The expected intensity of infrared emission versus wavelength at various radial distances from the Sun. The cosmic infrared background was measured at 3 and >100 microns by the COBE satellite, but measurements from 5 to 100 microns were obscured by the zodiacal light. The blue curves are the emission from the zodiacal dust; the level at 5 AU is from a model. The cosmic infrared background may be detectable by Interstellar Probe beyond ~10 AU as the zodiacal dust decreases. The sensitivity goal for a suitable infrared detector is indicated (dotted gray line). The emission from the interstellar medium (red) was determined from COBE measurements.

The Cosmic Background Explorer (COBE) satellite detected the cosmic infrared background at wavelengths beyond 140 microns and established limits on the energy released by all stars since the beginning of time. COBE results at shorter wavelengths were obscured by the very bright foreground emission from zodiacal light. However, the zodiacal dust density decreases with radius and it is expected that beyond ~10 AU Interstellar Probe may be able to detect the cosmic infrared background at wavelengths below 140 microns as the signal from the zodiacal light decreases.