A crane moves the launch abort system tower into place on the Ares I-X rocket. At 98 metres tall, the Ares rocket is almost twice the height of a space shuttle and its fuel tank. (NASA)

NASA has completed the assembly of its Ares I-X rocket, the first new launch system dedicated to manned spaceflight in a quarter of a century.

An important step in the ambitious U.S. manned space program, the Ares I-X is the first version of a series of rockets set to carry the U.S. space agency's next-generation Orion spacecraft after the space shuttle fleet is retired in 2010.

The Orion-Ares combination is not due to launch until 2015 at the earliest.

However a report from the U.S. Human Space Flight Plans committee issued on Friday said federal budget cuts have made impossible the agency's current plans to land astronauts on the moon by 2020. The committee said the project's 10-year, $108 billion US budget has been shaved by $30 billion in the most recent federal budget, putting the moon mission plans in jeopardy.

First test due in October

The announcement of the milestone assembly, also on Friday, was strangely muted for NASA, with the news coming in a blog post on NASA's website and an announcement through the social messaging service Twitter.

The 98-metre Ares rocket is standing in the vehicle assembly building at Kennedy Space Center.

NASA has scheduled the first test flight of the Ares I-X rocket for late October. Before being launched, the rocket will be tested to ensure it can endure the strain of launch and ascent.

On Monday NASA also launched a rocket carrying an inflatable landing technology for use in future missions.

The mushroom-shaped Inflatable Re-entry Vehicle Experiment uses a lightweight inflatable shell to help provide a landing module add more drag as it enters the atmosphere of a planet like Mars.