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Posted by baalke on January 5, 2007, 4:42 pm
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http://pluto.jhuapl.edu/overview/piPerspectives/piPerspective_current.php
The PI's Perspective
Alan Stern
New Horizons in 2007
January 5, 2007
What a memorable year for New Horizons! After the final few ground
preparations and flight approvals, we launched at 1900 GMT (2 p.m. EST)
on January 19. I will never forget the sight of the giant,
210-foot-tall
"A Train" leaving Florida for the Kuiper Belt, and how filled with
pride
I was for everyone who worked to see this milestone come to pass.
Launch was all we could have wished for. As a result, following launch,
we only needed tiny trajectory correction maneuvers to put us on course
for the Pluto aim point at Jupiter.
In 2006 New Horizons raced its way out of the inner solar system toward
the gateway world Jupiter, king of the so-called "second zone" of our
planetary system, which it will fly past on February 28, 2007.
On the way to Jupiter, the New Horizons team undertook a series of
virtually flawlessly executed, multi-month spacecraft and instrument
payload checkouts, an unexpected small-asteroid flyby, and
behind-the-scenes preparations for our Jupiter encounter - which begins
this month!
Since I last wrote in this space, at the start of November, New
Horizons
has moved outward almost another 100 million miles - from roughly 4.1
astronomical units to almost 5 AU from the Sun. Our spacecraft
continues
to perform well, and tracking plots show we're right on course. Last
month, the spacecraft ground team uploaded further updated fault
protection and correction software.
In November and December we concentrated on cruise science observations
by our in situ instrument suite. In particular, the Solar Wind at Pluto
(SWAP) and Pluto Energetic Particle Spectrometer Science Investigation
(PEPSSI) plasma instruments have both been calibrating on and studying
the interplanetary medium. At the same time, the Venetia Burney Student
Dust Counter (VB-SDC) has been recording micrometeoroid impact data as
the spacecraft traverses the asteroid belt to Jupiter.
During this same time, we received two kinds of good news on our
communications capability. The first was a successful test of our dual
transmitter capability. This means that we can, beginning this spring,
increase our data rates by a factor of 1.5 to 2 times what we had
planned prior to launch. This will speed the downlink of both
engineering and science data during cruise, as well as at all of our
flyby targets - from Jupiter to Pluto to Kuiper Belt objects beyond.
Also, as you might recall from my last post
<http://pluto.jhuapl.edu/overview/piPerspectives/piPerspective_11_1_2006.php>,
in late November New Horizons flew almost directly behind the Sun as
seen from Earth. This is called a "solar conjunction," and it causes
interference with radio communications due to the competition between
the spacecraft signal and the nearby Sun, which is a radio noise source
to ground receivers during these times. (You can think of it as the
spacecraft being in the radio glare of the Sun.) Although we
conservatively planned on an eight-day communications outage due to the
position of New Horizons, we found that our pre-flight radio
interference calculations were very much on the safe side. In fact, we
received data from New Horizons for much of this "blackout" period. Now
that we've calibrated our communications capability through an actual
in-flight solar conjunction, we know that future conjunctions, which
along our trajectory occur late each year, will be less trouble and
shorter than our first one - typically lasting just a handful of days.
The Year Ahead
Turning now to 2007, our Jupiter encounter has just begun. In total the
encounter spans six months, from January through June. In future
columns, I'll provide many more details. I plan to write those at an
increasing pace until we pass Jupiter at the very end of February.
For now, I'll say that our mission and payload operations teams,
working
with our Jupiter Encounter Science Team (JEST), have been striving to
plan and test more than 100 Jupiter observing sequences comprising more
than 700 separate observations of Jupiter.
The first of these occurs January 5, with a Radio Science Experiment
(REX) calibration using Jupiter.
Over the next couple of weeks, PEPSSI and SWAP will continue to observe
the interplanetary medium as we approach Jupiter, and Ralph and the
Long
Range Reconnaissance Imager (LORRI) will begin imaging the giant
planet.
If you're following closely on our Web site, you'll see us posting a
New
Horizons Jupiter "image of the week" beginning in mid-January.While
this
is all I want to say about our Jupiter encounter just now, I do want to
tell you about our big picture plan for 2007.
Most of the first half of the year is, as you might imagine, focused on
the Jupiter encounter. But that isn't all we'll do. We also have two
opportunities for course correction maneuvers - one in mid-February and
one in mid-May. We'll almost certainly execute a trajectory trim burn
in
May, as our post-Jupiter encounter work settles down; that maneuver is
currently estimated to cost us about 2 meters per second (5 miles per
hour) in fuel. We could delay this maneuver until the fall, but it
would
cost more fuel then, because we'd be letting differences caused by our
actual (non-perfect) Jupiter encounter aim point build up longer.
Whether we'll need the pre-encounter February burn is something we'll
decide in mid-January. I'll keep you posted. So far, it looks like we
can skip that maneuver.
