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A Note on the Influx of Extraterrestrial Dust as an Energy Source in the E Region
Author(s) -
Fiocco Giorgio
Publication year - 1966
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1002/rds196612252
Subject(s) - ionization , atmosphere (unit) , extraterrestrial life , physics , environmental science , atmospheric sciences , geology , ion , meteorology , astronomy , quantum mechanics
Some connection between sporadic E layer irregularities and incoming extraterrestrial dust at heights of llO km and above has been indicated by the comparison of optical radar and ionosonde data [Fiocco, 1965]. The object of this note is primarily to point out the possible importance of the influx of extraterrestrial dust to the energy balance of the E region. Much independent evidence suggests that the average influx rate on earth of small particles of extraterrestrial origin, ranging in diameter from 0.1 µ to 100 µ, is of the order of 10 4 tons/day and that peaks of the order of 10 5 tons/day or even 10 6 tons/day may be possible. If these estimates are correct, and since the particles enter the earth's atmosphere at speeds of the order of 10 km/s, their influx may represent an average energy input for a vertical column in the E region of the order of 10 −2 erg/cm 2 sec and as high as 1 erg/cm 2 sec. If it were possible to fully convert this energy into ionization, for a column of 10‐km length and a recombination coefficient α = 10 −8 cm 3 sec −1 , electron densities of the order of 10 5 cm −3 and higher would be achieved, which are in excess of what is needed in a sporadic E layer. While this process may therefore in some cases supply the background ionization necessary for the formation of the layer, and other processes may be operative in organizing the distribution of charge in space, it is possible that the way by which the dust particles dissipate their energy may, by itself, directly lead to the formation of a layer. The energy of small particles characterized by a constant area‐over‐mass ratio would be dissipated in a height interval of a few tens of kilometers, the length of the interval depending upon size and angle of incidence. However, fragmentation in flight of the micrometeoroids due to mechanical, thermal, and electric effects [Fiocco and Colombo, l964] may cause the dissipation to take place in a much shorter interval of altitudes, possibly less than a scale height.