Long Duration Stratospheric Systems

Technical Summary of the Flight System

StratoCruiser Propulsion Module offers unprecedented mobility and measurement capability combining the persistence of balloon platforms for greatly extended observing times, station keeping over the central U.S. in July and August, and recovery of the experiment following the system deployment.

The StratoCruiser design includes onboard solar power and battery systems, propulsion consists of dual electric motors and high-altitude propellers sized for cruise at 5m/s and sprint at 8 m/s at 65,000 ft. The motors are each sized to provide the full thrust required for redundancy and flexibility when steering with differential thrust. The baseline motor is a Motenergy ME1114 rated to 10 kW continuous power and weighing 16 kg each. At 5 m/s cruise, the motors each consume about 1.2 kW electric power. At 8 m/s sprint, required motor power is 4.2 kW each.

The solar power system was designed to allow the vehicle to operate for the 6-week mission at latitudes up to 49N. It consists of 20% efficiency solar cells mounted on 50m² hinged arrays. These 10 kW peak arrays are sized to provide an average of 7kW through the day at latitudes up to 49N when angled to maximize collection. The 50m² array is broken down into 2.5x5m sections to enable easy transportation and integration at the launch site. The battery system is based on 140 W-hr/kg lithium-polymer batteries. It is sized for a 80% depth of discharge to enable the batteries to last through a multi-year science campaign. Total battery storage is 25 kW-hr weighing 185 kg. An additional 50 kg includes cabling, power regulators and controllers.

The StratoCruiser super pressure pumpkin balloon is designed to fly at a constant 65000 ft altitude with 1600 kg suspended mass, under conditions that range from hot southwestern United States to cold storms in the daytime. It does so by being pressurized to 1200 Pascals above ambient under normal environmental conditions with a maximum 1400 Pascal limit for the hot thermal cases. This limit places the film stresses and tendon load in the typical range for the larger pumpkin balloons, giving the 1200 Pascal normal operation an extra level of structural margin for ASC⁵ENA.

Protocol for NASA Balloon Operations has been fully vetted with the direct involvement of NASA Goddard Space Flight Center, Wallops Island Flight Facility and the Columbia Scientific Balloon Facility. The flight operations protocol will be initiated at launch of the StratoCruiser system from Fort Sumner, NM. The balloon ascent will be under the control of the CSBF and the link between the CSBF operations control center and the The Integrated Forecasting, Navigation and Science Control Center SCC will commence when CSBF has verified that the balloon system is functioning normally.