Don’t they?

Gravity waves goodbye to LISA?

Posted in Science Politics, The Universe and Stuff with tags , , , on April 8, 2011 by telescoper

It seems that we’re not allowed to have any good news these days without a bit of bad to go with it. This week it has emerged here and there that the US National Aeronautics and Space Administration (better known as NASA) is pulling the plug on one of the most exciting space missions on its drawing board. Feeling the pressure of budget constraints and a ballooning overspend on the James Webb Space Telescope (JWST), NASA has decided not to participate further in the Laser Interferometric Space Antenna, a.k.a. LISA. The project teams working on LISA have been disbanded, and the shutters have been pulled down on a project which would have revolutionised astrophysics by opening up new possibilities of observing astronomical objects using gravitational waves, rather than electromagnetic radiation.

This does not mean that LISA is necessarily completely dead. For one thing, it was always planned to be a partnership between NASA and its European counterpart ESA (the European Space Agency); you can find ESA’s LISA page here. In fact a technological demonstrating mission LISA-Pathfinder, operated by ESA, is scheduled for launch in 2013.
It remains possible that ESA will proceed on its own with some version of LISA, although given its own financial constraints it is unlikely that it will be able to fund the full original mission concept. The best we can hope for, therefore, is probably some slimmed-down low-budget version and perhaps an even later launch date.

I still hold out some hope that LISA might come out of mothballs when gravitational waves are actually detected. This may well be accomplished by Advanced LIGO, a ground-based interferometric system based in the states, although it has to be said that gravitational waves have been “on the brink of detection” for at least 30 years and still haven’t actually been found. When detection does become a reality it might galvanise NASA into finding room in its budget again.

This news will be a particularly concern for the sizeable Gravitational Physics group here in the School of Physics & Astronomy at Cardiff University. However, LISA was very much in the planning and development stages so it won’t impact their current work. I haven’t had the chance to discuss the news about LISA with members of this group, so I’d be interested to receive comments from them, or indeed anyone else who knows more about what NASA’s decision may or not mean for the future of gravitational wave physics.


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First Science from Planck

Posted in The Universe and Stuff with tags , , , , , , , , , on January 11, 2011 by telescoper

It’s been quite a long wait for results to emerge from the Planck satellite, which was launched in May 2009, but today the first science results have at last been released. These aren’t to do with the cosmological aspects of the mission – those will have to wait another two years – but things we cosmologists tend to think of as “foregrounds”, although they are of great astrophysical interest in themselves.

For an overview, with lots of pretty pictures,  see the European Space Agency’s Planck site and the UK Planck outreach site; you can also watch this morning’s press briefing in full here.

A repository of all 25 science papers can be found here and there’ll no doubt be a deluge of them on the arXiv tomorrow.

A few of my Cardiff colleagues are currently in Paris living it up at the junket working hard at the serious scientific conference at which these results are being discussed. I, on the other hand, not being one of the in-crowd, am back here in Cardiff, only have a short window in between meetings, project vivas and postgraduate lectures  to comment on the new data. I’m also sure there’ll be a huge amount of interest in the professional media and in the blogosphere for some time to come. I’ll therefore just mention a couple of things that struck me immediately as I went quickly through the papers while I was eating my sandwich; the following was cobbled together from the associated ESA press release.

The first concerns the so-called  ‘anomalous microwave emission’ (aka Foreground X) , which is a diffuse glow most strongly associated with the dense, dusty regions of our Galaxy. Its origin has been a puzzle for decades, but data collected by Planck seem to confirm the theory that it comes from rapidly spinning dust grains. Identifying the source of this emission will help Planck scientists remove foreground contamination which much greater precision, enabling them to construct much cleaner maps of the cosmic microwave background and thus, among other things, perhaps clarify the nature of the various apparent anomalies present in current cosmological data sets.

Here’s a nice composite image of a region of anomalous emission, alongside individual maps derived from low-frequency radio observations as well as two of the Planck channels (left).

Credits: ESA/Planck Collaboration

The colour composite of the Rho Ophiuchus molecular cloud highlights the correlation between the anomalous microwave emission, most likely due to miniature spinning dust grains observed at 30 GHz (shown here in red), and the thermal dust emission, observed at 857 GHz (shown here in green). The complex structure of knots and filaments, visible in this cloud of gas and dust, represents striking evidence for the ongoing processes of star formation. The composite image (right) is based on three individual maps (left) taken at 0.4 GHz from Haslam et al. (1982) and at 30 GHz and 857 GHz by Planck, respectively. The size of the image is about 5 degrees on a side, which is about 10 times the apparent diameter of the full Moon.

