The Final Frontier

Chris - Some of today's presentations at the AAAS science conference here in Boston were quite literally out-of-this-world.  That's because scientists were explaining how they're looking for Earth-like planets.  In other words, other worlds that could harbour life elsewhere in our Milky Way galaxy.  How do planets form in the first place and why are they all different shapes and sizes?  Earlier today I caught up with Michael Meyer who's been trying to solve this planetary puzzle at the University of Arizona.

Michael - I study star formation and planet formation.  In particular, in the last few years we've been using NASA's Spitzer space telescope to understand the formation and evolution of planetary systems.  We pick groups of stars that are very young, groups that are middle aged and groups of stars that are older and hope that we're watching a movie of what unfolds as one cohort evolves into the next.

Chris - This gives you some clues as to what's going on 4.5 billion years ago in our own solar system, in other words how we got here?

Michael - That's what we hope.  Our programme is specifically focussed on studying sunlight stars in the disc of our Milky Way galaxy.  We have a sample of 300 stars with ages only 3 million years after the stars first formed up to 30 million, 100 million, 300 million, a billion and then up to 3 billion years old.  Not quite as old as our star, the sun.

Chris - How long does it take a system of planets to form in the first place?

Michael - It depends on which kind of planet were talking about.  Our programme has been trying to study the evolution of dust and gas content.  On the gas front we've determined that the amount of stuff needed to form Jupiter mass planets goes away on time scales of 3-to-10 million years.  A planet like Jupiter has to form really fast.  We think planets like Earth probably took 10-50 million years to form, at least in our own solar system.  The new data we've received from the Spitzer space telescope seems to suggest that those processes might be very common about some of those stars.

Chris - That's not very long though, is it?  That suggests that once planets are going to happen they happen quick.

Michael - That's right.  If you sort of have a bunch of rocky things of order a kilometre in size and hit a go button gravity takes over and they will, on time scales of 10 to hundreds of millions of years, form most of the planets and the complement that we know of in our solar system.

Chris - Chat's the sort of step-by-step system of events that seems to happen to give rise to planets once'star begins to form?

Michael - Well, the disc of gas and dust that's left over from star formation is really a key part of that whole process or forming a young, sun-like star.  Over time the gas and dust evolves in that the particles - the little dust grains that give a lot of the infra red emissions we see - can smash into each other and stick.  It's kind of like the particles are in soot that you see rising from chimneys.  Those tiny, tiny particles come together and form larger and larger things like pebbles and rocks and eventually the things that we might identify as boulders and then grow up to objects as large as the moon and Mars.  That is the cascade of collisions that we think leads to planets like Earth.

Chris - Why are all the planets on the same planet though?  Why do we find that they all go round lined up?  Why does all that material settle into a disc, I suppose, rather than planets here and there all round the star?

Michael - If you imagine our star like the sun forming from a cloud of dust and gas in space that's rotating, albeit ever so slowly, as that cloud contracts a lot of the material if forced into a disc by a principle of physics known as the conservation of angular momentum.  It's the same thing that whizzes you to the outer edge of your car as you're speeding round a curve in the motorway.  That same physical principle operates on spinning clouds of gas that form sun-like stars.  It almost forces you into a situation where you collect mass in the centre but you must be surrounded by a disc of material left out there.

Chris - What makes the difference between whether we end up with a planet a bit like the Earth or one that's made of gas, like Jupiter?  How does that happen?

Michael - Well, even to form a planet like Jupiter you need to start with a core that probably looks similar to a few-to-ten-times the mass of the Earth.  The processes that lead from those tiny dust grains up to pebbles and boulders and things like the Earth take a certain amount of time.  If you can get ten Earth masses of rocky material together about the distance of Jupiter from its sun before the gas goes away you have the potential to serve as a focal point, a nucleation site if you will of swarming and gathering the gas together.  If that process takes too long and the gas is blown away before it can happen you might not have a Jupiter.  Earth-like planets, we think, form anyway.  Whether there is or isn't gas there you can still over a more leisurely period of time - 10, 30, 40, 50 million years - form rocky planets.  We think that's one reason why we're seeing evidence of planet formation like rocky planets like Earth much more common[ly] than the evidence so far that we see for gas giant planets.

Chris - Is there any kind of magic formula where you always end up with planets that are certain sizes or are you now finding that in fact it's just a mixed bag?

Michael - Much more so a mixed bag.  Our idea of planet formation suggests that it's messy.  It's a very complex process.  We think that's what leads to the large diversity of planetary systems that we see around stars like the sun.

Chris - How does that effect our prospects of finding another Earth-like planet out there somewhere?

