Dr. David H. Grinspoon, Senior Scientist, Planetary Science Institute, moderates a panel at the “Ancient Earth, Alien Earths” Event at NASA Headquarters in Washington, DC Wednesday, August 20, 2014. The event was sponsored by NASA, the National Science Foundation (NSF), and the Smithsonian Institution and highlighted how research on early Earth could help guide our search for habitable planets orbiting other stars. Photo Credit: (NASA/Aubrey Gemignani)

New Horizons science team members: Dr. John Spencer, senior scientist at the Southwest Research Institute, left, Dr. Jeffrey Moore, senior scientist at NASA Ames Research Center, second from left, Dr. David H. Grinspoon, senior scientist at the Planetary Science Institute, center, Dr. Bonnie Buratti, senior scientist at NASA's Jet Propulsion Laboratory, second from right, and Dr. Fran Bagenal, senior scientist at the University of Colorado, are seen during a panel discussion at the "NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy of Exploration" event on Monday, August, 25, 2014, in the James E. Webb Auditorium at NASA Headquarters in Washington, DC. The panelists gave their accounts of Voyager's encounter with Neptune and discussed their current assignments on NASA's New Horizons mission to Pluto. Photo Credit: (NASA/Joel Kowsky)

Jim Green, director, Planetary Science Division, NASA Headquarters, Washington, left, is seen with fellow panelists Carey Lisse, senior astrophysicist, Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, Kelly Fast, program scientist, Planetary Science Division, NASA Headquarters, Washington, and Padma Yanamandra-Fisher, senior research scientist, Space Science Institute, Rancho Cucamonga Branch, California during a media briefing where they outlined how space and Earth-based assets will be used to image and study comet Siding Spring during its Sunday, Oct. 19 flyby of Mars, Thursday, Oct. 9, 2014 at NASA Headquarters in Washington. Photo Credit: (NASA/Joel Kowsky)

Panelists, from left, Jim Green, director, Planetary Science Division, NASA Headquarters, Washington, Carey Lisse, senior astrophysicist, Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, Kelly Fast, program scientist, Planetary Science Division, NASA Headquarters, Washington, and Padma Yanamandra-Fisher, senior research scientist, Space Science Institute, Rancho Cucamonga Branch, California, are seen during a media briefing where they outlined how space and Earth-based assets will be used to image and study comet Siding Spring during its Sunday, Oct. 19 flyby of Mars, Thursday, Oct. 9, 2014 at NASA Headquarters in Washington. (Photo credit: NASA/Joel Kowsky)

Panelists, from left, Jim Green, director, Planetary Science Division, NASA Headquarters, Washington, Carey Lisse, senior astrophysicist, Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, Kelly Fast, program scientist, Planetary Science Division, NASA Headquarters, Washington, and Padma Yanamandra-Fisher, senior research scientist, Space Science Institute, Rancho Cucamonga Branch, California, are seen during a media briefing where they outlined how space and Earth-based assets will be used to image and study comet Siding Spring during its Sunday, Oct. 19 flyby of Mars, Thursday, Oct. 9, 2014 at NASA Headquarters in Washington. (Photo credit: NASA/Joel Kowsky)

Panelists, from left, Jim Green, director, Planetary Science Division, NASA Headquarters, Washington, Carey Lisse, senior astrophysicist, Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, Kelly Fast, program scientist, Planetary Science Division, NASA Headquarters, Washington, and Padma Yanamandra-Fisher, senior research scientist, Space Science Institute, Rancho Cucamonga Branch, California, are seen during a media briefing where they outlined how space and Earth-based assets will be used to image and study comet Siding Spring during its Sunday, Oct. 19 flyby of Mars, Thursday, Oct. 9, 2014 at NASA Headquarters in Washington. (Photo credit: NASA/Joel Kowsky)

Dr. Phoebe Cohen, Professor of Geosciences, Williams College, speaks on a panel at the “Ancient Earth, Alien Earths” Event at NASA Headquarters in Washington, DC Wednesday, August 20, 2014. The event was sponsored by NASA, the National Science Foundation (NSF), and the Smithsonian Institution and was moderated by Dr. David H. Grinspoon, Senior Scientist at the Planetary Science Institute. Six scientists discussed how research on early Earth could help guide our search for habitable planets orbiting other stars. Photo Credit: (NASA/Aubrey Gemignani)

Dr. Christopher House, Professor of Geosciences, Pennsylvania State University, speaks on a panel at the “Ancient Earth, Alien Earths” Event at NASA Headquarters in Washington, DC Wednesday, August 20, 2014. The event was sponsored by NASA, the National Science Foundation (NSF), and the Smithsonian Institution and was moderated by Dr. David H. Grinspoon, Senior Scientist at the Planetary Science Institute. Six scientists discussed how research on early Earth could help guide our search for habitable planets orbiting other stars. Photo Credit: (NASA/Aubrey Gemignani)

Dr. Timothy Lyons, Professor of Biogeochemistry, UC Riverside, speaks on a panel at the “Ancient Earth, Alien Earths” Event at NASA Headquarters in Washington, DC Wednesday, August 20, 2014. The event was sponsored by NASA, the National Science Foundation (NSF), and the Smithsonian Institution and was moderated by Dr. David H. Grinspoon, Senior Scientist at the Planetary Science Institute. Six scientists discussed how research on early Earth could help guide our search for habitable planets orbiting other stars. Photo Credit: (NASA/Aubrey Gemignani)

