A cut presumably draws blood anywhere in the universe, whether in an Earthly suburb or on some future interstellar voyage yet undreamed outside science fiction. In space, however, clotting's the challenge. A recent study by University of Florida Health scientists, published in the journal Biomedicines, reveals a space oddity—platelets become less effective at clotting after about five days in the microgravity of outer space. Platelets are components of blood that help stop bleeding.