The STS-3xx missions were developed in the aftermath of the loss of "Columbia". However, NASA spent some effort researching rescue options even before the disaster. Before the ISS was launched, or in the event of a Shuttle being unable to reach the station, crews would have had to transfer directly between Shuttles. The orbiters would have been unable to dock, so while they used their RMS arms to grapple each other, the crew would have made an EVA between the Shuttles. This would have been carried out using the two EVA-designated mission specialists wearing the &lt;a href="Extravehicular%20Mobility%20Unit"&gt;Shuttle/ISS Extravehicular Mobility Unit&lt;/a&gt; (EMU) spacesuits, while the remaining crew would have been sealed up in pressurized Personal Rescue Enclosure and carried over either by hand, or using a pulley system (akin to that of a clothesline pulley) like that employed in the Apollo program for lifting samples from the Moon's surface into the Lunar Module.