SAN JUAN, Puerto Rico (AP) — The National Science Foundation says it could cost up to $50 million just to clean up the debris at a renowned radio telescope that collapsed last year in Puerto Rico. It said Friday that investigations into what caused the cables to fail are still ongoing. The Arecibo telescope was until recently the world’s largest radio telescope and was used to study pulsars, detect gravitational waves, search for neutral hydrogen and detect habitable planets, among other things. The NSF noted that results from the forensic evaluations won’t be ready until late this year.