Jonathan's Space Report
No. 560 2006 Jan 21, Somerville, MA
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New Horizons
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The New Horizons probe to Pluto was launched at 1900:00 UTC on Jan 19
from pad 41 at Cape Canaveral by Atlas V flight AV-010.
The powerful Atlas 551 rocket, with five solid boosters, roared off the
Florida pad after two days of delays. The solids separated at 1 min 45s into
launch, arcing into the mesosphere before falling to Earth. The
5-meter-diameter fairing separated at 3min 23s, followed seconds
afterwards by the two pieces of the CFLR (Centaur Forward Load Reactor),
a contraption that connects the smaller 3.1m-diameter Centaur to the
fairing for structural stiffness. By this time Atlas was in space, with
the fairing probably reaching an apogee of 150 km or so. Atlas shut down
at 4min 27s, falling away 6s later, and the Centaur second stage ignited
at 4min 33s as the trajectory flattened out, reaching orbit insertion at
1910:08 UTC with a 167 x 213 km parking orbit. The vehicle coasted for
20 minutes and restarted over South Africa, with a 9-min burn taking the
Centaur to 800 km altitude at a velocity of 12.4 km/s, a hyperbolic
Earth orbit which will take the Centaur out to the asteroid belt. At
1939 UTC the spin-table on the forward end of the Centaur began to
rotate, and the injection stage with the payload separated. The
injection stage is an Alliant (Thiokol) Star 48B solid motor, the same
motor used on Delta 2 third stages and on the old Shuttle PAM-D flights.
Solid kick motors like to be spinning when they fire to even out any
misalignment of the thrust direction, hence the spin table - although
the Star 48B also has a set of small hydrazine rockets to correct any
unwanted nutation. After the Star 48B burn, the payload had reached
escape velocity not only with respect to the Earth but also relative to
the Sun (The velocity was 16.2 km/s relative to the Earth
and I estimate an asymptotic velocity of 12.3 km/s, corresponding to
42.6 km/s relative to the Sun and leading to a heliocentric eccentricity
of around 1.05). New Horizons separated from the Star 48B at 1944 UTC and
released two `yo-yo weights' on long wires; as NH spun around, the wires
unwound and then were released, taking angular momentum with them and
leaving the probe spinning much more slowly, around 5 rpm. NH now must
depend on its own propulsion system, four small 4.4N thrusters, to
adjust its course, with the first trajectory correction maneuvers coming
over the next several weeks.
New Horizons will fly around 2.3 million km from Jupiter on 2007 Feb 28,
and the Pluto/Charon system in 2015, with possible Kuiper Belt Object
flybys in around 2017. The probe has a dry mass of around 401 kg and a
launch mass of 478 kg (including the hydrazine course correction
propellant). It features a 2.1-m diameter high gain antenna for
communications with Earth (as well as radiometry of Pluto) and a
radioisotope thermoelectric generator (RTG) which uses the heat of 11 kg
of decaying Pu(238)O2 to provide 240 W of electrical power. This
particular model of RTG is the GPHS-RTG, also used on Cassini.
New Horizons has the following science instruments:
- Ralph, the high resolution imager, with a 0.08m telescope
and a suite of detectors: MVIC (Multispectral Visible Imaging Camera),
which has three black-and-white and four color CCD detectors, and LEISA
(Linear
Etalon Imaging Spectral Array), a 1.25-2.5 micron IR spectrometer.
MVIC should reach 0.25 km/pixel at closest approach.
- Alice, the UV spectrometer covering the 500-1800A range.
- LORRI, the long range imager with a 0.21m aperture telescope
and visible CCD detector.
- SWAP (Solar Wind at Pluto), low energy particle spectrometer
- PEPSSI (Pluto energetic particle spectrometer science investigation),
high energy ion mass/energy spectrometer
- SDC (Student Dust Counter), measuring particle impacts.
- REX (Radio experiment), using the main dish to study radio propagation
through the Plutonian atmosphere.
Stardust
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The Stardust probe landed successfully on Jan 15 in the highest velocity
reentry ever. The capsule has now been opened and mission scientists
report that it contains plenty of samples of comet 81P/Wild 2.
Stardust approached Earth from a 0.98 x 2.68 AU x 3.6 deg solar orbit.
Passing the Moon on Jan 14 at 1830 UTC, Stardust approached the Earth on
a 22 km perigee, 42.1 deg hyperbolic orbit. The SRC (Sample Return
Capsule) was ejected at 0557 UTC on Jan 15. At 0613 UTC Stardust fired
its engines to raise perigee to 258 km, and swung past the Earth at 1000
UTC, passing lunar orbit outbound at 0130 UTC on Jan 16. The Stardust
bus will leaving the Earth-Moon system on Jan 17 into a 0.92 x 1.70 AU x
1.9 deg orbit.
Meanwhile, the SRC reached 125 km altitude at 0957 UTC on Jan 15,
travelling almost horizontally (a flight path angle of -8.2 degrees) at
12.9 km/s. It deployed its main parachute at 1004 UTC and landed at 1010
UTC in the Utah Test and Training Range (UTTR).
This is the second spacecraft recovery from beyond lunar orbit; the first
was Genesis, which landed on 2004 Sep 8, also in the UTTR.
Erratum
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Oops - Parus/Tsikada and Transit operated near 0.15 GHz, not 0.15 MHz!
And Richard Langley points out to me that the Transit satellites
continued transmitting after 1996 in a non-navigation role as the Navy
Ionospheric Monitoring System. They certainly were still going strong as
late as 2001, but the web site which described the system is no longer
active; can anyone report which if any of the NIMS/Transit satellites
are still operating?
Table of Recent Launches
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Date UT Name Launch Vehicle Site Mission INTL.
DES.
Dec 21 1838 Progress M-55 Soyuz-U Baykonur LC1/5 Cargo 47A
Dec 21 1934 Gonets-D1M ) Kosmos-3M Plesetsk LC132/1 Comms 48A
Kosmos-2416 ) Comms 48B
Dec 21 2233 Insat 4A ) Ariane 5GS Kourou ELA3 Comms 49A
MSG 2 ) Weather 49B
Dec 25 0507 Kosmos-2417 ) Proton-K/DM2 Baykonur LC81/23 Navigation 50A
Kosmos-2418 ) Navigation 50B
Kosmos-2419 ) Navigation 50C
Dec 28 0519 GIOVE A Soyuz-FG/Fregat Baykonur LC31/6 Navigation 51A
Dec 29 0228 AMC 23 Proton-M/Briz-M Baykonur LC200 Comms 52A
Jan 19 1900 New Horizons Atlas V 551 Canaveral SLC41 Pluto probe 01A
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| Jonathan McDowell | phone : (617) 495-7176 |
| Somerville MA 02143 | inter : jcm@host.planet4589.org |
| USA | jcm@cfa.harvard.edu |
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