 The Cosmic Dust Collector (CDC) mission uses two small metallic rectangular boxes carried under each wing that are designed to open at altitude and collect "interplanetary dust particles", or in other words the remains of small meteorites or rocks from space that accumulate in the upper atmosphere, on an adhesive strip.At the end of the assigned track the boxes then automatically close at high altitude and after landing the adhesive strip is removed and returned to the U.S. for analysis.The missions also allowed the WB-57F crews to validate new radios and avionics and ensure these could interface correctly with European ATC agencies.