The second of the many other exciting results presented today that I wanted to mention is a release of new data on clusters of galaxies – the largest structures in the Universe, each containing hundreds or even thousands of galaxies. Owing to the Sunyaev-Zel’dovich Effect these show up in the Planck data as compact regions of lower temperature in the cosmic microwave background. By surveying the whole sky, Planck stands the best chance of finding the most massive examples of these clusters. They are rare and their number is a sensitive probe of the kind of Universe we live in, how fast it is expanding, and how much matter it contains.

Credits: ESA/Planck Collaboration; XMM-Newton image: ESA

This image shows one of the newly discovered superclusters of galaxies, PLCK G214.6+37.0, detected by Planck and confirmed by XMM-Newton. This is the first supercluster to be discovered through its Sunyaev-Zel’dovich effect. The effect is the name for the cluster’s silhouette against the cosmic microwave background radiation. Combined with other observations, the Sunyaev-Zel’dovich effect allows astronomers to measure properties such as the temperature and density of the cluster’s hot gas where the galaxies are embedded. The right panel shows the X-ray image of the supercluster obtained with XMM-Newton, which reveals that three galaxy clusters comprise this supercluster. The bright orange blob in the left panel shows the Sunyaev-Zel’dovich image of the supercluster, obtained by Planck. The X-ray contours are also superimposed on the Planck image.

UPDATES: For other early perspectives on the early release results, see the blogs of Andrew Jaffe and Stuart Lowe; as usual, Jonathan Amos has done a very quick and well-written news piece for the BBC.


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Hot Stuff, Looking Cool..

Posted in The Universe and Stuff with tags , , , , , on September 15, 2010 by telescoper

It’s nice for a change to have an excuse to write something about science rather than science funding, as a press release appeared today concerning the discovery of a new supercluster by Planck in collaboration with the X-ray observatory XMM-Newton.

The physics behind this new discovery concerns what happens to low-energy photons from the cosmic microwave background (CMB) when they are scattered by extremely hot plasma. Basically, incoming microwave photons collide with highly energetic electrons with the result that they gain energy and so are shifted to shorter wavelengths. The generic name given to this process is inverse Compton scattering, and it can happen in a variety of physical contexts. In cosmology, however, there is a particularly important situation where this process has observable consequences, when CMB photons travel through the extremely hot (but extremely tenuous) ionized gas in a cluster of galaxies. In this setting the process is called the Sunyaev-Zel’dovich effect.

The observational consequence is slightly paradoxical because what happens is that the microwave background can appears to have a lower temperature (at least for a certain range of wavelengths) in the direction of a galaxy cluster (in which the plasma can have a temperature of 10 million degrees or more). This is because fewer photons reach the observer in the microwave part of the spectrum that would if the cluster did not intervene; the missing ones have been kicked up to higher energies and are therefore not seen at their original wavelength, ergo the CMB looks a little cooler along the line of sight to a cluster than in other directions. To put it another way, what has actually happened is that the hot electrons have distorted the spectrum of the photons passing through it.

Here’s an example of the Sunyaev-Zel’dovich effect in action as seen by Planck in seven frequency bands:

At low frequencies (in the Rayleigh-Jeans part of the spectrum) the region where the cluster is looks cooler than average, although at high frequencies the effect is reversed.

The magnitude of the temperature distortion produced by a cluster depends on the density of electrons in the plasma pervading the cluster n, the temperature of the plasma T, and the overall size of the cluster; in fact, it’s propotional to n×T integrated along the line of sight through the cluster.

Why this new result is so interesting is that it combines very sensitive measurements of the microwave background temperature pattern  with sensitive measures of the X-ray emission over the same region of the sky. Plasma hot enough to produce a Sunyaev-Zel’dovich distortion of the CMB spectrum will also generate X-rays through a process known as thermal bremsstrahlung.  The power of the X-ray emission depends on the square of the electron density n2 multiplied by the Temperature T.

Since the Sunyaev-Zel’dovich and X-ray measurements depend on different mathematical combinations of the physical properties involved the amalgamation of these two techniques allows astronomers to probe the internal details of the cluster quite precisely.

The example shown here in the top two panels is of a familiar cluster – the Coma Cluster as mapped by Planck (in microwaves) and, by an older X-ray satellite called ROSAT, in X-rays. The two distributions have very similar morphology, strongly suggesting that they have a common origin in the cluster plasma.

