TORONTO -- As Earth’s closest orbit becomes overcrowded with satellites and space junk, companies are increasingly looking to the planet’s second-closest orbit for expansion – but it’s rife with danger.

Low Earth orbit (LEO), Earth’s closest orbit, is running out of room as tech companies, such as SpaceX, Amazon, and OneWeb, race to send up their own mega-constellations of communication satellites.

Elon Musk’s SpaceX plans to eventually launch 42,000 Starlink satellites into space, Amazon hopes to send 3,236 satellites, and OneWeb has plans for approximately 650 of its own satellites.

“I’m sure a lot of people think of space as being this vast space, no pun intended, so how are we possibly going to run out of room when we have these tiny little satellites compared to the size of the universe?” Tanya Harrison, the director of strategy at Planet Labs, told CTV’s Your Morning on Thursday.

“But the orbit altitudes that are actually useful for us here on the ground are quite limited.”

This is where medium Earth orbit (MEO) comes in.

Sending satellites a little farther to the next orbit when the lower one fills up makes sense in theory and is generally considered safer than risking collisions with fast-flying space junk. 

However, this higher orbit isn’t exactly inviting.

“Medium Earth orbit is a little bit odd in that it has a really harsh radiation environment,” Harrison explained.

“Some of the satellites that are there end up going through what are called the Van Allen belts and these are high-radiation environments, where charged particles from things like the sun can get trapped, and then they just get spun up to the point where they can cause a lot of damage to satellites.”

Harrison said these charged particles fly through these belts and can tear right through solar panels and cause damage to electronics.

The few satellites that are currently in MEO are in specific regions called “slots” that scientists have deemed safe.

These satellites are mostly used for communication, according to Harrison, because MEO provides a larger footprint than LEO and a shorter delay time for communication signals than the even further geostationary orbit (GEO).

And while that sounds promising, these satellites must have extra protection against radiation than those in LEO, which is more costly.

“We have radiation hardened technology,” Harrison said. “We use it on deep-space missions all the time to places like Mars or Jupiter or Pluto, but it’s very expensive and very heavy, which means it’s really expensive to launch it in the first place.”

Because the launch costs are so much cheaper and there isn’t a need for protective shielding from the radiation, Harrison said she predicts that commercial companies will continue to send their satellites into LEO for the time being.

“I think for now, we'll probably see a lot of folks hanging out in low Earth orbit until it becomes much more critical, we're running out of space much more quickly, and then maybe medium Earth orbit will start opening up as a place where we invest in the technology that could bring the cost down of that rad [radiation] hardening and the launch cost to get there,” she said.

“We're not quite there yet in terms of a commercial revolution for wanting a ton of satellites in medium Earth orbit.”