[El Gato]

It was the size of Jupiter’s orbit, but has reduced by 15%... I’m guessing that would put it about the size of Mars’s orbit

Uh, no. Jupiter's orbit is 483,632,000 miles from the sun (on average). Mars orbit has a radius of 141,635,300 miles.

85% of 483,632,000 miles is 411,087,200 miles, hardly anywhere near the orbital radius of Mars.

[OneWingedShark]

Hm, I’d have been closer with the asteroid field between Mars and Jupiter.