The bottom panels show comparisons with the distribution of galaxies as seen in the optical part of the spectrum. You can see that the hot gas I’ve been talking about extends throughout the space between the galaxies. In fact, there is at least as much matter in the hot plasma as there is in the individual galaxies in objects like this, but it’s too hot to be seen in optical light. This could reasonably be called dark matter when it comes to its lack of optical emission, but it’s certainly not dark in X-rays!

The reason why the intracluster plasma is so hot boils down to the strength of the gravitational field in the cluster. Roughly speaking, the hot matter is in virial equilibrium within the gravitational potential generated by the mass distribution within the cluster. Since this is a very deep potential well, electrons move very quickly in response to it. In fact, the galaxies in the cluster are also roughly in virial equilibrium so they too are pulled about by the gravitational field. Galaxies don’t sit around quietly in clusters, they buzz about like bees in a bottle.

Anyway, the new data arising from the combination of Planck and XMM-Newton has revealed not just one cluster, but a cluster of clusters (i.e. a “supercluster”):

It’s early days for Planck, of course, and this is no more than a taster.
The Planck team is currently analysing the data from the first all-sky survey to identify both known and new galaxy clusters for the early Sunyaev-Zel’dovich catalogue, which will be released in January of 2011 as part of the Early Release Compact Source Catalogue. The full Sunyaev-Zel’dovich catalogue may well turn out to be the most enduring legacy of the Planck mission.


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The Next Decade of Astronomy?

Posted in Science Politics, The Universe and Stuff with tags , , , , , , , on August 14, 2010 by telescoper

I feel obliged to pass on the news that the results of the Decadal Review of US Astronomy were announced yesterday. There has already been a considerable amount of reaction to what the Review Panel (chaired by the esteemed Roger Blandford) came up with from people much more knowledgeable about observational astronomy and indeed US Science Politics, so I won’t try to do a comprehensive analysis here. I draw your attention instead to the report itself  (which you can download in PDF form for free)  and Julianne Dalcanton’s review of, and comments on, the Panel’s conclusions about the priorities for  space-based and ground-based astronomy for the next decade or so over on Cosmic Variance.  There’s also a piece by Andy Lawrence over on The e-Astronomer’s blog. I’ll just mention that Top of the Pops for space-based astronomy is the Wide-Field Infrared Survey Telescope (WFIRST) which you can read a bit more about here, and King of the Castle for the ground-based programme is the Large Synoptic Survey Telescope (LSST). Both of these hold great promise for the area I work in – cosmology and extragalactic astrophysics – so I’m pleased to see our American cousins placing such a high priority on them. The Laser Interferometer Space Antenna (LISA), which is designed to detect gravitational waves, also did very well, which is great news for Cardiff’s Gravitational Physics group.

It will be interesting to see what effect – if any – these priorities have on the ranking of corresponding projects this side of the Atlantic. Some of the space missions involved in the Decadal Review in fact depend on both NASA and ESA so there clearly will be a big effect on such cases. For example, the proposed International X-ray Observatory (IXO) did less well than many might have anticipated, with clear implications for  Europe (including the UK).  The current landscape  of X-ray astronomy is dominated by Chandra and XMM, both of which were launched in 1999 and which are both nearing the end of their operational lives. Since X-ray astronomy can only be done from space, abandoning IXO would basically mean the end of the subject  as we know it, but the question is how to bridge the  the gap between the end of these two missions and the start of IXO even if it does go ahead but not until long after 2020? Should we keep X-ray astronomers on the payroll twiddling their thumbs for the next decade when other fields are desperately short of manpower for science exploitation?

On a more general level, it’s not obvious how we should react when the US gives a high priority to a given mission anyway. Of course, it gives us confidence that we’re not being silly when very smart people across the Pond endorse missions and facilities similar to ones we are considering over here. However, generally speaking the Americans tend to be able to bring missions from the drawing board to completion much faster than we can in Europe. Just compare WMAP with Planck, for instance. Trying to compete with the US, rather than collaborate, seems likely to ensure only that we remain second best. There’s an argument, therefore, for Europe having a programme that is, in some respects at least, orthogonal to the United States; in matters where we don’t collaborate, we should go for facilities that complement rather than compete with those the Americans are building.

It’s all very well talking of priorities in the UK but we all know that the Grim Reaper is shortly going to be paying a visit to the budget of the  agency that administers funding for our astronomy, STFC. This organization went through a financial crisis all of its very own in 2007 from which it is still reeling. Now it has to face the prospect of further savage cuts. The level of “savings” being discussed  – at least 25%  -means that the STFC management must be pondering some pretty drastic measures, even pulling out of the European Southern Observatory (which we only joined in 2002). The trouble is that most of the other ground-based astronomical facilities used by UK astronomers have been earmarked for closure, or STFC has withdrawn from them. Britain’s long history of excellence in ground-based astronomy now hangs in the balance. It’s scary.

