The astronomer bringing HARMONI to the Extremely Large Telescope – with Professor Niranjan Thatte

Professor Niranjan playing with a model of the Extremely Large Telescope

Professor Niranjan Thatte, principle investigator for the HARMONI instrument, with a Lego model of the ELT.
(Credit: Dave Fleming)

While the foundations for the Extremely Large Telescope (ELT) are taking shape on the Cerro Armazones mountain in Chile, teams in the UK are getting to work on the instrument that will allow the ELT to deliver amazing discoveries for decades to come.

This instrument is HARMONI: it will be the ELT’s work-horse spectrograph, analysing the light collected by the telescope to tell us about the properties of distant objects. While other instruments can be added to the ELT once it’s been built, HARMONI is one of its critical first-light instruments, and so must be designed and built in parallel with the telescope itself.

Niranjan Thatte, Professor of Astrophysics at the University of Oxford, is leading the project in collaboration with the Science and Technology Facility Council’s UK Astronomy Technology Centre and Rutherford Appleton Laboratory, and experts at Durham University. We caught up with him to find out how he became involved with the ELT and what it’s like to take the lead on such an incredible international project.

How did you first get involved with the ELT?

In 2006, I was at a meeting in Marseille where the ELT concept was presented to the astronomy community for the first time. Back in Oxford, I had been working on an instrument (an integral field spectrograph), which is now part of SINFONI on the Very Large Telescope (VLT).

The spectrograph had been very successful on the VLT – providing unprecedented views of some of the most distant galaxies known, and seeing a giant gas cloud being ripped apart by the black hole at the centre of our galaxy.

But there were no plans for a similar ‘integral field’ spectrograph to be included on the ELT at first light...

There had been a lot of focus on the next generation instruments, but that didn’t mean there wasn’t a need for a workhorse instrument like HARMONI.

After the meeting, in light of the discussions, ESO released a call for proposals for instrument concepts, and after 11 conceptual studies were carried out by leading instrument builders across Europe, they selected two instruments to be part of the ELT at first light – the camera MICADO and our integral-field spectrograph HARMONI.

We’ve been hearing a lot about how the design and construction of HARMONI is being led by the UK – what does this mean for UK scientists and researchers?

The UK is very much in a leadership role with HARMONI. It takes a lot of drive to pull a project like this together, and that drive is coming from the UK.

It also means that we are taking on lot of the responsibility.

Because of the scale of the project, all of the partners are taking on a part of the instrument and it will be assembled towards the end of the process. At that later stage, we want to have a coherent system – as the project leaders we’re responsible for addressing any problems and filling any gaps.

The upside to this is that UK scientists will have guaranteed observing time on the ELT, and early access to use the telescope and all of its instruments to do nifty pieces of science. The science team will put together a coherent programme, and all the members of the consortium will have use of the telescope.

Unfortunately, the glory part is still 10 years away! Really, we’re building the telescope for the next generation.

Wow! So how can you make sure that HARMONI will work the way it needs to?

It would be a different experience if we could walk down the hall and just talk to each other, but the size of the project that we are envisioning makes it impossible.

It all depends on a lot of motivated people going above and beyond the requirements of their job.

There are about 70 of us altogether – as well as at Oxford and the UK Astronomy Technology Centre in Edinburgh, we have other partners Lyon, Marseille, Tenerife, and Madrid – and we try to come together 2-3 times a year in person. We need to make the sum of the parts built at each institute to come together to form a coherent whole; an instrument that is more than the sum of its parts. This requires excellent communication so everyone can see the big picture.

There are a lot of video conferences and telephone calls, and it can be difficult, especially when we are working in different languages and cultures, so we have to be disciplined in how we work.

I’ve not found there are cultural differences; there are just differences between individuals. People are people and they have different approaches. You have to get to know them, and know how best to interact with them.

What is it about the project that excites you the most?

I enjoy the technical side of things and getting stuck into the detail of the project, thinking about why something should be done one way rather than another. It can seem obvious if you are using experience built up on other instruments, but sometimes the discussions you have make you think, and you have other ideas and see other ways of doing things.

That’s why I really enjoy brainstorms with other members of the team; it’s satisfying when ideas from a brainstorm turn into a concept for an instrument.

The adaptive optics, for example, are a phenomenal piece of technology: they are really advanced and can make minute adjustments to deformable mirrors 1000 times a second to compensate for the earth’s atmosphere, and learning about them has been really rewarding.

We are always learning, and doing things that we haven’t done before – this project is on a totally different scale to anything else I have worked on. These are not instruments that will fit in our labs, so testing will be interesting!

How does it feel working on such a ground-breaking project?

I feel extremely privileged. Astronomy was my hobby when I was in Bombay, when I built a little amateur telescope from scratch. Now I’m paid to do what I love. The only downside is that I don’t have any hobbies anymore!

I remember the first time I went to the Southern Hemisphere, to Australia, and the sky there is so spectacular. You can see the Milky Way stretching across the entire sky, and it creates an amazing sense of awe and wonder. We talk a lot about impact in terms of new technologies, but this type of project is also important because it fuels our curiosity about our place in the Universe.

It’s scary, but it’s very exciting. We want to do the most we can with the funding we have.

We are always trying to push the limits of what we can deliver.

Science and Technology Facilities Council Switchboard: 01793 442000