THE DAWN OF THE UNIVERSE. Macarena Garcia Marin is Project Scientist in the Webb Mission Office in Baltimore, Maryland. The James Webb Space Telescope (JWST) is the most advanced eye into the cosmos humans have ever had. Webb cost over $10 billion, took 17 years to develop and was launched on Christmas Day 2021. The British Astronomer Royal, Martin Rees, called it “the most ambitious and the most expensive instrument that any scientist has ever built.”

Macarena Garcia Marin, how many people worked on building the Webb space telescope? 

Up to 20,000, including scientists, mechanical engineers, software and system engineers and optics and materials experts, all working in a collaboration led by NASA between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA). You need a lot of expertise to crystallise all the scientific requirements into something that works in orbit around the Sun 1 million miles away from Earth.

How did developing this telescope help us advance on Earth? 

Whenever you develop these telescopes, there is a lot of advancement in industry. Often those advances leak into the medical field, with new devices and new technology. All the money that was invested in the Webb telescope was an investment in industry, engineering and people. It’s not only that you create the telescope, but you also learn new things and then use them for future development of, say, mobile phones.

“This is all about human exploration and really expanding the limits of what we know.”

Macarena Garcia Marin

This illustration shows what the hot rocky exoplanet TRAPPIST-1 b could look like.

Credit: Illustration: NASA, ESA, CSA, Joseph Olmsted (STScI)

Macarena Garcia Marin, what does your role as Project Scientist for Webb entail?

I am based at the Space Telescope and Science Institute (STScI) in Baltimore, Maryland, where the Mission Operations Center is. All commanding to the telescope is sent from here. I am the Webb Project Scientist for STScI, and my job entails interfacing with the science community to understand their needs and ensure they obtain good quality science data, as well as keeping them informed of latest news and any relevant information pertaining to the mission.

How many are you in the Mission Operations Center?

Working at STScI on Webb we have hundreds of people with expertise on different areas: coding, commanding, planning, scheduling, data management, operations and so forth. Sitting at the command center and actively communicating to the telescope, we normally have three people whenever we are in contact with the telescope.

Why is the James Webb Space Telescope so special?  

Webb is the biggest, most sophisticated telescope we have ever launched in space. Webb can peer further into space than ever before and sends back its images in infrared, capturing heat energy invisible to the naked eye to form an image. It allows us to observe objects with a lot of detail. Working in infrared allows us to look really far back into the past. From Mars down to the very first galaxies that were created in the Universe, Webb can observe everything and provide new insights. We are doing what the astronomical scientific community thinks is the right direction to push the limits of our knowledge.

What do astronomers mean when they say that they look back in time?

In a sense we all always are looking back in time, because light travels at a certain speed. For instance, light from the Sun takes about 8 minutes to get to Earth, and even your own reflection in a mirror takes a tiny fraction of time to travel to your eye: you are looking at an ever so slightly younger version of yourself. In addition to this, when light from astronomical objects travels toward us it does so in a Universe that is expanding, and so it shifts to redder colors. This is why you need infrared to observe the primordial galaxies: the light they emitted in the visible has shifted to the infrared.

Are the visible images received from the Hubble Space Telescope and the infrared images received from Webb complementary?

Absolutely! Webb and Hubble are very complementary and by putting their data together we can look at different parts of the astronomical objects, with different temperatures and colours and learn more about their intricate details.

Would you say Webb is revolutionizing astronomy?

Yes, in every possible way! We are seeing details never seen before, both in sensitivity and structures. It is like putting on new glasses and suddenly seeing very clearly. We are shedding new light into what we knew, and seeing new things never measured before.

How do you decide where Webb should look? 

In a year we can look at any point on the sky, and the astronomical community decides what to do. Typically, once a year we issue an open call for proposals inviting the astronomical community to submit their ideas on how to use the telescope. These are peer-reviewed by teams of experts on each topic. The reviewers don’t know who submits the proposals, so they only focus on the scientific merit. During the last of such calls, with a deadline on October 25th 2023, JWST observers submitted 1,931 unique proposals to STScI, setting a world record for astronomical proposal submissions, and requesting nine times more time than can be scheduled.

