After floundering on two previous launch attempts, South Korea is gearing up for a third try to orbit its own satellite Friday with a part-Russian, part-Korean rocket.

The Korea Satellite Launch Vehicle was placed on the launch pad in South Korea on Wednesday. Credit: Khrunichev
 
Engineers moved the rocket from an assembly hangar to the launch pad Wednesday, lifted the 108-foot booster vertical, and completed a countdown rehearsal Thursday, according to South Korea's Yonhap news agency.

The two-stage Korea Satellite Launch Vehicle 1, or KSLV 1, is scheduled to lift off during a launch window between 0630 GMT and 1000 GMT (2:30-6:00 a.m. EDT) Friday.

The opportunity extends from 3:30 p.m. to 7 p.m. local time at the Naro Space Center, a facility about 300 miles south of Seoul in the South Jeolla province near the southwestern tip of the Korean peninsula.

If the rocket works as designed, it will release a 200-pound test satellite named STSAT 2C about nine minutes after liftoff.

Two previous launches of the expendable rocket ended in failure.

In August 2009, one half of the launcher's nose fairing did not jettison as designed, and the extra mass caused a tumble and kept the rocket from reaching orbit.

Officials lost contact with the second KSLV launch in June 2010 about two minutes after liftoff, but a joint panel of Russian and Korean investigators could not agree on the cause of the explosion.

Russian engineers blamed the June 2010 explosion on the destruct system on the KSLV's Korean-made second stage. South Korean officials maintained the rocket's first stage - manufactured by Russian contractor Khrunichev - fell victim to an anomaly during its burn, according to South Korea's Ministry of Education, Science and Technology.

Both countries agreed to modifications to wiring for the flight termination system and payload fairing before the third launch, according to the Yonhap news agency.

Also called the Naro 1 rocket, the launcher weighs more than 300,000 pounds when filled with liquid and solid propellants.

Khrunichev built the kerosene-burning first stage and lent expertise in construction of the Naro launch pad and control center under a 2004 contract signed with the Korea Aerospace Research Institute.

South Korea has spent about $471 million in the Naro rocket program since 2002, according to Yonhap.

"Naro's third launch is an indispensable investment for the nation, laying the groundwork for Korea to emerge as a leading country in advanced space technology," said Roh Kyung-Won, director general of space and nuclear technology in South Korea's science ministry.

The joint Russian-Korean KSLV 1 rocket program is scheduled to end next year, and South Korea plans to develop an indigenous satellite launcher to fly by 2021.

Khrunichev's contribution to the KSLV 1 booster is based on the universal rocket stage designed for Russia's Angara launcher, which the country envisions will carry a wide range of satellites to space beginning in 2013, at the earliest. The Angara can fly with clusters of three to five universal first stages to haul heavier spacecraft to orbit.

A single kerosene-fueled RD-151 engine will generate 375,000 pounds of thrust to power the 10-story rocket off the launch pad. Produced by NPO Energomash, the RD-151 engine is a smaller version of the engine used on Zenit and Atlas rockets.

Passing the speed of sound in the first 55 seconds of flight, the KSLV will reach the upper atmosphere, release a clamshell-like aerodynamic nose shroud, and separate its Russian upper stage in the first four minutes of the mission.

The Korean-built solid-fueled upper stage will fire for 58 seconds to place the STSAT 2C spacecraft in a 186-mile by 932-mile orbit.