All three of these missions are planetary-science missions, housed in the only NASA division which visits worlds beyond our own. The New Horizons probe that visited Pluto this year was also a planetary-science mission. Dreier noted that the 2016 budget restores historically normal levels of funding to NASA planetary science, which had seen its budget sliced by 25 percent in the early part of this decade.
Because of those cuts, no new planetary-science missions will fly from the end of 2016 to the beginning of 2020. Dreier said this was “the longest gap in planetary science in at least 20 years.”
At the end of that period, as well, the one-year Juno mission at Jupiter and the 11-year-old Cassini-Huygens mission at Saturn will draw to a close.
“For the first time since the early 1970s, the U.S. will not have a robotic presence in the giant planets of the outer solar system” at that time, said Dreier.
After 2020, NASA is expected to launch new robotic missions to Mars and Europa, a moon of Jupiter believed to be more amenable to life than other worlds in the solar system. (A Congressional report attached to the 2016 budget encouraged NASA to make the Europa mission a rover, rather than a lander or an orbiter. Dreier said he was not sure whether NASA would obey the report.)
Beyond planetary science, the coming years are likely to be busy for NASA. In 2017, the agency hopes to complete its commercial-crew development program with SpaceX and Boeing, which will once again launch allow crewed missions to fly to the International Space Station from American soil. It also hopes to advance its Space Launch System, the largest U.S. rocket system constructed since the Apollo era’s Saturn V. The Space Launch System will permit crewed missions to travel past the moon and robotic missions to reach gas giants and the outer solar system without using the gravity slingshot of Earth or Venus.