“There has been emphasis on studying rocky exoplanets, planets outside our solar system.”

Macarena Garcia Marin, what are astronomers seeing with Webb?

With Webb’s level of detail and sensitivity in the infrared, if we think about the primordial Universe we are observing galaxies never seen before and have detected the oldest star ever measured. In nearby galaxies we are learning about their intricate structural details. In the area of stellar evolution, we are seeing the birth and death of stars with new detail, and have measured very small brown dwarfs that challenge star formation theories. We are learning about the nature and processes dominating protoplanetary disks, disks of gas and dust surrounding a young star. In exoplanets, that is planets beyond our solar system, we are learning never seen before details about their atmospheres. In the solar system, we are encountering a wealth of new discoveries, from endogenous CO2 in Jupiter’s moon Europa, to detecting water plumes on Enceladus – the sixth-largest moon of Saturn – and a jet stream on Saturn.

How do you know what you are looking for when something has never been seen before?

You generally have a sense of what you’re after. For instance, if you want to detect ancient galaxies never seen before you will point the telescope to a dark region of the sky and take data for hours using different filters, that is colours, in the infrared. You then check your data looking for signatures that will give you a sense of how old the galaxy is: the galaxy will not be seen in the bluer colours, and will show in the redder ones. You will also compare with models and estimate the age. The ultimate way of determining the time you are looking at is to take a spectra: this will break the light into individual components, like a rainbow, and that makes it possible to identify specific features that are used to determine the age. We know where the feature is located in the local Universe, and by comparing with what is measured it’s possible to very accurately determine the age, that is the point of time when the object emitted its light.

Why is looking at star formation important to us?

The reason why stars are important to our solar system and to us is because a) they provide the materials, and b) they provide the conditions for a star to begin. The theory of stellar evolution explains how stars form and live, and how the conditions of the disk around a new star favours the formation of planets. The Sun and the solar system formed out of a disk that initially was a gigantic cloud of dust and gas. Those materials came from other generations of stars that exploded and enriched their environments. At some point it started collapsing on itself, and so you had at the centre a star forming, and that would have been the Sun, and around a very young Sun you had a huge disk where we had the conditions for all the planets to form. By that I mean you had the proper chemical elements coming from the stars, the proper temperatures, and the proper pressures. You can think of it as a baby star in the centre, a huge disk of material around and, within the disk, ices and other elements travelling around and getting the conditions to form closer to the Sun the planets that are rocky, like our Earth, and farther away from the Sun gas planets like Saturn. This is important because on our rocky planet Earth we have water, so that water had to be transported within the disk in the form of ices.

Have you found water in unexpected places?

With Webb we have found water on Enceladus, a moon of Saturn. This was not unexpected, but it provided confirmation that water is coming out of Enceladus in a plume and feeding the ring. We have also measured water in exoplanets, and water in the protoplanetary disks, the rotating disks of dense gas and dust surrounding a young newly formed star. Water is key for the presence of life as we understand it, but measuring water does not mean detecting life, it just may give the right environment for life to happen. 

In all this vastness why is Earth an important planet?  

It is important because Earth is a planet that hosts humans, and that is thanks to a combination of circumstances that were conducive to life. And we have intelligent life, which is something quite unique. Having said that, we are just a solar system within a galaxy that has billions of stars in it, each of them with the potential of having other planets, and there are billions of galaxies in the Universe. Statistically speaking there might be other planets that have conditions for life, but this planet is very special because it’s the one we belong to and the one we can live on, because in evolutionary terms we were designed to live here. 

With Webb have you also learnt directly about life on Earth?

Webb does not look at the Earth, there are Earth observation satellites to do so. Where Webb can help is in the area of understanding the conditions that make it possible to form rocky planets with an atmosphere, and the environments that are conducive to life. There has been emphasis on studying rocky exoplanets, planets outside our solar system. We have measured the temperature in some of them and are searching for a rocky exoplanet with an atmosphere. That is still not confirmed but the search continues.

