A Soyuz rocket topped with the new Poisk module for the International Space Station took a train ride to historic Launch Pad No. 1 at the Baikonur Cosmodrome on Sunday morning, two days before the new component begins its trek to the orbiting complex.

The Soyuz rocket is poised on the launch pad Sunday morning. Credit: Roscosmos

After arriving at the pad, the 168-foot-tall rocket was lifted upright and swing arms were extended around the vehicle.

Launch Pad No. 1, also known as Gagarin's Start, hosted the launches of Sputnik 1 and the first manned space mission.

Liftoff of Poisk is scheduled for 1422 GMT (9:22 a.m. EST) from the Kazakhstan launch site, beginning a two-day journey to the space station.

The Soyuz rocket's three kerosene-fueled stages will accelerate the payload to more than 17,000 mph, reaching orbit about nine minutes after launch.

Poisk, which means "explore" in Russian, will be ferried to the station by a service module designed for the Progress resupply ship. The Progress bus provides electrical power through solar panels and propulsion to guide Poisk to the outpost.

The new module, stretching 8 feet wide and more than 13 feet long, is the first major Russian addition to the station since the Pirs docking compartment was launched in 2001. Poisk is nearly identical to Pirs.

Three engine burns later Tuesday and Wednesday will put the spacecraft on course to approach the station. The terminal phase of the rendezvous will commence about two hours before docking Thursday morning.

Approaching with guidance from the Kurs automated radar system, the Progress and Poisk module should reach the complex a few seconds before 1544 GMT (10:44 a.m. EST) Thursday.

Weighing more than 8,000 pounds, Poisk will dock to the zenith, or space-facing, docking port of the transfer section of the Zvezda service module.

"This zenith port on ISS today has what's referred to as a hybrid port," said Mike Suffredini, NASA's space station program manager. "It's ready to accept this particular vehicle and once it docks, the Progress bus portion of it will depart and what's left is a standard probe and cone port. That will allow us then to have a fourth docking port on the Russian segment."

Poisk and the Progress bus before attachment to the Soyuz rocket. Credit: Energia

Also called Mini-Research Module 2, Poisk will give the station another port for visiting Soyuz vehicles and Progress logistics freighters. That will be crucial to future station operations because of the high frequency of visiting missions.

"You can tell from all this traffic why that's important to us," Suffredini said.

The station will be home to six residents for much of the rest of its life, requiring two Soyuz capsules to be at the outpost at once. The other two docking ports will be used in rotation by other Soyuz missions, Progress craft and the European Automated Transfer Vehicle, another robotic cargo ship.

The Russian segment today includes three docking locations, including the rear hatch of the Zvezda module, the Earth-facing port of the Zarya control module, and the Pirs docking compartment on the bottom of Zvezda.

Built by the Russian aerospace company Energia, Poisk will also be used as an airlock by Russian spacewalkers and a mounting platform for external science experiments. The module has two egress hatches and about 500 cubic feet of internal volume for storage and spacewalk preps.

About 1,800 pounds of cargo is loaded into Poisk's pressurized compartment for delivery to the space station.

After Poisk arrives at the outpost, the Progress space tug will be jettisoned from the module to re-enter the atmosphere.

The new module will be first utilized in January when a Soyuz vehicle is relocated at the station, according to NASA.

Russia is building a larger module as a docking extension for the Zarya module. That structure, called Mini-Research Module 1, will launch on the space shuttle next May to provide extra clearance between docking ports on the U.S. and Russian segments.