One of the challenges facing missions to other planetary bodies including Earth's Moon, Mars, Venus, Titan, Europa; and proximity operations (including sampling and landing) on small bodies such as asteroids and comets' is the ability to provide accurate altimetry for descent, then assess safe landing sites by surveying the landscape. To address NASA's need for space-hardened planetary entry, descent, and landing (EDL) and proximity-operations sensors, a low-cost, high-pixel-density avalanche photodiode detector array technology will be developed that is sensitive in the 0.9-μm to 1.7-μm spectral range and when operated at room temperature, can achieve nearly noiseless avalanche gain, allowing for near-single-photon sensitivity. In Phase I, a series of detector structures will be grown, fabricated, and tested. The performance of the detectors will be used to predict performance of the arrays when coupled to low-noise readout integrated circuits. Single element devices coupled to low-noise amplifiers will be used to validate the predictive models.