Information AboutNew Horizons |
| CATEGORIES ABOUT NEW HORIZONS | |
| nasa probes | |
| new frontiers | |
| pluto spacecraft | |
| jupiter spacecraft | |
| active extraterrestrial probes | |
| spacecraft escaping the solar system | |
| 2006 in space exploration | |
New Horizons is a NASA Unmanned Mission to fly by Pluto and Its Moons . NASA may also approve flybys of one or more Kuiper Belt Objects . The craft was built primarily by Southwest Research Institute (SwRI) and the Johns Hopkins Applied Physics Laboratory (APL). The mission's principal investigator is S. Alan Stern of the Southwest Research Institute. ''New Horizons'' was successfully launched on 19 January 2006 . It is expected to arrive at Pluto in 2015 . The ''New Horizons'' spacecraft was launched directly into an Earth- and solar-escape trajectory. It had an Earth-relative velocity of about 16.21 km/s (36,300 mph) just after its last engine shut down, making it the fastest spacecraft launch ever. New Horizons is the first mission in NASA's New Frontiers mission category, larger and more expensive than Discovery Missions but smaller than "flagship" programs. MISSION PROFILE An . KinetX, Inc. of Tempe, AZ is the lead on the New Horizons' navigation team and is responsible for planning trajectory adjustments as the spacecraft speeds toward the outer solar system. Jupiter gravity assist flyby]] ''New Horizons'' is now proceeding to a Jupiter Gravity Assist in February 2007 . It will pass through the Jupiter system at 21 km/s (47,000 mph), with closest approach to Jupiter occurring at approximately 6 UTC 28 February 2007 . New Horizons was the first probe launched directly towards Jupiter since the Ulysses probe in 1990. Although there were backup launch opportunities in February 2006 and February 2007, only the first 23 days of the 2006 window permitted the Jupiter flyby. Any launch outside that period would have forced the spacecraft to fly a slower trajectory directly to Pluto, delaying its encounter by 2–4 years. The flyby will increase New Horizons' speed away from the Sun by nearly 4 km/s (9,000 mph), putting the spacecraft on a faster trajectory to Pluto, about 2.5 degrees out of the plane of the solar system (the " Ecliptic "). Pluto approach It is planned for New Horizons to fly within 10,000 km (6,213.7 mi) of Pluto. New Horizons will have a relative velocity of 13.78 km/s at closest approach, and will come as close as 27,000 km (16,800 mi) to Charon, although these parameters may be changed during flight. Kuiper Belt mission After passing by Pluto, New Horizons will continue further into the Kuiper Belt. Mission planners are now searching for one or more Kuiper Belt Objects on the order of 50–100 km (30–60 mi) in diameter for flybys 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. Current status Overall control, after separation from the launch vehicle, is performed at Mission Operations Center (MOC) at APL. The science instruments are operated at the Clyde Tombaugh Science Operations Center (T-SOC) in Boulder, Colorado. Navigation is not realtime, and performed at various contractor facilities. The ''New Horizons'' probe and its Atlas V launcher lifted off from Pad 41 at . ''New Horizons'' passed Lunar orbit before midnight EST on the same day, and is scheduled to reach Jupiter in February 2007. On January 28 and January 30, mission controllers guided the probe through its first trajectory correction maneuver (TCM), which was divided into two parts called TCM-1A and TCM-1B. The total velocity change of these two corrections was about 18 meters per second. TCM-1 was accurate enough to permit the cancellation of TCM-2, the second of three originally scheduled corrections. {Link without Title} During the week of February 20, controllers conducted initial in-flight tests of three onboard scientific instruments, the Alice ultraviolet imaging spectrometer, the PEPSSI plasma-sensor, and the LORRI long-range visible-spectrum camera. No scientific measurements or images were taken, but instrument electronics (and in the case of Alice, some electromechanical systems) were shown to be functioning correctly. {Link without Title} On March 9 at 1700 UTC, controllers performed TCM-3, the last of three scheduled course corrections. The engines burned for 76 seconds, adjusting the spacecraft's velocity by about 1.16 meters per second. {Link without Title} On April 7, 2006 at about 1000 UTC, the spacecraft passed the orbit of Mars, moving at roughly 21 km/s away from the Sun at a solar distance of 243 million kilometers. {Link without Title} Key mission dates
