25143 Itokawa (IPA [itokawa], Japanese 糸川) is an Apollo and Mars-crosser asteroid. It is currently the focus of scientific attention as it is undergoing detailed study by a Japanese space probe Hayabusa and may become the first asteroid whose sample is brought to Earth. It has been calculated that there is some probability that Itokawa will impact onto the Earth in the next million years. The word linear comes from the Latin word linearis, which means created by lines. ... September 26 is the 269th day of the year (270th in leap years) in the Gregorian Calendar, with 96 days remaining. ... 1998 (MCMXCVIII) was a common year starting on Thursday of the Gregorian calendar, and was designated the International Year of the Ocean. ... The provisional designation of comets and asteroids are similar to each other: they both follow a pattern set in 1925 by the Minor Planet Center of the IAU. Historical designations At first, astronomers strove to assign symbols to the minor planets: 1 Ceres a stylized sickle 2 Pallas a lozenge... Minor planets, or planetoids are minor bodies of the Solar system orbiting the Sun (or of other planetary systems orbiting other stars) that are larger than meteoroids (the largest of which might be taken to be around 10 meters or so across) but smaller than major planets (Mercury having a... The Apollo asteroid 25143 Itokawa. ... A Mars-crosser asteroid is an asteroid whose orbit crosses that of Mars. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... August 18 is the 230th day of the year (231st in leap years) in the Gregorian calendar. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... The Julian day or Julian day number (JDN) is the number of days that have elapsed since 12 noon Greenwich Mean Time (UT or TT) on Monday, January 1, 4713 BC in the proleptic Julian calendar . ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... In geometry, the semi-major axis (also semimajor axis) a applies to ellipses and hyperbolas. ... giga- (symbol: G) is a prefix in the SI system of units denoting 109, or 1 000 000 000. ... The metre, or meter, is a measure of length, approximately equal to 3. ... The astronomical unit (AU or au or a. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... A day (symbol: d) is a unit of time equal to 24 hours. ... In astronomy, a Julian year is a unit of time defined as exactly 365. ... The orbital speed of a body, generally a planet, a natural satellite, an artificial satellite, or a multiple star, is the speed at which it orbits around the barycenter of a system, usually around a more massive body. ... Look up second in Wiktionary, the free dictionary. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... A degree (in full, a degree of arc, arc degree, or arcdegree), usually symbolized °, is a measurement of plane angle, representing 1／360 of a full rotation. ... The Longitude of the ascending node () is one of the orbital elements used to specify the orbit of an object in space. ... The argument of the perihelion is one of the orbital elements describing the orbit of a planet. ... In the study of orbital dynamics the mean anomaly is a measure of time, specific to the orbiting body p, which is a multiple of 2π radians at and only at periapsis. ... For the majority of numbered asteroids, almost nothing is known apart from a few physical parameters. ... Mass is a property of a physical object that quantifies the amount of matter and energy it contains. ... The international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. ... Density (symbol: ρ - Greek: rho) is a measure of mass per unit of volume. ... A cubic centimetre (cm3) is an SI derived unit of volume, equal to the volume of a cube with side length of 1 centi metre. ... Gravity is a force of attraction that acts between bodies that have mass. ... In physics, for a given gravitational field and a given position, the escape velocity is the minimum speed an object without propulsion, at that position, needs to have to move away indefinitely from the source of the field, as opposed to falling back or staying in an orbit within a... In astronomy, a rotation period is the time an astronomical object takes to complete one revolution around its rotation axis. ... Asteroids are assigned a type based on spectral shape, color, and sometimes albedo. ... Approximately 17% of all known asteroids are of an S-type (for stony) composition. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us. ... Albedo is the measure of reflectivity of a surface or body. ... Temperature is also the name of a song by Sean Paul. ... The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ... The International Phonetic Alphabet (IPA) is a system of phonetic notation devised by linguists to accurately and uniquely represent each of the wide variety of sounds (phones or phonemes) used in spoken human language. ... The Apollo asteroid 25143 Itokawa. ... A Mars-crosser asteroid is an asteroid whose orbit crosses that of Mars. ... For other uses, see Hayabusa (disambiguation). ...

