The item in Science Alert's A Harvard Astrophysicist Says Outer Space Is Actually Closer Than We Think (see also Science; Outer space may have just gotten a bit closer) talks about the recent Acta Astronautica article by Jonathan McDowell The edge of space: Revisiting the Karman Line, and ends with the quip:
That doesn't mean we're going to see any commonly used definitions change soon, though: McDowell first proposed his 80-kilometre boundary line in 1994 - over 25 years ago. Perhaps we need a new term for it instead: the McDowell line.
I think the idea is that once something that's been in Earth orbit drops to the Karman line in circular orbit, it's "toast" in that it's fate is fairly well sealed and it has hours to perhaps a day at most before burning up.
Earlier, the article says:
So back to McDowell. He chose for his proposed boundary the 80-kilometre mark, just below the mesopause - the boundary between the lower mesosphere and the upper thermosphere, and the coldest point in the Earth's atmosphere.
And this is because of the satellites. McDowell analysed over 90 million points of orbital data from 43,000 satellites dating back to 1957, using archives maintained by the North American Air Defence Command.
Most of the satellites fly pretty high, but he identified 50 that flew below the 100-kilometre mark, down as low as the 80-kilometre mark, over two or more complete revolutions of Earth.
"Are you going to say [these satellites are] in space and then not in space every 2 hours?" he told Science. "That doesn't seem very helpful."
While orbits in natural decay will circularize first before burning up, I'm trying to understand if able-bodied spacecraft with some remaining propulsion in elliptical orbits can dip below the Karman line once or twice, and then at apoapsis boost back to an orbit with a higher periapsis so that they can "Die Another Day."
Question: Have spacecraft ever dipped below the Karman line and then safely returned to spaceflight? Please use the 100 km line, not the proposed 80 km discussed at the beginning.
edit: Responding to comments, yes, aerobraking would count, as long as it involved dropping below the Karman line in the Earth's atmosphere temporarily. Also, 'dipped' means going below for a short time, such as a fraction of an orbit as discussed in the links above. Not landing, then being launched again at a later date.