Jonathan's Space Report No. 560 2006 Jan 21

Status Report From: Jonathan's Space Report
Posted: Sunday, January 22, 2006

New Horizons

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.


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.


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

Date UT       Name            Launch Vehicle  Site            Mission    INTL.  
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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