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000-Clementine.gif000 - Clementine55 visiteDescription
Clementine was a joint project between the Ballistic Missile Defense Organization (BMDO, nee the Strategic Defense Initiative Organization, or SDIO) and NASA. The objective of the mission was to test sensors and spacecraft components under extended exposure to the space environment and to make scientific observations of the Moon and the near-Earth asteroid 1620 Geographos. The Geographos observations were not made due to a malfunction in the spacecraft. The lunar observations made included imaging at various wavelengths in the visible as well as in ultraviolet and infrared, laser ranging altimetry, gravimetry, and charged particle measurements. These observations were for the purposes of obtaining multi-spectral imaging the entire lunar surface, assessing the surface mineralogy of the Moon and obtaining altimetry from 60N to 60S latitude and gravity data for the near side. There were also plans to image and determine the size, shape, rotational characteristics, surface properties, and cratering statistics of Geographos. Clementine carried 7 distinct experiments on-board: a UV/Visible Camera, a Near Infrared Camera, a Long Wavelength Infrared Camera, a High Resolution Camera, two Star Tracker Cameras, a Laser Altimeter, and a Charged Particle Telescope. The S-band transmitter was used for communications, tracking, and the gravimetry experiment.
Spacecraft and Subsystems
The spacecraft was an octagonal prism 1.88 meters high and 1.14 m across with two solar panels protruding on opposite sides parallel to the axis of the prism. A high-gain fixed dish antenna was at one end of the prism, and the 489 N thruster at the other end. The sensor openings were all located together on one of the eight panels, 90 degrees from the solar panels, and protected in flight by a single sensor cover. The spacecraft propulsion system consisted of a nonpropellant hydrazine system for attitude control and a bipropellant nitrogen tetraoxide and monomethyl hydrazine system for the maneuvers in space. The bipropellant system had a total capability of about 1900 m/s with about 550 m/s required for lunar insertion and 540 m/s for lunar departure. Attitude control was achieved with 12 small attitude control jets, two star tracker cameras, and two inertial measurement units. The spacecraft was three-axis stabilized in lunar orbit via reaction wheels with a precision of 0.05 Deg. in control and 0.03 Deg. in knowledge. Power was provided by gimbaled, single axis, GaAs/Ge solar panels which charged a 15 amp-hour, 47-w hr/Kg Nihau (Ni-H) common pressure vessel battery. Spacecraft data processing was performed using a MIL-STD-1750A computer (1.7 million instructions per second) for savemode, attitude control, and housekeeping operations, a RISC 32-bit processor (18 million ips) for image processing and autonomous operations, and an image compression system provided by the French Space Agency CNES. A data handling unit sequenced the cameras, operated the image compression system, and directed the data flow. Data was stored in a 2 Gbit dynamic solid state data recorder.
Mission Profile
The mission had two phases. After two Earth flybys, lunar insertion was achieved approximately one month after launch. Lunar mapping took place over approximately two months, in two parts. The first part consisted of a five hour elliptical polar orbit with a periapsis of about 400 Km at 30 degrees south latitude and an apoapsis of 8300 Km. Each orbit consisted of an 80 minute lunar mapping phase near periapsis and 139 minutes of downlink at apoapsis. After one month of mapping the orbit was rotated to a periapsis at 30 degrees north latitude, where it remained for one more month. This allowed global imaging and altimetry coverage from 60 degrees south to 60 degrees north, over a total of 300 orbits. After a lunar/Earth transfer and two more Earth flybys, the spacecraft was to head for Geographos, arriving three months later for a flyby, with a nominal approach closer than 100 Km. Unfortunately, on May 7, 1994, after the first Earth transfer orbit, a malfunction aboard the craft caused one of the attitude control thrusters to fire for 11 minutes, using up its fuel supply and causing Clementine to spin at 80 rpm. Under these conditions, the asteroid flyby could not yield useful results, so the spacecraft was put into a geocentric orbit passing through the Van Allen radiation belts to test the various components on board. The mission ended in June 1994 when the power level onboard dropped to a point where the telemetry from the spacecraft was no longer intelligible.
