NASA's Mission To Pluto

Latest News - 15th July, 2015

Since January 2006 we have been following the progress of New Horizons as it zoomed across the solar system towards distant Pluto. The probe was launched on 19th January, 2006 and the spacecraft zoomed past Pluto on 14th July, 2015 with all instruments functioning normally.  It is now headed into the unknown and uncharted regions beyond Pluto. For the latest images and news click here.

Mission Milestones
February 2007 Jupiter gravity assist
March 2007 - June 2015 Interplanetary cruise
July 2015 Pluto-Charon encounter
2016-2020 Kuiper Belt objects encounter
NASA’s "New Horizons" spacecraft - the first ever mission to Pluto and the Kuiper Belt (a distant region of ancient, icy, rocky objects at the edge of the solar system) - successfully launched from Cape Kennedy in Florida on 19th January, 2006.  The spacecraft is certain to send a significant amount of new information back to Earth.  The huge distance to Pluto means that New Horizons is not expected to arrive at its destination until July 2015.

Launching a spacecraft to Pluto was not an easy task for NASA, due to budget cuts, start-and-stop mission planning and hardware building.  But these problems were overcome, the craft was assembled, and successfully launched on this extraordinary expedition to the edge of the solar system.  The cost of the mission, including the launch vehicle and operations through the Pluto-Charon encounter, will be roughly $650 million.

The spacecraft was launched using the New Horizons booster, a Lockheed Martin Atlas 5 first stage with five strap-on solid rocket boosters, a powerful Centaur second stage, topped by a STAR 48B solid propellant-fuelled third stage.

The New Horizons spacecraft is roughly 8 feet (2.5 meters) across and weighs roughly 1,025 pounds (465 kilograms)—about half a ton—when loaded with fuel.  Power Source is a single radioisotope thermoelectric generator (RTG), the same type which powered (and still powers) the Voyager spacecraft, back in the 1970's.  Recently, the Hubble Space Telescope has observed that Pluto may have not one, but three moons, which adds to the mysteries New Horizons is expected to resolve.

Suite of seven instruments
The first 13 months after launch were taken up with spacecraft and instrument checkouts, instrument calibrations, trajectory correction manoeuvres.  Spacecraft operators also rehearsed their Pluto encounter as the craft passed Jupiter between February 25 and March 2, 2007.

Data sent from New Horizons is being received on Earth through NASA’s Deep Space Network, dispatched onward to the spacecraft’s Mission Operations Centre at Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. APL manages the mission for NASA and built the New Horizons spacecraft. A radio signal moving at the speed of light takes about four hours to reach Pluto from Earth.

New Horizon carries a suite of seven scientific instruments:

  1. Alice is an ultraviolet spectrometer used for measuring gas composition
  2. Ralph combines an infrared spectrometer (LEISA) for mapping surface composition with a colour optical imager (MVIC) for mapping surface structure and composition
  3. REX is a radio experiment for measuring atmospheric composition and temperature
  4. LORRI is an optical telescope that provides the highest resolution imaging of the surface
  5. PEPSSI is a plasma-sensing instrument for measuring particles escaping from Pluto's atmosphere
  6. SWAP is a plasma-sensing instrument for measuring the properties of the solar wind at Pluto, Pluto's atmospheric escape rate, and for searching for a magnetosphere around Pluto. The "solar wind" is a stream of charged particles streaming away from the Sun at high speed.
  7. SDC, an instrument used to measure dust impacts at the New Horizons spacecraft during its entire trajectory, was built by students at the University of Colorado in Boulder.

Nuclear-powered probe
New Horizons is outfitted with a compact nuclear power system.  The hardware converts the heat generated from the natural decay of radioactive fuel into electricity.  The RTG consists of two major elements: a heat source that contains plutonium dioxide in the form of ceramic pellets and a set of solid-state thermocouples that convert the plutonium’s heat energy to electricity.  Like any NASA mission designed to use an RTG, New Horizons has undergone extensive, multi-agency safety and risk reviews throughout its development.

Latest News
29th May, 2015: in its first scan of the Pluto system for unknown objects that could threaten a spacecraft’s safety, the New Horizons spacecraft has so far detected “no new moons, rings or anything else to be concerned about.” In an update, the mission team wrote that this sets limits on the size of any moon “outside the orbit of Pluto’s largest and closest moon, Charon,” as well as any rings. A second scan with “twice the sensitivity of the initial” one is scheduled Friday and Saturday.
10th December, 2014: New Horizons spacecraft came out of hibernation for its long-awaited 2015 encounter with the Pluto system. Operators at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., confirmed at 9:53 p.m. (EST) that New Horizons, operating on pre-programmed computer commands, had switched from hibernation to “active” mode. Moving at light speed, the radio signal from New Horizons – currently more than 2.9 billion miles from Earth, and just over 162 million miles from Pluto – needed four hours and 26 minutes to reach NASA’s Deep Space Network station in Canberra, Australia. Since launching on January 19, 2006, the spacecraft has spent 1,873 days — about two-thirds of its flight time — in hibernation. Its 18 separate hibernation periods, from mid-2007 to late 2014, ranged from 36 days to 202 days in length. The team used hibernation to save wear and tear on spacecraft components and reduce the risk of system failures. The wake-up sequence had been programmed into the onboard computer in August, and started aboard the spacecraft at 3 p.m. EST on Dec. 6. About 90 minutes later, New Horizons began transmitting word to Earth on its condition, including the report that it is back in "active" mode. The control team will now spend the next several weeks checking out the spacecraft and making sure its systems and science instruments are operating properly. They’ll also continue to build and test the computer-command sequences which will guide New Horizons through its flight to, and reconnaissance of, the Pluto system. With a seven-instrument science payload that includes advanced imaging infrared and ultraviolet spectrometers, a compact multi-colour camera, a high-resolution telescopic camera, two powerful particle spectrometers and a space-dust detector, New Horizons will begin observing the Pluto system on Jan. 15th. New Horizons’ closest approach to Pluto will occur on July 14, but plenty of highlights are expected before then, including, by mid-May, views of the Pluto system and its moons better than even the mighty Hubble Space Telescope can provide.
25th August, 2014:  New Horizons has traversed the orbit of Neptune. This is its last major "crossing" en route to Pluto.  The spacecraft  reached this point - nearly 2.75 billion miles (4.4. billion kilometres) from Earth -- in a record eight years and eight months.  The milestone matches precisely the 25th anniversary of the historic encounter of NASA's Voyager 2 spacecraft with Neptune on Aug. 25, 1989.

