WASHINGTON (AFP) - NASA is pushing back a space shuttle Atlantis mission to the International Space Station by four days to November 16 so that it can test an experimental rocket, the US space agency said. The date will be officially confirmed by mission administrators Tuesday during a meeting to evaluate preparations for the Atlantis mission. The decision to push back the launch is intended to optimize the agencys ability to launch both Ares I-X and Atlantis before the end of the year, NASA said in a statement. The Ares I-X is the first test flight for NASAs Ares I an experimental rocket. NASA said it has scheduled launch opportunities for Ares I-X for October 27, 28 and 29. A team at the Kennedy Space Center in Cape Canaveral, Florida is in charge of preparations for both the Atlantis and Ares I-X launches. The Ares I is being developed to carry NASAs new Orion capsules, the replacement spacecraft expected to launch from 2015, after the retirement of the shuttle program. The development is part of the Constellation program proposed by former president George W. Bush, with the goal of returning men to the moon by 2020 and eventually undertaking manned missions to Mars. The future of the Constellation, at least as originally envisioned, has been thrown into doubt by the findings of a commission of independent experts appointed by President Barack Obama to examine the program. Their summary report released in September suggest five possible options for the program, but warned that continuing as planned would require an additional three billion dollars a year in funding. The full report is set to be released Thursday, and the White House has yet to make any official announcement on the programs future, but the Ares program is proceeding despite the uncertainty. The Atlantis is set to carry six astronauts to the ISS during an 11-day mission. The launch will be the fifth and last shuttle mission for 2009. There are just five more shuttle launches scheduled before the planned September 2010 retirement of the fleet. But the White House could yet decide to extend the program through 2011 to reduce US reliance on Russias Soyuz craft for astronaut transport to the ISS while the Orion capsules are being constructed.