The GRBAlpha mission is a 1U Cubesat proof-of-concept mission for a small gamma-ray burst detector. It was launched on March 22, 2021 on a Russian Soyuz 2-1a Fregat rocket from the Baikonur Cosmodrome. The satellite weighs roughly 1 kg and is 10 x 10 x 11 cm in overall size. Original plans called for a one year operational lifespan, but the satellite remains operational to date (Oct 2024). GRBAlpha is an international collabration between various research institutions, including the Konkoly Observatory (Hungary), Technical University of Košice (Slovakia), Masaryk University (Czech Republic), and Hiroshima University (Japan). Primary funding was provided by the Hungarian Academy of Sciences.

It is a proving ground for the future “Cubesats Applied for Measuring and Localising Transients” (CAMELOT), a planned constellation of 3U Cubesats to provide continuous all-sky coverage and accurate localization. GRBAlpha carries a 1/8 effective area sized version of the detectors intended for CAMELOT: sufficient to demonstrate the mission concept and intercalibrate observed light curves with existing operational GRB missions.

Initial settings onboard used a relatively long four second binning, making the instrument undersensitive to short GRB events, but one second binning and independent triggering is in an experimental phase. The small detector size means that GRBAlpha does not saturate on the very brightest events, such as GRB221009A, the brightest GRB observed to date, which overwhelmed many other GRB detectors in orbit at the time. The average observational rate to date is roughly one GRB or other transient high-energy event every five days.

Mission Characteristics

Lifetime

Energy Range : 30–900 keV (lower limit degraded to aprx 60 keV after two years)

Special Features : 1U Cubesat configuration for ridesharing launch.
1/8th effective area design to prove CAMELOT mission concept.
Smallest space-based operational observatory to date.

Payload :

• Gamma-ray Detector. A single CsI(Tl) crystal measuring 75 x 75 x 5 mm. The scintillation is observed by low voltage lightweight silicon photomultipliers.

Science Highlights:

• Charactization of peak intensity and time of bright burst events;
• Prove operational concept of future CAMELOT satellite constellation;
• Co-observe with gravitational wave detectors and other observatories as part of multimessenger astronomy.