Several senior members of the New Horizons science team were young members of Voyager's science team in 1989.  Many remember how Voyager 2's approach images of Neptune and its planet-sized moon Triton fueled anticipation of the discoveries to come. They share a similar, growing excitement as New Horizons begins its approach to Pluto.  Voyager's visit to the Neptune system revealed previously unseen features of Neptune itself, such as the Great Dark Spot, a massive storm similar to, but not as long-lived, as Jupiter's Great Red Spot. Voyager also, for the first time, captured clear images of the ice giant's ring system, too faint to be clearly viewed from Earth.

Many researchers feel the 1989 Neptune flyby - Voyager's final planetary encounter - might have offered a preview of what's to come next summer.  Scientists suggest that Triton, with its icy surface, bright poles, varied terrain and cryo-volcanoes, is a Pluto-like object that Neptune pulled into orbit.  Scientists recently restored Voyager's footage of Triton and used it to construct the best global colour map of that strange moon yet - further whetting appetites for a Pluto close-up.

Similar to Voyager 1 and 2's historic observations, New Horizons also is on a path toward potential discoveries in the Kuiper Belt, which is a disc-shaped region of icy objects past the orbit of Neptune, and other unexplored realms of the outer solar system and beyond.

1st June, 2013:  Back in 2005 and 2006, when Pluto’s second and third moons (Nix and Hydra) were discovered, searches by astronomers for still more moons didn’t reveal any. So the accidental discovery of Pluto’s fourth moon by the Hubble Space Telescope in mid-2011 (during a search for Plutonian rings) raised the possibility that the hazards in the Pluto system might be greater than previously anticipated. Those concerns were amplified when Hubble discovered a fifth moon in 2012. As a result of those discoveries, the New Horizons science and operations teams began to more carefully scrutinize the true level of hazards to our spacecraft at closest approach and devise mitigation strategies to make sure the encounter with Pluto would be successful.  These assessments are now largely completed and it has been determined that:
  • New Horizons benefits from its approach trajectory because that trajectory is steeply inclined to Pluto’s satellite plane and associated debris hazards that models show should lie close to the satellite plane. As a result, most of the risk New Horizons faces occurs only at closest approach, when the spacecraft is very near the satellite plane
  • The Pluto system appears to be far safer than early fears and initial calculations indicated when the new moons began popping up. In fact, the best current models predict a 0.3% (1-in-300) chance of a mission-ending impact near closest approach on the nominal trajectory. Much of the reason for this lowered risk assessment is that more sophisticated dust-impact models revealed a decrease (by about a factor of 100) in lethal impact probability for trajectories that fly into the region where New Horizons is aimed now – a region where the gravitational effects of Pluto’s largest moon Charon clear debris. Another important factor is that when spacecraft components were tested against high-velocity impacts using gun ranges in New Mexico and Ohio, it was found that the spacecraft shielding is considerably “harder”– that is, more resistant to impacts – than preflight estimates indicated
  • The New Horizons closest-approach aim point is one of the safest possible aim points – if not the safest aim point – in the Pluto system. This is because the spacecraft is headed to a closest approach in the region that Pluto’s Texas-sized moon Charon efficiently clears of debris. In fact, Charon offers such a good hazard-removal service that even if a recent impact onto a small moon created debris near Charon’s orbit just months before encounter, Charon would clear almost all of it by the time the spacecraft arrives


New Horizons came to within 1.4 million miles of Jupiter on Feb. 28, using the planet's gravity to trim three years from its travel time to Pluto. For several weeks before and after this closest approach, the piano-sized robotic probe trained its seven cameras and sensors on Jupiter and its four largest moons, storing data from nearly 700 observations on its digital recorders and gradually sending that information back to Earth. About 70 percent of the expected 34 gigabits of data has come back so far, radioed to NASA's largest antennas over more than 600 million miles. This activity confirmed the successful testing of the instruments and operating software the spacecraft will use at Pluto.
The New Horizons Jupiter encounter is under way!  The spacecraft received its "slingshot" velocity boost on 28th February and has picked up another 9,000mph as a result, making its new velocity more than 52,000mph.  The spacecraft has begun sending back pictures from the Jupiter encounter, including this shot of Io.  Also in the flight plan: the first-ever trip down the long "tail" of Jupiter's magnetic field, which extends tens of millions of miles beyond the planet.  
The New Horizons team got a faint glimpse of the mission’s distant, main planetary target when one of the spacecraft’s telescopic cameras spotted Pluto for the first time.  The Long Range Reconnaissance Imager (LORRI) took the pictures during an optical navigation test on Sept. 21-24, and stored them on the spacecraft’s data recorder until their recent transmission back to Earth. Information source: NASA Website

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