Alan Stern outlines New Horizons’ extended mission at Planetary Science Conference

Michael Cole

New Horizons Principal Investigator Alan Stern. Photo Credit: Southwest Research Institute

HOUSTON, Texas — Alan Stern, primary investigator of the New Horizons mission to Pluto, laid out the future of the mission in an address to the 47th Lunar and Planetary Science Conference in Houston, Texas, on Monday, March 21.

Stern was the first of his New Horizon team members who are scheduled to present data on the mission to the conference throughout the week. That team is continuing to receive data from the spacecraft from its July 14, 2015, flyby of Pluto for the next several months. However, they are also preparing for the spacecraft’s extended mission.

“The centerpiece of our extended mission proposal is a close flyby, a much closer flyby than our flyby of Pluto, to a small Kuiper Belt object discovered by the Hubble Space Telescope (HST) for New Horizons,” Stern said. “Actually, our team led that observing campaign. The object is called 2014 MU69.”

HST discovered MU69 in June of 2014 and identified it as a possible second Kuiper Belt Object (KBO) for New Horizons to target after its flyby of Pluto. Additional observations of the object and further calculations of its orbit resulted in MU69 being designated as the second close flyby destination for New Horizons in August of 2015.

“We don’t know its size but we can make good guesses about its albedo and, therefore, derive its size from its brightness,” Stern said. “It is somewhere between 20 and 40 km across. So it’s like the scale of Eros (the near-Earth asteroid visited by the NEAR spacecraft).”

MU69’s orbit suggests an extremely high probability that the object is a Cold Classical KBO – meaning its origin was not somewhere dramatically closer to the Sun, but actually out in the Kuiper Belt.

“It is an object that’s always been cold,” Stern said. “Unlike all the comets and other small bodies that we’ve flown by, this is probably our opportunity for the most pristine object anyone has ever been able to study.”

The flyby will take place on January 1, 2019. But it is only the centerpiece of a much more comprehensive investigation of the Kuiper Belt. Four other objectives will stretch the extended mission from 2016 to 2021.

“In addition to making a close flyby of MU69, we’re also going to be close enough in range to study quite a number of other small KBOs, and some large ones that are on the Pluto scale,” Stern said.

New Horizons will be able to study them in ways that could never be accomplished from Earth. The closeness of the spacecraft will enable high-resolution observations, and the ability to look for satellites that cannot be seen from Earth observatories or with the Hubble Telescope.

“Because we are looking back on the rest of the solar system, at the Kuiper Belt and the Centaur Population,” Stern said, “we’re going to be able to study another 18 or 20 small bodies to determine whether or not the recently discovered rings around the centaur Chariklo are a common occurrence, or something anomalous. And I don’t know of any other way over the next several years, except through New Horizons, that we can develop a data set like that.”

New Horizons’ plasma instrument and dust instrument will be busy throughout the extended mission, collecting data on how space weathering affects the surfaces and regoliths of KBOs. NASA has also asked to potentially re-purpose New Horizons late in the extended mission to do some observations for astrophysics investigations.

“You may recall that Voyager was used in the same way in the 1990s,” Stern said. “I’m very happy if New Horizons is able to contribute something more than even planetary science. So we are making that option available to NASA as well.”

“We flew nine-and-a-half years and 3 billion miles to get to our target – the Kuiper Belt. Not just Pluto. The Kuiper Belt,” Stern concluded. “New Horizons will be busy each and every year making multiple KBO observations so that we really develop this fantastic data set by the end of the process. That gives us one KBO up close with as good as 25-meter per pixel resolution. And in addition, the study of dozens of other KBOs.”

The New Horizons mission, launched on January 19, 2006, has yielded numerous historic discoveries, and continues to exceed all expectations.