NASA's New Great Observatory Takes Shape with IPAC's Support

Community Announcement • March 17th 2016

In mid-February, NASA gave the official go-ahead for the Wide-Field Infrared Survey Telescope (WFIRST), a next generation observatory slated to launch into space in the mid-2020s. Teams of scientists and engineers are now honing the concept for WFIRST as a fast, deep, mapping engine at near-infrared wavelengths for addressing fundamental questions about dark energy, exoplanets and numerous other topics in astrophysics. In this development, IPAC at the California Institute of Technology in Pasadena is playing a critical role.

From all-sky surveys to studying exoplanets, IPAC has a long history working on precursor missions to WFIRST. With this new project, IPAC is sharing the WFIRST science center activities with the Space Telescope Science Institute (STScI) in Baltimore, under leadership from NASA's Goddard Space Flight Center in Greenbelt, Maryland and in close collaboration with NASA's Jet Propulsion Laboratory (JPL).

"By leveraging our experience with previous and ongoing missions, IPAC is bringing a wealth of expertise to the WFIRST formulation phase," said George Helou, Executive Director of IPAC and Research Professor of Physics in the Division of Physics, Math and Astronomy at Caltech. "We at IPAC are all very excited about being a part of WFIRST and are happy to work with the outstanding teams at Goddard, JPL and STScI in this endeavor."

WFIRST will capture near-infrared light using a 7.8-foot (2.4-meter) mirror, the same size as the Hubble Space Telescope's, but WFIRST will take in a field of view 100 times larger and with the same image quality. This vast perspective will enable WFIRST to survey a billion galaxies and delve into the mystery of dark energy, which is thought to cause the acceleration of the universe's expansion.

Managing the huge amounts of data yielded by major sky surveys is a complex task that IPAC has handled before with the Spitzer Space Telescope, the Wide-field Infrared Survey Explorer (WISE), and the Two Micron All Sky Survey (2MASS).

"Large astronomical surveys are part of the IPAC DNA," said Roc Cutri, Deputy Director of IPAC and Task Lead for the WFIRST effort at IPAC.

Another primary science goal for WFIRST will be the discovery of thousands of new exoplanets. As it sets its sights on the densely populated inner regions of the Milky Way, WFIRST will detect exoplanets through gravitational microlensing, wherein passing foreground stars and their orbiting worlds temporarily warp and amplify the light of background stars. The technique is handy for revealing exoplanets that happen to lie in the line of sight towards the center of our Milky Way. It is also the easiest way to find small planets like Mars far from their star, and even free-floating planets not bound to any star.

"Spitzer observations of microlensing have taught us some important lessons that we will apply to WFIRST in preparation for its quest for thousands of exoplanets," said Sean Carey, who leads the Spitzer Science Center team participating in microlensing observations.

Also on WFIRST's science agenda: the detailed examination of nearby exoplanets, and in this realm again, IPAC brings know-how from the NASA Exoplanet Science Institute (NExScI) and the Spitzer mission. Scientists have trained Spitzer on large and medium-sized, warm exoplanets in order to collect scant light-bearing signatures of the chemical compositions of their atmospheres. WFIRST will extend this approach to cooler, smaller worlds farther from their stars, helping scientists better understand the atmospheric chemistries and conditions for potentially habitable exoplanets.

Enabling these critical advances in exoplanet research will be WFIRST's coronagraph, an instrument that JPL will build and deliver, and for which IPAC will focus on optimizing data collection and analysis. A coronagraph blocks out the overwhelming brightness of a primary object, such as a star, permitting study of any comparatively dim objects in the vicinity, such as planets.

IPAC is also helping to develop other promising astrophysical applications for coronagraphy. For instance, WFIRST's coronagraph could obscure the light of dominatingly bright stars to search for their hard-to-see stellar companions or surrounding nebulosities. This approach could also allow WFIRST to peer into protoplanetary disks, where planets arise.

"Besides planets themselves, coronagraphs can help in seeing brand new worlds taking shape in the dusty disks encircling young stars," said Rachel Akeson, Deputy Director of the NASA Exoplanet Science Institute and member of the coronagraphy support team for WFIRST at IPAC.

Furthermore, the coronagraph on WFIRST may even deepen our understanding of objects in the distant universe. With its unique ability to blot out the blinding light from the centers of galaxies, WFIRST will give us a high-resolution look at the gas and stars surrounding quasars, which are distant, matter-gorging, supermassive black holes. Extremely bright and point-like, these objects will lend themselves well to occultation by the WFIRST coronagraph, revealing key details that would otherwise be lost in the quasars' glare.

"While the coronagraph is being built to study nearby exoplanets, there is a wealth of extragalactic science that can be addressed by the high-contrast imaging and spectroscopy it will provide," said Lee Armus, deputy lead for the IPAC WFIRST team.

The preparation for WFIRST science by IPAC will be further helped along by the deployment of Euclid, a joint European Space agency and NASA space telescope project taking to the skies in 2020. Euclid will rely on essentially the same detector technology as WFIRST, but in a smaller format. "We are looking forward to learning a lot of lessons from Euclid that will be applicable to WFIRST," said Helou.

NASA has selected a dozen science teams to investigate how to maximize the science return from WFIRST. These teams include ten IPAC scientists, spanning topics from exoplanets to cosmology. The researchers' efforts will lay out the extraordinary science made possible by WFIRST next decade and thereafter. Brain-storming already started, as more than a hundred and fifty scientists gathered in Pasadena for a conference entitled "Community Astrophysics with WFIRST: Guest Observer and Archival Science." ‐

"The community is really excited about the rich and diverse science that can be achieved with WFIRST, and that was clearly reflected in the strong response and quality of the presentations," said Armus.

"Every time we've built an observatory, we have been surprised and delighted by all the innovation the astronomical community brings to the use of the observatory," said Helou. "As we get closer to WFIRST's deployment and into the mission phase itself, I am sure the astronomical community will come up with great ideas we haven't even dreamt of yet."