# Distributed Architectures and Constellations for \(\gamma\)-ray Burst Science
## 4 The Role of Distributed Architectures in Tomorrow's Multi-Messenger Astrophysics
### A Powerful Combination of Nano- and Micro-/Small Satellites
The equatorial ejecta are expected to be rich in heavier elements, known as lantanides, and produce long-lasting infrared emission. UV and blue emissions are produced early in the kilonova and last for only about a day. This may arise from free neutrons or from lantanide-poor polar ejecta with a higher electron fraction. While the properties of the tidal ejecta are sensitive to the mass ratio of the neutron stars, the properties of the polar and wind ejecta are sensitive to the neutron star radii and to the nature of the merger product. The different ratios between the observed kilonova fluxes obtained by near-UV, optical and near-infrared observations, will allow us to identify and constrain the properties of the different ejecta [13]. In particular, UV observations, performed in the first few hours of the kilonova (unavailable for GW170817), will probe the mass, composition, and thermal content of the fastest ejecta and allow us to constrain its geometry, quantity, and kinematics, as well as the nature of the merger product. Micro-satellites carrying relatively small (with a collecting area around 200 cm\({}^{2}\)) near-IR and near-UV space telescopes will probe the emission from kilonovae out to the distance beyond 200 Mpc. Observations in the near-IR should also allow us to detect afterglows at redshifts z \(>\) 5, corresponding to the first billion years of the Universe. Long GRBs are mostly observed at cosmological distances, with the most distant GRB detected at the redshift of z = 9.4, which corresponds to a look-back time of 13.3 billion years, only 500 million years after the Big Bang. Long GRBs are thus excellent probes for examining the early Universe, when the first massive stars and their host galaxies were being formed, the first heavier elements were produced, and the diffuse interstellar and intergalactic matter was re-ionised. To truly exploit long GRBs as probes of the early Universe, we need to identify more GRBs from the first billion years after the Big Bang. This can only be achieved by rapid near-infrared, follow-up observations from space, capable of imaging the afterglows of GRBs at the edge of the observable Universe. This was the main goal of the Theseus mission [22], which unfortunately was not selected by ESA for realization. CubSats again can provide a contribution here; see, for example, the SkyHopper proposal [23] [[https://skyhopper.research.unimelb.edu.au/](https://skyhopper.research.unimelb.edu.au/)]([https://skyhopper.research.unimelb.edu.au/](https://skyhopper.research.unimelb.edu.au/)) accessed on 1 December 2021. Next to the near-IR and near-UV telescopes, the constellation would also benefit from a microsatellite carrying a wide-field 10 cm\({}^{2}\)-20 cm\({}^{2}\) X-ray telescope observing in the 0.5-8 keV band. Since GRBs are bright in X-rays, a rapidly slewing X-ray telescope can aid the quick arcmin scale identification of the GRB position in the sky. The time and spectral evolution of the early X-ray emission can also provide valuable information about the possible two-step collapse model (through a short-lived massive neutron star) and the jet geometry of the source.