Talk

While I was a graduate student at Oxford, the astronomy department ran something they called 'the secret seminars'. These were talks given by students for students as practice at presenting their research to an audience without feeling intimated by the far more knowledgable faculty.

I hated these.

The problem was that preparing a talk is time consuming, giving it is stressful and to do both the above without a seriously good reason when there is beer to be drunk down the local pub is hardly to be desired.

However, looking back, I think learning to enjoy giving talks is one of the most useful skills I have developed as a researcher.

Scientific papers are the currency of academia. Largely, the more papers you publish, the more successful you are considered to be and therefore the chances of procuring that next job or research grant are that much higher. While there is no substitute for this means of assessment, many of the people whose work I know best I became familiar with because I had heard them give a great talk at a conference or as a visiting speaker.

For me, once I realized that my audience were interested, not critical, and no one minded if I made the odd mistake, I relaxed and started to enjoy my presentations. As a speaker, you get to hog everyone's entire attention for the duration of your talk and if you're lucky, someone will be so excited that they'll invite you to their tropically-located institute to give a seminar when your own home is waist deep in snow. What's not to like?

I also feel that giving talks has done more to publicize my work than even my published papers.

With this in mind, I took the opportunity while visiting Santiago in Chile to give two talks; one at the European Southern Observatory (ESO) and a second at one of universities in the city; the Pontificia Universidad Catolica (PUC). While I was keen to visit both institutes, these talks did present two slightly unusual problems:

The first was that my entire audience was likely to be observers. That was, astronomers who actually looked through telescopes at real stars and did not just build them in a computer.

In my theorist's opinion, that is one weird idea.

Chile is home to many of the world's telescopes for studying the southern sky. ESO itself operates three observatories in the country to give European astronomers access to the second hemisphere. Chile's high mountains and the mercilessly dry conditions of the Atacama desert make it an excellent location for getting the most out of the instruments. This makes the Chilean capital of Santiago an observers' domain with few researchers familiar with --or possibly even interested in-- my own field.

However, I was confident. I had made a couple of movies from my latest simulation results and who doesn't like movies? Nobody. Plus, movies are almost impossible to do with observational data because you'd have to observe for millions of years to cover a reasonable period of time on astronomical scales. Despite what it may feel like, this is longer than your average PhD.

So there was no doubt about it; all those observers would be jealous.

The second problem was that my audience would primarily have English as their second language. English is the language of choice for astronomy (a fact for which I am eternally grateful) with all major journals across the globe published in that language. This meant that despite being in Spanish-speaking Chile, my talk was expected to be in English. While this was probably fortunate (I only knew three words in Spanish, one of which 'bano' --meaning bathroom-- I had only learnt that morning), it was harder for the younger students who were not yet used to receiving English at speed.

This I found a more difficult problem to tackle. If I spoke very slowly, then the talk would seem stilted to the more fluent English speakers. I'd also be able to cover much less material. On the other hand, if I spoke at normal speed, it might be too quick for the students to all follow.

In the end, I spoke normally but tried to ensure the key points were clearly visible on the slides for people to read. Plus, I had movies. Who doesn't like movies?

There is always a tense moment after talks where you wonder if anyone is going to ask a question or if you lost your whole audience after slide number two. In some ways, having no questions is great since they can be annoyingly insightful at picking up holes in your work. On the other hand, it might also imply your research was too uninteresting for comment, which doesn't bode well for people wanting to read your paper or remembering to invite you out for a drink after the next conference. To my pleasure and possible surprise, both ESO and PUC were very tolerant of the theorist who had arrived in their midst and sparked an interesting discussion after I had finished speaking. Not only was this beneficial to my work, it was also a relief to know what I had presented was interesting to this broad audience.

As to the second problem, one of the students had the solution himself:

"Could I have a copy of your presentation as a PDF document? .... Though I suppose that won't allow me to see the movies."

Everyone likes movies.

Catch a falling star

Observational astronomy normally conjures up images of sparkling white domes set on the edge of cliffs above ethereal views morphed out of cloud tops. For the Canadian Automated Meteor Observatory (CAMO), however, the reality ... is a pig farm. Literally. I couldn't help feel that southern Ontario had been a bit short changed. 

This particular swine-based observatory is one half of a twin set (the second is located a pig-free field 50 km away) of telescopes operated by the University of Western Ontario (UWO) that are used to measure the position and velocity of meteors. Paul Wiegert from UWO visited McMaster to give last week's Origins Colloquium and explained why they were searching for shooting stars.

