9969 Braille

From Wikipedia, the free encyclopedia
Jump to: navigation, search
9969 Braille
PIA01345.jpg
9969 Braille, as imaged by Deep Space 1
Discovery and designation
Discovered by E. F. Helin & K. J. Lawrence
Discovery date May 27, 1992
Designations
MPC designation 9969 Braille
Named after Louis Braille
Alternative names 1992 KD
Orbital characteristics
Epoch April 10, 2007
Aphelion 3.355258248767612 AU
Perihelion 1.33334143409973 AU
Semi-major axis 2.34429984143367 AU
Eccentricity 0.431241085063454
Orbital period 1311.046707341689 d
Mean anomaly 53.44583107846355°
Inclination 28.8950758886474°
Longitude of ascending node 242.0860869040194°
Argument of perihelion 355.6230995683221°
Physical characteristics
Dimensions 2.1 km × 1 km × 1 km
Mass 7.8×1015g
Mean density 3.9 g cm-3[1]
Sidereal rotation period 226.4 h
Geometric albedo 0.34
Surface temp. min mean max
Kelvin ~238
Celsius
Spectral type Q-type asteroid
Absolute magnitude (H) 15.8

9969 Braille is a small Mars-crossing asteroid that orbits the Sun once every 3.58 years.[2] It was discovered in 1992 by astronomers at Palomar observatory and later named after Louis Braille, the inventor of the writing system for the blind. It was photographed in closeup by the spacecraft Deep Space 1 in 1999, but a malfunction resulted in indistinct images.

Discovery and naming[edit]

Discovered on May 27, 1992, by E. F. Helin and K. J. Lawrence working at the Palomar observatory as part of NASA's Planet-Crossing Asteroid Survey, it was given the provisional designation 1992 KD.[3] Later, it was renamed Braille in honour of Louis Braille as suggested by Kennedy Space Center software engineer Kerry Babcock in The Planetary Society's contest titled "Name That Asteroid".[4][5]

Orbit[edit]

Orbit of 9969 Braille (blue), planets (red) and the Sun (black). The outermost planet shown is Jupiter.

Braille has an unusually inclined orbit, and belongs to the somewhat rare class of asteroids known as Mars-crossing asteroids. Simulations of its orbit by scientists of the Deep Space 1 project predict that it will evolve into an Earth-crossing orbit in about 4000 years.[6] Although its closest approach to the Sun is closer than Mars orbit, its highly elliptical orbit takes it almost half-way to Jupiter at its apoapsis, and as such its semi-major axis is too large for it to be classified as an Amor asteroid.

Physical characteristics[edit]

Braille is a Q-type asteroid, composed mostly of olivine and pyroxene. Early ground-based observations had suggested that it could have been a V-type asteroid with similarities of composition between it and the much larger 4 Vesta. The asteroid is irregularly shaped, measuring approximately 2.1 km × 1 km × 1 km.

Exploration[edit]

Detailed information about Braille comes primarily from the Deep Space 1 probe, which passed within 26 km of the asteroid on July 29, 1999,[7] and from extensive ground based observations done in conjunction with the mission.[2] By the time Deep Space 1 reached Braille, its ultraviolet spectrometer had failed, but it did return two CCD images of medium resolution and three infrared spectra during the encounter. However, although the probe came within 26 km of Braille, the images and spectra were taken from an approximate distance of 14 000 km, due to problems with the tracking system.[8]

The main purpose of the Deep Space 1 mission was technology testing, but the encounter with Braille was of strong scientific value. No lone asteroid as small as Braille had previously been observed from such a short distance.[9]

References[edit]

  1. ^ I. Richter, D.E. Brinza, M. Cassel, K.H. Glassmeier, F. Kuhnke, G. Mussmann, C. Othmer, K. Schwingenschuh and B.T. Tsurutani (May 1, 2001). "First Direct Magnetic Field Measurements of an Asteroidal Magnetic Field: DS1 at Braille". Geophysical Research Letters 28 (10): 1913–1916. Bibcode:2001GeoRL..28.1913R. doi:10.1029/2000GL012679. 
  2. ^ a b Buratti, B. J.; Britt, D. T.; Soderblom, L. A.; Hicks, M. D.; Boice, D. C.; Brown, R. H.; Meier, R.; Nelson, R. M.; Oberst, J.; Owen, T. C.; Rivkin, A. S.; Sandel, B. R.; Stern, S. A.; Thomas, N.; Yelle, R. V. (January 2004). "9969 Braille: Deep Space 1 infrared spectroscopy, geometric albedo, and classification". Icarus 167 (1): 129–135. Bibcode:2004Icar..167..129B. doi:10.1016/j.icarus.2003.06.002. 
  3. ^ Susan Lendroth (July 28, 1999). "Spacecraft Target Asteroid Named in Planetary Society Contest". The Planetary Society. Retrieved January 8, 2008. 
  4. ^ MPC 35492 Minor Planet Center
  5. ^ "Asteroid target gets new name". Cable News Network. July 26, 1999. Archived from the original on February 8, 2008. Retrieved January 8, 2008. 
  6. ^ Calvin J. Hamilton. "Asteroid Braille". 
  7. ^ "A CLOSE-UP OF AN ASTEROID". National Aeronautics and Space Administration. 
  8. ^ M. Lazzarin, S. Fornasier, M. A. Barucci and M. Birlan (May 24, 2001). "Groundbased investigation of asteroid 9969 Braille, target of the spacecraft mission Deep Space 1". Astronomy & Astrophysics 375 (1): 281–284. Bibcode:2001A&A...375..281L. doi:10.1051/0004-6361:20010789. Retrieved January 7, 2008. 
  9. ^ Oberst, J.; Mottola, S.; di Martino, M.; Hicks, M.; Buratti, B.; Soderblom, L.; Thomas, N. (September 2001). "A Model for Rotation and Shape of Asteroid 9969 Braille from Ground-Based Observations and Images Obtained during the Deep Space 1 (DS1) Flyby". Icarus 153 (1): 16–23. Bibcode:2001Icar..153...16O. doi:10.1006/icar.2001.6648. 

External links[edit]