[clmul]

If we are talking about visual light astronomy (the wavelengths where black satellites could help), a majority of astronomy is ground based. There exists just a single capable space observatory in visual light, the Hubble telescope, which will be going out of service in a few years. There's some metrics here[1] which show that about 10% of the most cited papers use Hubble data, which is still quite impressive. This is dated though, it could very well be that Hubble is becoming less relevant with recent advances in technology.

[1] http://www.stsci.edu/%7Ewebdocs/STScINewsletter/2003/spring_...