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The Rosetta Mission – Part One

It started with Giotto about 30 years ago…

On the beginnings of Rosetta

It started with Giotto about 30 years ago, ESA’s first deep space mission which flew past Halley’s comet in 1986.  At that point, we knew already what we had to do next.  Giotto flew very quickly past Halley, at hundreds of kilometres a second; we needed to get next to a comet to observe it for a long time, to see how it worked.  A comet’s a very interesting body, it’s frozen when it’s far away from the sun, but when it gets towards the sun it gets warmed and the ices on the comet start to sublimate: they change directly from a solid to a gas and they throw off tons of material a second.  So to see how that interaction works, you’ve got to get up close and personal, and that’s what Rosetta was developed from.  And so, yeah, in the 80s we were already thinking about that, we’d originally spoken about having a mission that would go to a comet, land on it, grab a piece and then bring it back to Earth.  That was shown to be a bit too extravagant at the time and the next best thing is to, instead of bringing material to your laboratory, is to take the best laboratory out to the material that you want to study, and that’s what fundamentally Rosetta is now.  We went there to deploy a lander but also, it’s key to remember this, the orbiter has been there for over a year and will continue to fly around the comet as long as we can to get that whole picture, that dynamic interaction picture.

On working on the mission day to day

My role in the mission, I perceive it as a small one, Rosetta is a team of people; there are certain people who are at the top of the pyramid, I’m more like an ether that intermingles everything: whether you determine that that’s a pleasant smelling gas or a nasty smelling gas depends on some of the interactions I am going through at the time.  My job is to ensure that the science that we want to do on the mission is being done, so it’s an interface between the science community who are led by all of the key scientists, the lead scientists on each of the instruments. They front the science community, I discuss with them what we want to do and we encourage the engineers to try and carry that out. It’s also within my remit…and actually one of my more day to day tasks is to try and get that group of scientists to in some way have a common direction, because they may not always have a similar point of view of what should be prioritised so it’s that kind of…I’m an interface in many ways, I’m a scientific interface to engineering, but also some kind of politician in terms of trying to get the core members of the team to try and agree. It’s said that I be trying to make everyone equally happy, but I think most of the time at least I try to keep everyone equally unhappy as well, so it’s that balance.

On the inter-disciplinary nature of the mission

For me Rosetta…one of the challenges - I knew it would be - is exactly due to the science it’s investigating, cometary science. I moved from a pure plasma physics mission, a space plasma physics mission called Cluster where the payload is designed to look at plasma only, and moving to Rosetta I knew that I would be dealing with many other scientific disciplines so chemists as well as physicists, biologists to some extent, but it’s mainly chemists and, of course, you’re always dealing with engineers because we’re flying 1.3 billion euros worth of equipment up there, give or take, depending on how you cost it.

But that’s the challenge as well, that’s part of the challenge, to try and get everyone to have a core direction in terms of the science that you want to do; as there are some physicists that want to do one set of investigations, or a particular style of investigation, but then you also have geologists that want to do something.  A good example here is, you can measure one particular entity, so let’s talk about dust flying off the comet.  One instrument will want to look at the comet itself because its aperture is in that direction, so then it receives the dust directly and it can measure the momentum of this dust. Another measurement can be carried out with a camera, but you have to point the spacecraft 90 degrees to the direction of the comet to do a similar measurement and so you have to do those trades to say, well, you do it this week, next week we’ll do it that way, so it’s that kind of…I wouldn’t say massaging but you’re trying to resolve these kind of discussions all the time and do similar measurements but then also very different measurements, studying the different facets of science.

On the process

The process of going from a thought, effectively around a table, if you were, during coffee during a previous mission, to then the inception of and the development and building of a spacecraft is a very long process, an arduous process, and there’s a lot of evolution involved.  Rosetta was originally a completely different mission, it was a sample return mission, but then it’s developed into what it is now and that’s driven by risk, what is appropriate from a cost perspective, and also what is technically…what we’re technically capable of producing.  I would say, actually, if Rosetta didn’t exist now and somebody presented it to ESA we probably wouldn’t select it because it has so much risk.  If we consider a lot of other missions, planetary missions that go and investigate the surface of a planet, so we want to go and land on the moon or Mars, we’ve sent many probes to those bodies first to study them, you look at them from the ground as well, and then after a number of missions you then go and land.  When we look at Mars, it takes people months, almost years really, to select where to land whereas we sent a probe that was going to do both things within a couple of months, well we did it as well. So that kind of risk, I’m not sure if we are capable of taking those kind of risks at the moment, or its not in the system that we work with, so when we were talking about Rosetta there was maybe a little bit more momentum in terms of, right,  let’s get this done, let’s try and do this, but there were bumps and, well, there were mountains to climb over the time we had for the mission, and ultimately we got there, though.

- Dr Matt Taylor