In a move that's been expected since last week, the Astros have signed MLB.com #20/Baseball America #25 international prospect Ronny Rafael to a $1.5 million contract. Rafael, 16, is a righty-hitting OF from the Dominican Republic, and the $1.5 million bonus is, I believe, the second biggest international deal in Astros franchise history (behind only Ariel Ovando's $2.6 million in 2010). You can read Rafael's MLB.com prospect profile over here.
Evan Drellich reports that Houston has also signed OF Angel DeLeon, OF Hector Martinez, and RHP Cristofer Melendez.