New Horizons: Outbound at 7 AU
- From: baalke@xxxxxxxxxxxxx
- Date: Wed, 01 Aug 2007 15:32:07 -0700
http://pluto.jhuapl.edu/overview/piPerspectives/piPerspective_current.php
New Horizons - The PI's Perspective
Outbound at 7 AU
Alan Stern
August 1, 2007
Since I last wrote here, in mid-June, New Horizons has continued its
speedy journey from Jupiter's orbit (at 5.2 astronomical units
toward Saturn's at 9.5
AU. On average, we travel about a third of an astronomical unit each
month, or roughly a million miles per day. So, as August begins, we're
nearing the halfway point in the Jupiter-to-Saturn leg of our journey,
set to reach 7 AU on Aug. 6. We'll pass Saturn's orbit (but not
Saturn,
which will be far away from our path) next June.
During the six weeks since I last wrote, the spacecraft has primarily
been in hibernation. In fact, since June 27, we've been in hibernation
except for a brief, nine-day wakeup that began on July 12.
The highlight of the mid-July wakeup period was the opening of the
solar
occultation port (SOCC) on the Alice UV spectrometer. This was the
last
of the seven instrument aperture doors we opened on New Horizons. Like
the other openings, this one also went smoothly. Now, Alice can use
its
pinhole-sized SOCC aperture to stop down the intensity of sunlight by
a
factor of about 6,000, making it possible to trace the density and
composition of Pluto's atmosphere versus altitude without blinding the
detector. After opening the door, the spectrometer gathered its
first-light SOCC spectrum by observing the B star Bellatrix. The Alice
UV spectrometer also performed a series of self-tests and received a
software update.
Other activities during the July wakeup included onboard
data-compression testing, some LORRI and SWAP instrument tests, and a
data dump of the Venetia Burney Student Dust Counter's memory.
New Horizons was returned to hibernation on July 21 and it will remain
in hibernation until Aug. 16, when we wake it up for about three
months
of intensive onboard activities that include instrument calibrations
and
tests and a small course correction maneuver.
Until then, we will "listen" to its telemetry or beacon tone
broadcasts
four times per week, but we won't be actively controlling the
spacecraft
-- all commands it executes were stored in onboard memory before
entering this second hibernation period.
While our spacecraft slumbers, our ground team is busy planning those
activities for the wakeup period, which will stretch into mid-
November.
Simultaneously, our science team continues to analyze Jupiter data and
work to select a final target distance for our Pluto closest approach.
I'll have more to say about that next time I write. For now, however,
I
want to tell you that in early July the team completed a series of
eight
scientific papers about some of our most important Jupiter system
results, and submitted those papers to the journal Science for
publication this fall.
Engineers are busy building a second New Horizons Operations Simulator
(NHOPS II) that will serve as both an insurance policy against the
failure of NHOPS I during the long flight to Pluto and the Kuiper
Belt,
and also as a "surge" simulator for times when NHOPS I is booked up.
NHOPS II, replete with high-fidelity engineering models of the
instrument payload and spacecraft subsystems, will be completed and
then
extensively checked out early next year.
In other news, it is my pleasure to tell you that our project manager,
Glen Fountain of the Applied Physics Laboratory, has been selected to
receive the American Institute of Aeronautics and Astronautics (AIAA)
2007 von Braun Award for
Excellence in Space Program Management. This award recognizes an
individual for outstanding contributions in the management of a
significant space or space-related program or project. I think Glen
was
an obvious choice, but I am biased, of course. Nonetheless, we're
proud
of him and look forward to Sept. 19, when he'll be presented with the
award in conjunction with the AIAA Space Conference and Exhibit in
Long
Beach, Calif.
Well, that's what I wanted to tell you about this time. I'll be back
with more news in September. In the meantime, keep on exploring, just
as
we do.
.
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