Plan needed for mega-constellation satellites disposal

The operators of proposed satellite mega-constellations can greatly mitigate the risk of future collisions by rapidly de-orbiting their spacecraft at the end of service.

On the other hand, doing only the bare minimum required by international "clean space" guidelines could significantly endanger the environment.

This is the take-home from a new study led from the UK's Southampton University.

It urges operators to dispose of old satellites within five years.

At the moment, best practice just calls for redundant hardware to come out of the sky within 25 years.

There is increasing concern about the growth in space debris, or junk.

Sixty years of orbital activity have littered the sky with millions of objects, ranging in size from flecks of paint to old rocket stages. These now pose a threat to current and future missions, particularly as the skies are set to get even busier.

A number of companies, including OneWeb, Boeing, SpaceX and Samsung, are developing projects to launch thousands of satellites to deliver broadband and other telecoms services across the entire globe.

New high-volume spacecraft manufacturing techniques and lower rocket prices are set to transform this business sector.

Operators are expected to start deploying their constellations from next year, to altitudes just above 1,000km.

In their modelling study, Southampton's Dr Hugh Lewis and colleagues put a "synthetic", or representative, 1,000-satellite constellation into the current orbital climate, and then simulated the possible outcomes over the next 200 years.

The study showed that even with high compliance to current "rules", the number of catastrophic collisions over the period could increase by about 50% if old practices are maintained.