Surface Ice
On October 7, 2009, the presence of water ice was confirmed on the surface of this asteroid using NASA’s Infrared Telescope Facility. The surface of the asteroid appears completely covered in ice. As this ice layer is sublimated, it may be getting replenished by a reservoir of ice under the surface. Organic compounds were also detected on the surface.
Scientists hypothesize that some of the first water brought to Earth was delivered by asteroid impacts after the collision that produced the Moon. The presence of ice on 24 Themis supports this theory. Because of its proximity to the sun (~3.2 AU), the widespread ice on the surface of 24 Themis is somewhat unexpected. The surface ice may be replenished by a sub-surface reservoir of water or impact gardening—a lunar phenomenon in which the moon overturns surface material at a rate of 1 m/ Gyr.
An alternative mechanism to explain the presence of water ice on 24 Themis is similar to the hypothesized formation of water on the surface of the Moon by solar wind. Trace amounts of water would be continuously produced by high-energy solar protons impinging oxide minerals present at the surface of the asteroid. The hydroxyl surface groups (S–OH) formed by the collision of protons (H+) with oxygen atoms present at oxide surface (S=O) can further be converted in water molecules (H2O) adsorbed onto the oxide minerals surface. The chemical rearrangement supposed at the oxide surface could be schematically written as follows:
- 2 S-OH → S=O + S + H2O
or,
- 2 S-OH → S–O–S + H2O
where S represents the oxide surface.
Read more about this topic: 24 Themis
Famous quotes containing the words surface and/or ice:
“All forms of beauty, like all possible phenomena, contain an element of the eternal and an element of the transitory—of the absolute and of the particular. Absolute and eternal beauty does not exist, or rather it is only an abstraction creamed from the general surface of different beauties. The particular element in each manifestation comes from the emotions: and just as we have our own particular emotions, so we have our own beauty.”
—Charles Baudelaire (1821–1867)
“I also heard the whooping of the ice in the pond, my great bed-fellow in that part of Concord, as if it were restless in its bed and would fain turn over, were troubled with flatulency and bad dreams; or I was waked by the cracking of the ground by the frost, as if some one had driven a team against my door, and in the morning would find a crack in the earth a quarter of a mile long and a third of an inch wide.”
—Henry David Thoreau (1817–1862)