Reaching for the stars

Harvesting data from ESA deep space missions

Why Colombo Bolognesi’s transistors play a crucial role for ESA and why he is so passionate about building semiconductors. 

There was great enthusiasm and relief among the Rosetta Mission team at the ESA Operations Centre in Darmstadt on this Friday morning,
12th November 2014. The European Space Agency ESA’s Rosetta spacecraft had just successfully deployed the Philae lander to the surface of the 67P/Churyumov-Gerasimenko comet. 

«I would not have initiated
work on this type of semiconductor
if ESA had not asked me to.»

During the months to follow, Rosetta would transmit thousands of radio messages back to Earth carrying masses of data collected by Philae and the orbiter. More happy faces were seen that morning at ETH Zurich in the team of Colombo Bolognesi, Professor of Millimeter-Wave Electronics. He and his group had designed and fabricated the semiconductor components, which amplified the very weak radio signals reaching the Earth from Rosetta and other space missions, making the data contained available for scientific analysis. Without such tiny highly refined devices, cooled to –258°C and operating at the heart of ESA ground stations antennas, earthbound scientists could access neither their experimental results nor the output of scientific imagers. 

Building transistors – a fascinating task 

“When I visit the ESA website and consider the pictures originating from various missions, I have a sense of accomplishment thinking the bits making up these amazing images went through our devices!”, Colombo Bolognesi says with laughter when we meet him on a spring morning in his spartan but disco ball-equipped ETH Zurich office. Transistor technology has fascinated Colombo Bolognesi since he was an engineering student, and this passion still drives him today. “The amazing thing is you can substitute just a few atoms here and there to achieve marked changes in device performance. We know the properties of certain materials well enough so that we can engineer tailor-made devices for specific applications by “alloying” or mixing these materials in specific proportions. This gives me a lot of satisfaction”, he says. “Building” a semiconductor on the atomic layer level is a fascinating process that tests one’s understanding and control of nature and requires working in a cleanroom laboratory with highly specialised tools. The device engineers deposit layer upon layer of crystals consisting of selected elements to form an atomic layer stack with the desired characteristics. Crystalline layers are deposited on indium phosphide wafers from which chips can eventually be cut off. Essentially, the periodic table of the elements forms the alchemist’s toolbox with which Colombo Bolognesi and his PhD students create novel semiconductors. 

As our daily lives become increasingly digitised, the demand for novel higher performance semiconductors grows continuously. Faster internet services, self-driving cars or even high-resolution movies on smart phones rely on the swift wireless transmission of ever-increasing masses of data. Such high-speed wireless networks represent a more down-to-earth application for the type of semiconductors Colombo Bolognesi is developing. In the years past, he and his team have focused their research mainly on the production of high-speed transistors based on certain material systems involving phosphide and nitride compounds (InP, AlGaN). It was exactly this kind of InP-based semiconductors (specifically, high-speed low-noise “High Electron Mobility Transistors” or “HEMTs”) which was used by ESA to amplify radio signals from different remote spacecraft missions such as Rosetta. 

Cooperation with ESA – a challenging partnership

Colombo Bolognesi’s cooperation with ESA began some ten years ago, when he was appointed Full Professor at ETH Zurich. ESA inquired if he would continue a cooperation established by his predecessor to develop a new generation HEMT built on indium phosphide (InP). Colombo Bolognesi agreed. He had dreamed of working with this technology already as a PhD student some 20 years before, and he seized the opportunity to enter this research field. Cooperation with ESA is quite special: Researchers like Colombo Bolognesi are considered contractors. ESA issues a call for tenders; researchers or companies submit their bids including a compliance matrix addressing ESA’s specifications. They have to indicate in detail which specifications they can fulfil and which will not be met. 

«The ultra-low noise transistor technology
developed by your group played a key role
in recovering scientific data
and gave Europe independency
on a technology not available elsewhere
due to ITAR export control.»
Dr. Klaus-Jürgen Schulz, Head of the ESA Ground Stations Engineering Division.

ESA then selects with whom they will cooperate as primary contractor. Additional participants might also be invited to act as sub-contractors. ESA projects usually last two to three years marked by milestones where the contractors have to deliver definite results. Funds are paid in instalments when milestones are delivered. The typical envelope for such ESA projects amounts to 250,000 Euros and covers the salary of the PhD students as well as material and lab costs. This is not much compared to the resources
researchers can receive from research agencies like the Swiss National Science Foundation or the Horizon 2020 Programme of the European Union. So what are the benefits when cooperating with ESA? Colombo Bolognesi’s answer is surprising but quite convincing: “One of the main benefits is that I would not have initiated work on this type of semiconductor if ESA had not asked me to. 

