Original article

MIT Lincoln Laboratory: https://www.ll.mit.edu/news/high-orbit-satellites-could-light-way-travel-moon

Introduction

The LightHOUSE concept proposes cooperative optical beacons in very high Earth orbits to provide GPS-like navigation and communications for spacecraft in cislunar space. It is good IELTS practice for infrastructure and aerospace engineering vocabulary.

Vocabulary

cislunar — relating to the region between Earth and the Moon; beacon — a signal source used for navigation; constellation — a coordinated group of satellites; orbit determination — calculating a spacecraft’s orbit; baseline — reference distance used for measurement; propellant — material used to generate thrust; corrective maneuver — movement made to correct a trajectory; optical communication — communication using light; radiation hardening — making electronics resistant to radiation; asymmetry — unequal distribution of capabilities; technical hurdle — difficult engineering obstacle; refine — improve gradually; substantial investment — large commitment of resources; routine — normal and regular.

Reading comprehension

1. Why may the Deep Space Network become insufficient for future cislunar traffic?

Reference answer
The DSN is a limited shared ground-based resource, while the number of missions requiring navigation and communication support is expected to grow.

2. How would LightHOUSE determine spacecraft position and velocity?

Reference answer
Multiple cooperative optical beacons would provide measurements from different locations, allowing the spacecraft’s position and motion to be calculated.

3. Why use extremely high orbits?

Reference answer
High orbits provide broad geometric coverage across cislunar space and long baselines useful for navigation.

4. What does it mean for the system to be highly asymmetric?

Reference answer
The infrastructure satellites carry much of the sophisticated equipment and computation, allowing user spacecraft to use simpler systems.