The first manned superpressure balloon has been developed to provide a means for accurately following a parcel of air, making physical and chemical measurements en route. The use of new high strength fabrics allows the construction of a balloon that contains its lifting gas (helium) under pressure, thereby providing long term flight stability unachieved by any other method. Three flights, each in excess of 30 hours duration, have already been achieved, demonstrating the ability of such vehicles to remain stably in a parcel of air without perturbing air chemistry in any way. Such a platform will allow the precise determination of air trajectories over many hundreds of miles. The use of trained observers on board will facilitate the collection of atmospheric data: ozone, NO*, SO2, temperature gradients, turbulence, and other.