11 February is the International Day of Women and Girls in Science, an annual event championed by the United Nations in recognition of the gender imbalance in science, technology, engineering and mathematics (STEM) fields.
Across RHEA Group, we have many women working in ground-breaking engineering projects and leading science programmes, including European Space Agency (ESA) missions. Among them is Greta de Marco, who works as a Spacecraft Operation Engineer on ESA’s Integral and XMM-Newton missions. Launched in 2002, Integral is ESA’s International Gamma-Ray Astrophysics Laboratory, while XMM-Newton, launched in 1999, detects X-ray sources.
In September 2021, just 7 months after Greta started working on Integral, the spacecraft went into emergency ‘safe mode’ and she found herself part of the team that had only a few hours to save the mission. Later, she was a lead member of the team that developed a new safe mode for Integral, which should help to further extend its operational lifetime.
Main image: Artist’s impression of Integral © ESA. Illustration by D. Ducros
What is your day-to-day role?
I am part of the flight control team for the Integral and XMM missions, which are essentially huge telescopes in space. We manage the day-to-day activities – not the overall scheduling, but we intervene when something is wrong, for example if we cannot command the spacecraft to ensure the scientific target is in the field of view, or there is some other anomaly. We might also get involved in changing where the sensors point when there are what we call “targetable opportunities”; these are unpredictable interesting phenomena, such as a supernova or colliding black holes, that the scientific community becomes aware of and wants to look at as soon as possible.
We also take care of maintenance and undertake development that could benefit the future of the missions, such as additional automation. These two missions are very old, so we are trying to bring them into the 21st century! The aim of these telescopes is to enable science, and with no mission there is no science. We are serving the scientific community by making sure all their targets are observed and they get the scientific data that is needed.
How did you become a space engineer?
I was fascinated by space as a child and my mother instilled in me a passion for maths and sciences. I did a degree in Aerospace Engineering and then a Master’s in Space Engineering because I knew I wanted to work in this field and these seemed like the best degrees to make that possible. I would have studied Astrophysics, but at the time I did not understand how broad the opportunities might be if I studied Astrophysics instead of Engineering.
However, my real passion for working in space came when I took part in the Erasmus programme while doing my Master’s degree. During this time, the students on my course were invited to go to the annual SECESA (Systems and Concurrent Engineering for Space Applications) conference that the university was hosting. Through that I learned about internships at ESA and was successful in applying for one after I graduated.
After that, I spent time working in the pre-launch phase of space missions before moving to work for RHEA in my current role.
What happened to Integral in September 2021 and how did you help?
Because of COVID restrictions, I was one of only a few people working in the office when we received a call that there was a problem with Integral. We already knew the propulsion system was not working well but now one of the spacecraft’s three ‘reaction wheels’, which help control the direction of the spacecraft, suddenly turned off – we later concluded this was because a single charged particle travelling through space triggered a switch. The spacecraft started spinning and the thrusters, which should have helped stabilize it, actually increased its rotational speed so that the sensors that track its position using the stars could not function anymore.
All the time, Integral’s batteries were depleting because it was no longer facing the Sun. If its batteries had dipped below a certain threshold, it would have entered an energy-saving mode that powered off all unnecessary components, including the onboard computer that we needed to control its orientation and make it face the Sun. And then the mission would have been lost.
In the end, we were able to use different onboard sensors to determine Integral’s orientation and little by little we brought it to a stable position pointing in the right direction. We were ‘learning by doing’: it took hours.
I was too new to be able to contribute much while the anomaly was happening as it was a very complex situation. But I played a supporting role, doing data retrieval and keeping a record of all the events because afterwards you need to go through them to try to understand what happened. My biggest contribution started the following day when we needed to ‘recover’ all the instruments that we had powered off to avoid draining the batteries. It took days to get them all working again because Integral is old and instead of it holding information in memory like modern satellites, I had to reload everything manually for each instrument.
What was your role in the development of Integral’s new ‘safe mode’?
After this event, we knew we needed a new ‘safe mode’ for Integral, which took a year and a half to develop. My contribution to this was quite big: I wrote the prototype with a colleague and then I took care of testing in the simulator, reviews with industry, making the design as robust as possible, the deployment of the software, and so on. That took a lot of time. Now we are doing the same for XMM, just to be prepared.
With this new safe mode in place, if anything happens while we do not have a ground station link, the spacecraft should go into a safe state pointing at the Sun, waiting for us to contact it. Previously we needed to be able to contact it from the ground to initiate this. One benefit of this improvement is that Integral’s mission has been extended because not only is it safe, but having an on-board safe mode means we can reduce the time we need to use a ground station and therefore reduce costs.
How does it feel to save a mission?
One of the first things they tell you in mission operations is not to personify the spacecraft. But that is very hard because you take care of this ‘baby’ every day. When the reaction wheel problem happened, I did not really think about Integral that way as I was quite new, but now it would be different!
When we saved Integral and when we were successful with the new safe mode it was great to feel part of something really huge. It is always a team effort and very rewarding. In a way I wish I had known more the first time, but still there was all this adrenaline and so I experienced a physical feeling of success when it was all over, not just a mental one. The second time I knew perfectly well what I was doing and so it felt different – but in a way it was more rewarding because I was a much bigger part of it.
Now when I am on call, I am responsible for the satellite and for making science happen. If there is a problem and you fix it, you are directly contributing to that specific scientific discovery. Knowing the scientists could not do it without you is both great and scary at the same time – you have these two huge ‘babies’ in your hands and there is so much money involved!
What tips do you have for any women and girls considering a science career?
Firstly, study the subjects you prefer. Then talk as much as you can to people who are working in a wide range of environments, because often in high school they do not know what the working world can offer you – they do not know what the opportunities are if you study different subjects. I am contributing to an Italian STEM-focussed website that is featuring as many women as possible to give this kind of information to young people.
Space is a cool field. There is always something new to learn and new technology to explore, and you have to think outside the box. In particular, I love to go to conferences where you get a lot of people who are passionate about the subject. Ideally you want to enjoy your job, so when you mix with many people like this it is a real boost – it is powerful and reminds you that what you do is not ‘standard’, even if it is what you do every day.
