January 5, 2009

As the new year takes root, the New Horizons team is about to celebrate the third anniversary of our launch on January 19, 2006.

If you've been following our progress on Twitter or just reading posts on our Web site, then you know our spacecraft has covered well over one-third of the distance to Pluto in those three years, putting it now almost half a billion kilometers beyond Saturn. You might also know that since I last wrote here, we've completed our 2008 spacecraft and payload checkout, recalibrated our seven scientific instruments, and refined our trajectory knowledge accuracy. We've even had a chance to collect cruise science data on the deep-space plasma and dust environment, as well as some scientifically unique imagery to yield photometric phase curves of Uranus, Neptune and Pluto.

Since December 16, when we concluded our 3.5-month active period for 2008, our baby has been hibernating again. New Horizons will remain in this low-activity hibernation state until mid-summer, when we'll roust her for another annual checkout.

But enough progress reporting. In this blog entry, I want to take a broader look at the big events along the remaining years of cruise flight to Pluto, and give you a bird's-eye view of what lies ahead until the main event kicks off, six years from this month.

Three Years and Counting

As I noted above, we're completing our third year of flight this month. A top-level way to look at our main mission is that our spacecraft is racing 24/7 for nine years begin our exploration of the Pluto system in January 2015, culminate that exploration with the Pluto flyby in July 2015, and follow that with nine months of transmitting data back to Earth. (Of course, we all hope the mission will be extended to fly on to explore primordial Kuiper Belt objects, but that's a story I'll detail some other day.)

But, let's look into our flight to Pluto at the next level of detail. The nine-year flight can be broken down into three, three-year phases: early cruise (2006-2008), mid-cruise (2009-2011), and late cruise (2012-2014).

Early cruise is now behind us, and it was a busy time -- no doubt about it. It included a full spacecraft checkout after launch and an intensive period of payload commissioning and calibration, and certification of vehicle and payload readiness for Pluto. It also included three trajectory correction maneuvers, a fleeting asteroid encounter, a six-month Jupiter system flyby, eight major flight software loads and a smattering of cruise Science activities. Moreover, our ground team also planned, executed and analyzed data from our Jupiter encounter, built a backup spacecraft avionics simulator called NHOPS II, designed detailed plans for our Pluto encounter, and began writing the actual command sequences that will drive New Horizons through its most intensive ("core") exploration period -- the seven days before and two days after closest approach to Pluto.

With the dawning of 2009, mid-cruise is now beginning. Although the next three years will be quieter than the past three, they are just as crucial to the success of New Horizons.

During mid-cruise, New Horizons will race from its current position just beyond 12 astronomical units from the Sun to almost 22 AU -- ending up more than a quarter-billion kilometers beyond Uranus' orbit and well toward Neptune's. In terms of mid-cruise flight activities, we will conduct annual spacecraft and instrument checkouts, as well as a little more cruise science. But in addition, we plan to conduct some encounter test activities in 2010 and 2011. Based on our tracking data, we are also expecting another (small) course correction - less than one meter per second - in 2010. Meanwhile, on the ground, in addition to planning and executing the spacecraft operations of mid-cruise, we will finish sequencing the nine-day "core" encounter command load, fully test it on the New Horizons spacecraft simulators at the Johns Hopkins Applied Physics Laboratory (APL), and plan the surrounding nine weeks of approach and departure activities closest to Pluto.

Late in mid-cruise we'll also initiate our KBO target search, and we also plan to replace the original (2004-era) computers in our Mission Operations Center (MOC) and Science Operations Center (SOC), so that at encounter these systems are still young enough to be fully reliable. With a mission staff of less than ten people -- just half the size it was in early cruise, and more than 10 times smaller than what Voyager needed to fly across the same territory on its way to Uranus and Neptune -- one thing is for sure: the Earthly crew of New Horizons is going to be very busy in during mid-cruise.

During late cruise, which begins in January 2012, we'll still (of course) conduct annual spacecraft and instrument checkouts, collect cruise science and perform trajectory corrections (if our navigation and mission design team deems them necessary). But we'll also complete the KBO target search, complete the planning for the distant approach phase to Pluto, and carry out a comprehensive series of "contingency events" on the mission simulator to prove our spacecraft is capable of detecting and recovering from the most likely kinds of faults that could occur during the encounter in 2015.

But the planned centerpiece activities of late cruise will come in 2012 with a full-up in-flight encounter dress rehearsal (on the spacecraft) of the core nine-day encounter sequence, and a complete pre-encounter calibration of our instrument payload in 2014. We've also planned for a backup, second dress rehearsal onboard New Horizons in 2014, but we'd prefer to skip that and save the fuel and project costs if the 2013 dress rehearsal goes well. Also in 2013-2014, our APL mission team will staff up to prepare for 24/7 encounter activities in 2015 with -- hold your breath -- a whopping 20 people, including the project manager, navigation team, flight planners, flight controllers, education and public outreach, and a part-time secretary. By contrast, Voyager 2's "skeleton" extended mission operations team for its 1989 Neptune encounter involved almost 150 people; robotic spaceflight sure has become much more efficient over the past 20 years.

Looking Ahead

With that overview in mind, you have a good idea of what's ahead on the journey to Pluto - and you can see we're not just twiddling our thumbs and waiting for the big events of 2015. In fact, I hope this "big picture" roadmap of our cruise flight and ground activities allows you to see the mission as we see it: a long, carefully orchestrated preparation for the one-shot chance to explore the archetype of dwarf planets, Pluto, and its system of moons. The United States and NASA will ultimately invest more than $700 million in this expedition, and we're working hard to make sure we get the scientific goods at the far frontier of our solar system.

Arrival at Pluto: High noon (GMT) on Tuesday, July 14, 2015! (Artwork by Dan Durda and Ken Moscati) But over the next six years, as we guide our bird to its target, plan every detail of her approach and close-up explorations, and test for her ability to react to unforeseen circumstances, we will also be doing one more thing: Continuing to be aware that "Murphy" - the infernal daemon of spaceflight - always lurks, challenging us to be ever vigilant across 3-billion-plus miles of abyssal vacuum and over 3,000 days of flight.

The scientific community and the taxpayers of the United States have entrusted us with a very special opportunity to explore a planet that is a billion miles farther away from Earth than any ever visited, and in doing so, to shed light on an impossibly ancient and yet entirely new frontier. So we aren't taking our opportunity for granted, even during the "quiet" of mid-cruise. Well, that's the PI's update for this time. I'll be back with more news soon. In the meantime, keep on exploring, just as we do!

- Alan Stern