‘Wooden satellites step in the right direction. Toxic metals linger for long in atmosphere’

Rocket launches release toxic chemicals into the upper atmosphere, and most satellites in low-Earth orbit eventually decay and burn up on re-entry. Since aluminium makes up a significant fraction of most satellite bodies, it deposits large quantities of aluminium oxide in the mesosphere, a compound that can catalyse ozone destruction and linger there for decades. This is a slow, invisible form of pollution, but the numbers are not trivial, and will only grow as satellite mega-constellations multiply. Exploring materials like wood is a promising step in the right direction.

And it is not an isolated effort. For instance Manastu Space, an IIT Bombay alumni startup, is developing green propulsion systems to eliminate toxic propellants in satellite thrusters. These are exactly the innovations we need.

Rapid growth of space exploration is delivering enormous benefits, but it comes with a cost that we are only beginning to understand.

The writer is an astrophysicist at IIT Bombay.