There are a number of factors in the re-entry of small satellites that have not been sufficiently investigated using empirical measurements. The re-entry of the 28 kg NorSat-TD satellite gave a unique opportunity to perform a detailed measurement campaign to assess the conditions on the way down through very low Earth orbit (VLEO). The satellite underwent natural decay due to drag from 370 km altitude in March 2025 until final contact at 150 km altitude in May later that year. Very few operational satellites cross this region of the atmosphere. This project is backed by the European Space Agency (ESA).

A key deliverable for the project will be the reconstruction of environmental conditions experienced during re-entry. These results will be compared to available state-of-the-art atmospheric models. The results will also include an assessment of the consequences of thermal albedo for the Earth on operations in VLEO.

The reconstruction and simulation of the satellites attitude on re-entry will be used in a unique study of the feasibility of semi-controlled re-entry of small satellites without the use of propulsion. The project will investigate this from an operational point of view by defining a control envelope in various stages of VLEO and attempt to simulate successful targeting using only attitude control.

A precise orbit determination using GPS measurements from 370 to 150 km altitude will form the basis of comparison for other parts of the project. A post-processed kinematic (PPK) method will be used on the carrier phase measurements that were recorded through VLEO.

The project will also consider a stipulated ground risk for the re-entry of NorSat-TD. This will be based on a 3D model and simulated and recorded atmospheric conditions. Onboard temperature measurements and attitude evolution will provide key insights in the disintegration of the satellite.

We anticipate this project will provide new and meaningful insight to smallsat operators on the topic of controlled re-entry. The project will also support the modelling of atmospheric conditions in VLEO with comparisons to state-of-the-art models.

The project kicked off in 2025 and is expected to last until June 2026. Analyses are ongoing and we will present first insights from the project, based on recent results.