252 Encyclopedia of the Solar System
TABLE 1 Numbers of Classified Non-Antarctic Meteorite Falls and Finds, Including Those from
Hot and Cold Deserts.
Meteorite Fallsa Findsa,b ANSMETc Meteorite Fallsa Findsa,b ANSMETcChondrites 797 > 814 2925 (11557) Achondrites 81 > 73 184
CI1 5 0(2) 0(0) Acapulcoites 1 1 5(12)
CM/C2 17 6(85) 51(200) Lodranites 1 0 }(14) 4(4)
C other 18 14(225) 58(182) Winonaites 0 3(10) 1(1)
E 17 8(307) 43(103) Angrites 1 1(3) 2(2)
H 316 405 1048 (4194) Aubrites 9 3(2) 7(38)
L 350 350 1140 (4562) Howardites 20 4(58) 26(44)
LL 72 30 574 (2299) Eucrites 29 12(137) 66(124)
Other 2 1(34) 11(17) Diogenites 11 0(81) 22(24)
Ureilites 5 3(90) 34(47)
Irons 40 >690(34) 47 ( 97 ) Lunar 0 1(22) 8(15)
Martian 4 3(17) 8(8)
Stony-Irons 12 > 61 13 Other 0 3(9) 1(4)
Mesosiderites 7 21(10) 11(29)
Pallasites 5 40(4) 2(11)aData from Grady (2000) updated to Nov. 2004 (J. N. Grossman, USGS, personal communication). These do not include 41 unclassified stony or 8
unclassified iron meteorites.
bExcept for Lunar and Martian meteorites, numbers in parentheses indicate fragments (uncorrected for pairing) recovered as meteorite clusters fromhot and
cold deserts (ANSMET data not included): These are not combined with corresponding non-desert-cluster finds (Grady, 2000; Grossman, personal
communication). The∼16,500 JARE samples are incompletely classified and, except for lunar and martian meteorites, are not included in this table:
Ordinary chondrites from hot and other cold deserts (other than ANSMET) are also omitted Because of their special importance, numbers of lunar and
martian meteorites (cf. http://epsc.wustl.edu/admin/resources/ meteorites/moonmeteorites.html and http://curator.jsc.nasa.gov/curator/antmet/
marsmets/contents.htm, respectively) in parentheses are the meteorite falls corrected for pairing.
cAntarctic Search for Meteorites (ANSMET) recoveries from West Antarctica. Numbers in parentheses are fragments recovered: Associated numbers are
corrected for known pairings or by estimating (italics) four fragments per fall. (Data from K. Righter, NASA—JSC.)Despite this history, and direct evidence for meteorite
falls, scientists generally began to accept them as genuine
samples of other planetary bodies only at the beginning of
the 19th century. Earlier, acceptance of meteorites as being
extraterrestrial and, thus, of great scientific interest, was
spotty. One might laboriously assemble a meteorite col-
lection only to have someone later dispose of this invalu-
able material. This occurred, for example, when the noted
mineralogist, Ignaz Edler von Born, discarded the imperial
collection in Vienna as “useless rubbish” in the latter part
of the 18th century. With the recognition that meteorites
sample extraterrestrial planetary bodies, collections of them
proved particularly important. In 1943, with the imminent
invasion of Germany, the Russian government planned for
“trophy brigades” to accompany their armies and collect
artistic, scientific, and production materials as restitution for
Russian property seized or destroyed by Nazi armies during
their occupation of parts of Russia. Meteorites that fell in
Russia, fragments of which were acquired by and housed in
German collections, were explicitly identified as material to
be seized. In late 2004, the price for a meteorite from Mars
was at least $4000/g (the current price of gold is $14/g).
Apart from its recovery and preservation, Ensisheim is
a typical fall. For finds, some peculiarity must promote
recognition—hence, the high proportion of high-density,
iron meteorites outside of Antarctica (Table 1). Observed
falls are taken to best approximate the contemporary popu-
lation of near-Earth meteoroids. Of course, bias may affect
the fall population. Some data suggest that highly friable
meteoroids are largely or totally disaggregated during at-
mospheric passage.
The initial entry velocities of meteorites range from 11 to
70 km/s, average 15 km/s, and cause surface material to
melt and ablate by frictional heating during atmospheric
passage. Heat generation and ablation rates are rapid and
nearly equivalent, so detectable heat effects only affect a
few millimeters below the surface: The meteorite’s inte-
rior is preserved in its cool, preterrestrial state. Ablation
and fragmentation—causing substantial (∼90%) mass loss
and deceleration, often to terminal velocity—leave a dark
brown-to-black, sculpted fusion crust as the surface, diag-
nostic of a meteorite on Earth (Fig. 1a). If it is appropri-
ately shaped perhaps by ablation, a meteoroid may assume
a quasi-stable orientation late in its atmospheric traversal.
In this case, material ablated from the front can redeposit as
delicate droplets or streamlets on its sides and rear (Fig. 1b).
The delicate droplets on Lafayette’s fusion crust would have
been erased in a few days’ weathering: It must have been re-
covered almost immediately after it fell. Yet, when Lafayette
was recognized as meteoritic during a 1931 visit to Purdue