Time of Entering Atmosphere

if not defined targetalt set targetalt to body:atm:height.

set rt to time:seconds + eta:periapsis.
lock altthen to body:altitudeof(positionat(ship,rt)).
set wiggle to 500.
set step to orbit:period / 2.
set iterations to 0.
until abs(altthen -targetAlt) < wiggle {
	if altthen < targetAlt { set rt to rt - step. set step to step / 2. wait 0. set iterations to iterations + 1. }
	if altthen > targetAlt { set rt to rt + step. set step to step / 2. wait 0. set iterations to iterations + 1. }
}
lock rteta to rt-time:seconds.
print "rt is timestamp of " + round(altthen) + " m, and rteta is the eta.".