HIGHPER (High-altitude Propeller Evaluation Research)

HIGHPER is the acronym for High-altitude Propeller Evaluation Research. The purpose of this experiment by JAXA was to conduct high-altitude testing of a propeller designed for the latest design iteration of the Mars Airplane Balloon Experiment (MABE) a probe designed to conduct extensive exploration near the Martian surface using the planet's thin atmosphere. Electric propellers are especially suitable for long-term missions, as they do not require fuel. Developing a propeller-driven Mars exploration aircraft requires the design and creation of highly aerodynamic propellers and the development of a system that can operate in low-pressure/low-temperature environments.

With these requirements in mind, HIGHPER performed a high-altitude propeller test using a small rubber balloon with the goal of measuring the propeller performance in a Mars-simulated environment and establish design guidelines, as well as identify necessary development components for mounting a propeller on a Mars exploration aircraft.

The system consists of a gondola in the form of a rectangular box weighing approximately 2 kg equipped with a single propeller on its side, measuring 300 mm in diameter with two blades. The motor and thrust detection unit are covered by a wind shield in the shape of a square pyramid. After leaving the ground, the gondola ascends, and the propeller is rotated at specified speeds at various altitudes to measure its performance. Measurements include thrust, torque, propeller rotation speed, atmospheric pressure, atmospheric temperature, and the gondola's orientation. Commands to turn the propeller on and off are sent via a LoRa transceiver, and various data are downlinked through a radio transmitter provided by the JAXA balloon group. After reaching the target altitude, the gondola is released from the balloon and gently descends to the ocean surface, ending the experiment.

Balloon launched on: 8/21/2024 at 5:00 JST
Launch site: Multipurpose Aviation Research Field, Taiki-Cho, Hokkaido, Japan  
Balloon launched by: Institute of Space and Astronautical Science (ISAS) / Japan Aerospace Exploration Agency (JAXA)
Balloon manufacturer/size/composition: Weather Balloon  
Flight identification number: BS24-04
End of flight (L for landing time, W for last contact, otherwise termination time): 8/21/2024 at ~ 7:00 jst
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): ~ 2 h
Landing site: In the Pacific Ocean, 96 km SSE of Taiki, Japan

The rubber balloon of 11 meters of diameter was launched as mission BS24-04 from Taiki Aerospace Research Field at 5:00 jst (Japan Standard Time) on August 21th, 2024. After a nominal ascent at 380 meters per minute, it reached a maximum altitude of 23 km on the Pacific Ocean about 65 km SSE of Taiki. The total climb time was of one hour. Once the balloon reached that altitude the payload was jettisoned and slowly descended to the Pacific Ocean about 96 km SSE of Taiki.

• High-altitude testing of Mars aircraft propellers using a rubber balloon (in Japanese) Scientific Balloon Symposium 2023
• News of the launch (in Japanese) JAXA website