To stimulate new technologies NASA has initiated a series of missions under the New Millennium Program including Deep Space 2 (DS-2), a novel low cost microprobe for Mars. Due to DS2’s entry scenario the instruments on board are expected to experience ∼1000,000g decelerations. A pressure sensor is needed which will not suffer offset or sensitivity errors due to the violent nature of the deployment, and will fit in a 5cm × 2cm × 0.5cm -50 gram budget. The small daily changes in Martian atmospheric pressure (∼1mB) must also be measured in the presence of large daily temperature fluctuations (∼50K). Space-rated pressure sensors meeting these requirements are not available, and off the shelf piezoresistive pressure sensors are not accurate enough for such applications. This work shows that many of the performance limitations of piezoresistive sensors are not fundamental, but instead are associated with package-induced stress or poor temperature compensation. Further, modest effort in packaging and calibration can bring the performance of inexpensive piezoresistive sensors into the range of more expensive absolute pressure sensors.