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(29075) 1950 DA
Encyclopedia
1950 DA is a near-Earth asteroid. It is notable for having the highest known probability
of impacting
Earth
(between 0 and 0.33%). It has the highest Palermo rating
with a value of 0.17 for a possible collision in the year 2880. For a brief period in late December 2004, asteroid 99942 Apophis
held the record for Palermo scale values, with a value of 1.10.
at Lick Observatory
. It was observed for seventeen days and then lost because of the short observation arc resulting in large uncertainties in Wirtanen's orbital solution. On 31 December 2000, it was recovered as and 2 hours later was recognized as 1950 DA.
observatories from March 3 to 7 2001.
The studies showed that the asteroid has a mean diameter of 1.1–1.4 km (3,600-4,600 ft). Optical lightcurve analysis by Lenka Sarounova and Petr Pravec
shows that its rotation period is 2.1216 ± 0.0001 hours. Due to its short rotation period and high radar albedo
, 1950 DA is thought to be fairly dense (more than 3 g/cm³) and likely composed of nickel-iron.
The next radar opportunity for 1950 DA is in 2032.
If 1950 DA continues on its present orbit, it will approach near to the Earth on March 16, 2880. However, over the intervening time, its rotation will cause its orbit to slighlty change as a result of the Yarkovsky effect
. Available radar and optical data suggest two possible pole directions; one trajectory misses the Earth by tens of millions of kilometers, while the other has an impact probability of roughly 1 in 300.
The energy released by a collision with an object the size of 1950 DA would cause major effects on the climate
and biosphere
which would be devastating to human
civilization
. The discovery of the potential impact has heightened interest in asteroid deflection strategies
.
Probability
Probability is ordinarily used to describe an attitude of mind towards some proposition of whose truth we arenot certain. The proposition of interest is usually of the form "Will a specific event occur?" The attitude of mind is of the form "How certain are we that the event will occur?" The...
of impacting
Impact event
An impact event is the collision of a large meteorite, asteroid, comet, or other celestial object with the Earth or another planet. Throughout recorded history, hundreds of minor impact events have been reported, with some occurrences causing deaths, injuries, property damage or other significant...
Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
(between 0 and 0.33%). It has the highest Palermo rating
Palermo Technical Impact Hazard Scale
The Palermo Technical Impact Hazard Scale is a logarithmic scale used by astronomers to rate the potential hazard of impact of a near-earth object . It combines two types of data—probability of impact, and estimated kinetic yield—into a single "hazard" value...
with a value of 0.17 for a possible collision in the year 2880. For a brief period in late December 2004, asteroid 99942 Apophis
99942 Apophis
99942 Apophis is a near-Earth asteroid that caused a brief period of concern in December 2004 because initial observations indicated a small probability that it would strike the Earth in 2029. Additional observations provided improved predictions that eliminated the possibility of an impact on...
held the record for Palermo scale values, with a value of 1.10.
Discovery and name
1950 DA was first discovered on February 23, 1950, by Carl A. WirtanenCarl A. Wirtanen
Carl Alvar Wirtanen was an American astronomer who worked at Lick Observatory.He discovered periodic comet 46P/Wirtanen, as well as eight asteroids, including notably the Apollo asteroid 1950 DA, which may have a non-negligible probability of impacting the earth in the year 2880...
at Lick Observatory
Lick Observatory
The Lick Observatory is an astronomical observatory, owned and operated by the University of California. It is situated on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, USA...
. It was observed for seventeen days and then lost because of the short observation arc resulting in large uncertainties in Wirtanen's orbital solution. On 31 December 2000, it was recovered as and 2 hours later was recognized as 1950 DA.
Observations
On March 5th, 2001, 1950 DA made a close approach to the Earth of 0.0520726 AU. It was studied by radar at the Goldstone and AreciboArecibo Observatory
The Arecibo Observatory is a radio telescope near the city of Arecibo in Puerto Rico. It is operated by SRI International under cooperative agreement with the National Science Foundation...
observatories from March 3 to 7 2001.
Petr Pravec
Petr Pravec is a Czech astronomer, born in Třinec, a prolific discoverer of binary asteroids using lightcurve photometric studies. He is leading the effort of a large consortium of stations called BinAst to look for multiplicity in the NEA and inner main-belt populations...
shows that its rotation period is 2.1216 ± 0.0001 hours. Due to its short rotation period and high radar albedo
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
, 1950 DA is thought to be fairly dense (more than 3 g/cm³) and likely composed of nickel-iron.
Possible Earth impact
That 1950 DA has one of the best-determined asteroid orbital solutions is due to a combination of:- an orbit moderately inclined (12 degrees) to the ecliptic plane (reducing in-plane perturbationsPerturbation (astronomy)Perturbation is a term used in astronomy in connection with descriptions of the complex motion of a massive body which is subject to appreciable gravitational effects from more than one other massive body....
) - high-precession radar astrometry that is more accurate the visual measurements
- a 60 year observation arc
- an uncertainty region controlled by resonanceOrbital resonanceIn celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers. Orbital resonances greatly enhance the mutual gravitational influence of...
The next radar opportunity for 1950 DA is in 2032.
If 1950 DA continues on its present orbit, it will approach near to the Earth on March 16, 2880. However, over the intervening time, its rotation will cause its orbit to slighlty change as a result of the Yarkovsky effect
Yarkovsky effect
The Yarkovsky effect is a force acting on a rotating body in space caused by the anisotropic emission of thermal photons, which carry momentum...
. Available radar and optical data suggest two possible pole directions; one trajectory misses the Earth by tens of millions of kilometers, while the other has an impact probability of roughly 1 in 300.
The energy released by a collision with an object the size of 1950 DA would cause major effects on the climate
Climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
and biosphere
Biosphere
The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth, a closed and self-regulating system...
which would be devastating to human
Human
Humans are the only living species in the Homo genus...
civilization
Civilization
Civilization is a sometimes controversial term that has been used in several related ways. Primarily, the term has been used to refer to the material and instrumental side of human cultures that are complex in terms of technology, science, and division of labor. Such civilizations are generally...
. The discovery of the potential impact has heightened interest in asteroid deflection strategies
Asteroid deflection strategies
Asteroid mitigation strategies are "planetary defense" methods by which near-Earth objects could be diverted, preventing potentially catastrophic impact events. A sufficiently large impact would cause massive tsunamis or an impact winter, or both...
.
External links
- Orbital simulation from JPL (Java) / Ephemeris