PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = " B. CARCICH 2006-07-15 " RECORD_TYPE = STREAM OBJECT = INSTRUMENT_HOST INSTRUMENT_HOST_ID = "NH" OBJECT = INSTRUMENT_HOST_INFORMATION INSTRUMENT_HOST_NAME = "NEW HORIZONS" INSTRUMENT_HOST_TYPE = "SPACECRAFT" INSTRUMENT_HOST_DESC = " This description is based on several sources used with the permission of the New Horizons project, SWRI and JHU/APL: - Stern & Spencer, New Horizons: The First Reconnaissance Mission to Bodies in the Kuiper Belt, 2004 [STERN&SPENCER2004A] - The New Horizons web page originally at http://pluto.jhuapl.edu/ Overview ======== The New Horizons spacecraft observatory includes propulsion, navigation, and communications systems, plus the payload. The spacecraft is roughly 2.5 meters across and its mass is 465 kg including propellant. Design features include 64 Gbits of redundant solid-state data storage, a 290 m/s propulsion budget, and the capability to transmit data from 32 AU at almost 1 kilobit/second. The instrument payload [Stern & Cheng, 2002, STERN&CHENG2002] comprises the two-sensor RALPH Vis-IR remote sensing package, the ALICE UV imaging spectrometer, the REX radio/radiometry experiment, the two-sensor PEPPSI/SWAP plasma suite, the LORRI long-focal-length imager, and the SDC student-built dust counter. Payload ======= The New Horizons team selected instruments that not only directly measure NASA-provided items of interest (NASA AO 01-OSS-01, 2001, [NASAAO2001]), but also provide backup to other instruments on the spacecraft should one fail during the mission. The payload comprises seven instruments: RALPH ----- The main objectives for the RALPH instrument are to obtain high resolution color maps and surface composition maps of the surfaces of Pluto and Charon. The instrument has two separate channels: the Multispectral Visible Imaging Camera (MVIC) and the Linear Etalon Imaging Spectral Array (LEISA). A single telescope with a 3-inch (6-centimeter) aperture collects and focuses the light used in both channels. RALPH/MVIC operates at visible wavelengths and has 4 different filters for producing color maps. One filter allows measurement of the methane frost distribution over the surface, while the others are more generic and cover blue, red and near-infrared colors, respectively. MVIC also has two panchromatic filters that pass essentially all visible light. This will be useful for low-light level observations requiring maximum sensitivity. In all cases, the light passes from the telescope through the filters and is focused onto a charge coupled device (CCD). RALPH/LEISA operates at infrared wavelengths, and its etalon acts like a prism to bend different wavelengths of light by different amounts so that each wavelength can be analyzed separately. LEISA maps the distribution of frosts of methane (CH4), molecular nitrogen (N2), carbon monoxide (CO), and water (H2O) over the surface of Pluto and the water frost distribution over the surface of Charon. LEISA data may also reveal new constituents on the surfaces that have never before been detected. ALICE ----- Alice is an ultraviolet imaging spectrometer that probes the atmospheric composition of Pluto. Alice has two modes of operation: an airglow mode, which measures emissions from atmospheric constituents, and an occultation mode, which views either the Sun or a bright star through the atmosphere producing absorption by the atmospheric constituents. The Alice occultation mode occurs just after New Horizons passes behind Pluto and looks back at the Sun through the Pluto atmosphere. REX --- REX is an acronym for Radio EXperiment. It is integrated into the New Horizons radio telecommunications system. Using an occultation technique similar to that described above for the Alice instrument, REX probes the Pluto atmosphere. After New Horizons flies by Pluto, its 2.1 meter radio antenna points back at Earth. On Earth, powerful radio transmitters in the NASA Deep Space Network (DSN) point at New Horizons and send radio signals to the spacecraft. As the spacecraft passes behind Pluto, the atmosphere bends the radio waves by an amount that depends on the average molecular weight of the gas in the atmosphere and the atmospheric temperature. REX records the detected radio waves and sends the data back to Earth for analysis. REX also has a radiometry mode, which measures the weak radio thermal emission from Pluto itself. When REX looks back at Pluto following the flyby, radiometry data are taken to derive a value for the Pluto nightside temperature. LORRI ----- The instrument that provides the highest spatial resolution on New Horizons is LORRI - short for Long Range Reconnaissance Imager - which comprises a telescope with a 20.8cm aperture that focuses visible light onto a charge coupled device (CCD). LORRI has a very simple design; there are no filters or moving parts. Near the time of closest approach, LORRI takes images of the Pluto surface at 100m resolution. SWAP ---- The Solar Wind Analyzer around Pluto (SWAP) instrument measures charged particles from the solar wind near Pluto to determine whether Pluto has a magnetosphere and how fast the atmosphere is escaping. PEPSSI ------ Another plasma-sensing instrument, the Pluto Energetic Particle Spectrometer Investigation (PEPSSI), searches for neutral atoms that escape the Pluto atmosphere and subsequently become charged by their interaction with the solar wind. SDC --- The Student Dust Counter, which was later re-named The Venetia Burney Student Dust Counter (VSDC), is an Education and Public Outreach project. VSDC measures the dust density of the Interplanetary Dust Particles (IDP) by measuring the charge generated in the VSDC sensor from dust impact events. From this may be inferred the size and distribution of dust particles along the entire New Horizons trajectory, including regions of interplanetary space never before sampled. Such dust particles are created by comets shedding material and Kuiper Belt Objects (KBOs) colliding with other KBOs. The VSDC is managed and was built primarily by students at the University of Colorado in Boulder, with supervision from professional space scientists. Communications ============== The New Horizons mission operations team communicates with the spacecraft through DSN of antenna stations. The DSN consists of facilities in the Mojave Desert in California; near Madrid, Spain; and near Canberra, Australia. Power ===== Electrical power for the New Horizons spacecraft and science instruments is provided by a single radioisotope thermoelectric generator, or RTG, supplied by the Department of Energy. The New Horizons trajectory takes it more than 4 billion miles from Earth, where light from the Sun is 1,000 times fainter than at Earth. An RTG is used on missions, such as New Horizons, that can not use solar power - yet require a proven, reliable power supply that can produce up to several kilowatts of power and operate under severe environmental conditions for many years. Carrying out the New Horizons mission safely is a top priority at NASA. As part of that focus, NASA informed the public about use by New Horizons of an RTG by publishing a detailed Environmental Impact Statement - or EIS - and several fact sheets. The Final EIS, which includes public comments on the Draft EIS and the NASA responses to those comments, was released in July 2005. " END_OBJECT = INSTRUMENT_HOST_INFORMATION OBJECT = INSTRUMENT_HOST_REFERENCE_INFO REFERENCE_KEY_ID = "STERN&SPENCER2004A" END_OBJECT = INSTRUMENT_HOST_REFERENCE_INFO OBJECT = INSTRUMENT_HOST_REFERENCE_INFO REFERENCE_KEY_ID = "STERN&CHENG2002" END_OBJECT = INSTRUMENT_HOST_REFERENCE_INFO OBJECT = INSTRUMENT_HOST_REFERENCE_INFO REFERENCE_KEY_ID = "NASAAO2001" END_OBJECT = INSTRUMENT_HOST_REFERENCE_INFO END_OBJECT = INSTRUMENT_HOST END