Starshade Would Take Formation Flying to Extremes

Researchers working on ExEP’s Starshade Technology
Development, known as S5, have been tasked by NASA with developing starshade
technology for possible future space telescope missions. Get Into Formation

The specifics of a particular starshade mission –
including the exact distance between the two spacecraft and the size of the
shade – would depend on the size of the telescope. In fact, the work by Bottom and Flinois demonstrates that engineers
could reasonably meet the alignment demands of an even larger starshade (in
conjunction with a larger telescope), positioned up to 46,000 miles (74,000
kilometers) from the telescope.

Source: www.jpl.nasa.gov