ASTEROID SIZE-FREQUENCY DISTRIBUTION openParPART 2closePar

> this proposal requests an upgrade from priority 3 for etedesco.astsfdis the first two paragraphs below are an updated version of the abstract from the original proposal. the sizefrequency distribution of asteroids with diameters < 10 km is essentially unknown. we propose to use isocam (lw10, cam01) in microscanning mode to test current predictions of the number of asteroids per square degree down to sizes below 1 km. our objective is to measure the number of asteroids per unit area of sky observed as a function of ir brightness. (a 1 km mainbelt asteroid has a flux density at 12 microns of about 1 mjy.) from these data we will be able to constrain, and perhaps decide among, current estimates for the numbers of asteroids with diameters greater than 1 km. these estimates differ by up to a factor of six. any region of sky along the ecliptic is suitable for this purpose and two such regions were identified during the previous phase 2. each of the selected target regions contain no infrared sources from any of the iras catalogs, including extra galactic, or fss sources. in addition to the solar system science resulting from this study, we will provide data useful for assessing the contamination rate from asteroids in all isocam observations. we will also obtain data from which the brightness and smallscale structure of the zodiacal background can be determined. the additional images obtained by the proposed upgrade improve statistics and probe deeper into the stellar pointsource and zodiacal backgrounds. this facilitates identification of asteroids. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]