#project echo

Most good science fiction things bring a whole host of neat spaceship designs, so why didn't I think the same could happen for real-world satellites? The only satellites I really imagine are the usual box, maybe with some solar panels sticking out of the sides. But nope, balloon satellites are a thing too!

A balloon satellite is a literal balloon in space. It goes up, it inflates, it does the usual satellite things from there. The idea has been around for a while: The first balloon sat was Beacon 1, launched barely a year after Sputnik. The rocket fell apart during the launch, but I'll still give it credit for being the first design.

I'll be honest here: I have no idea why you'd want a satellite to be a balloon. It was a popular early design because balloon sats are huge and bright, making them easy to track. With 50s technology, tracking satellites was actually pretty hard.

That's the same reason some controversial modern artists have been trying to send up balloon satellites. Projects like Orbital Reflector (2018) were meant to be extremely visible from the ground as an art piece. Note if you find yourself in the position of doing that: Please don't do that. It just messes up astronomy. SpaceX had to redo the design of their Starlink satellites to reduce their brightness.

They're visible because they can be *huge*. 1960's Project Echo used balloons with a 100-foot diameter, only weighing 150 pounds. They're not weather balloons, there's no atmosphere holding them together, so the skin has to be resilient. Supposedly Echo could even withstand meteorite punctures with a system for injecting extra gas when needed.

How about the downsides then? Even in low Earth orbit, there's atmospheric drag. It's not enough to do anything useful with (like aircraft wings), but it will slow things down, bit by bit. The ISS needs to re-boost itself about once a month to stay in orbit. Large objects like certain 100-foot balloons have even more drag. Making it even more complex, objects with a large size absorb radiation pressure from the sun, turning them into a solar sail and slowing them more.

Project Echo was meant to only demonstrate the feasibility of satellite communication, so the balloons didn't need to last long. They stayed up for 5.5 years. The design was pretty clever, actually. The satellites were passive (no electronics rebroadcasting), but were able to be the host of the world's first satellite telephone conversation. How?

They're shiny! That colossal balloon was used as gigantic space-based reflector. A ground station sent up signals, and a device (The Holmdel Horn, which I'd love to cover later) would pick up the reflection and convert the signal into a telephone conversation.

Chapter Seven: Project Echo