Is it possible for an amateur astronomer to assist with detecting near-Earth asteroids or comets? If so, what would be the minimum telescopic aperture and type of photographic equipment required to conduct this kind of research?
Amateur astronomers can and do play an important part in detecting near-Earth objects. Today more than 5% of all near-Earth objects are discovered by amateurs and this proportion is on the increase. The Minor Planets Centre (http://www.minorplanetcenter.net/) based at Harvard University is the organisation responsible for cataloguing and archiving all discoveries of small bodies in the solar system and have a wealth of information to help potential amateur astronomers. The professional search programs typically use telescopes with a diameter of ~1m; LINEAR, one of the longest running and most successful programs currently has two 1m telescopes and a 0.5m telescope. When conducting searches smaller telescopes are to some extent preferred since they have a larger field of view and can image a larger area of the sky at once.
When you have your telescope, discovering asteroids is still not trivial! Because these objects are particularly faint (due to their size), the detectors being used (usually a CCD) need to be sensitive enough to be able to distinguish them from the background noise from the device. For CCDs, when they are cooled the background noise is reduced and because of this, most of the CCD detectors you can purchase for amateur astronomy today use fans to cool the CCD well below the ambient temperature.
Even with both of these, the main requirement to successfully discover asteroids and other small (and faint) objects is a dark site with good seeing (clear, still skies). Combining all of these things together means you could potentially discover some new asteroids!