New Horizons Probe Closes in on Pluto Showing Stunning Image

New Horizons Probe Closes in on Pluto Showing Stunning Image

NASA’s New Horizons probe is just five days and a few hours away from its closest approach to Pluto after a nine-and-a-half year journey.  Once counted as the ninth planet in the solar system, Pluto was redesignated a “dwarf planet” by the International Astronautical Union (IAU) in 2006, months after New Horizons was launched, a decision that remains controversial in the planetary science community and with the public.

Principal Investigator Alan Stern often jokes that New Horizons is a mission characterized by delayed gratification because of the long journey to Pluto and the 9-hour two-way travel time for radio signals to get to and from the spacecraft.  It will make its closest approach to Pluto at 7:49:47 am Eastern Daylight Time (EDT) on July 14, but mission control at the Johns Hopkins University Applied Physics Lab (APL) in Laurel, MD will not get the confirming signal that the close approach took place until 9:02 pm EDT.  The spacecraft is designed to focus its resources on obtaining science data during the encounter rather than transmitting it back to Earth and only engineering data will be transmitted the day of the encounter, Stern said on Monday.

A glitch over the weekend generated concern about the spacecraft’s health, but mission controllers quickly realized what went wrong and remedied it.  Essentially the main computer became overloaded and crashed trying to do too many things at once — burning data to flash memory at the same time it was compressing data.  As programmed to do when such an anomaly occurs, the probe switched to a backup computer, which sent a signal to Earth that humans needed to intervene.  They did, reset the computer, and although a small amount of data collection did not take place, Stern described the loss as inconsequential.

The close approach is on July 14, but the 9-day “flyby sequence” already has begun and runs through July 16.  Science data from the close approach will be sent back to Earth beginning July 15 Stern explained.  The probe will pass Pluto at a distance of 7,800 miles (12,500 kilometers) above its surface.  Pluto and New Horizons are approximately 3 billion miles (4.9 billion kilometers) from Earth.  New Horizons was launched on January 19, 2006.

Plenty of data has been returned already, however, throughout the journey and especially during the past months as the probe nears the dwarf planet.  Pluto has five moons, the largest of which is Charon.  This image, courtesy of APL, was taken on July 7 by the Long Range Reconnaissance Imager (LORRI) on New Horizons and shows both bodies.


 New Horizons image of Pluto and Charon.  Photo Credit:  Johns Hopkins University Applied Physics Lab New Horizons website.

NASA has a number of media briefings scheduled in the upcoming days, many of which will be broadcast on NASA TV.  There are daily live mission updates at 11:30 am EDT July 9-12 and then the following:

  • Monday, July 13:  Media briefing, 11:00 am – 12:00 pm EDT
  • Tuesday, July 14 — day of closest encounter: 
    • Arrival at Pluto countdown, 7:30 – 8:00 am EDT
    • Media briefing, 8:00 – 9:00 am EDT
    • NASA TV Program “Phone Home” broadcast from mission control at APL, 8:30 – 9:15 pm EDT (signal should be received at 9:02 pm EDT)
    • Mission Briefing, 9:30 – 10:00 pm EDT
  • Wednesday, July 15: Media Briefing “Seeing Pluto in a New Light,” 3:00-4:00 pm EDT

All times are subject to change.  NASA and APL will post updates on their websites.

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