238P/Read (P/2005 U1) is a main-belt comet discovered on 24 October 2005 by astronomer Michael T. Read using the Spacewatch 36-inch telescope on Kitt Peak National Observatory. It has an orbit within the asteroid belt and has displayed the coma of a traditional comet. It fits the definition of an Encke-type comet with (TJupiter > 3; a < aJupiter).
|Discovered by||Michael T. Read|
|Discovery date||24 October 2005|
|Main-belt comet |
Encke-type comet 
|Epoch 7 January 2006|
|Uncertainty parameter 1|
|Aphelion||3.9645 AU (Q)|
|Perihelion||2.3647 AU (q)|
|3.1646 AU (a)|
|0.6 km (approx.)|
|1.0 g/cm3 (assumed)|
|19.62 to 23.41|
Before it was discovered 238P came to perihelion on 2005 July 27. When it was discovered on 2005 October 24, it showed vigorous cometary activity until 2005 December 27. Outgassing likely began at least 2 months before discovery. The activity of 238P is much stronger than 133P/Elst-Pizarro and 176P/LINEAR. This may indicate that the impact assumed to have triggered 238P's activity occurred very recently.
238P/Read was the target of a mission proposal in NASA's Discovery Program in the 2010s called Proteus, however it was not selected for further development. Discovery program's founding mission was to an asteroid, but it went to a Near-Earth asteroid. A mission to a main-belt asteroid was proposed in the 1990s (also see Deep Impact (spacecraft)).
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