I hope the government can be persuaded that STFC should be spared another big cut and I’m sure that there’s extensive lobbying going on.  Indeed, STFC has already requested input to its plans for the ongoing Comprehensive Spending Review (CSR). With this in mind, the Royal Astronomical Society has produced a new booklet designed to point out the  relevance of astronomy to wider society. However I can’t rid from my mind the memory a certain meeting in London in 2007 at which the STFC Chief Executive revealed the true scale of STFC’s problems. He predicted that things would be much worse at the next CSR, i.e. this one. And that was before the Credit Crunch, and the consequent arrival of a new government swinging a very large axe. I wish I could be optimistic but, frankly, I’m not.

When the CSR is completed then STFC will have yet again to do another hasty re-prioritisation. Their Science Board has clearly been preparing:

… Science Board discussed a number of thought provoking scenarios designed to explore the sort of issues that the Executive may be confronted with if there were to be a significant funding reduction as a result of the 2010 comprehensive spending review settlement. As a result of these deliberations Science Board provided the Executive with guidance on how to take forward this strategic planning.

This illustrates a big difference in the way such prioritisation exercises are carried out in the UK versus the USA. The Decadal Review described above is a high-profile study, carried out by a panel of distinguished experts, which takes detailed input from a large number of scientists, and which delivers a coherent long-term vision for the future of the subject. I’m sure not everyone agrees with their conclusions, but the vast majority respect its impartiality and level-headedness and have confidence in the overall process. Here in the UK we have “consultation exercises” involving “advisory panels” who draw up detailed advice which then gets fed into STFC’s internal panels. That bit is much like the Decadal Review. However, at least in the case of the last prioritisation exercise, the community input doesn’t seem to bear any obvious relationship to what comes out the other end. I appreciate that there are probably more constraints on STFC’s Science Board than it has degrees of freedom, but there’s no getting away from the sense of alienation and cynicism this has generated across large sections of the UK astronomy community.

The problem with our is that we always seem to be reacting to financial pressure rather than taking the truly long-term “blue-skies” view that is clearly needed for big science projects of the type under discussion. The Decadal Review, for example, places great importance on striking a balance between large- and small-scale experiments. Here we tend slash the latter because they’re easier to kill than the former. If this policy goes on much longer, in the long run we’ll end up a with few enormous expensive facilities but none of the truly excellent science that can be done from using smaller kit.  A crucial aspect of this that that science seems to have been steadily relegated in importance in favour of technology ever since the creation of STFC.  This must be reversed. We need a proper strategic advisory panel with strong scientific credentials that stands outside the existing STFC structure but which has real influence on STFC planning, i.e. one which plays the same role in the UK as the Decadal Review does in the States.

Assuming, of course, that there’s any UK astronomy left in the next decade…

Space: The Final Frontier?

Posted in The Universe and Stuff with tags , , , , , , , on July 9, 2010 by telescoper

I found this on my laptop just now. Apparently I wrote it in 2003, but I can’t remember what it was for. Still, when you’ve got a hungry blog to feed, who cares about a little recycling?

It seems to be part of our nature for we humans to feel the urge  to understand our relationship to the Universe. In ancient times, attempts to cope with the vastness and complexity of the world were usually in terms of myth or legend, but even the most primitive civilizations knew the value of careful observation. Astronomy, the science of the heavens, began with attempts to understand the regular motions of the Sun, planets and stars across the sky. Astronomy also aided the first human explorations of own Earth, providing accurate clocks and navigation aids. But during this age the heavens remained remote and inaccessible, their nature far from understood, and the idea that they themselves could some day be explored was unthinkable. Difficult frontiers may have been crossed on Earth, but that of space seemed impassable.

The invention of the telescope ushered in a new era of cosmic discovery, during which we learned for the first time precisely how distant the heavenly bodies were and what they were made of.  Galileo saw that Jupiter had moons going around it, just like the Earth. Why, then, should the Earth be thought of as the centre of the Universe? The later discovery, made in the 19th Century using spectroscopy, that the Sun and planets were even made of the same type of material as commonly found on Earth made it entirely reasonable to speculate that there could be other worlds just like our own. Was there any theoretical reason why we might not be able to visit them?

