http://pluto.jhuapl.edu/overview/piPerspective.php?page=piPerspective_1_5_2009

The PI's Perspective
New Horizons
Welcome to Mid-Cruise!
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
http://www.twitter.com/NewHorizons2015> 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.

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
--- SBBSecho 2.12-Win32