Elapsed Mission Time
(1/19/06 19:00:00 UTC)
2776 Days (7.61 yrs.) 07 Hours 18 Minutes
Pluto’s Closest Encounter Operations Begin:
(4/12/15 00:00:00 UTC)
529 Days (1.45 yrs.) 21 Hours 41 Minutes
Pluto Closest Approach:
(7/14/15 11:49:59 UTC)
689 Days (1.89 yrs.) 09 Hours 30 Minutes
New Horizons Position and Course in 3 Dimensions:
New Horizons has just completed a summer of intensive activities and entered hibernation on Aug. 20. The first of these, conducted in early July, was planned imaging of Pluto and its largest satellite, Charon. As you can see from the image and caption, they accomplished this using the LORRI long-focal length camera. Seeing these images, revealing their target as a true planetary binary, viscerally signaled to them that they were getting close to their destination and the end of the long, 3-billion-plus mile cruise started out on back in January 2006.
New Horizons spied fainter Charon aside brighter Pluto in early July using our Long Range Reconnaissance Imager called LORRI.
Then routine parts of the activities included thorough checkouts of all the backup systems (result: they work fine!) and of all our scientific instruments (they work fine too!). The team also updated the onboard fault protection (a.k.a. “autonomy”) software, collected interplanetary cruise science data, and tracked the spacecraft for hundreds of hours to improve their trajectory knowledge. Added to this mix of routine summer wake-up activities for New Horizons were two major activities that had never been performed before. One unique activity was a complete flight rehearsal of the final week of flyby activities on approach to Pluto, along with the first data transmissions that will follow. This dry run, in which the actual flight sequence for closest encounter was loaded aboard New Horizons and executed exactly as it will be in July 2015, was a major test — and it succeeded brilliantly! They had planned this test for more than six years and rehearsed it on the ground simulators dozens of times to work out the details and shake out the bugs. The team even ran a 22-hour segment of it on New Horizons in the summer of 2012 as a mini-test.
Flight controllers in the New Horizons Mission Operations Center at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, keep an eye on the spacecraft’s vitals near the end of the Pluto-encounter rehearsal on July 14.
But actually executing the whole operation this summer was the biggest effort yet, and New Horizons performed outstandingly! Although the final, excruciatingly detailed engineering reviews of the rehearsal won’t come out until early September, the clear success revealed in quick-look data analysis proved to the team that the close encounter sequence and spacecraft will perform as planned. It also yielded a bonus — the measured fuel usage of the close encounter sequence was a little lower than predicted, showing they will have a bit of bonus fuel in the tank after Pluto for the exploration of Kuiper Belt Objects. And if these activities weren’t enough to signal a fast-approaching encounter, a third event in July put the icing on that cake. That event, two years in the making, was a scientific conference sponsored by the New Horizons project to review everything known about Pluto and its satellites, their origin and evolution, and to hear informed scientific predictions about what New Horizons will find.
Alan Stern the Principal Investigator added, "And, oh yes, one more “finding” that I’m pleased to report (as many at the conference also noted): Throughout the proceedings, scientists of all stripes, including some who don’t regard dwarf planets as planets, repeatedly referred to both Pluto and Charon (though never their small moons) as “planets.” I wasn’t very surprised by this, since I hear it a lot at other conferences too, until one colleague asked me, “Why do you think [names withheld] referred to Pluto and Charon as planets when they didn’t sign the petition rejecting the IAU’s planet definition that excludes dwarf planets?” I was surprised by her answer to her own question: “I think it’s because they subconsciously think of Pluto and Charon as planets, and they can't help but say it in when referring to them.” I just smiled, filing that as a note to relay to you the readers here."
Participants at the Pluto system science conference gather for a group photo. How many fingers are they holding up?
For now the spacecraft will remain in hibernation almost continuously until June 2014. That hibernation will be interrupted by a short, two-week wakeup in January 2014 for antenna repointing, new command loads and a few routine spacecraft-maintenance activities. Starting in June the team will wake New Horizons for two months, starting with optical navigation (“homing”) activities using the Long-Range Reconnaissance Imager (or LORRI) to refine the course to Pluto. Next summer, they will also likely conduct a small course correction using onboard rocket engines to trim up the approach trajectory and closest-approach timing. Then they will conduct another complete checkout of the backup systems and science instruments aboard New Horizons.