Description

Itokawa was discovered in 1998 by the LINEAR project. It is named after Hideo Itokawa, a Japanese rocket scientist. It is an S-type asteroid. Radar imaging by Goldstone revealed a somewhat elongated shape. [1] The word linear comes from the Latin word linearis, which means created by lines. ... Hideo Itokawa (糸川英夫, July 20, 1912 – February 21, 1999) was a pioneer of Japanese rocketry and of the Japanese space program. ... Approximately 17% of all known asteroids are of an S-type (for stony) composition. ... This long range radar antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll[1]. Radar is a system that uses radio waves to detect, determine the distance of, and map, objects such... The Goldstone Deep Space Communications Complex (GDSCC) —commonly called the Goldstone Observatory— is located in Californias Mojave Desert (USA). ...

The Hayabusa mission has confirmed these findings and also suggests that Itokawa may be a contact binary formed by two or more small asteroids that have gravitated toward each other and stuck together. The Hayabusa images show a surprising lack of impact craters, and a very rough surface studded with boulders, these particular boulders were referred by the mission team, as being in a 'rubble'. This extrememly queer as this suggest appart from a gravitational field, one would require another force for sustaining the boulders and preventing them from escaping; This suggests a new field in planetary astroid physics is an inevitability. [2] This would mean that Itokawa is not a monolith but rather a ‘rubble pile’ formed from fragments that have cohered over time. Contact binaries are a type of binary stars where both components of the binary fill their Roche lobes. ... Tycho crater on Earths moon. ... A monolith is a monument or natural feature such as a mountain, consisting of a single massive stone or rock. ... In astronomy, rubble pile is the informal name for an asteroid that is not a monolith, consisting instead of numerous pieces of rock that have coalesced under the influence of gravity. ...

Hayabusa mission

The Japanese probe Hayabusa arrived in the vicinity of Itokawa on September 12, 2005 and initially "parked" in an asteroid-sun line at 20 km, and later 7 km, from the asteroid. Hayabusa landed November 20 for thirty minutes, but failed to operate a device designed to collect soil samples. On November 25, a second landing and the sampling sequence was performed. For other uses, see Hayabusa (disambiguation). ... September 12 is the 255th day of the year (256th in leap years). ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ...

Named surface features

Names have been proposed for the largest surface features on Itokawa by Hayabusa scientists, and are being considered by the International Astronomical Union's Small Body Task Group.

References

1. ^ ^a b c Akira Fujiwara, et al., The Rubble-Pile Asteroid Itokawa as Observed by Hayabusa, Science, Vol. 312. no. 5778, pp. 1330 - 1334, June 2, 2006
2. ^ ^a b Shunsuke Abe, et al., Mass and Local Topography Measurements of Itokawa by Hayabusa, Science, Vol. 312. no. 5778, pp. 1344 - 1347, June 2, 2006
3. ^ M. Kaasalainen, et al., CCD photometry and model of MUSES-C target (25143) 1998 SF36, Astronomy and Astrophysics, v.405, p.L29-L32 (2003)

External links

• Gazetteer of Planetary Nomenclature
• MIT's LINEAR asteroid named for Japan's 'Dr. Rocket' (MIT press release)
• Latest news and images from Hayabusa (JAXA Hayabusa official page)
• Hayabusa's Scientific and Engineering Achievements during Proximity Operations around Itokawa (JAXA press release)
• Earth impact probability of the Asteroid (25143) Itokawa to be sampled by the spacecraft Hayabusa (paper abstract)
• Astronomy Picture Of The Day: Approaching Asteroid Itokawa, A Robot's Shadow on Asteroid Itokawa, The Missing Craters of Asteroid Itokawa, Smooth Sections on Asteroid Itokawa
• Special issue: Hayabusa at Itokawa, Science, Vol. 312, no. 5778, June 2 2006
• Initial Scientific Results of Hayabusa’s Investigation on Itokawa ~Summary of the Special Issue of “Science”Magazine~ (ISAS/JAXA press release)