Dr. Dawn Sumner, Professor of Geology, UC Davis, speaks on a panel at the “Ancient Earth, Alien Earths” Event at NASA Headquarters in Washington, DC Wednesday, August 20, 2014. The event was sponsored by NASA, the National Science Foundation (NSF), and the Smithsonian Institution and was moderated by Dr. David H. Grinspoon, Senior Scientist at the Planetary Science Institute. Six scientists discussed how research on early Earth could help guide our search for habitable planets orbiting other stars. Photo Credit: (NASA/Aubrey Gemignani)

An audience member asks the panelists a question at the “Ancient Earth, Alien Earths” Event at NASA Headquarters in Washington, DC Wednesday, August 20, 2014. The event was sponsored by NASA, the National Science Foundation (NSF), and the Smithsonian Institution and was moderated by Dr. David H. Grinspoon, Senior Scientist at the Planetary Science Institute. Six scientists discussed how research on early Earth could help guide our search for habitable planets orbiting other stars. Photo Credit: (NASA/Aubrey Gemignani)

David Grinspoon, senior scientist at the Planetary Science Institute discusses Pluto and the Human Imagination, Monday, Dec. 31, 2018 at Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. Photo Credit: (NASA/Bill Ingalls)

David Grinspoon, senior scientist at the Planetary Science Institute discusses Pluto and the Human Imagination, Monday, Dec. 31, 2018 at Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. Photo Credit: (NASA/Bill Ingalls)

Panelists discuss how research on early Earth could help guide our search for habitable planets orbiting other stars at the “Ancient Earth, Alien Earths” Event at NASA Headquarters in Washington, DC Wednesday, August 20, 2014. The event was sponsored by NASA, the National Science Foundation (NSF), and the Smithsonian Institution and was moderated by Dr. David H. Grinspoon, Senior Scientist at the Planetary Science Institute. Photo Credit: (NASA/Aubrey Gemignani)

Dr. Shawn Domagal-Goldman, Research Space Scientist, NASA Goddard Space Flight Center, speaks on a panel at the “Ancient Earth, Alien Earths” Event at NASA Headquarters in Washington, DC Wednesday, August 20, 2014. The event was sponsored by NASA, the National Science Foundation (NSF), and the Smithsonian Institution and was moderated by Dr. David H. Grinspoon, Senior Scientist at the Planetary Science Institute. Six scientists discussed how research on early Earth could help guide our search for habitable planets orbiting other stars. Photo Credit: (NASA/Aubrey Gemignani)

Dr. Shawn Domagal-Goldman, Research Space Scientist, NASA Goddard Space Flight Center, speaks on a panel at the “Ancient Earth, Alien Earths” Event at NASA Headquarters in Washington, DC Wednesday, August 20, 2014. The event was sponsored by NASA, the National Science Foundation (NSF), and the Smithsonian Institution and was moderated by Dr. David H. Grinspoon, Senior Scientist at the Planetary Science Institute. Six scientists discussed how research on early Earth could help guide our search for habitable planets orbiting other stars. Photo Credit: (NASA/Aubrey Gemignani)

Dwayne Brown, NASA public affairs officer, left, moderates a media briefing where panelist, seated from left, Jim Green, director, Planetary Science Division, NASA Headquarters, Washington, Carey Lisse, senior astrophysicist, Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, Kelly Fast, program scientist, Planetary Science Division, NASA Headquarters, Washington, and Padma Yanamandra-Fisher, senior research scientist, Space Science Institute, Rancho Cucamonga Branch, California, outlined how space and Earth-based assets will be used to image and study comet Siding Spring during its Sunday, Oct. 19 flyby of Mars, Thursday, Oct. 9, 2014 at NASA Headquarters in Washington. (Photo credit: NASA/Joel Kowsky)

Dr. David H. Grinspoon, senior scientist at the Planetary Science Institute, speaks about working on NASA's Voyager team while serving as moderator for a panel discussion at the "NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy of Exploration" event on Monday, August, 25, 2014, in the James E. Webb Auditorium at NASA Headquarters in Washington, DC. The panelists gave their accounts of Voyager's encounter with Neptune and discussed their current assignments on NASA's New Horizons mission to Pluto. Photo Credit: (NASA/Joel Kowsky)

Panelists (from left) Ellen Stofan, NASA Chief Scientist, left; John Grunsfeld, Associate Administrator for NASA's Science Mission DIrectorate, second from left; John Mather, Nobel Laureate and Senior Project Scientist for the James Webb Space Telescope (JWST) at NASA's Goddard Space Flight Center, third from left; Sara Seager, MacArthur Fellow and Professor of Planetary Science and Physics at the Massachusetts Institute of Technology, third from right; Dave Gallagher, Director for Astronomy and Physics at NASA's Jet Propulsion Laboratory, second from right; and Matt Mountain, Director of the Space Telescope Science Institute and Telescope Scientist for the JWST, right; are seen during a panel discussion on the search for life beyond Earth in the James E. Webb Auditorium at NASA Headquarters on Monday, July 14, 2014 in Washington, DC. The panel discussed how NASA's space-based observatories are making new discoveries and how the agency's new telescope, the James Webb Space Telescope, will continue this path of discovery after its schedule launch in 2018. Photo Credit: (NASA/Joel Kowsky)