Hubble mosaic of the Triangulum galaxy (M33)
APRIL 4, 2019

Set to Survey the Sky

WFIRST passed a major mission review, allowing staff to begin the next phase of development.


It’s hard not to be wowed by the Wide Field Infrared Survey Telescope (WFIRST): When it launches in the mid-2020s, its field of view will be 100 times the size of the Hubble Space Telescope’s with the same size mirror. This enables it to produce surveys that will allow researchers to revolutionize the field of astronomy with the extremely rich data it produces.

In February 2018, WFIRST passed a combined system requirements and mission definition review, and in May formally began its preliminary design phase, a project milestone. Astronomers, scientists, and engineers at the institute support the observatory in partnership with teams at NASA’s Goddard Space Flight Center, NASA’s Jet Propulsion Laboratory (JPL), the California Institute of Technology/IPAC, industrial and foreign partners, and WFIRST’s Formulation Science Working Group and Science Investigation Teams. 

This new phase of development means the group is focused on completing detailed requirements and producing preliminary designs of the WFIRST Science Operations Center systems at the institute. Here, we provide a preview of the data it will deliver, along with major 2018 accomplishments.

Deep Sky Surveys

One of WFIRST’s science goals is to explore the nature of dark energy, a mysterious force speeding the universe’s expansion. It will accomplish this through survey programs, including one that will observe thousands of supernovas and gather observations in multiple tiers (shallow and wide to deep and narrow). In particular, observations of white dwarf supernovas will tell us about the evolution of dark energy over time by identifying supernovas at different points of cosmic history. Astronomers prize white dwarf supernovas because they provide a precise measure of distance that can be used to calculate the expansion of space. The supernova observations will also show how quickly the universe enriched itself with heavy elements.

A second survey will measure distances, shapes, and colors of over a billion galaxies and observe more than 10,000 large galaxy clusters. This galaxy survey, combined with the supernova survey, will allow researchers to measure the evolution of dark energy over time and constrain its nature, which is crucial since it makes up approximately 73 percent of the universe. WFIRST’s surveys will provide observations of galaxies throughout the history of the universe, equaling Hubble’s iconic deep surveys in depth but expanding their area by thousands of times.

WFIRST will also monitor our own galactic bulge for exoplanets with masses as low as Mars passing in front of background stars, causing them to brighten in what are called planetary microlensing events. It will also discover about 70,000 new planets as they pass in front of their host star, dimming the star’s light, and provide a rich data set of tens of thousands of individual measurements of over 1 million stars. By probing these large survey data sets, researchers will be able to study the physics of stars, potentially reshaping how we understand stellar evolution.

Preparing Significant Collaborations

Like all of our missions, WFIRST’s data can be combined with those from other telescopes, including Hubble and the upcoming James Webb Space Telescope. The WFIRST surveys will discover many objects that astronomers will then want to study in more detail with Webb by using its large mirror and many observing modes. It also has promising overlap with the Large Synoptic Survey Telescope (LSST), a ground-based, wide-field telescope that will photograph the entire available sky every few nights beginning in 2021.

Science teams recently proposed observing the same deep fields with LSST that WFIRST will capture. While WFIRST will specialize in the infrared, LSST will gather light from bluer wavelengths, providing more information of the same areas of the sky to produce a full panchromatic picture once they are combined—and lead to invaluable constraints on theoretical models about galaxy formation. This proposal, which was published in a white paper in November 2018, is the result of partnerships formed between LSST and WFIRST science team members through workshops and working groups.

Data Accessible to All

The sheer quantity of data WFIRST will provide is astounding. In its first three months of operations, WFIRST’s Wide Field Instrument will provide a data stream that is equivalent to what Hubble has produced since launching in 1990. Its data will be immediately available to all researchers, allowing them to quickly hone in on areas of interest and begin investigating topics that span the breadth of astronomy.

To prepare, the institute’s WFIRST staff have delivered their operations concepts, including how the data management system will run within the Barbara A. Mikulski Archive for Space Telescopes (MAST), to help astronomers digest this enormous data set for their research.

The team continued to create tools to help the science community prepare to observe with WFIRST, which are currently available in MAST and on GitHub, and include an exposure time calculator, a point spread function model, and an image simulator. The team also maintains the Field of View Overlay Tool, which allows users to become familiar with the WFIRST capabilities to perform surveys of wide fields.

All of this work builds excitement for the surveys WFIRST will produce. Its abundance of data will reveal remarkable details that lead us to improve our understanding of the evolution and formation of the universe.


Size and scale of the Triangulum galaxy (M33)
The mosaic of the Triangulum galaxy (M33), shown at the top of the page, includes 54 individual Hubble Space Telescope fields of view, which were stitched together. WFIRST could produce a significantly larger view with only one pointing. Credit: NASA, ESA, and M. Durbin, J. Dalcanton, and B.F. Williams (University of Washington).