b'Carnegie Science|Fall 2019 17This artists illustration shows the GJ 357 planetary system. Image courtesy Carl Sagan Institute/Jack MaddenSUPPORT:TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASAs Goddard Space Flight Center. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASAs Ames Research Center in Californias Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MITs Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes, and observatories worldwide are participants in the missionCarnegies Sharon Wang noted, This planetary system helps demonstrate how crucial tools such as the PFS are for TESSs success.All of PFS team memberswhich also include Fabo Feng, Paul Butler, Jeff Crane, and Stephen Shectmanare coauthors on the paper. GJ 357 c, which has a mass at least 3.4 times Earths, orbits the star every 9.1 days at a distance of a bit more than twice its sibling GJ 357 b. It has an equilibrium temperature of around 260F (127C).GJ 357 d, the systems farthest-known planet, has a mass at least 6.1 times Earths and orbits the star every 55.7 days at a distance of about 20% of that between Earth and the Sun. The planets size and composition are unknown, but with an equilibrium temperature of -64F (-53C) the planet seems more glacial than habitable. Future studies are needed to determine if it has a dense atmosphere. If so, it could trap enough heat to warm its surface enough to host liquid water.Studying the detailed composition of the atmospheres of nearby exoplanets will be a task for NASAs James Webb Space Telescope, slated to launch in 2021, and by the new generation of so-called extremely large ground-based telescopes now under construction, including the Giant Magellan Telescope that is being built at Las Campanas. This artists illustration shows a depiction of GJ 357 d, one of the planets found. Image courtesy NASAs Goddard Space Flight Center/Chris Smith'