Hubble To Lend Pluto Probe Helping Hand in Search for Secondary Target


WASHINGTON — Senior astronomers approved a plan to use the Hubble Space Telescope to search for a faraway space rock for the New Horizons probe to rendezvous with after it completes primary observations of Pluto in 2015, NASA announced June 16.

The news comes less than two weeks after the Senate Appropriations Committee urged the agency to find a follow-up New Horizons target.

“The Committee encourages the planetary science community to select the secondary destination as soon as possible,” Senate appropriators wrote in the report accompanying their 2015 Commerce, Justice, Science Appropriations bill, which along with two other spending bills was rolled up into the “minibus” spending package the full Senate began debating June 17.

New Horizons, a roughly $650 million planetary science mission and the first in NASA’s medium-sized New Frontiers program, launched in 2006 on a flyby mission to Pluto. The probe will not enter orbit around the dwarf planet, but instead go zipping by in 2015 on path that may, or may not, lead to a 2016 encounter with a small body in the Kuiper Belt — a band of rocky objects orbiting about 30 to 50 times farther from the sun than Earth.

“We’re looking for objects so faint they are at the limit of astronomical capability,” Alan Stern, principal investigator for New Horizons and former head of NASA’s Science Mission Directorate, wrote in a June 16 email. “Even for Hubble, this is challenging.”

Nevertheless, Stern thinks there is a 95 percent chance of finding a suitable Kuiper Belt object using Hubble. That compares with a 40 percent probability of success using ground-based telescopes, which must contend with the distorting influence of Earth’s atmosphere when they observe the heavens, Stern said.

Senior astronomers on the Hubble Space Telescope Time Allocation Committee gave the New Horizons team permission to use the flagship observatory for a preliminary Kuiper Belt object search. If the team finds at least two such objects along New Horizon’s trans-Pluto flight path, they will be given even more Hubble time, said Ray Villard, a spokesman for the Space Telescope Science Institute in Baltimore.

The preliminary search, which began June 16 when NASA issued the press release announcing the effort, will take place over 40 Hubble orbits. A follow-on scouting period, should the team earn one, will take up 120 orbits, Villard said. Hubble orbits Earth roughly once every 96 minutes.

The team in charge of the New Horizons Kuiper Belt Object Survey, as the search is officially known, is led by John Spencer, institute scientist at the Southwest Research Institutes’s Department of Space Studies in Boulder, Colorado.

The Hubble Space Telescope Time Allocation Committee, made up of senior scientists drawn from the astronomy community at large, approved time for the New Horizons Kuiper Belt Object Survey as part of their annual review of proposals for Hubble’s General Observer Program. The review took place at the Space Telescope Science Institute, which runs Hubble science operations on NASA’s behalf and is itself run by the Association of Universities for Research in Astronomy, an academic consortium with about 50 member institutions.


Follow Dan on Twitter: @Leone_SN