Altitude was tracked from the ground, by reflecting radar off the probe's "starute", a square mylar parachute and radar reflector.
Later in the same story General Ramey is reported to have said that it was a "starshaped tinfoil target designed to reflect radar."
I read that those shallow-angle variations reflect radar off in funny directions.
Some modern aircraft are made partly of plastic composite materials that do not reflect radar strongly.
Water vapor reflects radar to a lesser extent than do water's other two phases.
Curtains that reflect radar.
All such equipment strongly reflects radar.
Dr. Kotov said he expected it to interest makers of military aircraft: it is strong and does not reflect radar.
"An ionized gas that reflects low-frequency radar."
The tiny controlled vortexes produced by microflaps have been shown by wind tunnel tests to be capable of controlling relatively enormous airplanes - and they do not reflect radar.