After our Jupiter encounter, we'll also begin preparing for spacecraft
hibernation, which will begin in July. I like to say that hibernation
is
the highway that will take us to Pluto. After all, we count on
hibernation to both lower mission-operations costs and to reduce wear
and tear on most spacecraft systems as we fly out to Pluto.
Before we go into hibernation, however, we need to downlink all of the
Jupiter data we collect and complete the last 10% (or so) of the
instrument payload commissioning activities. Back in September, we put
these tests off until spring 2007 to give our flight control team more
time to concentrate on Jupiter encounter planning.
In April, we'll also conduct a test run of spacecraft hibernation.
Although we did this in ground testing, we want to gain some flight
experience before the big plunge into long-term hibernation this
summer.
And when we do begin hibernation operations, we'll keep a close eye on
the spacecraft health with multiple weekly Deep Space Network (DSN)
passes for a few months, declining to weekly passes for another few
months.
In all, we won't settle into long-term hibernation operations until
mid-2008. And meanwhile, from late September through late November,
we'll wake New Horizons up for the first of our annual, two-month
spacecraft and instrument payload checkouts. During this time we'll
also
conduct more cruise science observations, just as we'll do in
subsequent
annual wake up periods.
Also this spring, we'll test some backup thrusters to alleviate the
primary thruster overuse issue that I wrote about in my last update.
And we'll once again uplink a few updates to our onboard fault
protection and correction software, which continually matures as we
fly our spacecraft.
Finally, late in the year, from roughly December 11-17, we'll
experience
our second solar conjunction period, limiting radio communications
again.
As you can see from all this, 2007 is going to be a busy year for our
operations team. In addition, our science team will be happily flooded,
getting the Jupiter data reduced and archived, and analyzing the data
to
report initial results. Even our engineering team will be busy this
year
- building "NHOPS 2," a second New Horizons OPerations Simulator. NHOPS
2 will contain a replica of all spacecraft system and instrument
avionics. We want it to serve as a ready-to-go backup in case anything
breaks on our primary NHOPS 1 system during the long cruise to Pluto.
It
will also be useful for relieving some of the simulation load on NHOPS
1, which we seem to use 24-7. NHOPS 2 is scheduled to be complete by
early 2008.
Meeting the 'Girl Who Named Pluto'
As I close this column, I want to tell you about a very special
occasion. On December 19, mission co-investigator Dr. Mihaly Horanyi
and
I met just outside London and traveled to the home of Mrs. Venetia
Burney Phair - "the little girl who named Pluto" as a primary school
student back in 1930. Mihaly came over from Germany, where he is
spending a sabbatical year; I was on my way to Italy to give a talk.
Mrs. Phair, now almost 88, is an impressive lady - cogent, resolute and
full of the verve of life. We got to know each other and shared stories
at an Italian restaurant. Then she showed us her family albums
documenting the events surrounding the naming of Pluto, almost 80 years
prior. Then Mihaly (the principal investigator of our Student Dust
Counter instrument) and I presented Mrs. Phair with plaques dedicating
the SDC in her honor and commemorating an asteroid we asked the
International Astronomical Union to name for her. Mihaly also presented
Mrs. Phair with a small model of New Horizons.
Mrs. Phair, her son Peter, and several of their friends then joined us
after these ceremonies for tea and cookies. It was fun to meet Venetia
in person and to hear about how she came to name Pluto so long ago.
She's healthy and witty and wishing for a chance to be at our Pluto
encounter in 2015; that seems like something we should make happen. She
also tells me she's always wanted to meet Patsy Tombaugh, widow of
Pluto's discoverer, Clyde Tombaugh. It was a memorable day.
Next time, I'll have another special item to write about: something we
call "New Horizons kids." I'll say more in a couple of weeks.
Well, that's all I have time to write just now. I'll be back with an
update later in January as Jupiter nears. In the meantime, keep on
exploring!
-Alan Stern
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Posted by robert casey on January 6, 2007, 2:36 pm
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baalke@earthlink.net wrote:
> http://pluto.jhuapl.edu/overview/piPerspectives/piPerspective_current.php
>
> an unexpected small-asteroid flyby
Were they able to get any images or other science from this asteriod?
Or, if it didn't yet happen, will they?
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Posted by Paolo Ulivi on January 6, 2007, 2:51 pm
Please log in for more thread options robert casey wrote:
> baalke@earthlink.net wrote:
>
>> http://pluto.jhuapl.edu/overview/piPerspectives/piPerspective_current.php
>>
>
>> an unexpected small-asteroid flyby
>
>
> Were they able to get any images or other science from this asteriod?
> Or, if it didn't yet happen, will they?
See
http://pluto.jhuapl.edu/overview/piPerspectives/piPerspective_7_14_2006.php
--
ICBM Address: 45deg 31m 0.9s N 9deg 19m 24.9s E
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