Subject: Voyager(s)
They just keep on giving, even though their primary missions ended 40 years ago.

https://www.iflscience.com/nas...

"Scientists expected that the edge of the heliosphere, called the heliopause, can move as the Sun's activity changes, sort of like a lung expanding and contracting with breath," a NASA statement explains.

...

While not a hard edge, or a "wall" as it has sometimes been called, here both spacecraft measured temperatures of 30,000-50,000 kelvin (54,000-90,000 degrees Fahrenheit), which is why it is sometimes also referred to as a "wall of fire".