No theoretical reason, perhaps, but certainly practical ones. For a start, there’s the small matter of getting “up there”. Powered flying machines came on the scene about one hundred years ago, but conventional aircraft simply can’t travel fast enough to escape the pull of Earth’s gravity. This problem was eventually solved by adapting technology developed during World War II to produce rockets of increasingly large size and thrusting power. Cold-war rivalry between the USA and the USSR led to the space race of the 1960s culminating in the Apollo missions to the Moon in the late 60s and early 70s. These missions were enormously expensive and have never been repeated, although both NASA and the European Space Agency are currently attempting to gather sufficient funds to (eventually) send manned missions to Mars.

But manned spaceflights have been responsible for only a small fraction of the scientific exploration of space. Robotic probes have been dispatched all over the Solar System. Some have failed, but at tiny fraction of the cost of manned missions. Landings have been made on the solid surfaces of Venus, Mars and Titan and probes have flown past the beautiful gas giants Jupiter, Saturn, Uranus and Neptune taking beautiful images of these bizarre frozen worlds.

Space is also a superb vantage point for astronomical observation. Above the Earth’s atmosphere there is no twinkling of star images, so even a relatively small telescope like the Hubble Space Telescope (HST) can resolve details that are blurred when seen from the ground. Telescopes in space can also view the entire sky, which is not possible from a point on the Earth’s surface. From space we can see different kinds of light that do not reach the ground: from gamma rays and X-rays produced by very energetic objects such as black holes, down to the microwave background which bathes the Universe in a faint afterglow of its creation in the Big Bang. Recently the Wilkinson Microwave Anisotropy Probe (WMAP) charted the properties of this cosmic radiation across the entire sky, yielding precise measurements of the size and age of the Universe. Planck and Herschel are pushing back the cosmic frontier as I write, and many more missions are planned for the future.

Over the last decade, the use of dedicated space observatories, such as HST and WMAP, in tandem with conventional terrestrial facilities, has led to a revolution in our understanding of how the Universe works. We are now convinced that the Universe began with a Big Bang, about 14 billion years ago. We know that our galaxy, the Milky Way, is just one of billions of similar objects that condensed out of the cosmic fireball as it expanded and cooled. We know that most galaxies have a black hole in their centre which gobbles up everything falling into it, even light. We know that the Universe contains a great deal of mysterious dark matter and that empty space is filled with a form of dark energy, known in the trade as the cosmological constant. We know that our own star the Sun is a few billion years old and that the planets formed from a disk of dusty debris that accompanied the infant star during its birth. We also know that planets are by no means rare: nearly two hundred exoplanets (that is, planets outside our Solar System) have so far been discovered. Most of these are giants, some even larger than Jupiter which is itself about 300 times more massive than Earth, but this may simply because big objects are easier to find than small ones.

But there is still a lot we still don’t know, especially about the details. The formation of stars and planets is a process so complicated that it makes weather forecasting look simple. We simply have no way of knowing what determines how many stars have solid planets, how many have gas giants, how many have both and how many have neither. In order to support life, a planet must be in an orbit which is neither too close to its parent star (where it would be too hot for life to exist) nor too far aware (where it would be too cold). We also know very little about how life evolves from simple molecules or how robust it is to the extreme environments that might be found elsewhere in our Universe. It is safe to say that we have no absolutely idea how common life is within our own Galaxy or the Universe at large.

Within the next century it seems likely that we will whether there is life elsewhere in our Solar System. We will probably also be able to figure out how many earth-like exoplanets there are “out there”. But the unimaginable distances between stars in our galaxy make it very unlikely that crude rocket technology will ever enable us to physically explore anything beyond our own backyard for the foreseeable future.

So will space forever remain the final frontier? Will we ever explore our Galaxy in person, rather than through remote observation? The answer to these questions is that we don’t know for sure, but the laws of nature may have legal loopholes (called “wormholes”) that just might allow us to travel faster than light if we ever figure out how to exploit them. If we can do it then we could travel across our Galaxy in hours rather than aeons. This will require a revolution in our understanding not just of space, but also of time. The scientific advances of the past few years would have been unimaginable only a century ago, so who is to say that it will never happen?

