Satellite AEPEX (Atmospheric Effects of Precipitation through Energetic X-rays)
Type CubeSat
Units or mass 6U
Status not launched, expected in 2024
Launcher Firefly Alpha, (ELaNa 52)
Entity name University of Colorado Boulder
Institution University
Entity type Academic / Education
Headquarters US
Partners Smead Aerospace

Investigate electrons that fall into Earth’s atmosphere from the Van Allen radiation belts. Image the Earth's upper atmosphere in X-rays


Investigate electrons that fall into Earth’s atmosphere from the Van Allen radiation belts. These electrons interact with the atmosphere and have major implications for the atmospheric ozone balance.

Scientific investigation mission that aims to better understand the influence of the magnetosphere on the Earth’s upper atmosphere through energetic particle precipitation (EPP).

One of the key uncertainties in reaching closure on how EPP impacts the atmosphere is the lack of knowledge regarding how much energy is put into the atmosphere via EPP. To address this uncertainty, the primary objective of AEPEX is to quantify the energy deposition to the atmosphere from energetic particles that precipitate from the radiation belts and other sources.

AEPEX will image the Earth's upper atmosphere in X-rays from low-Earth orbit, nominally 500 km altitude to ensure a reasonable field-of-view. A high inclination is required to ensure coverage of the radiation belts; a polar orbit (90-degree inclination) is preferred, so that through orbit precession, varying magnetic local times (MLT) are sampled over the duration of the mission. The LASP ground station in Boulder will be used for both UHF and S-band communications.

Primary mission objectives:

  1. Measure the X-ray flux emitted by the atmosphere and the precipitating electron distribution, and use these measurements to determine the precipitating flux and energy deposition.
  2. Image the X-ray emitting region to measure the spatial extent of precipitation events. Due to AEPEX’s nature as an education and research mission, much of the research work is done by undergraduate and graduate students. This work is invaluable to students as they learn and become well versed in space science. In working on the project, these students become knowledgeable and appreciative of the amateur radio art and go on to form the next generation of radio amateurs. AEPEX also specifically studies the space weather environment and X-ray impacts on the lower ionosphere, which plays an important role in how HF waves propagate and affect the space environment. 

As of June 2023, all of the AEPEX subsystems, electronics boards, structure components, and instrument components are complete, fully tested, and flight-ready. The AFIRE instrument has been delivered for integration; the AXIS instrument will be completed and ready for integration in July 2023. Integration has begun, and all spacecraft subsystems are completed and integrated, along with flight software. Solar panels are near completion and will be ready for integration in July. Environmental testing is expected to begin in August 2023, including end-to-end tests, comprehensive performance tests, integrated instrument performance characterization, deployment testing, thermal vacuum testing, and spacecraft vibration testing. Following testing, the full system is expected to be ready for delivery to the launch services provider in October 2023.

Sources [1] [2] [3] [4] [5]
Photo sources [1] [2]
COTS subsystems
  • BATTERY - Space Inventor BAT-P3
  • ADCS - Blue Canyon XACT
  • TRANSCEIVER - Space Quest TRX-U
  • ANTENNA - Clyde Space S-band
Subsystems sources [1]

Last modified: 2023-12-18

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