 that we are prepared. She says that right now there are no specific or credible threats. They are back on Earth in quotation marks. Four volunteer crew members who spent more than 12 months inside NASA's first simulated Mars environment at the Johnson Space Center in Houston, including Ross Brockwell. Very grateful to have had this incredible opportunity to live for a year within the spirit of planetary adventure towards an exciting future. They emerged from a 17,000 square foot space. Chuck Sievertson, ABC News.