253 Mathilde
Synodic rotation period | 417.7 h (17.40 d)[2] 17.406 ± 0.010 d[6] (17 d 9 h 45 min) | |
0.0436±0.004[2] | ||
Temperature | ≈ 174[7] K | |
Cb[2] | ||
10.3[2] | ||
Mathilde (
Mathilde was visited by the NEAR Shoemaker spacecraft during June 1997, on its way to asteroid 433 Eros. During the little flyby, the spacecraft imaged a hemisphere of the asteroid, revealing many large craters that had gouged out depressions in the surface. It was the first carbonaceous asteroid to be explored and, until 21 Lutetia was visited in 2010, it was the largest asteroid to be visited by a spacecraft.
Observation history
In 1880, Johann Palisa, the director of the Austrian Naval Observatory (
Among his discoveries was the asteroid 253 Mathilde, found on November 12, 1885. The initial
In 1995, ground-based observations determined that Mathilde is a C-type asteroid. It was also found to have an unusually long period of rotation of 418 hours.[10]
On June 27, 1997, the NEAR Shoemaker spacecraft passed within 1,212 km of Mathilde while moving at a velocity of 9.93 km/s. This close approach allowed the spacecraft to capture over 500 images of the surface,[8] and provided data for more accurate determinations of the asteroid's dimensions and mass (based on gravitational perturbation of the spacecraft).[5] However, only one hemisphere of Mathilde was imaged during the fly-by.[11] This was only the third asteroid to be imaged from a nearby distance, following 951 Gaspra and 243 Ida.
Characteristics
Mathilde is very dark, with an
The density measured by NEAR Shoemaker, 1,300 kg/m3, is less than half that of a typical carbonaceous chondrite; this may indicate that the asteroid is very loosely packed rubble pile.[5] The same is true of several C-type asteroids studied by ground-based telescopes equipped with adaptive optics systems (45 Eugenia, 90 Antiope, 87 Sylvia and 121 Hermione). Up to 50% of the interior volume of Mathilde consists of open space. However, the existence of a 20-km-long scarp may indicate that the asteroid does have some structural strength, so it could contain some large internal components.[11] The low interior density is an inefficient transmitter of impact shock through the asteroid, which also helps to preserve the surface features to a high degree.[4]
Mathilde's
See also
References
- ^ ISBN 0-7503-0693-9.
- ^ a b c d e f Unless otherwise noted, parameters are per: Yeomans, Donald K. (29 August 2003). "253 Mathilde". JPL Small-Body Database Browser. NASA. Retrieved 12 May 2016.
- ^ For semi-major axis a, orbital period T and eccentricity e, the average orbital speed is given by:
ISBN 0-387-94746-9.
- ^ .
- ^ PMID 9405343.
- .
- ^ For asteroid albedo α, semimajor axis a, solar luminosity , Stefan–Boltzmann constant σ and the asteroid's infraredemissivity ε (≈ 0.9), the approximate mean temperature T is given by:ISBN 978-0-12-088589-3.
- ^ a b c Williams, David R. (18 December 2001). "NEAR Flyby of Asteroid 253 Mathilde". NASA. Archived from the original on 18 August 2006. Retrieved 10 August 2006.
- ^ Raab, Herbert (2002). "Johann Palisa, the most successful visual discoverer of" (PDF). Astronomical Society of Linz. Archived from the original (PDF) on 28 September 2007. Retrieved 27 August 2007.
- ^ a b c Savage, D.; Young, L.; Diller, G.; Toulouse, A. (February 1996). "Near Earth Asteroid Rendezvous (NEAR) Press Kit". NASA. Archived from the original on 19 March 2012. Retrieved 29 August 2007.
- ^ .
- ^ Pon, Brian (30 June 1999). "Pavement Albedo". Heat Island Group. Archived from the original on 29 August 2007. Retrieved 27 August 2007.
- Bibcode:2007LPI....38.2366K.
- ^ Blue, Jennifer (29 August 2007). "Categories for Naming Features on Planets and Satellites". USGS. Archived from the original on 24 August 2007. Retrieved 29 August 2007.
- ^ Lang, Kenneth R. (2003). "2. Asteroids and meteorites, Size, color and spin". NASA's Cosmos. NASA. Archived from the original on 6 August 2012. Retrieved 29 August 2007.
- .
External links
- Bowell, Ted & Koehn, Bruce (2 September 2007). "The Asteroid Orbital Elements Database". Lowell Observatory. Retrieved 2 September 2007.
- Staff (28 August 2007). "Discovery Circumstances: Numbered Minor Planets". Minor Planet Center. Archived from the original on 10 May 2008. Retrieved 2 September 2007.
{{cite web}}
: CS1 maint: bot: original URL status unknown (link) - Hall, Alan (30 June 1997). "NEAR-ing Mathilde". Scientific American. Retrieved 29 August 2007.
- Flyby gif parent page
- 253 Mathilde at AstDyS-2, Asteroids—Dynamic Site
- 253 Mathilde at the JPL Small-Body Database