Wake Up, Sleeping Pluto Probe

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More than halfway through its 10-year, 3-billion-mile journey to Pluto, NASA’s New Horizons spacecraft is being roused from hibernation this week to relay some tracking information back to Earth, a rather slow and deliberate process considering that the probe is so far away round-trip communications take five hours.

Lead scientist Alan Stern marked the occasion of New Horizon’s halfway point by paying a visit to the family of the late Clyde Tombaugh, the astronomer who in 1930 discovered Pluto.

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“Being able to share this milestone with Clyde’s family and to see their smiles really capped the first half of the journey for me,” writes Stern in his blog.

The main purpose of the probe’s 10-day wakeup is to tweak the position of its communication antenna to account for the motion of the Earth around the sun, and to gather tracking data for the navigation team, Stern says.

New Horizons was launched in January 2006. It is expected to encounter Pluto and Pluto’s moon Charon in July 2015, becoming the first spacecraft to visit Pluto and other icy bodies in the Kuiper Belt.

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Flight controllers are also working to restore a second spacecraft which put itself into an unplanned hibernating state. The Saturn-orbiting Cassini probe shut down unexpectedly last week, missing an opportunity to collect science information during a flyby of the moon Titan.

Engineers have figured out that the spacecraft put itself into what’s called “safe mode” because of a flip of a bit in the command and data system computer.

“The bit flip prevented the computer from registering an important instruction, and the spacecraft, as programmed, went into the standby mode. Engineers are still working to understand why the bit flipped,” NASA said in a statement.

Managers expect it will take until Nov. 24 to fully restore Cassini to service.

Images: Hubble Space Telescope images of Pluto are probably the best we’ll see until New Horizon arrives; New Horizons lead scientist Alan Stern and family members of Pluto discoverer Clyde Tombaugh toast New Horizon’s halfway mark. From left Annette Tombaugh Sitze, Patsy Tombaugh, Alan Stern and Wilbur Sitze. Credit: Space Telescope Science Institute NASA