Michael - Well, as I said, we think our research suggests that planets like Earth could be very common.  Like Earth simply means that they're rocky and that they're relatively close to their host star.  Exact analogues are probably rare but what is it about the Earth that gives the possibility for the emergence of life?  That's what all of us would really like to know.  It would help us to better assess whether the sixty per cent of sun-like stars that we think might be forming terrestrial planets, whether those rocky planets could be places where life could develop.

Chris - Do you know what those magic ingredients are?

Michael - The elemental compositions that lead to life?  Well, have a favourite word that we use in the emerging interdisciplinary field of astrobiology that's CHONSP: carbon, hydrogen, oxygen, sulphur, nitrogen and phosphorous.  Those are the elements, the stuff of life that leads to the biochemistry of life.

Chris - Is it, based on your measurements, likely that most of these rocky worlds that form around planets will have a fairly even smattering of those or are there special accumulations of certain things in certain places that happen?

Michael - The chemistry of forming planetary systems is very complicated.  We believe in a general way that the farther out you go the more likely you are to retain the carbon, nitrogen and oxygen in icy materials that could be very important to the emergence of life.  In the inner part it's a bit of a mixed bag.  The chemistry and the dynamics are so complex I can imagine a wide range of compositions for terrestrial planets.

Chris - Is it just stars a bit like our sun that we think give the best prospects for the evolution of life?  Could we just be looking at any old star and hope to find some life there?

Michael - I think in our ignorance we focus on things we know.  We only know of one planet that has given rise to life so we focus on terrestrial planets and we focus on stars like the sun.  Again, in our ignorance that's what we know.  I think over the years we're getting a sense that our perspective is a bit myopic.  We need to step back and look at the formation and evolution of planetary systems around a whole host of stars.  We shouldn't forget that the very first planets were discovered around the dead remnant of a very massive star, a pulsar.  The first rocky terrestrial planets were in fact found in such an extremely exotic environment.  As we learn more about how planets could form around stars much less massive than the sun, the cold, red end dwarfs: those are the most common stars in the Milky Way galaxy and if they are suitable places for life then life could be more common than we even could imagine.

Chris - I have to ask you to speculate with that point.  What do you think the chances are during your professional life that we're going to find it?

Michael - I don't know.  What I do know is that in the coming decades we will learn a tremendous amount about how common Earth-like planets are around stars like the sun.  Whether or not we detect the biochemical signatures of disequilibrium which is really the stuff of life in the atmospheres of planets around other stars I can't venture a guess.  I do believe that the biochemical origins of life will remain one of the key problems in science for the next century.

Chris - What are the big questions that are out there that we want to answer with the next generation of space telescope?

John - I think the number one question is how did we get here and are we alone?  Astronomers can tackle some pieces of this question by looking at the first objects that formed after the Big Bang, looking to see how galaxies are made, how stars and planets are formed from their gas clouds and finally how did the Earth come to be like it is?

Chris - How are you hoping to answer those things?

John - We have in mind a telescope which will be much larger and more powerful than the Hubble space telescope and would be launched in 2013 into deep space by a consortium of NASA leading the partnership with European and Canadian space agencies; pieces from around the world coming together to make this happen.  Launch in 2013 on the Ariane rocket from French Guyana, near the equator.

Chris - When you say deep space, why can we not just put it in orbit around the Earth?

John - We need to put the telescope far from Earth so that it can cool down to a lower temperature so that it can detect the infrared radiation that is now the new frontier in space astronomy.

Chris - That's interesting.  Why do you want to look at infra red?  It seems paradoxical to look at light that we, as humans, can't see.  I suppose that we as humans get used to seeing things we can see rather than some things like infra red we can't.

John - Yes, the new technology has opened up a new window for us.  Infra red light comes to us from the most distant parts of the universe because of the expansion which causes something we call a red shift.  Also we get to look inside clouds of dust and gas where things are cooler.  Where they're not warm enough to emit radiation that we can see with our eyes but they still put out immense amounts of heat radiation.  If you wanted to see yourself at a great distance you might use an infrared telescope.

Chris - Where will this telescope actually go?  How far from Earth have you got to put it out there?

John - It's put out at 1.5 million kilometres from Earth, a place called Lagrange point 2 which orbits the sun along with the Earth every year.

Chris - How's it powered, solar?

John - It does receive power from the sun with solar cells.

Chris - What major experiments will it be doing as a telescope?

John - It has four instruments on it, cameras and spectrographs to cover the entire range of wavelengths from 0.6 microns which is red light that you can see with your eye way out into the near and mid-infrared.  These four instruments will be able to look at distant galaxies, stars, planets, clouds of gas where they've been made and even little objects in the outer solar system.

Chris - Dare I ask what's the price tag?

John - The lifecycle cost from the first day to the very last is four and a half billion dollars, which is actually less than the similar tag for the Hubble space telescope even though the telescope is much more powerful.