A 'shooting star' or 'meteor' is the name of the flash of light in the sky caused by an extraterrestrial rock heating up as it falls through the Earth's atmosphere. Typically, a meteor will only be 3 mm in size but travelling at a notable speed of 30 km/s. Prior to its atmospheric entry, the rock is known as a meteoroid and if it actually reaches the Earth's surface before being completely burned up, it becomes a meteorite. To complete the journey, a starting meteoroid must be larger than sizeable 1 m in diameter. The biggest meteors are called fireballs, with the Peekskill fireball being one famous example. This fell over the United States in 1992 and was recorded on the camera of a woman who happened to be filming her son's football match at the time. The resulting meteorite struck a car that was for sale, raising its price from a few hundred to a quarter of a million dollars. A second example was the Grimsby fireball which fell in 2009 and was filmed here at McMaster by an instrument owned by Professor Doug Welch from the top of the Physics department.

Where, though, do these Earth-bound rocks come from? Professor Wiegert explained that there are three possible sources. The first is from comets in our Solar System; dirty snowballs that heat up as they approach the Sun, producing a tail of rocky particles. These objects are usually trapped by the Sun's gravitational pull in the same way that the Earth is, but are on highly eccentric orbits so their passes by the Earth can be up to thousands of years apart. Should the Earth's orbit intersect the orbital path of a comet, the extended trail of debris left in the comet's wake can produce a meteor shower, such as the annual Perseids shower each summer: a more attractively stunning version of the trail of slime left by a departed slug.

A second source of meteors is a collision between two asteroids or a planet with an asteroid; rocky bodies that are smaller than planets, but also orbit around the Sun. The larger meteors that survive their decent to become meteorites typically come from this source. Contrary to what you might expect, a meteorite is typically cold when it reaches the ground. This is because it consists of the core of the meteor that is not burned up travelling through the atmosphere. The end part of the meteorite's journey is known as the 'dark flight' where it falls from the average height of a commercial aircraft without burning. The fact that this rock is not heated to high temperatures has important implications for the transmission of life across space; it could be possible that microbes shielded safely in the cold core of meteors might survive to populate a new world.

This consideration leads to the question as to whether there is a third source of meteorites: solid particles that originate from outside our Solar System. Since we find evidence of asteroid collision debris from the Moon and Mars, might we not also have received material from further away? From star systems billions of kilometres from our own?

Material from Mars found on Earth is not uncommon. It is estimated that around 500 kg or 15 individual meteorites per year hit the Earth from the red planet. However, the vastness of space makes interstellar rock transfer a whole new game. Approximately 100 rocks with diameters greater than 10 cm (the minimum size needed to protect biological molecules in space) are estimated to leave our Solar System from a terrestrial planet every year. Unfortunately, that only equates to the chance of striking another terrestrial planet to be a minute 10^-4 per billion years. Even if you were to lower your requirements and ask what the probability was of such a rock merely being captured by another star system, in the hope that this would eventually lead to a collision with a planet, the chance is only 1 per billion years. This makes the odds of us receiving biological material from another star system incredibly unlikely.

What though, asked Professor Wiegert, about smaller meteorids? Ones that are too small to be biological carriers but might still arrive in the Earth's atmosphere? Are we able to detect these and get a handle on how many we receive? It was this goal of finding such tiny object that CAMO was designed. Such small pieces of material will be very hard to detect, especially since they will burn up long before you have the chance to hold them in your hand and put them under a microscope. However, if they come from outside the Solar System, their expected velocity is very high, equal to around 20 km/s on arrive in our Solar System which will be accelerated to 46.6 km/s as they are drawn towards the Sun.

So has CAMO detected any of these interstellar visitors?

Possibly; but it's very hard to confirm. One of the problems is the giant planets in our Solar System, namely Jupiter and Saturn, are able to sling shot rocks to much higher speeds that they would otherwise obtain, making it look like they originate from further afield. It is important for CAMO to get an accurate measurement for both the meteor's position and velocity to rule out this possibility.

CAMO began taking data only last summer but perhaps soon we will know if our atmosphere is receiving the most distant of visitors.

Mission to Mars

"Would you go?"

The question was from my office mate, Kelly Foyle, a postdoc working with Christine Wilson on observations of star formation in disk galaxies. We were discussing the first Origins Institute Colloquium of the year which had been given by Canadian astronaut, Dave Williams, on the prospect of a manned mission to Mars.

