July 29, 2013
Scientists on the New Horizons mission are beginning to plan in earnest how they will evaluate the data that will begin flowing back from Pluto in less than two years, when the nuclear-powered probe begins sending “better than Hubble” imagery of the distant body and its satellites.
The spacecraft's Long-Range Reconnaissance Imager (Lorri) has already resolved Pluto and Charron, its largest satellite, into two distinct objects (see image, page 22). With the resolution improving by the day, the mission team has planned and uploaded its flyby choreography, and has sent out a call to astronomers for parallel observation from Earth and its environs before, during and after the July 14, 2015, encounter.
The team also has completed a rehearsal with the spacecraft, and conducted a detailed scientific workshop at the Johns Hopkins University's Applied Physics Laboratory (APL) here, where New Horizons was built. There are no plans to retarget the probe again.
“The security that we get by knowing that we've practiced all of these observations on the spacecraft outweighs the flexibility that we would want to be able to do any last-minute targeting,” says astronomer Leslie Young of the Southwest Research Institute (SWRI), who led the team that planned the encounter.
On a mission that has been under consideration since before NASA launched its first Voyager mission to the outer planets on Sept. 5. 1977, long before Pluto was downgraded from the ninth planet to a Kuiper Belt object large enough to be termed a dwarf planet, the two years remaining before the flyby are a virtual blink of the eye. Planning for the encounter started in 2000, when the New Horizons team was preparing its mission proposal, and started “in earnest” after the spacecraft hurtled past Jupiter and gave its operators some experience collecting data at a real planet.
“We are really at this moment, in July of 2013, kicking off this encounter,” says SWRI's Alan Stern, the mission's principal investigator. “We've just finished a nine-day close encounter rehearsal on the spacecraft. The spacecraft performed flawlessly. The entire close-approach sequence was put up on the spacecraft, and it ran from July 5 to July 14, and the spacecraft got an A-plus.”
The mission-science conference at APL gave researchers an idea of what they can expect to receive in the year-and-a-half that it will take after the close encounter to transmit all the data over the 5 billion km (3 billion mi.) that will separate New Horizons from Earth. There are seven instruments on New Horizons, carefully selected after a lot of scientific argument to glean as much information about the outer Solar System as possible. The ink on textbooks rewritten to accommodate discoveries from the Hubble Space Telescope is barely dry, but the scientists here expect they will need to be rewritten again once the spacecraft draws close enough to the Pluto system to incorporate an unprecedented flood of information about the unexplored region.