9 YEARS AND 3,000,000,000 MILES Pluto’s new moons in sight It has been more than nine years and While still at a distance of more than 55 3 billion miles since the New Horizons million miles from the Plutonian system, spacecraft launched in early 2006. observations by long-range imager showed Pluto’s largest known moon, Charon, plus This is the rst mission to Pluto and the smaller moons Nix and Hydra. New Horizons Kuiper Belt, a gigantic zone of icy also saw, for the rst time, the tiny moons of bodies and mysterious small objects Kerberos and Styx, originally discovered in orbiting beyond Neptune. It marks the 2011 by the Hubble Space Telescope. rst direct exploration of this zone of our solar system, beyond the inner rocky planets and outer gas giants. Some very busy hours near Pluto HYDRA The craft was designed at the Johns Hopkins University Applied Physics If all goes as KERBEROS Laboratory (APL) in Laurel, Md. When it planned at reaches Pluto on July 14, it will take precisely 1 almost 4 /2 hours for a radio signal to 07:49:58 EDT on travel from it to the mission operations July 14, New center at APL. Horizons, traveling at more than eight miles per second, will be at its closest CHARON point to Pluto. STYX The route to Pluto and beyond PLUTO In February 2007, New Horizons took 09:00 Pluto orbit advantage of a gravity-assist slingshot from Jupiter, speeding New Horizons 08:00 up to more than 51,000 mph. 07:00 It will be less Pluto orbit than 8,000 New Horizons New Horizons miles from the ight dwarf planet’s NIX path surface and Saturn about 17,900 miles from the Earth largest moon, Neptune Jupiter Uranus Charon.

APL scientists may redirect the craft KUIPER BELT farther out from the system if there is a strong possibility of impacting debris.

THE TINY NEW HORIZONS SPACECRAFT IS JAM-PACKED WITH SCIENTIFIC EXPERIMENTS

Long Range Reconnaissance Imager (LORRI) Star Trackers LORRI is the highest resolution instrument on The star trackers are dual cameras used to compare board. At Pluto, LORRI will take images in which the observed star fields against an on-board database football-field-sized features will be visible. of more than 18,000 star patterns.

Ralph Alice The Student Dust Solar Wind At Counter (SDC) Pluto (SWAP) Using a single telescope Alice is an with a 3-inch aperture, ultraviolet The SDC, which was The SWAP this compound imaging designed, built and instrument will instrument collects spectrometer that operated by measure charged many wavelengths of separates light students at the particles from the light to obtain into its constitu- University of solar wind near high-resolution surface ent wavelengths Colorado, faces in Pluto to determine composition maps of and will probe the direction of how fast its the surfaces of Pluto the atmospheric spacecraft travel so atmosphere is and its moons both in composition of it is exposed to dust escaping. visual and infrared. Pluto. particle impacts.

Reaction Control Jets Propellant Tank The New Horizons spacecraft This tank, made of corrosion- controls its attitude in space resistant titanium and nestled in through the use of short bursts the center of the spacecraft where from these small thrusters it can be kept warm, carries arrayed around the vehicle. enough liquid hydrazine to supply New Horizons will only be able the reaction control jets for the to alter its course by less than entire 15+ year duration of the 2 degrees at Pluto. New Horizons mission.

Pluto Energetic Particle Spectrometer Low Gain Antenna 1 Science Investigation (PEPSSI) Sitting just above the propellant tank PEPSSI is a plasma-sensing is one of two LGAs, which provided instrument that will search for communications with Earth during neutral atoms that escape Pluto's launch and early operations. atmosphere and subsequently become charged by their interac- High Gain Antenna (HGA) tion with the solar wind. The HGA main dish collects incoming signals but also forms outgoing signals. The Radio Experiment HGA Feedhorn As the spacecraft passes behind The feedhorn directs the radio signals Pluto, with respect to Earth it will in and out of the spacecraft. precisely measure how incoming radio signals are aected by the thin Pluto atmosphere. Low Gain Antenna 2

Radioisotope Thermoelectric Generator (RTG) Weight and size of New Horizons Pluto is so far from the sun that power production with The spacecraft weighed a mere 1,054 solar cells is impractical, so New Horizons uses a pounds at launch (about as much as a decaying radioisotope as a battery to produce about couple of snowmobiles). 200 watts of electrical power for the spacecraft and its instrument payload at Pluto. The weight of the spacecraft structure was minimized by using honeycomb aluminum panels. This design cuts the Medium Gain Antenna (MGA) weight of each panel by 90 percent of and HGA Secondary Dish an equally strong solid aluminum panel. The Earth-facing side of the dish redirects R2-D2 to scale incoming and outgoing signals to and from Aside from the the MGA on the spacecraft-facing side. communication dishes and the Sun Sensor radioisotope battery tube, the whole For maximum data rate, the HGA must be framework is about kept pointing toward Earth. If the space- six feet on a side and craft loses track of its attitude, this sun about two feet deep sensor will allow the spacecraft to regain a (about the size of a sun-pointing orientation and receive grand piano). commands from Earth.

Source: Johns Hopkins University Applied Physics Laboratory THE WASHINGTON POST