I considered my answer carefully. To be one of the first humans to set foot on another planet; what an incredible prospect! I could practically hear my eight year old self, fresh from my first trip to a planetarium, jumping up and down shouting 'take me, take me!' And yet ….

"No," I said slowly. "There's too much here I couldn't leave behind for so long."

The problem with Mars is that it's really far away. Both the Earth and Mars are on elliptical orbits around the Sun, which means that their distances from each other changes continuously. The closest they have been recently was in 2003, where they were 55,000,000 km apart. While that makes even a trip round the Earth (40,075 km) seem like peanuts, the furthest Mars and Earth can be apart is 401,000,000 km. This difference is why Mars is sometimes easy to see in the sky and at other times very hard to find.

Because of this distance, an expedition to Mars would take of order three years. It would comprise of 6-7 months travel time to reach the red planet, two years on the planet surface and another 6-7 months for the return journey. For comparison, the moon can be reached in three days while journeys to the International Space Station are quicker still. This presents any would-be expedition with a problem that has never had to be tackled before; what do you do when something goes awry and you can't just come back? All previous space trips have been able to have the back-up plan of returning to Earth quickly if necessary, but a Mars-bound vessel would have to 'abort to Mars' once it was sufficiently far away from Earth. Any repairs or necessary adjustments would therefore have to be able to be performed while in space with the tools and supplies already on-board. Even though advice could be received from Earth, the twenty minute latency on communications from Mars to Earth would be too long for medical procedures to be conducted via this method; the knowledge as well as the equipment would have to be with the astronauts themselves.

In addition to this, Dave Williams placed a lot of emphasis on the problems of keeping the astronauts healthy, both in body and mind. In the low gravity of space, the human body can start to waste away which causes problems when the astronauts return to Earth. For instance, while astronauts use their arm muscles to propel themselves around the space craft, their leg muscles get little use and loose their strength. The heart muscle deconditions and bone density drops at a rate of 15% per month. Astronauts can also suffer from lower back pain as their body elongates in an environment free of the downward pull of a planet. Dave revealed that he is 6' 1'' on Earth but almost 6' 3'' in space. There is also the unknown long-term effects from exposure to cosmic ionizing radiation; high energy particles that we are shielded from on Earth by the protective cocoon of our atmosphere. Dave explained that when you close your eyes in a dark room in space, you can still 'see' flashes of light that come from this radiation passing through you. What damage they might do over a long period of exposure is unknown.

There is also the mental strain of being contained in a confined area in extreme isolation for such a prolonged period of time. Entertainment and variation in food will also be difficult, since astronauts will grow bored of eating the same meals for several years.

Once on Mars, the astronauts will be in a strong gravity field once again, although Mars' gravity is only 40% that of Earth. However, unlike on Earth, there will not be people able to help the new arrivals until they can re-adjust to the forces on their body and there will be much work to do.

To combat these problems, exercise machines have been developed specifically to keep astronauts in shape while in space. Harnesses are used to pull the user down onto the running machines and a DVD player screen help maintain a sense of orientation. Meanwhile, the University of Guelph is researching into producing crop yields on another planet and NASA are exploring different possibilities for transportable shelters to take to Mars. Dave mentioned the idea that the perfect candidate for this mission might be different than for previous expeditions into space, due to the long duration and uncertainties being faced. He suggested that older people in their 70s might potentially prefer to make the journey, since their families would be grown and long-term health effects that could occur 10-20 years later would be less of an issue.

While the space program may not yet be recruiting astronauts specifically for the Mars mission, Dave thinks there is a high chance in it happening within our lifetime. It was a strange thought to think that you could be sitting beside the first person who will set foot on an alien world. Who knows? When I reach 70 I might even change my mind and be signing up myself!

So what is it really like in space? Dave told us that he gets the most questions about how astronauts shower and use the toilet when they stay at the International Space Station. He describes the shower, which looks like a cylinder with a lid. Soapy water is used to cover your body which is then vacuumed away. The toilet, he said, uses another vacuum system. The basic idea of such a device is that you want things to go away from you. On Earth, gravity does all the work when you flush, but in space a vacuum has to be used to remove the bodily waste from the toilet bowl, where it is then stored and returned to Earth. This final point left Masters student, Mikhail Klassen, with one question:

"Why, oh why do they bring human waste back to Earth when there is infinity on all sides of you?"

It was a mystery that would have to be left for another day.