Editor's note: Dr. Neil Gehrels of the Goddard Space Flight Center passed away on Feb. 6. He began his career there after earning his doctorate from Caltech in 1982, becoming world renowned for gamma ray astronomy. He was named chief of Goddard's Astroparticle Physics Laboratory in 1995. He served as a project scientist and investigator on a number of landmark missions, among them the Wide Field Infrared Survey Telescope (WFIRST). Dr. Gehrels wrote this update on the WFIRST mission just a few weeks before his death; it is published here as a tribute to him.

Neil Gehrels, NASA Goddard Space Flight Center, chief, Astroparticle Physics Laboratory

2016 will go down as a memorable year for the Wide Field Infrared Survey Telescope (WFIRST). We started the year with a huge NASA review. It was called KDP-A (critical design point A), and was our opportunity to convince NASA that WFIRST was ready to move into Phase A. Importantly, this step is the one to make WFIRST an official NASA mission with a budget line in the high-level NASA budgets. The final step was a presentation to top NASA management, chaired by the NASA Associate Administrator and including the Heads of NASA's Directorates, Center Directors and representatives from the Exoplanet Program office and WFIRST project.

A lot has been happening since the review. On the technology side, the Coronagraph and the Wide Field Instrument infrared detectors have passed their technology milestones on schedule. It is so amazing to see these large high-tech instruments start to take shape. On the science-center side, there is a good working relationship formed between Goddard, the Infrared Processing and Analysis Center (IPAC) and the Space Telescope Science Institute (STScI). We had a meeting at Princeton organized by David Spergel to discuss organizing early data challenges to get thinking going on data processing. There have been regular meetings organized by Jeremy Kasdin to move the coronagraph hardware and data aspects forward.

Now for my favorite subject, the Formulation Science Working Group. This is the group made up of the Principal Investigators of the Science Investigation Teams, Project Science and HQ Science leads, and foreign observers. I chair the group with Kasdin and Spergel as co-chairs. We have had three meetings this year pinning down the mission requirements and working closely with the Project team to make decisions on the instrument configuration. We are also having fun thinking about the science of WFIRST: dark energy, exoplanet survey, direct imaging of exoplanets, and general astrophysics (from planetary objects, to stellar systems, to galaxies across the ages, and cosmology).