«A tiny group consisting of a professor,
two scientific employees and two PhD students
can compete with major aerospace corporations.»

As an engineer, I prefer working on things with real applications and I am less interested in doing research just for the sake of publications. So the ESA invitation to build a novel transistor offered a great opportunity for meaningful work: ESA deep space network applications have the most demanding performance requirements for semiconductors, and as the ultimate “system integrator” ESA put me in touch with top-level technology end users, in this case radio astronomers in Spain. Had I started this research just on my own, aiming to produce competitive transistors of this type, I could not even have tested them on the level astronomers need to fulfil their requirements. ESA created this opportunity.” 

Securing European independency

Since 2005, Colombo Bolognesi was involved in four ESA projects, designing, developing and perfecting his HEMTs. They are used to amplify the signals from several ESA as well as NASA deep space missions like Mars Express, Venus Express, Planck Herschel or Rosetta. In the meantime, his team’s work came to be highly regarded by radio astronomers and by ESA itself. In a letter of appreciation Klaus-Jürgen Schulz, Head of the ESA Ground Stations Engineering Division, wrote: “The ultra-low noise transistor technology developed by your group … played a key role in recovering scientific data and gave Europe independency on a technology not available elsewhere due to ITAR export control.” In fact, such transistors historically cannot be bought easily on the world market as they are subject to the U.S. International Traffic in Arms Regulation. This motivated Colombo Bolognesi and a couple of his students to found the start-up DIRAMICS ( with support of the ESA Business Incubation Centre ESA BIC Switzerland. The company will commercialise a decade’s worth of developments in low-noise transistor technology achieved through cooperation with
ESA. DIRAMICS designs and builds discrete transistors or complete customised low-noise amplifiers. The small spin-off will compete with major U.S. aerospace corporations. It has already begun to sell chips, even to some American companies.

«I prefer working on things
with real applications and I am less interested
in doing research just for the sake of publications.»

As an engineer, Colombo Bolognesi pragmatically targets useful applications for his technologies. However, at the same time, he has clear ideas on the type of research that makes sense for him: “As engineers, our devices help make the internet faster, sometimes enabling worthwhile applications like tele-medicine. But do we really need a faster internet to watch movies on the train? When I develop semiconductors for ESA, I contribute to our understanding of the universe. I don’t grasp all the science behind the data our transistors help to harvest. But gazing at images from worlds that we could only dream of seeing before is both truly humbling and rewarding!”.

The European Space Agency ESA’s

mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world. ESA consists of 22 member states, including Switzerland. By coordinating the financial and intellectual resources of its members it can undertake programmes and activities far beyond the scope of a single European country. ESA`s job is to draw up the entire European space programme and carry it through.

The Swiss Space Office

is located at the State Secretariat of Education, Research and Innovation SERI. It coordinates Swiss space affairs and acts as a gateway to ESA project funding in Switzerland.

ESA BIC Switzerland

is one of ESA’s 16 European Business Incubation Centres supporting selected entrepreneurs with comprehensive commercial and technical assistance to help them start up businesses that apply space technology to non-space industrial, scientific and commercial fields. It was opened in 2016 and is managed by ETH Zurich, in collaboration with the Institut für Jungunternehmen IFJ, Impact Hub Zurich and the Ambassador Platform of the European Space Agency’s ARTES Applications programmes, AP Swiss.

Interview with Colombo Bolognesi
Colombo Bolognesi

Colombo Bolognesi studied Electrical Engineering at the McGill University in Montreal, Canada, graduating with a Bachelor in Electrical Engineering in 1987, followed by a Master Degree in Electrical Engineering from Carleton University Ottawa in 1989. He continued his studies in the USA at the University of California, Santa Barbara, where he gained a PhD in Electrical Engineering in 1994. He then worked as a BiCMOS Process Integration Engineer for Nortel for one year. In 1995, he became Professor for Engineering Science and Physics at Simon Fraser University Burnaby, Canada, and remained in this position until 2006 when he was nominated Full Professor of Millimeter-Wave Electronics at ETH Zurich.

image by Rickard Lövblom
image by ESA
image by Olivier Ostinelli