Ten Facts about Space Exploration

  1. The human exploration of space began on October 4th 1957 when the Soviet Union launched Sputnik the first man-made satellite. The first man in space was also a Russian, Yuri Gagarin, who completed one orbit of the Earth in the Vostok spacecraft in 1961. Apparently he was violently sick during the entire flight.
  2. The first man to set foot on the Moon was Neil Armstrong, on July 20th 1969. As he descended to the lunar surface, he said “That’s one small step for a man, one giant leap for mankind.”
  3. In all, six manned missions landed on the Moon (Apollo 11, 12, 14, 15, 16 and 17; Apollo 13 aborted its landing and returned to Earth after an explosion seriously damaged the spacecraft). Apollo 17 landed on December 14th 1972, since when no human has set foot on the lunar surface.
  4. The first reusable space vehicle was the Space Shuttle, four of which were originally built. Columbia was the first, launched in 1981, followed by Challenger in 1983, Discovery in 1984 and Atlantis in 1985.  Challenger was destroyed by an explosion shortly after takeoff in 1992, and was replaced by Endeavour. Columbia disintegrated over Texas while attempting to land in 2003.
  5. Viking 1 and Viking 2 missions landed on surface of Mars in 1976; they sent back detailed information about the Martian soil. Tests for the presence of life proved inconclusive, but there is strong evidence that Mars once had running water on its surface.
  6. The outer planets (Jupiter, Saturn, Uranus and Neptune) have been studied by numerous fly-by probes, starting with Pioneer 10 (1973) and Pioneer 11 (1974) . Voyager 1 and Voyager 2 flew past Jupiter in 1979;  Voyager 2 went on to visit Uranus (1986)  and Neptune (1989) after receiving a gravity assist from a close approach to Jupiter. These missions revealed, among other things, that all these planets have spectacular ring systems – not just Saturn. More recently, in 2004, the Cassini spacecraft launched the Huygens probe into the atmosphere of Titan. It survived the descent and sent back amazing images of the surface of Saturn’s largest moon.
  7. Sending a vehicle into deep space requires enough energy to escape the gravitational pull of the Earth. This means exceeding the escape velocity of our planet, which is about 11 kilometres per second (nearly 40,000 kilometres per hour). Even travelling at this speed, a spacecraft will take many months to reach Mars, and years to escape the Solar System.
  8. The nearest star to our Sun is Proxima Centauri, about 4.5 light years away. This means that, even travelling at the speed of light (300,000 kilometres per second) which is as fast as anything can do according to known physics, a spacecraft would take 4.5 years to get there. At the Earth’s escape velocity (11 kilometres per second), it would take over a hundred thousand years.
  9. Our Sun orbits within our own galaxy – the Milky Way – at a distance of about 30,000 light years from the centre at a speed of about 200 kilometres per second, taking about a billion years to go around. The Milky Way contains about a hundred billion stars.
  10. The observable Universe has a radius of about 14 billion light years, and it contains about as many galaxies as there are stars in the Milky Way. If every star in every galaxy has just one planet then there are approximately ten thousand million million million other places where life could exist.

Herschel’s First Year in Space

Posted in The Universe and Stuff with tags , , on May 14, 2010 by telescoper

Just about to journey to the RAS for the Annual General Meeting  and the last club dinner before the summer break, I’m reminded by a tweet from Chris North that it’s exactly a year since we gathered nervously, fortified by booze, to watch the launch of the far-infrared observatory Herschel, together with its sister spacecraft Planck.  I haven’t got time to write much about this because I’ve got a train to catch, but you can in any case find a nice retrospective of the Herschel’s first year in space here. I couldn’t resist, however, putting up the nice video that’s been put together by the European Space Agency to mark the anniversary.

It’s all  been going swimmingly on the Herschel front since the launch, and the first science papers have been making their way onto the ArXiv this week. Thankfully it’s not been quite the deluge that I’d feared, more of a steady stream. I’ve even had a chance to read a few of them.

The next major milestone coming up will be announcement of opportunity for open time access (OT1) which will  be released on 20th May with a deadline of 22nd July. I’m sure the huge success that Herschel has been so far will mean a lot of people putting in proposals. There is talk of putting in a proposal for a big cosmology survey – a sort of son of ATLAS and HERMES –  which will be good timing for me and my little team at Cardiff because our theoretical models are almost ready to rumble…

Anyway, here’s to at least another three years of Herschel, although I’ll have to wait until this evening to raise a glass!

Starchild

Posted in The Universe and Stuff with tags , , , on May 10, 2010 by telescoper

It’s been a busy day today,  so I’ve decided to be lazy and plunder the online stack of juicy Herschel images for a pretty picture to show. This one has done the rounds in the popular media recently, which is not surprising given how strange it looks.