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000-Kaguya.jpgThe Kaguya (SELENE) Probe64 visiteThe SELenological and ENgineering Explorer "KAGUYA"(SELENE), Japans 1st large Lunar Explorer, was launched by the H-IIA rocket on September 14, 2007 (JST). The mission, which is the largest Lunar Mission since the Apollo Program, is being keenly anticipated by many countries.
The major objectives of the Mission are to understand the Moons origin and evolution and to observe the Moon in various ways in order to utilize it in the future. The Lunar Missions that have been conducted so far have gathered a large amount of information on the Moon, but the mysteries of its origin and evolution have been left unsolved.
KAGUYA will investigate the entire Moon in order to obtain information on its elemental and mineralogical composition, geography, surface and sub-surface structure, the remnant of its magnetic field and its gravity field.
The results are expected to lead to a better overall understanding of the Moons evolution. At the same time, the observation equipment installed on the orbiting satellite will observe plasma, the electromagnetic field and high-energy particles. The data obtained in this way will be of great scientific importance for exploring the possibility of using the moon for human endeavors.MareKromium
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001-Ceres-alone.jpg1-Ceres from Hubble Space Telescope58 visiteNASA's Hubble Space Telescope took these images of the asteroid 1 Ceres over a 2-hour and 20-minute span, the time it takes the Texas-sized object to complete one quarter of a rotation. One day on Ceres lasts 9 hours.
Hubble snapped 267 images of Ceres as it watched the asteroid make more than one rotation. By observing the asteroid during a full rotation, astronomers confirmed that Ceres has a nearly round body like Earth's. Ceres' shape suggests that its interior is layered like those of terrestrial planets such as Earth. Ceres may have a rocky inner core, an icy mantle, and a thim, dusty, outer crust.
The "Bright Spot" that we see is a mistery: it is (obviously) brighter than its surroundings, but it is still very dark (very low albedo) reflecting only a small portion of Sunlight.
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004-Ceres.jpgMoments of 1-Ceres (1)52 visiteDa "NASA - Picture of the Day", del 21 Agosto 2006:"Is 1-Ceres an Asteroid or a Planet?
Although a trivial designation to some, the recent suggestion by the Planet Definition Committee of the International Astronomical Union would have 1-Ceres reclassified from Asteroid to Planet.
A change in taxonomy might lead to more notoriety for the frequently overlooked world. Ceres, at about 1000 Km across, is the largest object in the main Asteroid Belt between Mars and Jupiter. Under the newly proposed criteria, Ceres would qualify as a planet because it is nearly spherical and sufficiently distant from other planets. Pictured above is the best picture yet of Ceres, taken by the Hubble Space Telescope as part of a series of exposures ending in 2004 January. Currently, NASA's Dawn mission is scheduled to launch in 2007 June to explore Ceres and Vesta, regardless of their future designations".
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007-Ceres-PIA10235.jpg1-Ceres (natural colors, from HST - credits: NASA/ESA et al.)52 visiteCaption NASA:"This is a NASA Hubble Space Telescope color image of 1-Ceres, the largest object in the Asteroid Belt.
Astronomers enhanced the sharpness in these Advanced Camera for Surveys images to bring out features on Ceres' surface, including brighter and darker regions that could be asteroid impact features.
The observations were made in Visible and UV Light between December 2003 and January 2004.
The colors represent the differences between relatively red and blue regions. These differences may simply be due to variation on the surface among different types of material.
Ceres' round shape suggests that its interior is layered like those of terrestrial planets such as Earth. Ceres may have a rocky inner core, an icy mantle, and a thin, dusty outer crust inferred from its density and rotation rate of 9 hours. Ceres is approximately 590 miles (about 950 Km) across and was first discovered in 1801".MareKromium
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015-The Moon from Clem-FarSide-PIA00304.jpg002 - The Far-Side of the Moon54 visiteClementine Project Information
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Clementine was a joint project between the Strategic Defense Initiative Organization and NASA. The objective of the mission was to test sensors and spacecraft components under extended exposure to the space environment and to make scientific observations of the Moon and the near-Earth asteroid 1620 Geographos. The observations included imaging at various wavelengths including ultraviolet and infrared, laser ranging altimetry, and charged particle measurements. These observations were originally for the purposes of assessing the surface mineralogy of the Moon and Geographos, obtaining lunar altimetry from 60N to 60S latitude, and determining the size, shape, rotational characteristics, surface properties, and cratering statistics of Geographos.
