The American National Space Administration - ANSA - launched a second space vessel to follow the trajectory of the Liberty 1 piloted by George Taylor, John Landon, Thomas Dodge and Maryann Stewart, which had launched in January 1972.
According to the 2011 novel Conspiracy of the Planet of the Apes and the 2018 novel Death of the Planet of the Apes, the Liberty ships were reverse engineered from technology of classified origin, and were propelled by an experimental photon propulsion drive designed by Dr. Hasslein. Three months after the crew of the Liberty 1 entered hibernation, it collided with a ship exactly identical with itself, automatically setting an emergency course for Earth and crash-landing there nine months later (by ship-time). Back at ANSA, the X-Comm technology allowed Dr. Hasslein to monitor progress, but communications had abruptly stopped. However, Landon's location transmission signal somehow found its way back through the time distortion to the place they had left, prompting ANSA to consider sending a second Liberty craft along the same trajectory, either as a rescue mission or, more likely, as a suicide mission which would nevertheless prove time-travel theory.
The skeleton crew chosen for this mission (as the trajectory was already pre-set), consisted of Colonel Maddox and Major Brent. They were led to believe, by General Lazenbe, that they could hope to return to their own time. However, their ship collided with the 2,000-year-old satellite USA-33 and crashed, and was even more extensively damaged than the Liberty 1, having landed on solid ground rather than water. Col. Maddox died shortly after impact. The wreck of the ship was later scavenged for spare parts by Doctor Milo's assistant, Doctor Seraph, allowing him to combine the two shipwrecks into one working craft.
- The ship's chronometer displayed '3955' at the time of the crash. This discrepancy with the date in the earlier ship - '3978' - has never been fully reconciled. The 2018 novel Death of the Planet of the Apes depicts Milo briefly, but successfully, rebooting the first ship's chronometer which corrects itself to 'January 25 3979' (two months after its crash). However, the clock immediately short-circuits and has to be replaced with that from the second ship, which remains stuck at '3955'. This is why Zira quotes that year when she is questioned in Escape from the Planet of the Apes.
- The prop model of the ship was recycled from Planet of the Apes, the space vessel that brought Taylor into the future. Brent's ship had 'United States' painted down the front, while Taylor's ship was devoid of any markings at all. The large full-scale model was designed by Bill Creber, production designer, and Holdereed Maxy, set designer on the first film. It had fairly heavy sheet steel frames spaced about 18 inches apart and was covered with two layers of thin sheet steel. Inside was only a platform for the actors so it would appear there really was an interior room.
- Escape from the Planet of the Apes and (most likely) the Planet of the Apes television series used a slightly smaller prop ship. The two original full scale ships - the 'Planet'/'Beneath' model with the circular 'hatch' missing near the front, and the shorter 'Escape'/'TV' version - were both last seen rusting in outside storage during the 1970s, and have presumably long since rotted away.
- The name Liberty 2 first appeared in the 2011 novel Conspiracy of the Planet of the Apes, which suggested there were a total of five vessels in Project Liberty.
- Beneath the Planet of the Apes
- Neil Foster & Michael Whitty's Beware The Beast (fan fiction)
- Conspiracy of the Planet of the Apes
- Death of the Planet of the Apes
- The Flight of the Icarus (detailed design blue-prints of the ship), by Jim Key - 'Sci-Fi & Fantasy Models' #38 (1999)
- Behind the Planet of the Apes (documentary)
- 'Icarus' Overview at The Last Flight of the Icarus
- 'Icarus' FAQ at The Last Flight of the Icarus