Image Credits: ESA / PACS & SPIRE Consortium, Dr. Annie Zavagno, LAM, HOBYS Key Programme Consortia

This image shows a Galactic bubble (technically an HII emission region) called RCW 120 that contains an embryonic star that looks set to turn into one of the brightest stars in the Galaxy. It lies about 4300 light-years away. The star is not visible at these infrared avelengths but its radiation pressure pushes on the surrounding dust and gas. In the approximately 2.5 million years the star has existed, it has raised the density of matter in the bubble wall by so much that the material trapped there can now collapse to form new stars.

The bright knot to the right of the base of the bubble is an unexpectedly large, embryonic star, triggered into formation by the power of the central star. Herschel’s observations have shown that it already contains between 8-10 times the mass of our Sun. The star can only get bigger because it is surrounded by a cloud containing an additional 2000 solar masses.

Not all of that will fall onto the star, because even the largest stars in the Galaxy do not exceed 150 solar masses. But the question of what stops the matter falling onto the star is an astrophysical puzzle. According to theory, stars should stop forming at about 8 solar masses. At that mass they should become so hot that they shine powerfully at ultraviolet wavelengths exerting so much radiation pressure that it should push the surrounding matter away, much as the central star did to form this bubble in the first place. But this mass limit is must be exceeded sometimes, otherwise there would be no giant stars in the Galaxy. So astronomers would like to know how some stars can seem to defy physics and grow so large. Is this newly discovered stellar embryo destined to grow into a stellar monster? At the moment, nobody knows but further analysis of this Herschel image could give us invaluable clues.

It also reminds me a little bit of the Starchild from 2001: A Space Odyssey…

To Mars or not to Mars?

Posted in Science Politics, The Universe and Stuff with tags , , , , , on April 17, 2010 by telescoper

Amongst  the news this week was President Obama’s announcement of a new space exploration policy for NASA. Out goes the Constellation program, including the Orion crewship, its Ares launch rocket, and the rest of the project’s Moon-bound architecture. Obama says NASA were on an unsustainable path, costing too much money and taking too long to develop. Instead he’s given them extra funds ($6 billion, modest by the standards of space exploration) and told them to find new ways of putting people into space. Obama’s particular goal is to send someone to Mars by the mid 2030s and return them safely to Earth. I think Obama’s plans have ruffled a few feathers, especially among those longing for a return to the Moon, but it seems to me to be both bold and intelligent. 

The European Space Agency also has a programme – called Aurora – which includes components involved with both robotic and human exploration. This programme is a kind of optional extra within the ESA budget and countries that wanted to join in were asked to pay an extra contribution. The UK opted in so now we pay a top-up on our subscription to ESA in order to participate. This will be one of the things that transfers to the new UK Space Agency, when it’s up and running properly, from the Science and Technology Facilities Council (STFC).

Thus far the UK policy has been not to get involved in human space exploration. There are a lot of reasons behind that, but one of the most important is sheer cost. Space exploration is expensive by its very nature, but involving human beings creates enormous extra costs connected with keeping them alive and keeping them safe while they are in space. Since our national expenditure on space exploration has largely been channelled through STFC (or its predecessor PPARC) where it has had to compete for funds with “pure” science activities in the areas of particle physics and astronomy (and, more recently, nuclear physics).

I think the scientific argument against funding human exploration has always been as follows. There aren’t many things that people could do on Mars that a robot couldn’t – here I’m talking just about scientific experiments and the like. Human space exploration is much more expensive than the robotic variety. The scientific value for money is consequently much higher for robotic missions ergo, since money is tight, we don’t do human space exploration. Plus, we couldn’t afford it anyway…

The other factor is that there aren’t many feasible targets for manned spaceflight in the first place. The Moon and Mars are basically it. Other objects in the solar system are either too distant or too inhospitable (or both) to be considered. Unmanned probes haven’t all been successful, but some certainly have paid off enormously in scientific terms. I give the Cassini-Huygens mission to Saturn (and its extraordinary moon Titan) as an example that has turned out, in my opinion, to be nothing short of sensational. The images of Titan’s surface sent back by Huygens were gobsmackingly amazing, for instance.

Before going on let me point out that I’m a cosmologist, not a planetary scientist. There’s a tendency among scientists to think that their own field is more important than the others with which it has to compete for funding. It’s perfectly natural that someone working on galaxy formation should find galaxies more interesting than planets, and vice-versa. We all pick what we want to work on, and obviously we pick what interests us most.  But any scientist worth his/her salt should have enough of a grasp of the big picture to recognize outstanding work in disciplines other than their own.  I don’t want anyone to think that the following comments are intended to suggest that there isn’t excellent work going on in the UK and rest of the world in the field of planetary exploration.

