Weather is the only thing standing in the way of Tuesday evening's scheduled launch of a Minotaur 1 rocket with a technology demonstration satellite for the U.S. Air Force, officials said Monday.

Forecasters are predicting a 50 percent chance weather will prohibit the 69-foot-tall rocket from blasting off between 8 p.m. and 11 p.m. EDT Tuesday from Wallops Island, Va.

"There's a front that's over the top of us, so we'll get rain and low cloud ceilings off an on all day tomorrow," said Keith Koehler, spokesperson for NASA's Wallops Flight Facility, which is hosting the launch.

Koehler said iffy weather is expected through at least Thursday, but the launch team is hopeful skies will clear long enough Tuesday for the Minotaur to safely lift off.

The Minotaur 1 is carrying an 880-pound tactical research satellite called TacSat 3 and a small NASA biology laboratory named PharmaSat. Three other secondary payloads will also be launched for academic and industrial institutions.

Officials say the launch, scheduled for just a few minutes after sunset, could be visible across the mid-Atlantic region from North Carolina to New Jersey.

Engineers completed their final readiness review Saturday to close out a few minor issues before clearing the $88 million mission for launch.

"The satellite is in good shape and the rocket and the range are ready," Koehler said. "We're just waiting to see what the weather is going to do."

The Minotaur will launch from pad 0B at the Mid-Atlantic Regional Spaceport, a privately-operated facility at Wallops that has been used for two previous space launches since 2006.

Orbital Sciences Corp., the prime contractor for the Minotaur 1 booster, is modifying a nearby launch pad to be the home of their new Taurus 2 rocket.

The Taurus 2 will begin launching a new cargo-carrying freighter to the international space station by early 2011.

During Tuesday's launch, the Minotaur 1's first stage will ignite to propel the solid-fueled rocket southeast away from the launch pad.

The stage, which will burn for about one minute, is a M55A1 motor taken from stockpiles of retired Minuteman ballistic missiles.

A Minuteman second stage will take over a minute after liftoff at an altitude of about 20 miles and a downrange distance of about 14 miles. The second stage skirt will be jettisoned a few seconds later.

After reaching an altitude of more than 75 miles in barely two minutes of flight, the Minotaur's Minuteman heritage will give way to components built for Orbital's Pegasus and Taurus rockets.

The Orion 50XL third stage motor will fire for 75 seconds to continue the push toward orbit.

The Minotaur's enlarged 61-inch-diameter titanium payload fairing will be let go during the third stage burn.

After consuming the third stage consumes its solid propellant, the rocket will coast upward for more than five minutes, soaring to nearly 300 miles above Earth to reach the mission's injection altitude.

The Orion 38 will ignite for about 69 seconds to reach a targeted orbit about 290 miles high with an inclination of 40.5 degrees.

Separation of the TacSat 3 spacecraft is scheduled for T+11 minutes, 58 seconds above the central Atlantic Ocean.

After another coast period and a collision avoidance maneuver to move itself away from TacSat 3, the fourth stage will begin releasing the flight's secondary payloads with PharmaSat at T+22 minutes, 2 seconds.

See our launch timeline for more details.