NEW HORIZONS when it collides with the solid-state detector. From this, scientists can determine the composition of each particle. PEPSSI can measure energetic particles up to 1,000 kiloelectron volts (keV), many times more energetic than SWAP can. Together the two instruments make a powerful combination for studying the Pluto system. Student Dust Counter (SDC) Mass: 1.9 kilograms (4.2 pounds) Average Power: 5 watts Development: Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder Principal Investigator: Mihaly Horanyi, University of Colorado at Boulder Purpose: Measure concentration of dust particles in outer solar system Designed and built by students at the University of Colorado at Boulder, the SDC will detect microscopic dust grains produced by collisions among asteroids, comets, and Kuiper Belt Objects during New Horizons’ long journey. Officially a New Horizons Education and Public Outreach project, SDC is the first science instrument on a NASA planetary mission to be designed, built and “flown” by students. The SDC will count and measure the sizes of dust particles along New Horizons’ entire trajectory and produce information on the collision rates of such bodies in the deep outer solar system. SDC will also be used to search for dust in the Pluto system; such dust might be generated by collisions of tiny impactors on Pluto’s small moons.The instrument includes two major pieces: an 18-by-12-inch detector assembly, which is mounted on the outside of the spacecraft and exposed to the dust particles; and an electronics box inside the spacecraft that, when a hit occurs on the detector, deciphers the data and determines the mass and For a chart of instrument speed of the particle. Because no dust detector has ever flown beyond 18 astronomical technical specifications, units from the Sun (nearly 1.7 billion miles, about the distance from Uranus to the Sun), SDC visit the New Horizons data will give scientists an unprecedented look at the sources and transport of dust in the Web site at http://pluto. solar system. jhuapl.edu/spacecraft/ With faculty support, University of Colorado students will also distribute and archive data instruments.html. from the instrument, and lead a comprehensive education and outreach effort to bring their results and experiences to classrooms of all grades over the next two decades. Spacecraft Systems and Components Structure New Horizons’ primary structure includes an aluminum central cylinder that supports honeycomb panels, serves as the payload adapter fitting that connects the spacecraft to the launch vehicle, supports the interface between the spacecraft and its power source, and houses the propellant tank. Keeping mass down, the panels surrounding the central cylinder feature an aluminum honeycomb core with ultra-thin aluminum face sheets (about as thick as two pieces of paper). To keep it perfectly balanced for spinning operations, the spacecraft is weighed and then balanced with additional weights just before mounting on the launch vehicle. Command and Data Handling The command and data handling system – a radiation-hardened 12-megahertz Mongoose V processor guided by intricate flight software – is the spacecraft’s “brain.” The processor distributes operating commands to each subsystem, collects and processes instrument data, and sequences information sent back to Earth. It also runs the advanced “autonomy” algorithms that allow the spacecraft to check the status of each system and, if necessary, correct any problems, switch to backup systems or contact operators on Earth for help. For data storage, New Horizons carries two low-power solid-state recorders (one backup) that can hold up to 8 gigabytes (64 gigabits) each. The main processor collects, compresses, reformats, sorts and stores science NASA’s First Mission to Pluto and the Kuiper Belt 21