A rocket designed to replace the aging space shuttle is set for its first test-flight, despite questions over the future of the programme, BBC reported.
The 100m-long Ares I-X has a four-hour launch window for blast-off from Nasa's Kennedy Space Center.
The two-minute flight will allow Nasa to test technology crucial for the development of the manned Ares I craft.
A high-profile report has cast doubt on the future of the Ares rocket, which is intended to enter service in 2015.
The Augustine panel, which had been asked to review the US human spaceflight programme, published its report last Thursday just days before the scheduled launch.
Although the panel supported the Ares I-X test flight, it questioned the need to develop the Ares I rocket, part of the Constellation programme commissioned by the previous administration and intended to return the US to the Moon by 2020.
In particular, the panel queried the cost and design of the craft as well as its development time.
"With time and sufficient funds, Nasa could develop, build and fly the Ares I successfully," the report said, "the question is, should it?"
The $450m (300m euros; £275m) Ares I-X is what Nasa describes as a "pathfinder" vehicle.
"It is a chance for the agency to remind itself what it takes to build a vehicle," explained Robert Ess, Ares I-X mission manager.
Nasa has not designed a new launch vehicle for more than three decades and has lost much of the expertise in the area, according to some critics.
"Ares I-X is all about information; about gathering data," Mr Ess told BBC News.
"We have a lot of computer models that we think show it all works. We're very confident we can do it but the proof is actually doing it for the first time."
The Ares I-X is the longest, thinnest vehicle ever designed and built by the US space agency.
Its shape has been determined by the design of its solid rocket booster - itself a modified version of the units used to lift the shuttle into orbit.
"[We wanted] to use as much existing technology as possible," said Mr Ess. "Given that we have the space shuttle booster and given that it is 14-and-a-half-feet in diameter, we didn't want to change that. That architecture drives the length of it."
The final Ares I design calls for the shuttle booster to be upgraded from four to five segments for the first stage of the rocket. The Ares I-X, though, will fly with just four segments and an additional unit that merely simulates an extra portion of booster.
Engineers saw value in flying the more limited configuration to get engineering flight data as soon as possible rather than wait the extra year or two before a five-segment booster became available.
The I-X vehicle is 100m (320ft) tall and has been designed to be as close as possible to the eventual Ares I rocket.
However, the top half of the launcher, like the fifth segment of the booster, is a dummy. What would be an upper-stage, with a crew capsule and its emergency escape mechanism, are mock-ups made to the correct shape and weight.
"We have been building the simulators for over two years now. It has been a very long and very intense process," explained Jonathan Cruz, deputy project manager for the Ares I-X crew module and launch abort system.
"[They] are incredibly accurate. One reason why it has been so difficult and taken so long to build this is because we are building this to exact tolerances."