I do think, however, that there is a big difference in character between fundamental science (especially particle physics and cosmology) and planetary exploration. In fundamental physics we are attempting to uncover the nature of basic constituents of the universe and the general laws that govern the structure of matter and how it interacts and evolves – in other words, its scope is (or at least tries to be) universal. It’s certainly this aspect – trying to unravel an enormous cosmic puzzle – that drew me into cosmology. By contrast, the study of a particular planet – even a fascinating one, such as Saturn with all the beautiful orbital dynamics going on in its ring system – lacks this aspect of universality. That’s why cosmology interests me more than planetary exploration does. This is nothing more than a statement of personal interest.

Having said that – and pointing out  again that I’m no particular expert on the Solar System – I don’t find the Moon and Mars very  interesting from a scientific point of view compared with, say,  the outer planets which I find fascinating. Others – a great many others, in fact – obviously do see a lot of interest in Mars. I’m not at all convinced about the scientific merit of some other space probes either, especially the planned Mercury orbiter BepiColombo. But there we are. We can’t all expect to agree on everything. What I’m trying to say, though, is at the moment these different types of activity are funded from the same pot. In order to draw up an order of priority, STFC has to compare apples with oranges with predictably bizarre outcomes.

Moreover, space exploration – especially human space exploration – isn’t just about science. There are definite commercial opporunities in space, in both short and long term.  Space missions often  provide results that are fairly easily accessible to non-scientists, so has considerable popular appeal as well as inspiring young people to take up science and engineering subjects. It has immense cultural impact too, altering the way we think about ourselves and our place in the Universe. But these aren’t unique to space exploration. Particle physics and astronomy do this too.

 But the overriding factor is the politics. When NASA put a man on the Moon 40 years ago, it was never about science – it was a political statement made right at the height of the Cold War. We no longer have a Cold War, but nations still feel the need to show off to each other. It’s called national pride. Politicians know how this works, and how it can turn into votes…

So we shouldn’t think of the plan to put a man on Mars as being primarily a scientific thing anyway. I’m quite comfortable with that.  My worry – if the UK decides to take part in manned Mars exploration – is that the money will come from the already dwindling pot allocated to fundamental science. Particle physics and astronomy research in the UK is on the ropes after the recent devastating cuts. Any more blows like this and we’ll be on the floor. I’m deeply worried that far worse is already on the way – a combination of public spending cuts after the general election and political directives to devote more to space exploration.

The new UK Space Agency could be either a hero or a villain, and I don’t know how it will turn out. On the one hand, the creation of this organization may prevent the fundamental sciences from being squeezed further by expensive space projects. In this way it might represent a recognition of the different characteristics I talked about above. The industrial and commercial aspects of space exploration are present in the new outfit too.  On the other hand, the result of hiving off the “glamorous” space parts of STFC may lead to further cuts in what is left behind. I’m also nervous about the future relationship between UKSA and STFC, especially the extent to which the former can demand research grant funding from the latter.

I’m sorry this has been such a long and rambling post, but this has been on my mind for quite some time and I wanted at last to put something together about it. I could summarise what I’m saying as follows:

  •  I’m not convinced about the scientific case for Mars exploration – particularly if it involves manned missions
  • BUT it’s not my field so it’s not my decision to make
  • AND there’s more to Mars than science anyway
  • SO by all means do it if there’s a will
  • BUT for heavens sake don’t pay for it by killing off the rest of astronomy

This is something that I’d be genuinely interested in hearing other views on. What is stated above is my opinion and is not intended to be representative of anyone, but I’d be very interested in hearing other views through the comments box.

Protostars in the Rosette Nebula

Posted in The Universe and Stuff with tags , , , , , on April 13, 2010 by telescoper

Every now and again I remember that I should  pretend that this is an astronomy blog. A new press release from the European Space Agency just reminded me again, by unveiling a wonderful new Herschel image of part of the Rosette Nebula:

This isn’t really one for the cosmologists as it concerns a star-forming region in our own Galaxy. Herschel collects the infrared light given out by cool dust; this image is a three-colour composite made of wavelengths at 70 microns (blue), 160 microns (green) and 250 microns (red). It was made with observations from Herschel’s Photoconductor Array Camera and Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE). The bright smudges are dusty cocoons containing massive protostars. The small spots near the centre of the image are lower mass protostars.

This is a wonderful demonstration of how Herschel is able to see massive objects – probably about ten times the mass of the Sun – previously hidden from view within the nebular dust. Studies such as this will help astronomers understand much better the processes by which stars form in regions such as this.

PS. If you want to know why this is called the Rosette Nebula, you need to see what the whole thing looks like in optical light: