A year after it was put into orbit by an Ariane 5 rocket on December 25, 2021, the James-Webb space telescope has already delivered many photos that have gone around the world. Presented as the “mission of the century”, does the 10 billion dollar machine keep its promises? Interview with Nancy Levenson, director of the Space Telescope Scientific Institute (STScI) in Baltimore, USA, the organization that coordinates and controls activities with the telescope.
RFI: After spending a year in space, what condition is the James-Webb Space Telescope (JWST) in? He was hit by a micrometeorite, one of his instruments, MIRI, had some problems, is that solved?
Nancy Levenson: This is indeed the most important thing: it is in good condition. Its performance is even better than expected.
JWST has been operational for 6 months, it has already made many observations. Which one do you remember?
It’s both complicated and unfair to choose! But I can remember some that were really impressive. First of all, we were able to observe the very young Universe. We can not only observe the most distant galaxies, but we have also been able to estimate when they formed. We now have verified data from galaxies that arose just a few hundred million years after the Universe began. It is simply amazing to be able to observe them. This improves our understanding of how these galaxies form and evolve. It really is a booming area.
In a completely different area, I think all of the exoplanet observations and discoveries have been wonderful. We have been able to analyze the atmosphere of planets that orbit stars other than the Sun. We were able to understand their composition, which, in turn, tells us about the formation of these planets. There have been discoveries, such as the observation of photo-chemical reactions in these atmospheres. There were also confirmations, such as the detection of water vapor in some of them.
Do the observations made by JWST already lead us to have to rework the models explaining the formation of the first galaxies?
Absolutely. I think we will have to adjust our models because we have observed that these first massive galaxies appeared very early in the life of the Universe, earlier than previously thought. We will have to explain it.
Precisely, when the first observations of these galaxies were published, we observed a kind of “race” to find the oldest, as if the community was still struggling to understand the new tool made available to it. Do you share this observation?
I’m not sure we can convince the scientists to go slower. I recognize that there was. But it is always necessary to supplement these first observations. We often only have estimated distances, estimated ages for these early galaxies. But we arrive at the moment when we enrich the first observations with spectroscopic data which will allow us to confirm the first measurements. This has already enabled us to complete certain observations. Of course, it will take time to do this for all candidate galaxies for the title of oldest. But that’s what we’re working on.
In this context, the first scientific meeting around JWST data was organized in Baltimore last week. What came out of it?
Personally, it was very pleasant and stimulating to see all that was being said. Indeed, it was very good to have this opportunity for the community to share and present their new data. There were many moments of excitement during the week when the results were presented. The levels of detail, the quality of certain data, which previously could only be obtained for the nearest galaxies, we now have for others much further away. Spectrographic data [l’analyse de la lumière reçue par le télescope permet de déterminer quels sont les composés chimiques qui l’ont émise ou qu’elle a traversé – Ndlr]are perfect…this level of detail is really only possible with JWST.
Precisely, a spectrographic analysis is eagerly awaited: that of the observation of the planets of the TRAPPIST-1 system, which includes three rocky planets in the habitable zone of their star. You have announced that the results of this observation will soon be published. Without divulging, can you tell us more?
The important thing is that the observations have been made and the analyzes have begun. But we will have to wait for more details. We can make the connection with your previous remark on the “race”. The community that works on exoplanets is generally very careful to have analyzed everything before making their discoveries public. But indeed, they were able to observe several planets of this system, including one which is in the habitable zone, where the presence of liquid water is possible. We are all waiting!
Beyond these results, what are you particularly expecting in 2023?
It’s hard to say, but we’ll continue to get results in the areas we’ve started looking at. We are also going to launch the general observation program: it will be easier for scientists to get their data and I think it will allow us to get data in many different areas, from different groups of researchers. I can’t wait to see this.
And you, as director of the Space Telescope Institute, have 10% of the JWST observing time. What are you going to use it for?
Indeed, it is one of the best parts of my job! For the first year, the first observation cycle, most of this time was allocated to the preliminary scientific program. We made an effort to have observations very early and then share all the data with everyone. I still have some observation time left, which allows me to respond favorably to scientists who do not have access to JWST time to observe. Typically, it’s for transients, things that change. There was recently a gamma ray burst that was observed. We did not expect it and this dedicated, flexible time made it possible to use JWST. Finally, there are of course the new discoveries as they happen and the scientists who need access to the telescope. I therefore accept some of these proposals during the year. We are also awaiting proposals for the second round of observations. The deadline is the end of January, this will then give us time to review all this, make the selection and start the cycle from July.
With hindsight, do you consider that JWST constitutes the announced revolution?
Absolutely. Moreover, the most important thing is that it concerns all areas of astrophysics. He is not excellent in just one area. We talked about the young Universe and galaxies, exoplanets… but there is also the formation of stars. The clouds of dust and ice that form discs around these stars and where the planets appear. Personally, it’s the cores of active galaxies that interest me, the supermassive black holes at their center that feed on all this matter. We get exquisite detail on what goes inside, but also what gets ejected in the process. JWST touches all areas of astrophysics. The community is also very creative in the way it uses it.
JWST comes in addition to another space telescope, Hubble. How are the links between the two machines articulated?
They complete each other. Both are unique in their respective fields, and there are plenty of studies where we absolutely need both. Hubble is essential for observations in the ultraviolet range, it sheds another light on us. To get the full picture of astrophysical objects, we need all of that. I am also quite curious to see how we will continue to share this work from both Hubble and JWST.