  We investigate the stability of magnetically trapped atomic Bose-Einstein
condensates and thermal clouds near the transition temperature at small
distances 0.5 microns < d < 10 microns from a microfabricated silicon chip. For
a 2 microns thick copper film the trap lifetime is limited by Johnson-noise
induced currents and falls below 1 s at a distance of 4 microns. A dielectric
surface does not adversely affect the sample until the attractive
Casimir-Polder potential significantly reduces the trap depth.
