The Final Ascent: How Space Shuttle Atlantis and STS-135 Concluded Thirty Years of Shuttle History

The Minimalist Crew and the High-Stakes Rescue Plan

Unlike typical space shuttle missions that carried six or seven astronauts, STS-135 flew with a lean crew of only four. Because Atlantis was the absolute last shuttle flight, there was no backup shuttle standing by on a neighboring pad for a launch-on-need rescue mission (STS-335) if Atlantis suffered thermal tile damage during ascent.

If the thermal protection system was compromised, the four astronauts would have taken refuge on the International Space Station as a 'safe haven,' returning to Earth one by one over a year aboard Russian Soyuz spacecraft. The reduced crew size ensured that Soyuz life-support logistics remained viable in an emergency.

Stocking the Station: The Raffaello Logistics Cargo

With the retirement of the shuttle fleet, NASA faced a multi-year gap in heavy domestic cargo launch capacity until commercial providers matured. STS-135's primary objective was packing the ISS with critical supplies.

Atlantis delivered the 21-foot Italian-built Raffaello module containing food, clothing, scientific experiment racks, and heavy mechanical spares—including the Robotic Refueling Mission (RRM) payload to test satellite propellant transfer in orbit—providing the station with a multi-year operational supply cushion.

The Historic Handover: The Flag for Commercial Crew

During the mission, Commander Chris Ferguson presented the ISS crew with an American flag that had flown on the very first space shuttle mission (STS-1 Columbia in April 1981). The flag was mounted to the hatch of the Harmony module with the instruction that it would remain on the ISS until the next American spacecraft launched from US soil retrieved it.

Nine years later, on May 31, 2020, STS-135 pilot Doug Hurley flew back to the station as commander of SpaceX's Demo-2 Crew Dragon flight alongside Bob Behnken, fulfilling the shuttle's legacy and inaugurating the modern commercial human spaceflight era. Atlantis is proudly displayed today at the Kennedy Space Center Visitor Complex.

What the evidence does not settle

The retirement of the shuttle fleet left the United States without domestic crew launch capability for nine years (2011–2020), requiring NASA to purchase seats aboard Russian Soyuz spacecraft at costs rising to over $80 million per seat.