What have we learned about the Milky Way, our home galaxy?

We have learned a lot about individual objects in our galaxy. Everything related with Solar System, exoplanets, protostars, protoplanetary disks and so forth are findings in our own galaxy. In the heart of the Milky Way, we find one of the most extreme and turbulent environments of star formation. In it, Webb has discovered a vast region of energetic photons, energy packets being emitted by young massive stars.

Have you also discovered other previously unknown galaxies?

Yes, Webb has discovered never seen before distant galaxies and protoclusters, early strands of the cosmic web that connects galaxies, and the most distant supermassive black hole ever detected.

Macarena Garcia Marin

A high-definition image from NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) unveils intricate details of supernova remnant Cassiopeia A (Cas A), and shows the expanding shell of material slamming into the gas shed by the star before it exploded.

Credit: NASA, ESA, CSA, STScI, Danny Milisavljevic (Purdue University), Ilse De Looze (UGent), Tea Temim (Princeton University)

Macarena Garcia Marin

NASA’s James Webb Space Telescope’s exquisite sensitivity and highly specialized instruments are revealing details into how one of Saturn’s moon’s feeds a water supply to the entire system of the ringed planet. Enceladus, a prime candidate in the search for life elsewhere in our solar system, is a small moon about four percent the size of Earth.

Credits: Science
Gerónimo Villanueva (NASA-GSFC)
NASA, ESA, CSA, STScI, Leah Hustak (STScI)

Macarena Garcia Marin

Artist’s impression of a baby star still surrounded by a protoplanetary disc in which planets are forming. Using ESO’s very successful HARPS spectrograph, a team of astronomers has found that Sun-like stars which host planets have destroyed their lithium much more efficiently than planet-free stars. This finding does not only shed light on the low levels of this chemical element in the Sun, solving a long-standing mystery, but also provides astronomers with a very efficient way to pick out the stars most likely to host planets. It is not clear what causes the lithium to be destroyed. The general idea is that the planets or the presence of the protoplanetary disc disturb the interior of the star, bringing the lithium deeper down into the star than usual, into regions where the temperature is so hot that it is destroyed.

Macarena Garcia Marin

This image from the NIRCam (Near-Infrared Camera) instrument on NASA’s James Webb Space Telescope shows the central portion of the star cluster IC 348. Astronomers combed the cluster in search of tiny, free-floating brown dwarfs: objects too small to be stars but larger than most planets. They found three brown dwarfs that are less than eight times the mass of Jupiter. The smallest weighs just three to four times Jupiter, challenging theories for star formation.

Credit: NASA, ESA, CSA, STScI, Kevin Luhman (PSU), Catarina Alves de Oliveira (ESA)

Macarena Garcia Marin

A team of scientists has used NASA’s James Webb Space Telescope to observe an exceptionally bright gamma-ray burst, GRB 230307A, and its associated kilonova. Kilonovas—an explosion produced by a neutron star merging with either a black hole or with another neutron star—are extremely rare, making it difficult to observe these events. The highly sensitive infrared capabilities of Webb helped scientists identify the home address of the two neutron stars that created the kilonova.

NASA, ESA, CSA, STScI, Andrew Levan (IMAPP, Warw)

Macarena Garcia Marin

This panchromatic view of galaxy cluster MACS0416 was created by combining infrared observations from NASA’s James Webb Space Telescope with visible-light data from NASA’s Hubble Space Telescope.

Credit: NASA, ESA, CSA, STScI, Jose M. Diego (IFCA), Jordan C. J. D’Silva (UWA), Anton M. Koekemoer (STScI), Jake Summers (ASU), Rogier Windhorst (ASU), Haojing Yan (University of Missouri)

“Webb has discovered never seen before distant galaxies and protoclusters, early strands of the cosmic web that connects galaxies, and the most distant supermassive black hole ever detected.”

Macarena Garcia Marin, how are you learning more about the life cycles of stars?

