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Posted by canopus56 on June 18, 2009, 1:57 pm
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POST 1 on visibility
The LRO-LCROSS launch is set for a 5:12EDT (3:12 MDT) (21UT) today.
(At the time of this posting, the launch counter is at 4:40.) The
following message was just posted on another newsgroup by the Horizons
Team. The LCROSS Centaur booster trans-lunar orbit projected
coordinates have been updated into the Horizons system.
http://ssd.jpl.nasa.gov/horizons.cgi
Use "LCROSS" as the "Target Body". RA-Dec predicted positions are
topocentric sensitive, so use your local "named location" city as the
geographic location, not geocentric.
Live coverage begins at 2pm EDT (20UT).
http://www.nasa.gov/multimedia/nasatv/index.html
KSC live launchpad video of the launch can be seen at:
http://countdown.ksc.nasa.gov/elv/
Typical pre-launch countdown activities for an Atlas V launch can be
found at:
NASA Atlas V Countdown 101 FAQ
http://www.nasa.gov/mission_pages/launch/atlas_V_count_101.html
A primitive first-order model of outbound Centaur visibility during
trans lunar orbit can be found at physical pages 7, 74-83 (digital
pages 10, 77-86) of Issue No. 13 of Selenology Today at:
http://digidownload.libero.it/glrgroup/selenologytoday13.pdf (4.5
megs)
(mag 6.5 at 5k decreasing to mag 13.8 at 150,000k)
There is no magnitude estimate in the Horizons system empheris.
There is no list of scheduled hydrogen fuel dumps. At a mission
briefing on June 16, an LRO project scientist stated all fuel dumps
would be completed before hand-off of the Centaur to LCROSS team
flight control 4 hours into the flight.
- Clear Skies Canopus56
=======
Horizons Message
With the shuttle launch scrubbed, the Moon-fated
LCROSS mission is currently go for 2009-Jun-18 21:12 UTC
launch (tomorrow).
The trajectory has been updated accordingly in Horizons
(based on navigation team planning), for those who want
to track it, or avoid confusing it for an asteroid in
Earth vicinity.
http://ssd.jpl.nasa.gov/?horizons
----------------------------------------------------------
Jon Giorgini | Navigation & Mission Design Section
Senior Analyst | Solar System Dynamics Group
show/hide quoted text
<snip> | Jet Propulsion Laboratory
POST 2 on visibility
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Launch visibility update from the LCROSS Flight Director's Blog
Canopus56 Note: The flight director's comments regarding Perth,
Australia as being favored for the initial launch track discusses only
the first few hours of flight and not the subsequent trans lunar orbit
trajectory through flight hour 30. Generate a Horizons ephemeris for
an extended prediction across several days. The LCROSS-Centaur may be
visible for up to the first 30 hours of its outbound flight by scopes
of 10-12 inches of aperture.
LCROSS Flight Director Paul D. Tompkins
Posted on Jun 18, 2009 02:21:32 AM Paul.D Tompkins
=============================
show/hide quoted text
<snip>
3. Finally, one of my readers suggested a really great idea. He
wanted to know if our Centaur would be venting gas as part of its
sequence. The reason he asked is that under the right lighting
conditions, the sunlight high above Earth can actually illuminate the
vented gases, making them visible from the ground. He said he was
able to observe this effect as a kid right after the Apollo 14
launch. Cool!
So, I've tracked this down, and our Navigation team has provided some
data for those of you with enough experience might be able to use to
predict LCROSS's early-mission trajectory. Here is the information
and some figures (attached). Best for our friends in the
Southeast...and by that I mean Australia, Indonesia, Singapore and
Thailand...enjoy...and thank you for such a great idea! From our
extended Navigation team:
--------------------------------
"I have used the P10 trajectory for 18 Jun in SOAP to assess
visibility starting at separation from LRO. Attached are two SOAP
screen shots showing links to some major cities. The yellow line
running NNW to SSE is the terminator. Locations sufficiently to the
left of this line (preferably with Sun elevation less than -12 degree
though this limit occurs early) would be best situated to observe the
blowdown event assuming it occurs before the sky gets too bright.
Perth is most favored, with Sun El -6 degree at 22:49 UTC, almost an
hour after LRO separation.
The red line is the ground track (leading part only). The yellow line
extending to the right is the link to the Sun (LCROSS in sunlight).
The time ticks on the trajectory line (lower left, gray; upper right,
light blue) are spaced at five minutes. There is also a light blue
link from LCROSS to the current position of the ground track. We have
posted the LCROSS trajectory on the JPL Horizons system (18 Jun P10):
telnet horizons.jpl.nasa.gov 6775
lcross
Availability of the LCROSS trajectory on Horizons has been announced
on Seesat-L (where those interested in observing fuel dumps from
Centaur rockets have been known to gather):
www.satobs.org/seesat/Jun-2009/0077.html
Horizons can be used to generate topocentric ephemeris data."
--------------------------------
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Posted by canopus56@yahoo.com on June 18, 2009, 6:23 pm
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Based on the Horizons ephemeris data (for my o.p. at W111), it appears
the outbound LROSS Centaur will not be observable during its trans
lunar orbit phase over the next 4 days. LCROSS is going to the Moon
and the Moon is approaching the new phase. During entire apparent
orbit, the LCROSS Centaur booster will be less than 20 degs of the
Sun.
- Clear Skies - Canopus56
P.S. - I understand that the NASA LCROSS team may broadcast a live
video feed from the satellite does its gravity assist fly by of the
Moon. The satellite will then pass into cruise orbit.
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