SPACECRAFT SUBSYSTEMS Structural overview The spacecraft is comparable in size and general shape to a grand piano and has been compared to a "piano glued to a sports-bar-sized satellite dish". Its simplicity in design mimicks that of the design of the Pioneer 10 and Pioneer 11 probes of the early 1970's, but it benefits from 30+ years of technology refinements and low-power electronics. Many subsystems and components have flight heritage from APL's CONTOUR spacecraft, which in turn had heritage from APL's TIMED spacecraft. Structural The spacecraft's body forms a triangle, almost 2.5 feet (0.75 m) thick. (The Pioneers had hexagonal bodies, while the Voyager s, Galileo , and Cassini-Huygens had decagonal [10-sided , hollow bodies.) An aluminum tube forms the main structural column, between the launch vehicle adapter ring at the "rear," and the 2.1 m radio Dish Antenna affixed to the "front" flat side. The titanium fuel tank is in this tube. The RTG attaches with a 4-sided titanium mount resembling a gray pyramid or stepstool. Titanium provides strength and thermal isolation. The rest of the triangle is primarily sandwich panels of thin Aluminum facesheet (less than 1/64" or 0.4 mm) bonded to aluminum honeycomb core..]] Propulsion/Attitude Control The spacecraft has both spin-stabilized (cruise) and three-axis stabilized (science) modes, controlled entirely with Hydrazine Monopropellant . Seventy-seven kilograms of hydrazine provides a Delta-V capability of over 290 m/s after launch. The spacecraft's on-orbit mass including fuel will be over 470 kg for a Jupiter flyby trajectory, but would have been only 445 kg for a direct flight to Pluto. This would have meant less fuel for later Kuiper Belt operations and is caused by the launch vehicle performance limitations for a direct-to-Pluto flight. There are 16 thrusters, in large (1 lbf or 4.4 N ) and small (0.18 lbf or 0.8 N) thruster circuits, with two redundant fuel routings. The large thrusters are primarily for course corrections, the small ones are primarily for attitude. Two star cameras are used for fine attitude control. They are mounted on the face of the spacecraft and provide attitude information while in spinning or in 3-axis mode. Between star camera readings, knowledge is provided by dual redundant IMUs (inertial measurement units). Electronically redundant Sun sensors can provide coarse attitude control in spin mode in the event of an anomaly. Power/Thermal A cylindrical RTG protrudes from one vertex in the plane of the triangle. The radioisotope thermoelectric generator (RTG) will provide about 240 W , 30 VDC at launch, decaying to 200 W at encounter in 2015. The RTG, model "GPHS-RTG," was originally a spare from the Cassini Mission . The RTG contains 24 pounds (11 kg) of Plutonium-238 oxide pellets. Each pellet is clad in Iridium , then encased in a graphite shell. It was developed by the in New Mexico. Less than the original design goal was produced, due to delays at the Department Of Energy , including security activities, which held up production. The mission parameters and observation sequence had to be modified for the reduced wattage; still, not all instruments can operate simultaneously. The Department of Energy transferred the space battery program from Ohio to Argonne in 2002 because of security concerns. Overall, the spacecraft is thoroughly blanketed to retain heat. Unlike the Pioneers and Voyagers, the radio dish is also enclosed in blankets, blankets that extend to the body. The heat from the RTG also adds warmth to the spacecraft in the outer solar system. In the inner solar system, the spacecraft limits its activity, and opens louvers to radiate excess heat. Then, when the spacecraft is cruising inactively in the outer solar system, the louvers are closed, and the shunt regulator reroutes power to electric heaters. Telecommunications Communication will be via X Band , at a rate of 768 Bit/s from Pluto (38 kbit/s at Jupiter) to a 70 m Deep Space Network dish. The spacecraft uses dual redundant transmitters and receivers, and either right- or left-hand circular polarization. The downlink signal is amplified by dual redundant 12-watt TWTAs (traveling wave tube amplifiers) mounted on the body under the dish. In addition to the composite, high-gain dish (with well over 40 dB of gain and a half-power beam width of about a degree), there are two low-gain antennas and a medium-gain dish. The medium-gain antenna, with a 10-degree half-power beamwidth, is mounted to the back of the high-gain antenna's secondary reflector. The forward low-gain antenna is stacked atop the feed of the medium-gain antenna. The aft low-gain antenna is mounted within the launch adapter at the rear of the spacecraft. This