VERITAS: A Mission Concept for the High Resolution Topographic Mapping and Imaging of Venus

Magellan, a NASA mission to Venus in the early 1990's, mapped nearly the entire surface of Venus with an S-band (12 cm) synthetic aperture radar and microwave radiometer and made radar altimeter measurements of the topography. These measurements revolutionized our understanding of the geomorphology, geology and geophysical processes that have shaped the evolution of the surface of Venus. The Magellan spacecraft had an elliptical orbit with an apoapsis of approximately 8000 km and a periapsis of 257 km and an orbital inclination of 86°. In this way the radar was able to collect long strips of data approximately 10000 km in length running north to south with altitudes varying from 3000 km to 257 km. During the remainder of the orbit the collected data was down linked to earth. The SAR mode operated in burst mode fashion whereby it transmitted a small string of pulses up to a couple of hundred pulses in length followed by a quiescent period when the radar ceased transmission and allowed interleaved operation of the altimeter and radiometer modes. This mode of operation allowed for a significant reduction in downlinked SAR imaging data at the expense of azimuth (i.e. along-track) resolution. However, the lack of finer resolution imagery and topography of the surface than that obtained by the Magellan mission has hampered the definitive answer to key questions concerning the processes and evolution of the surface of Venus. The Venus Emissivity, Radio Science, InSAR Topography And Spectroscopy (VERITAS) Mission is a proposed mission to Venus designed to obtain high resolution imagery and topography of the surface using an X-band radar configured as a single pass radar interferometer coupled with a multispectral NIR emissivity mapping capability. VERITAS would map surface topography with a spatial resolution of 250 m and 5 m vertical accuracy and generate radar imagery with 30 m spatial resolution. These capabilities represent an order of magnitude or better improvement of the Magellan system and are expected to reveal definitive information on processes not possible with the Magellan data. The combination of surface topography and image data provide unprecedented knowledge of Venus' tectonic and impact history, the timing and mechanisms of volcanic resurfacing, and the mantle processes responsible for them. The combination of instruments on VERITAS, and in particular the InSAR instrument, is designed to address a series of focused hypothesis driven questions left unresolved by the Magellan mission for example: 1) Is there evidence for a past tectonic or cratered surface beneath the plains? and 2) How and when did Venus resurface? This talk will present an overview of the proposed VERITAS mission, the radar instrument design and trade options and the projected performance as well as a brief overview of some of the major science objectives. This research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.