New Horizons
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New Horizons is a NASA unmanned spacecraft designed to fly by Pluto and its moons (including Charon) and transmit images and data back to Earth. Mission planners hope that NASA will approve plans to continue the mission with a fly-by of a Kuiper Belt Object and return further data. A consortium of organizations, led by Southwest Research Institute and the Johns Hopkins Applied Physics Laboratory, has built the craft. The mission's principal investigator is S. Alan Stern of Southwest Research.
The primary scientific objectives are to characterize the global geology and morphology and map the surface composition of Pluto and Charon, and study the neutral atmosphere of Pluto and its escape rate. Other objectives include studying time variability of Pluto's surface and atmosphere; imaging and mapping areas of Pluto and Charon at high-resolution; characterizing Pluto's upper atmosphere, ionosphere, and energetic particle environment; searching for an atmosphere around Charon; refining bulk parameters of Pluto and Charon; and searching for additional satellites and rings.
A radioisotope thermoelectric generator (RTG) will generate the electrical energy required to run the spacecraft systems. Fueling for the RTG has been completed, though the generator is still being scrutinized for approval by the United States Department of Energy (DOE) for safety.
Mission profile
| Launch date | Pluto arrival |
|---|---|
| Launch windows 2006 | |
| Jan. 11-27 | July 14, 2015 |
| Jan. 28 | August 15, 2015 |
| Jan. 29-31 | July 12, 2016 |
| Feb. 1-2 | July 11, 2017 |
| Feb. 3-8 | July 10, 2018 |
| Feb. 9-12 | June 7, 2019 |
| Feb. 13-14 | July 20, 2020 |
| Launch windows 2007 | |
| Feb. 2-15 | 2019-2020 |
Mission operations planned to launch New Horizons on January 11, 2006, but later delayed its launch to January 17 to have time to do some additional tests on the launch vehicle. An Atlas V 551 rocket will launch the spacecraft, with a Star 48B third stage added to achieve the necessary escape velocity. New Horizons will then proceed to a Jupiter gravity assist in February 2007. New Horizons will be the first probe launched directly toward Jupiter since the Ulysses probe in 1990. Though there are backup launch opportunities in February 2006 and February 2007, only the first 23 days of the initial window permit the Jupiter fly-by. Any launch outside that period will force the spacecraft to fly a slower trajectory directly to Pluto, delaying its encounter by 2-4 years. The flyby will come within about 43 (±5) Jovian radii of Jupiter and will be the center of a 4-month intensive Jupiter system observation campaign. The flyby will put the spacecraft on a trajectory towards Pluto, about 2.5 degrees out of the plane of the solar system.
Observations of Pluto will begin 6 months prior to closest approach, exceeding for 150 days Hubble Space Telescope's resolution, and last another two weeks after the flyby. Long range imaging will include 40 km mapping of Pluto and Charon 3.2 days out. This is half the rotation period of Pluto-Charon and will allow imaging of the side of both bodies that will be facing away from the spacecraft at closest approach. It is planned for New Horizons to fly within 9600 km of Pluto at a relative velocity of 11 km/s at closest approach and to come as close as 27,000 km to Charon, although these parameters may easily be changed during the mission flight time. During the flyby the instruments should be able to obtain images with resolution as high as 25 m/px, 4-color global dayside maps at 1.6km resolution, hyper-spectral near-infrared maps at 7 km/px globally and 0.6 km/pixel for selected areas, characterization of the atmosphere, and radio science results.
After passing by Pluto, New Horizons will continue out into the Kuiper Belt. Mission planners now are searching for one or more Kuiper Belt Objects on the order of 50-100 km in diameter for fly-bys similar to the spacecraft's Plutonian encounter. As maneuvering capability is limited, this phase of the mission is contingent on finding suitable KBOs close to New Horizons' flight path.
Key Dates
- 24 September 2005 - Spacecraft flown to Cape Canaveral from Goddard Space Flight Center aboard a C-17 Globemaster III cargo aircraft
- 11 January 2006 - Primary launch window opens between 0706-0906 UTC
- 2 February 2006 - Primary launch window closes / secondary launch window opens. Launching in the secondary window would mean no Jupiter flyby, and a date for the Pluto flyby of sometime in 2019 or 2020. (Dates below here assume launch in primary window)
- 15 February 2006 - launch window closes.
- February 2007 - Jupiter flyby. Closest aproach will be between 25th Febuary and 2nd March, at a distance of around 2.3 million km.
- 14 July 2015 - best possible date for flyby of Pluto and Charon (depending on launch date, could be as late 2017 with a Jupiter flyby, or 2020 without).
- 2015-2020 - possible flyby of one or more Kuiper Belt objects (KBOs).
For the Pluto flyby, initial observations will begin 4 months before closest aproach, and all data should be downloaded 9 months after closest approach. An encounter with a KBO would start observations about a month beforehand, and return all data to Earth within two months.
Spacecraft and subsystems
The spacecraft forms a thick triangle with a cyclindrical RTG protruding from one vertex in the plane of the triangle and a 2.5 m radio dish antenna affixed to one flat side. Communication will be via X band at a rate of 768 bit/s from Pluto to a 70 m Deep Space Network dish (38 Kbit/s at Jupiter). The RTG will provide about 190 W at encounter in 2015. Hydrazine monopropellant is used for propulsion; a minimal delta-V capability of 290 m/s will be available after launch. The spacecraft has both three-axis stabilized and spin-stabilized modes. Star cameras are mounted on the side of the spacecraft for navigation. The spacecraft's on-orbit mass including fuel will be 465 kg for a Jupiter fly-by trajectory and 445 kg for a direct flight to Pluto. This means less fuel for later Kuiper Belt operations and is caused by the launch vehicle performance limitations for a direct-to-Pluto flight.
The spacecraft will carry seven scientific instruments. The Long Range Reconnaissance Imager (LORRI) consists of a visible light, high-resolution CCD Imager. The Pluto Exploration Remote Sensing Investigation (PERSI) consists of two instruments, Ralph telescope with two separate channels: a visible CCD imager (MVIC) and a near-infrared imaging spectrometer (LEISA), and an ultraviolet imaging spectrometer (Alice). The plasma and high energy particle spectrometer suite (PAM) consists of SWAP, a toroidal electrostatic analyzer and retarding potential analyzer, and PEPSSI, a time-of-flight ion and electron sensor. The Radio Science Experiment (REX) will use an ultrastable oscillator to conduct radio science investigations. The Student Dust Counter (SDC), built by students at the University of Colorado, will also be onboard to make dust measurements in the outer solar system.
Total mission cost is expected to be around 700 million US dollars over the lifetime of the primary mission and including the cost of launch. It replaces the cancelled Pluto Kuiper Express mission.
Hurricane Wilma
The Lockheed Martin Atlas 5 rocket that is being prepared to carry New Horizons into space was slightly damaged when Hurricane Wilma swept across Florida. Julie Andrews, spokeswoman for the Lockheed Martin Corp., stated, "We're pretty confident this isn't going to be a reason to hold up the launch". [1]
Trivia
The craft will include a payload of 430,000 names, a piece of Scaled Composites SpaceShipOne, and an American flag among other mementos to send into deep space.
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