High resolution data acquisition is the essential part of instrumentation used in space missions such as imagers, mass spectrometers, and magnetometers. An integrated solution for data acquisition facilitates spacecraft telemetry and is well suited for applications such as Integrated Vehicle Health Management (IVHM) used in Reusable Launch Vehicles (RLVs). This paper summarizes the design of a very high resolution 20-bit 1ksps sigma-delta Analog-to-Digital-Converter (ADC). Novel circuit design techniques are used so that the performance is maintained across a wide range of temperature (more than 300°C variation in temperature). The design of the essential building blocks is verified using the new PSP compact models of CMOS for low temperature developed at Arizona State University. The sigma-delta modulator consumes 1.5 mW from a 2.6V supply while provides 20 bits of resolution for a 1ksps signal. The figure-of-merit of 0.8pJ/conversion is competitive with the state-of-the-art design which only supports the military temperature-range.