Engineers at the Kennedy Space Center are gearing up to haul the towering Ares I-X rocket to launch pad 39B early Tuesday for an unmanned $445 million test flight Oct. 27 that likely will play a major role in the ongoing debate about NASA's post-shuttle manned space program.

NASA managers met early Monday and agreed the Ares I-X flight was now NASA's top near-term priority. Because many engineers supporting the Ares test also are needed for shuttle processing, work to ready Atlantis for launch on the next space station assembly and resupply mission will be stretched out a bit. NASA had been targeting Nov. 12 for launch, but managers today agreed on Nov. 16 as a more realistic "no-earlier-than" launch date, officials said.

But as of this writing, NASA does not have a slot on the U.S. Air Force Eastern Range launch schedule. A United Launch Alliance Atlas 5 rocket carrying an Intelsat communications satellite has the range booked for launch tries Nov. 14-15 and a Delta 4 carrying a military communications satellite is scheduled for launch Nov. 18.

Because of time needed to reconfigure range tracking and telemetry systems to support a different launch operation, the Delta would have to slip for NASA to have a shot at launching Atlantis on Nov. 16 at 2:28 p.m. EST.

Even if the Delta is delayed, NASA will have a relatively short launch window. Because of temperature constraints related to the space station's orbit, Atlantis must take off by Nov. 19 at the latest or the flight will be delayed to Dec. 6. The December launch window closes after Dec. 11 because of a conflict with the planned launch and docking of a Russian Soyuz spacecraft carrying three station crew members.

Hoping for the best, Atlantis' six crew members flew to the Kennedy Space Center on Monday to review emergency procedures at pad 39A. A dress-rehearsal countdown, originally planned for Wednesday, has been delayed to Nov. 3 because of the decision to prioritize the Ares I-X launch and the resulting slip of the shuttle's no-earlier-than launch date from Nov. 12 to Nov. 16.

At the Vehicle Assembly Building, NASA and contractor engineers spent the day Monday retracting access platforms and readying the Ares I-X rocket for the planned move to launch complex 39B. First motion is targeted for 12:01 a.m. EDT Tuesday.

The towering rocket, anchored to a modified shuttle launch platform by four massive bolts at the base of the booster's flared aft skirt, stands more than twice as tall as an assembled space shuttle and it is expected to sway slightly as NASA's crawler-transporter carries the "stack" to the launch pad. Officials say the tip of the rocket is expected to move back and forth about a foot depending on the wind and other factors.

While the rocket was engineered to withstand winds of up to 45 knots, the Ares I-X rollout constraint is 20 knots and forecasters are predicting a 90 percent chance of acceptable weather. Once at the pad, a new $13 million shock absorber system utilizing locomotive springs will be hooked up to hold the rocket steady until just before launch.

Liftoff is targeted for 8 a.m. on Oct. 27. Backup opportunities are available Oct. 28 and 29 if needed.

The Ares I rocket is a key element in NASA's post-shuttle Constellation program, which calls for replacing the shuttle with a safer, lower-cost rocket to ferry astronauts to low-Earth orbit and development of a large, unmanned heavy lift rocket - the Ares V - that would support eventual expeditions to the moon.

The Obama administration currently is reassessing NASA's manned space program and evaluating five options developed by an independent panel of space experts led by former Lockheed Martin CEO Norman Augustine. Only one of the five options includes the Ares I. But in recent hearings, lawmakers expressed reluctance to scrap the Constellation architecture and it's not yet clear what action the Obama administration might take, or when a decision will be made.

Given that backdrop in the policy arena, the planned test flight of the Ares I-X could prove critical to the future of the Constellation program. While a success would not guarantee a continuation of Constellation, a failure could prove fatal.

"You can't avoid that," former NASA Administrator Mike Griffin, who oversaw the implementation of the Constellation program, said in an interview. "Now, I'll say right on the heels of that remark I think that's regrettable. You don't hinge decision making on one test flight. I mean, that's not good engineering. But I think it's unavoidable that policy makers will look to the success or failure of this flight as a key to future decisions."

The 1.8-million-pound 327-foot-tall Ares I-X rocket is made up of a four-segment shuttle solid-fuel booster, a dummy fifth segment, a dummy second stage and a mockup of an Orion crew capsule and escape rocket. More than 700 sensors are mounted on the rocket to determine actual performance and the stresses the vehicle experiences, along with three television cameras.

Like any shuttle booster, the Ares I-X will fire for two minutes, boosting the vehicle to an altitude of about 130,000 feet and a velocity of nearly five times the speed of sound. At that point, roughly 43 miles due east of the Kennedy Space Center, the first stage will separate from the dummy upper stage and fall to the Atlantic Ocean in a test of new parachutes designed for the operational Ares I. The dummy upper stage, which will not be recovered, will crash into the ocean some 147 miles from the space center.

The cost of the Ares I-X project, including the rocket, launch pad modifications, computer modeling and data analysis, is expected to be around $445 million.

"We're incredibly excited to be on the cusp of flying the system, seeing what Ares I can do," Jeff Hanley, Constellation program manager at the Johnson Space Center in Houston, told CBS News.

The goal of the test flight is to verify computer models and flight characteristics during the critical first two minutes of flight when aerodynamic stresses are most severe.

While the real Ares I rocket features a first-stage booster with five fuel segments, engineers say the four-segment Ares I-X vehicle will closely mimic the flying characteristics of the manned version.

Engineers are especially interested in the acoustic environment a few seconds after launch, when the reflected sound of the accelerating booster hits the vehicle, causing vibrations that will be transmitted through the structure, and later, when the rocket accelerates through the speed of sound and experiences maximum dynamic pressure, or "max Q."

A space shuttle typically experiences between 720 and 750 pounds per square foot at max Q, but Ares 1-X will experience around 850 psf. Data from the test flight will tell engineers what sort of environmental conditions sensitive electronics might be subjected to and whether mitigations are needed.

Other areas of interest are longitudinal thrust oscillations and how much the vehicle rolls about its long axis.

Based on data from recent shuttle flights and the test firing of a five-segment Ares booster in Utah, Hanley said engineers do not believe thrust oscillation, a phenomenon that occurs toward the end of a booster's firing, is a major problem. Even so, current plans for the Ares I rocket call for springs, part of a passive "soft-ride" system, to be used between the first and second stages and between the second stage and the Orion crew capsule to damp out any significant vibrations.

Engineers also are studying an innovative system that would use the mass of the second-stage liquid oxygen in an eventual manned rocket to damp out unwanted vibration.

Roll control also doesn't appear to be a major issue, engineers say. All solid-fuel rockets experience some amount of roll due to the behavior of the high-speed exhaust plume and Ares I-X is equipped with roll control thrusters on the dummy second stage to counteract any unwanted motion.

Another issue involves the rocket's sideways drift as it climbs away from the launch pad. For the Ares I-X launch, the booster's nozzle will be canted slightly just after ignition to ensure a "walk-off" away from the launch pad gantry. This is not intended to prevent a crash into the tower, which engineers say is not a concern. Rather, it is to prevent the rocket's exhaust plume from damaging the pad if the launch-day winds push it toward the gantry.