James Webb head explains why the telescope is more advanced than anything ever built

We had the chance to speak to Dr. Stiavelli, the head of NASA’s James Webb Space Telescope project. He spoke candidly about where the project is headed, how it began, and what he sees in the future.

This is the first in a series of articles where we are given a rare look at the person who made the entire project happen with such great success.

Thank you for being part of our inquiry into the James Webb Space Telescope. How did you come to be head of the James Webb Space Telescope Project?

Stiavelli: When I joined Space Telescope Science Institute (STScI) in 1995, I was working on Hubble as an instrument scientist for the WFPC2 camera. Later I became an instrument scientist for instruments then under development, such as the Advanced Camera for Surveys (ACS) and later the Wide Field Camera 3 (WFC3). In 2008 I became the JWST project scientist at STScI. This made me a good candidate for becoming mission head when that position was vacated in 2012.

What was one big challenge you faced when designing the JWST?

The big challenge was that it was something significantly more advanced than anything built previously. This makes it difficult to perfectly assess what is easy and what is hard. First of all, there were ten technologies that we knew were not mature when we started, and they were developed to make them ready for flight.

We felt from the start that developing the sun shield and the primary mirrors were the two hardest steps. It turned out that the mirrors were "easier" than we thought, i.e., they were challenging, but our plans were adequate for the challenge. Instead, the sun shield remained challenging to the end.

The sun shield would be the one I would pick as the big challenge. Other parts that we thought were technologically ready, such as the refrigerator (cry-cooler) meant to keep the mid-infrared detectors cold, ended up being more challenging than we thought but still simpler than the sun shield.

Now that you have had great success with the JWST, is there anything you would improve or change about the telescope?

No, the telescope was designed having in mind certain types of scientific observations that had to be done and could not be done with other telescopes. This concept has been validated over time since none of the JWST science has been "touched" despite having been defined 20 years ago.

What are the main systems that look out into space? As we know, the telescope sees celestial bodies in infrared but does it see other light spectrums?

JWST is sensitive from the red portion of the visible spectrum to the medium infrared. The sensitivity in the red gives it overlap with Hubble.

How far is the JWST from Earth?

The L2 point is 1.5 million km away (just short of 1 million miles). However, the telescope follows a large orbit around that point so that the actual distance ranges from 1.5 M km all the way to ~1.7 M km.

Besides taking pictures of amazing stars and galaxies, what other types of data does the telescope collect?

The telescope can obtain spectra, i.e., it can disperse the light it receives into its constituent colors. This is important to derive the chemical and physical properties of the objects we observe. The detection of carbon dioxide in the atmosphere of an exoplanet was done with one of these spectrometers. The telescope includes also a coronagraph that enables us to see faint objects near bright objects and a very specialized mode called a Non-redundant mask that allows us under certain conditions to see simple objects with a sharper view than one would expect from a 6.5m telescope.

Are you taking on any new projects at this time?

Twenty years ago, I applied and after peer review was selected as an interdisciplinary scientist in the Science Working Group. As such I have 110 hours of guaranteed time on the telescope. For the first year, I am observing a lensing cluster of galaxies to take spectra of distant galaxies and three quadruply lensed quasars to study the properties of the lens galaxy and of the quasar host galaxy.

Where did you grow up and go to university?

I grew up in Italy and attended the University of Pisa (where I received my undergraduate degree) and the Scuola Normale Superiore of Pisa (where I received my Ph.D. in Physics).

From the Nasa files

Dr. Massimo Stiavelli is a humble person, extremely modest about his accomplishments, so we have added his credits here, from the NASA webpage.

Dr. Stiavelli has published more than 130 papers, including articles in the Astronomical Journal, the Astrophysical Journal, and the European Space Agency (ESA) Special Publication.

Before joining the Space Telescope Science Institute, Dr. Stiavelli was a tenured researcher at the Scuola Normale Superiore in Pisa, Italy. He taught courses in cosmology and complex dynamical systems and researched the formation of elliptical galaxies and central black holes.

He is very interested in outreach, giving talks at the institute, schools, and museums, and has made multiple appearances at the Baltimore Star Trek convention Shore Leave. He is often asked to make presentations at a number of high-level professional events throughout the year, including the Texas/ESO-CERN Symposium, First Stars series, National Research Council study, IAU (International Astronomical Union) Symposia, and many more.

Dr. Stiavelli manages and prioritizes the workflow for 300 scientists, engineers, and technical staff. He oversees the team’s strategic planning, priority setting, and interaction with contacts at NASA and also on external committees.

In his earlier work, he was a Fellow of the European Southern Observatory and was a post-doctoral scientist at Rutgers University in New Jersey. At Rutgers, he researched the stability of stellar dynamics models of galaxies. He started his career as a second lieutenant in the Italian Army.