We can see how stars are born, in the middle of a thick disk of gas and dust with powerful jets of emission to their sides, how they live, and how they die like a planetary nebula (a region of cosmic gas and dust formed from the cast-off outer layers of a dying star which is the destiny of our Sun) or a supernova (a powerful luminous explosion of a massive star). The life of a star depends on its mass, and stars are the factories where chemical elements are formed. Through all this process of collapsing and expansion and exploding as a supernova, stars generate chemical elements. They generate every chemical element in our Universe. You start with hydrogen and helium, but then you have anything like iron, gold, calcium, and we have measured, for the first time, tellurium formed by a kilonova (a bright blast of electromagnetic radiation that happens when two neutron stars or a neutron star and a stellar-mass black hole collide and merge). You and I are formed by elements that were created in the stars.

How do black holes and super massive black holes help our understanding of who we are and where we come from?

Stellar black holes are those that form at the end of the life of a very massive star. Because stars are responsible for the formation of the chemical elements we and our planet are formed of, one could see a connection there. Supermassive black holes are at the center of every galaxy; SgrA* is the one at the core of our Milky Way. Its importance for us has to be seen in the large context of galaxy evolution and how galaxies came to be. This is a big question for which we don’t have all answers yet.

Has data from Webb disrupted theories about the formation of the Universe?

Webb data has provided evidence of the presence of galaxies a few hundred million years after the Big Bang; these galaxies seem to be too massive according to theory, and it is making it important to go back and revisit models. This does not mean that models about the origin of the Universe or galaxy formation have to be completely changed or are not valid, but we need to adjust them to be able to explain what we are observing; and we need more data as well. 

What are the most exciting things you have discovered? 

For me the most exciting discoveries are those related with that primordial Universe where the very first galaxies were born, and where there are efforts to find the first generations of stars, known as Population III stars.

What are you working on next?

In the upcoming year Webb will keep on taking data to support all fields of astronomy. It will execute deeper observations, observations that need great stability and some different ways of using the instruments. It will also go back to re-observe objects, to either confirm their nature or discover new aspects about them. Webb will last about 20 years, limited by the fuel that it has onboard. 

How will even more advanced space telescopes being planned complement the work you are doing with Webb?

This is all about human exploration and really expanding the limits of what we know. Talking about a telescope that will build up on the technology used on Webb, the mission that comes to mind is the Habitable Worlds Observatory. This is a concept for a NASA flagship mission designed specifically to look for signs of life on potentially habitable exoplanets. It will push the limits of what Webb does on the study of exoplanets. If we talk overall about recent missions, the ESA-led EUCLID was launched in summer 2023 to explore the nature of dark energy and dark matter, which is also the objective of the Nancy Grace Roman Space Telescope. Webb studies dark matter indirectly, through gravitational lensing (the bending of light caused by gravity), so these two missions will expand what we can learn with it.

Might we discover a planet with advanced inhabitants studying us just as we are studying them?

Yes, I hope so. That would be great. I love that concept and I actually wish it would happen. Maybe they have a telescope looking at us and we don’t know that yet. One of the challenges is that even though there are billions and trillions of stars and galaxies and potential planets they would have to be a civilisation that is close enough and lives at the same time that we do. The Universe is about 13.8 billion years old. That is a long time and we are only a small fraction of that.

What is the length of the life of Earth?

Our planet will finish in about 5000 million years from now, because that’s when the Sun will become a red giant and obliterate the Earth. This will be a relatively short process in the context of the Universe, because the Sun becoming a giant is just a stage. We need to take care of our planet in the meantime.

Will we find another planet that is habitable?

Perhaps. But the question then would be, how do humans get there? Because this planet is probably going to be very, very far away, and we do not have, as of today, the technology. Human exploration of space is challenging and it is a slow process. We should think more in terms of keep exploring but take care of our own planet so it lasts for as long as it can for us to live in, because the possibility of going into space and colonising another planet is in my opinion still quite far away from our reach. I think we could do better on our own planet. 

Thank you very much.