NASA’s first Pluto probe roused itself from its final nap right on schedule, almost ready after a voyage of nearly nine years and 3 billion miles for a very close encounter with the dwarf planet next year.
The New Horizons spacecraft, which already has traveled farther than any other to reach its primary target, will start observations in January. It won’t reach its closest approach to Pluto—about 6,200 miles—until summer.
Mission controllers at the Johns Hopkins University Applied Physics Laboratory verified late Dec. 6 that New Horizons, operating on computer commands uploaded in August, had switched from hibernation to “active” mode.
Moving at light speed, the radio confirmation from the probe—then more than 2.9 billion miles from Earth and just over 162 million miles from Pluto—needed four hours and 26 minutes to reach NASA’s Deep Space Network station in Canberra, Australia.
“This is a watershed event that signals the end of New Horizons crossing of a vast ocean of space to the very frontier of our solar system, and the beginning of the mission’s primary objective: the exploration of Pluto and its many moons in 2015,” says Alan Stern of Southwest Research Institute in Boulder, Colo. He is the mission’s principal investigator.
Since launching on January 19, 2006, New Horizons has spent 1,873 days—about two-thirds of its flight time—in hibernation. Its 18 separate sleep periods, from mid-2007 to late 2014, ranged from 36 to 202 days in length. The team used hibernation to save wear and tear on spacecraft components and reduce the risk of system failures.
“New Horizons is on a journey to a new class of planets we’ve never seen, in a place we’ve never been before,” says project scientist Hal Weaver of APL. “For decades, we thought Pluto was this odd little body on the planetary outskirts; now we know it’s really a gateway to an entire region of new worlds in the Kuiper Belt, and New Horizons is going to provide the first close-up look at them.”
The New Horizons team will spend several weeks checking out the spacecraft, making sure its systems and science instruments are operating properly. They’ll also continue to build and test the computer-command sequences that will guide New Horizons through its flight to and reconnaissance of the Pluto system.
With a seven-instrument science payload that includes advanced imaging infrared and ultraviolet spectrometers, a compact multicolor camera, a high-resolution telescopic camera, two powerful particle spectrometers and a space-dust detector, New Horizons will begin observing the Pluto system on Jan. 15.
New Horizons’ closest approach to Pluto will occur on July 14, but plenty of highlights are expected before then, including, by mid-May, views of the Pluto system better than what the mighty Hubble Space Telescope can provide of the dwarf planet and its moons.
How hibernation worked
During hibernation, much of the New Horizons spacecraft was unpowered. The onboard flight computer monitored system health and broadcast a weekly beacon-status tone back to Earth. During its wake periods, mission controllers checked out critical systems, calibrated instruments, gathered some science data, rehearsed Pluto-encounter activities, and made course corrections.
New Horizons pioneered routine cruise-flight hibernation for NASA. Not only has hibernation reduced wear and tear, it also lowered operations costs and freed up NASA Deep Space Network tracking and communication resources for other missions.
The Johns Hopkins Applied Physics Laboratory manages New Horizons for NASA; it designed, built and operates the spacecraft. Southwest Research Institute leads the science team, payload operations, and encounter science planning.
Source: Johns Hopkins University