Chris - And when you say lifetime cost how long do you anticipate you'll be able to use this?

John - It'll take about another five and a half years to get it to launch and then we expect to run it for ten years.

Chris - That's quite cheap really, isn't it?  On a ten year running cycle that's not bad.

John - For what it can do it's quite cheap.  It's so spectacular in its capabilities that we expect miracles to be found, surprises to abound in the data and beautiful pictures as well.

Madeleine - in the Beijing Olympic village anticipation is building.  The athletes are preparing to represent their countries and Irish-born Sydney-sider Gary Leahy is gearing up to serve millions of meals.  Gary Leahy is senior executive chef for the Olympic Village.  He arrived in Beijing just over a month ago in preparation for his third Olympics.

Gary - The first two weeks were pretty good because obviously there's no athletes here we managed to get in a lot of sight-seeing.  I'm very impressed with Beijing as a city.  Then the athletes have started to come in and we've just been working so hard for the last two weeks.  We're doing about 33,000 meals a day and we peak at 60,000.

Madeleine - The dining hall at the Olympic village I understand can sit some 6,000 people.  I presume the kitchens are pretty large too?

Gary - Yeah.  The kitchen must be the size of a football field, or close to it.  We have the kitchen set up into five sections.  Each section has a menu and they fire the food, basically, then my job is I'm the expediter.  All the food comes through me and I'm the link between the kitchen and the front of house.

Madeleine - And on the menu there are plenty of options.  For breakfast there's scrambled eggs, sautéed zucchini [courgette], chicken with chick peas, octopus with peppers, red miso and conji.  Gary Leahy again:

Gary - You'll see a big Chinese influence here which is very popular.  Chinese food at all the games will actually be the most popular food that we do.  There's stir fries and there's soups.  There's a lot of Chinese, there's a lot of Mediterranean dishes, European-based dishes.  Everybody is served across the board, no matter what sort of taste or background you come from I think we've got it pretty much covered.

Madeleine - I mean, of course you're also dealing with athletes who most of whom would have strict diet regimes.  How do you account for that?

Gary - We probably have about 80 different items on the menu every day or meal period.  We also have Halal stations and we have designated equipment in the kitchen for just pork and designated pork cauldrons.  We're covering every base, really.

Madeleine - Since the Sydney Olympic games food security has become a much bigger issue.  In Sydney all the food came direct from the suppliers every day but in 2004 in the wake of terrorist attacks like 9/11 security was much tighter.  In Athens all food went to a warehouse first for security checks.  In Beijing the authorities are leaving nothing to chance.

Gary - Food safety is really tight and obviously the Beijing government have people in the kitchen as well.  Temperature checking, checking samples.  We had the Beijing hygiene bureau about two weeks ago and they were walking us or talking us through that.  Even the suppliers the Beijing government had employed to supply us with food.  There's people from the hygiene bureau tracking all the food literally from the farm to fork the food is tracked by hygiene bureau peoples to make sure everything is in top shape.

Madeleine - As the games draws closer and closer what's it like being in the village?  Obviously you've got a huge task ahead of you.  It's a very different task to the athletes but it must be getting pretty exciting?

Gary - Yeah.  The village is a buzz.  A lot of athletes are walking around, strolling down the streets and laughing.  It's really quite amusing, you know?  The buzz in the village is just fantastic.  The athletes are hanging their flags out of their apartments and, you know, it's really good.

Ben - So if there was never a Big Bang, we've always had stars around - we know that what happens inside stars is hydrogen is converted into heavier elements like helium. If there was no Big Bang then surely by now all the hydrogen would have been used up, is that right Sarah?

Sarah - Well yes. The idea that the universe has already existed is known as the Steady State theory. This was developed in the 40s as an alternative to the Big Bang theory which is that the universe came into being and began to expand about 13.7 billion years ago. The Steady State theory has lost favour since the 1960s because a lot of the evidence actually supports the Big Bang theory, particularly after the discovery of cosmic microwave background radiation which is the sort of thing that the James Webb telescope will be looking for. Ben - And it's actually some of the stuff that you pick up on static on your TV.

Sarah - Exactly, and on your radio as well. You might think that even after 13.7 billion years the hydrogen might have all been converted but hydrogen still makes up about 75% of the normal matter in the universe. Diana - That's quite a lot, isn't it? Why is there so much still out there?

Sarah - Most of it's actually in low density, low temperature clouds of hydrogen where there just isn't enough energy to fuse the nuclei to make helium or other elements. This isn't a spontaneous reaction. It takes a serious amount of energy to do it which is why it did happen a second or so after the Big Bang and why it still happens in stars like our own sun. The heat and the energy present is there to do it but it just isn't there elsewhere in the universe.