antenna is only used for early mission phases near Earth, and later emergencies if the spacecraft loses attitude control. To save mission costs, the spacecraft will be in "hibernation" between Jupiter and Pluto. It will awaken once per year, for 50 days, for equipment checkout and trajectory tracking. The rest of the time, the spacecraft will be in a slow spin, sending a beacon tone once per week. Depending on frequency, the beacon indicates normal operation, or one of seven fault modes. New Horizons is the first mission to use the DSN's beacon tone system operationally, the system having been flight-tested by the DS1 mission. Data Handling New Horizons will record scientific instrument data to its solid-state buffer at each encounter, then transmit the data to Earth. Data storage is done on two low-power Solid-state Recorders (one primary, one backup) holding up to 8 Gigabyte s (64 gigabits) each. Because of the extreme distance from Pluto and the Kuiper Belt, only one buffer load at those encounters can be saved. This is due to the fact that New Horizons will have exited the vicinity of Pluto (or future target object) by the time it takes to transmit the buffer load back to Earth. Part of the reason that there will be a delay between the gathering and transmission of data is because all of the New Horizons instrumentation is body-mounted. In order for the cameras to record data, the entire probe must turn, and the high-gain antenna may not be pointing toward Earth. This design was implemented to save weight and cost. Previous spacecraft, such as the Voyager Program probes, had a rotatable instrumentation platform that could take measurements from virtually any angle without losing radio contact with Earth. Flight Computer The spacecraft carries two Computer systems, the Command and Data Handling system and the Guidance and Control processor. Each of the two systems is duplicated for Redundancy , making for a total of four computers. The processor used is the Mongoose-V , a 12 MHz Radiation-hardened version of the MIPS R3000 CPU . To conserve heat and mass, spacecraft and instrument electronics are housed together in IEMs (Integrated Electronics Modules). There are two redundant IEMs. MISSION SCIENCE Instrument suite The spacecraft carries seven scientific instruments. ;Long Range Reconnaissance Imager (LORRI) : LOng '''R'''ange '''R'''econnaissance '''I'''mager -- a Visible-light , high-resolution CCD Imager with an 8.2 inch aperture and 1024x1024 CCD. The CCD is chilled to tens of degrees below freezing by a passive radiator. The Ritchey-Chretien telescope is made of Silicon Carbide , to reduce weight and prevent warping at low temperatures. Resolution is 5 Microradian s (approximately one Arcsecond ). ;Pluto Exploration Remote Sensing Investigation (PERSI) : This consists of two instruments: The Ralph telescope, 6 centimeters in aperture, with two separate channels: a visible-light CCD imager (MVIC- Multispectral Visible Imaging Camera) with broadband and color channels, and a near- Infrared imaging Spectrometer , LEISA (Linear Etalon Imaging Spectral Array). LEISA is derived from a similar instrument on the EO-1 mission. The second instrument is an Ultraviolet imaging spectrometer, '''Alice'''. Alice resolves 1,024 wavelength bands in the far and extreme ultraviolet (from 180 to 50 Nanometer s or 1800 to 500 Angstrom s), over 32 view fields. This Alice is derived from an Alice on the Rosetta mission, where it stood for 'A Lightweight Imaging spectrometer for Cometary Exploration.' Ralph, designed afterward, was named after Alice's husband on The Honeymooners . ; and Electron sensor. SWAP measures particles of up to 6.5 keV, PEPSSI goes up to 1 MeV. ;Radio Science Experiment (REX) : REX will use an ultrastable oscillator and some additional electronics to conduct radio science investigations using the communications channels. These are small enough to fit on a single card. Since there are two redundant communications subsystems, there are two, identical REX circuit boards. ;Student Dust Counter (SDC) : Built by students at the University of Colorado, the Student Dust Counter will operate continuously to make Dust measurements. Consists of a detector panel, about 18 inches x 12 inches (460 mm by 300 mm), mounted on the antisolar face of the spacecraft (the ram direction), and an electronics box within the spacecraft. The detector contains twelve PVDF panels which generate voltage when impacted. No dust counter has operated past the orbit of Uranus; models of dust in the outer solar system, especially the Kuiper Belt, are speculative.> |
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