system
Given the following post, respond as if you're commenting on Reddit:
human
Why aren't space-based radio telescopes really a thing?

So searching for radio telescopes I found that there are almost none currently operating in space and historically very few as well. Most of the big radio dishes in space are turned Earthwards for spying purposes.

As a layperson this strikes me as strange because it seems like a radio telescope would be significantly easier to build and launch than an optical telescope. 

A few possible guesses come to mind based on my small amount of astronomy knowledge:

Fewer advantages over land-based observation, relative to an optical scope?

Interferometry using huge numbers of smaller ground based dishes simply more useful?

Some engineering challenge I'm not considering?
gpt
There are a couple of good reasons to have space based observatories but all of them vanish when considering radio. 

You often put detectors in space to detect wavelengths that are absorbed by the atmosphere. The atmosphere is mostly transparent to radio wavelengths so we don't need to do that.

The motion of the atmosphere causes scintillation of light sources. The long wavelengths of radio are not susceptible to this.


In addition radio telescopes are massive. A 1m mirror for optical or IR is fairly effective both in space and on the ground. A 1 m radio dish is pretty small fry in radio astronomy. To be fair, you don't have to have quite the structural integrity for a radio dish versus a mirror but they still are bigger which means very expensive to launch.


So they aren't any better and are a lot more expensive.