SNR, which increases as the square root of the number of dates, is comparable to the number of pixels that images can place on a target.
Click here for plots of predictions of single-date SNR as a function of asteroid size, distance, and declination, for Arecibo and Goldstone.
These calculations assume a radar cross section equal to 10% of the target cross section, a four-hour rotation period, a diffuse scattering law, and an equatorial view. SNR equals the received power of an optimally filtered echo in units of the r.m.s. receiver noise fluctuation.
|Average Number of Objects per Year with Single-Date SNR Greater than|
|Before upgrade, using actual statistics since 1980||3||0.9||0.3||0.1|
|After upgrade, with current NEA pool||10||6||2||0.6|
|After Spaceguard Survey (lower bounds):|
|1 km or larger||80||20||10||4|
|300 m or larger||160||80||20||7|
|~30-parameter shape model:|||-->|
|identify binary system:|||--->|
|~100-parameter shape model:|||--->|
|see craters clearly:|||--->|