Science Spin January 2010

Meet the 'spaced out' mathematician

By Marie-Catherine Mousseau

In spite of his love of rockets as a child, Ed had not really planned his career in relation to space. He had even thought of doing Arts as a degree. However, he ended up studying maths. "My choice of mathematics was made for the following reasons: I enjoyed and obtained good results in mathematics and 'arts' subjects, ie languages, history, English; but I decided that I could pursue 'arts' subjects independently or through evening courses, etc., while for mathematics I really needed a teacher and a course of study."

His choice also made up for his mum's regrets, who had always felt sorry for his having opted for English instead of Maths. Ed obtained a B.A in Mathematics at Johns Hopkins University, Batimore, USA, and a Ph.D at Trinity College, Dublin. He was still not sure where that would lead him though. "When you study mathematics you are aware that there are very few jobs doing mathematics or even teaching mathematics to students for whom it is the primary subject. So I had an open mind about careers," he says. Having an open-mind did not exclude having preferences. "I always was interested in working in the space industry; so when just after completing my studies a friend from college told me about a position in his company, Computer Applied Techniques, Ltd. (CAPTEC), I applied for it."

Job

Ed didn't think getting the job was problematic: "At that time it was difficult to find people with experience in designing, building or testing this type of critical system (space software), so my lack of experience was not a particular disadvantage." But he agrees it's possible he had been lucky to come on the job market at the right time. "The big companies tend to go through cycles where they invest in in-house development and cycles where they try to do everything through outside contractors," he says. "Space work is dependent on government funding, also," he continues, "and the perception of governments as to the return on investment varies, so that projects can be cut back or scrapped." According to him, though, funding levels have remained relatively constant with respect to inflation.

Satellites

Ed's job consists of building onboard software to guide satellites (or spacecraft) in space. He explains the basis of his work: "I have to develop and understand algorithms (series of instructions in a sequence which can be included in a program), use programming, simulate the space environment and the spacecraft behaviour using Newton's laws," he said. "I found the work difficult at the beginning, because I was not trained in engineering and the documentation is not always easy to understand." But his mathematical background definitely helped and he soon got the hang of it.

But what does onboard software for guidance satellites mean exactly? Ed gives us two examples of large projects on which he worked. The first one is the Infrared Space Observatory, or ISO project. ISO is a satellite launched by the European Space Agency for observing distant objects in infra-red.

The software they designed was to enable self-guidance of the satellite in space, which according to Ed is critical for this type of satellites. "Self-monitoring was very important to avoid the many sources of light from the earth that could damage the instrument", he explains (see box). Ed is happy to have witnessed the successful completion of the mission with his working software. The satellite lasted up to 28 months, as Ed points out enthusiastically.

Comet

After the success of the ISO mission, Edward tackled another challenging project, called Rosetta. The Rosetta mission is to perform a task unheard of so far in the history of humanity: Landing on a comet. Because a comet's composition reflects the composition of the pre-solar nebula out of which the Sun and its orbiting planets developed, Rosetta has the potential to unravel the origin and evolution of the Solar System.Rosetta is to operate faraway in space, where communication delays would make monitoring from earth impossible. Here again, the spacecraft has to be able to self-monitor.

Ed's team intervened at the tricky part of the mission as they actually wrote a software part of the lander determining the way it separates from the mothership. "The comet is travelling extremely fast, so there is a critical three seconds window. If anything goes wrong during this tiny window of time, even just a computer reset, then the opportunity is lost," Ed says. But Rosetta's route to the comet is long. The spacecraft is also due to flyby and examine two asteroids on its way. Ed will have to wait a bit before witnessing whether the original make up of their lander will prove successful or not: Rosetta won't cross the comet's path for another four years or so.

Universe

The company Ed works for, CAPTEC, had no involvement in the design of the scientific instruments in either ISO or Rosetta. Both missions represent fundamental scientific projects aimed at increasing human knowledge of the Universe. On Rosetta, for instance, instruments have been taken on board to look at a comet's composition, as no comet has ever been studied before: "there would be cameras on the lander, instruments to measure pressure, temperatures, the composition of the comet's surface, " he says. "But these are taken care of by other companies."

They also work with scientific Institutes in close collaboration with space scientists and physicists. But such costly fundamental projects such as ISO and Rosetta are ultimately under the umbrella of ESA. That is actually what Ed enjoys most about working on space applications. These cannot be the result of the work of one person but on the contrary require the participation of a multitude of dedicated experts. As he put it, "space applications involve collaboration between a large number of highly skilled people to meet complex and demanding requirements while delivering a quality product (hopefully on time and within the budget allocated)."

So being able to communicate (especially where you are stuck or are having problems) is critical, "in fact it is more important to be able to (and to know when and to whom to) describe a problem than to solve it," he points out. "Similarly, being able to express oneself clearly is very important. Again it is probably more important to be able to describe a design or proposed solution at an early stage than to implement it and leave it poorly understood by others."
He adds: "And also you have to be prepared to wade into poorly structured and badly written documentation."

