New Horizons spacecraft will wake up today
Sen—Pluto, are you ready for your closeup? Controllers of the New Horizons spacecraft are counting down the days until the closest encounter with the dwarf planet about a year from now.
Meanwhile, today (15 June) they will temporarily wake up the spacecraft from its power-saving hibernation mode to check on its systems and perform some preliminary science ahead of the flyby in July 2015.
"This summer’s hibernation wakeup will be a particularly busy operation," wrote Alan Stern, the principal investigator of New Horizons, in an update on the spacecraft's web site.
"In addition to the complete checkout of the spacecraft’s primary and backup systems, and similar checkouts of all seven scientific instruments, we’ll also conduct our first optical navigation campaign to home in on Pluto, track the spacecraft to refine its orbit, do a host of instrument calibrations needed before encounter, carry out a small but important course correction, and gather some cruise science."
These 2010 Hubble Space Telescope images of Pluto represent some of the best pictures available of the dwarf planet to date. Image credit: NASA, ESA, and M. Buie/Southwest Research Institute
The spacecraft will be tasked to look at the light curves of Pluto and its satellites, sending back information on the brightness of each of these objects and their rotation. While this is possible to do from Earth, the blog post noted, the spacecraft will be closer and at a different angle. Controllers plan to produce a rotation movie of Pluto's largest moon, Charon.
New Horizons will also cross the orbit of Neptune on 25 August, which by pure coincidence is the 25th anniversary of when the Voyager 2 spacecraft made its closest approach to the blue gas giant.
Once the summer's work is over, controllers will put the spacecraft into hibernation again until December. That will be the beginning of the main event. Controllers will take an exact fix on Pluto's position that January. They expect the flyby to take place in July 2015. The spacecraft will remain awake for about two years, working on the flyby and also sending information back to Earth.
A documentary film about Pluto. Credit: The Mars Underground
"Although we still have a little more than 300 million miles [483 million km] and a year to go, the mileage and time already traveled account for nearly 90 percent of the total journey—so we are truly in the last stages of the cruise from Earth to the Solar System’s vast unexplored frontier," Stern added.
In a separate development, a new NASA-led study suggests that Pluto's moon Charon could have cracks in its surface. The moon, one-eighth the size of the dwarf planet, was probably formed when an object struck Pluto's surface in the distant past, and formed debris that eventually coagulated into Charon.
Since Charon and Pluto would have been extremely close in the first while after Charon formed, the gravitational attraction between the objects would have made their surfaces bulge towards each other and could have induced tidal heating in both Charon and Pluto.
If Charon is icy, the tidal heating could have heated up fluids below its surface, producing cracks and creating a global ocean. (That is also a theory for the cracked moons Europa and Enceladus.) But NASA cautioned that it's possible that the ocean, if it exists, would be frozen over now since Charon's orbit has migrated to a more stable location that does not have the same stresses.
The research was led by Alyssa Rhoden of NASA's Goddard Space Flight Center in Maryland and is available in the journal Icarus.