A novel design for an in situ atmospheric sensor for CO2 and trace gases is proposed. The sensor, named AirCore, provides the advantages of existing in situ sensors (e.g. high resolution) but eliminates possible biases in analysis that often originate from imperfect measurement condition. The AirCore provides a significant savings in cost and weight while increasing the capabilities of existing in situ sensors. The AirCore system consists of the AirCore gas sampler and the support system to accomplish its high altitude (nominally 70,000 ft.) mission. This support system includes the sensor launch and recovery components. The AirCore can be launched and recovered by a crew of two which reduces the operational cost of the system.