Future

Obviously Ed enjoys his work, and so much so that he has been working in the same company for 15 years. "I also have been lucky with my missions abroad, I have spent a lot of time in Holland, and in Cannes and Rome for my work, and have had shorter visits in other places: notably Toulouse, Grenoble, Munich and Darmstadt."

He has some regrets though, maybe those elicited by his original love - maths. "I think I could have been a good mathematics tutor and I regret that many people have had poor experiences in learning mathematics at school and university." He has new projects for the future which keep him motivated. He would like to participate in testing satellite guiding software or even operating satellites himself - that is starting to use the type of space software he has been building for years."I might also be interested to lead a larger project that I have been involved with," Ed says.

But he adds: "although I would still like to have some technical involvement." Like many scientists, Edward Bach will always remain an inventor at heart, more than a leader, who above all likes to think, create, and design things which do work.

 

PANEL ONE

Infrared Space Observatory

ISO, which stands for 'Infrared Space Observatory', was the world's first true orbiting infrared observatory. Launched by the European Space Agency, it was designed to observe the universe at the IR wavelengths (from 2.5 to 240 microns). In the infrared you can observe distant objects that you could not see in the visible because of all the surrounding dust. These can include galaxies or centres of galaxies, and even quasars (means 'Quasi Stellar'... these objects are so far away that they look just like a star but are in fact clusters of thousands of stars in the centres of distant galaxies). And looking further in space means looking back in time. Some of the questions ISO was designed to answer include the origin of planets, the birth and death of stars, the chemistry of the Universe or the history of galaxies.

While the software Edward Bach and his team built for ISO would accept ground commands designed to point the satellite in certain directions, its main purpose was automatic guiding. Ed explains why in this case you can't always rely on manual guiding of the satellite from the ground: "ISO had an eccentric orbit which at certain times directed it very close to the earth," he says. "There are lots of dangerous lights coming from there that can damage the instruments - mostly reflected sunlight from Earth, moon, planets, etc, in addition to direct light from the Sun - light sources which are important for this type of satellite to avoid." He adds: "and because there are so many, the satellite has to self-orientate."

Eight or nine people from CAPTEC worked on the ISO project for 18 months. These included a mix of mathematicians, physicists, computer scientists, electrical engineers, etc., who joined their effort for a fruitful result. Indeed, the mission was a great technical and scientific success - so successful that it was extended from the original planned 18 months and the satellite operated for 28 months.

Ed explains that they are two major constraints on a satellite's lifespan. They need to use Helium to cool the instruments, and this evaporates over time, and,
the propellant fuel, called hydrozine (an extremely poisonous liquid), gets used up. This satellite operated far better than specifications and its scientific results impacted on practically all fields of astronomy. Many of ISO's discoveries haven't come out yet because they are still being processed by the researchers.

The ISO satellite was developed, manufactured, integrated and tested by an industrial consortium made up of 32 companies, mostly from Europe, headed by Aérospatiale, France.

END PANEL ONE

 

PANEL TWO

The Rosetta project: Landing on a comet

Rosetta is a robotic spacecraft aimed at studying the comet 67P/Churyumov-Gerasimenko. Rosetta consists of two main elements: the Rosetta space probe (mothership) and the Philae lander. The probe is named after the Rosetta Stone, as it is hoped the mission will help unlock the secrets of the early solar system, before planets formed. The lander is named after the Nile island Philae where an obelisk was found which helped decipher the Rosetta Stone.

Rosetta is very special as it will be the first to orbit and land on a comet. No other previous mission has had the potential to look back to the infancy of our Solar System and elucidate the role that comets may have played in the beginnings of life on Earth.

As in the case of ISO, automatic guiding was required but not for the same reasons. Contrary to ISO, Rosetta is a deep space mission. This means it is dealing with a distant spacecraft which due to time constraints would be impossible to operate from the ground. Certain positions also have to be avoided; for instance looking directly at the sun would damage the telescope - "exactly like looking directly at the sun damage your eyes." Edward Bach points out.

But the core purpose of the software Ed and his team wrote is to ensure that the lander actually lands on the comet - which is a major challenge.Ed explains that the usual way that a lander gets separated from its mothership is using an explosive device. However, with an explosion you have only one chance - you cannot get it wrong and landing on a comet would be too small of a time window to take that risk.

The lander designers came up with an ingenious idea to solve this problem: using wax to connect the lander to the mothership. To separate it then you just need to melt the wax 'which is much softer and allows several attempts." Ed says. "Three of us were working full time on the lander software for 8 months," he indicates. "We wrote some of the algorithms ourselves and simulated the communication with the mothership and the hardware behaviour."

They also worked in collaboration with physicists and space scientists at the Max Planck Institute in Germany for the development of the algorithms. "Usually this type of experiments are developed with scientific Institutes," Ed points out. "And here again the ultimate customer was ESA," he adds. "It is very much a collaborative work."

Launched in 2004, Rosetta is still on his way to the comet which it is due to reach in early 2014. Following a period of observation and mapping it should land on the comet in November 2014. If it does land we'll have a drink with Ed.

To see where Rosetta is right now, click here.

END PANEL TWO