Clementine was launched on 25 January 1994 at 16:34 UTC (12:34 PM EDT) from Vandenberg AFB aboard a Titan IIG rocket. After two Earth flybys, lunar insertion was achieved on February 21. Lunar mapping took place over approximately two months, in two parts. The first part consisted of a 5 hour elliptical polar orbit with a perilune of about 400 km at 28 degrees S latitude. After one month of mapping the orbit was rotated to a perilune of 29 degrees N latitude, where it remained for one more month. This allowed global imaging as well as altimetry coverage from 60 degrees S to 60 degrees N.
After leaving lunar orbit, a malfunction in one of the on-board computers on May 7 at 14:39 UTC (9:39 AM EST) caused a thruster to fire until it had used up all of its fuel, leaving the spacecraft spinning at about 80 RPM with no spin control. This made the planned continuation of the mission, a flyby of the near-Earth asteroid Geographos, impossible. The spacecraft remained in geocentric orbit and continued testing the spacecraft components until the end of mission.
More information on the Clementine mission, instruments, and early results can also be found in the Clementine special issue of Science magazine, Vol. 266, No. 5192, December 1994.
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018-Vesta-6-PIA13428.jpgSome of the "Faces" of 4-Vesta, from Hubble Space Telescope95 visiteNASA's Hubble Space Telescope snapped these images of the Asteroid 4-Vesta in preparation for the Dawn Spacecraft's visit in 2011. Each of the 4 Hubble images captures views of Vesta during its 5,34-hour rotation period. Hubble's sharp "eye" can see features as small as about 40 Km (24,84 miles) across in these images. Vesta was 211 MKM (approx. 131 MMs) from Earth when Hubble made the observations.
The images show the difference in brightness and color on the Asteroid's Surface. These characteristics hint at the large-scale features that the Dawn Spacecraft will see when it visits the potato-shaped asteroid.
Astronomers used the images, taken with Hubble's Wide Field Camera 3, to better determine 4-Vesta's Spin Axis. Based on the HST observations, astronomers calculated a slightly different, and more precise, Rotation Axis for Vesta. The new calculation will change the pattern of sunlight expected to illuminate the Asteroid when Dawn arrives.
Determining a more accurate Spin Axis for 4-Vesta will also help scientists refine the Dawn Spacecraft's orbit around the Asteroid. Dawn will orbit the rocky object for a year, beginning in July 2011. The Spacecraft will then travel to the "Dwarf Planet" 1-Ceres, arriving in 2015.
Hubble has kept its "eye" on 4-Vesta for more than 15 years, beginning in 1994. Hubble images of 4-Vesta in 1997 helped astronomers discover the Asteroid's very large Impact crater. Astronomers combined views of 4-Vesta in Near-UltraViolet and blue light to construct these images and the images were taken on Feb. 25, 2010.MareKromium
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02-vg1_p21151.jpgJupiter, in true colors52 visite"Interstellar space is filled with material ejected by explosions of nearby stars" Stone added. "and Voyager 1 will be the first human-made object to cross into it".
Voyager Project Manager Ed Massey of JPL says the survival of the two spacecrafts is a credit to the robust design of the spacecraft, and to the flight team, which is now down to only 10 people.
"But its these 10 people who are keeping these spacecrafts alive. Theyre very dedicated. This is sort of a testament to them, that we could get all this done".
Between them, the two Voyagers have explored Jupiter, Uranus, Saturn and Neptune, along with dozens of their moons. In addition, they have been studying the Solar Wind, the stream of charged particles spewing from the sun at nearly a million miles per hour.
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022-vg2_4391335-2.jpgAnomalies near Japetus (Object "A" - detail mgnf)56 visitenessun commento
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023-vg2_4391335-3.jpgAnomalies near Japetus (Object "A" - detail super-mgnf)55 visitenessun commento
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024-vg2_4391335-4.jpgAnomalies near Japetus (Objects "B" and "C" - detail mgnf)55 visitenessun commento
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025-vg2_4391335-5.jpgAnomalies near Japetus (Object "B" - detail super-mgnf)55 visitenessun commento
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