Cernan performed a two-hour extravehicular activity, during which it was planned for him to demonstrate free flight in a self-contained rocket pack, the USAF Astronaut Maneuvering Unit.

On February 28, 1966, See and Bassett were flying from Texas to inspect the Gemini 9 spacecraft at the McDonnell Aircraft plant in St. Louis, Missouri.

The conditions at Lambert Field were poor and, as a consequence, in attempting a visual approach and landing, See hit one of the assembly buildings of the factory and caused the aircraft to crash, killing himself and Bassett instantly.

A second objective was a planned extravehicular activity (EVA), or "space walk", by the right-hand seat Pilot.

The plan was for him to move to the rear of the spacecraft and strap himself into the Air Force's Astronaut Maneuvering Unit (AMU), a 'rocket pack' which would allow the pilot controlled flight, independent of the capsule's life support system.

Use of the AMU was not achieved due to Cernan experiencing high cardiac stress, overheating, and fatigue during EVA.

The Augmented Target Docking Adapter (ATDA) had been designed for use as a contingency for the ATV, which had failed during the original Gemini 6 launch.

It was built using already tested equipment, and successfully launched on June 1, 1966, into a 298-kilometer (185 mi; 161 nmi) orbit using the Atlas SLV-3 rocket.

Two small roll transients were evident at liftoff and pogo effects were the lowest yet recorded on a Gemini launch.

Stafford made the first thruster burn 49 minutes after launch, to add 22.7 meters per second (74 ft/s) to their speed, raising their perigee from 160 to 232 kilometers (99 to 144 mi; 86 to 125 nmi).

An hour and 35 minutes later, Stafford corrected phase, height, and out-of-plane errors by pointing the spacecraft 40° down, and 3° to the left.

As they got closer, they found the ATDA to be in a slow rotation, with the conical nose shroud still attached, the two pieces hanging agape at the front like a giant, open jaw.

Their ability to rip open a space suit like a razor blade caused the salvage mission to be abandoned.

At the Cape, backup pilot Buzz Aldrin suggested that Cernan cut the electric wires with surgical scissors from the equipment pack.

An experiment on the ground demonstrated this could indeed slice the wires, but also showed the ATDA bristled with dangerous, sharp edges.

The Douglas technician who normally hooked up the lanyards knew what to do with the loose ends, even without the blueprint, but he was not permitted on the gantry.

The strangers fixing the ATDA's shroud looked at the dangling straps, wondered what to do with them, and taped them under the small fairings that protected the explosive bolts.

[8] After the launch, the Douglas engineer, with the help of Lockheed, set up a backup fairing and demonstrated the problem to McDonnell personnel and to George Mueller, NASA's Office of Manned Space Flight administrator.

Approximately half the food supply was eaten and the crew did not register any complaints about its quality during postflight debriefings.

[9] As soon as he left the spacecraft, he began tumbling uncontrollably, which was not helped by his umbilical which moved wildly and gave Cernan difficulty in controlling his movements.

While he was disconnecting himself from the capsule umbilical and hooking up to the backpack, his heart rate rose to about 155 beats per minute (bpm).

[13] After making all the necessary connections, Cernan rested for a few minutes while Mission Control decided whether or not to proceed with the AMU test.

After trying to remove a mirror mounted to the side of the spacecraft, his suit cooling system overheated and his face plate fogged up completely, blocking his vision.

As an astronaut's work load increased, he would begin to sweat, and within the confined suit the cooling system would be overwhelmed and the visor would fog.

It was very effective and there were very few cases where astronauts used the "High" Cooling selection, even though they were working hard on the Moon's surface in 100 °C (212 °F) sunlight.

[15] Since it would not have been acceptable for Stafford to cut Cernan loose in orbit, he stated that his plan was to make re-entry with the astronaut still attached by his umbilical.

This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.