Major space-based observatories are imperative in astronomy, but they take a long time to plan, build, and launch — and they aren’t cheap. A new study examines an interesting compromise: a low-cost, space-based gamma-ray detector that we could use while we wait for the next big observatory to launch.

Coverage and sensitivity of past and future missions for the X-ray to gamma-ray energy range (click for a better look!). The only past mission to explore the 1 MeV region was COMPTEL, on board CGRO. e-ASTROGAM is a proposed future space mission that would explore this range. [Lucchetta et al. 2017]
A Gap in Coverage
In the last few decades, we’ve significantly expanded our X-ray and gamma-ray view of the sky. One part of the electromagnetic spectrum remains poorly explored, however: the approximate transition point between X-rays and gamma rays near 1 MeV.
Space-based gamma-ray telescopes have been proposed for the future to better explore this energy range. But these major observatories have costs of around half a billion Euros and will take roughly a decade to build and launch. Is there a way to get eyes on this energy range sooner?
Scaling Down with CubeSat
A team of scientists led by Giulio Lucchetta (University of Padova and INFN Padova, Italy) has proposed an intriguing solution for the more immediate future: a nano-satellite telescope based on the CubeSat standard.
A CubeSat is a miniaturized satellite design that can be easily deployed in space, either from the International Space Station or by hitching a ride as a secondary payload on a large rocket. The size of a CubeSat is a standardized unit of measurement: a single CubeSat unit, or 1U, is a mere 10x10x10 cm and a maximum of 1.33 kg in weight.The gamma-ray telescope proposed by Lucchetta and collaborators would use a 2U standard for the instrument, so the instrument would be only 10x10x20 cm in size! The design for the telescope as a whole — including the on-board electronics and flight system — would likely require a 4U model.
The team’s proposed nanoscale observatory would be capable of detecting gamma rays from 100 keV up to a few MeV. In comparison to the major space-based observatories, this project would be very low-cost, at only half a million Euros — and such a telescope could go from build to launch in about a year.
Evaluating Performance

Estimated sensitivity of the proposed nanoscale satellite telescope (for tracked, untracked, and pair production events) compared to that of COMPTEL. [Lucchetta et al. 2017]
It seems that a nanoscale satellite like this one would helpfully cover the gap around 1 MeV and allow us to learn more about low-energy gamma rays while we wait for large future missions to launch. As an additional benefit, such a project could serve as a pathfinder mission to test technologies and algorithms to be used in larger missions in the future.
Citation
Giulio Lucchetta et al 2017 AJ 153 237. doi:10.3847/1538-3881/aa6a1b