Two Russian Soyuz rockets are poised for liftoff from opposite sides of the planet Tuesday, flying to orbit on unrelated missions demonstrating the flexibility of the venerable launch vehicle.

Photo of the Soyuz 2-1b rocket with the Resurs P1 satellite on the launch pad at the Baikonur Cosmodrome in Kazakhstan. Credit: Roscosmos

The first launch is scheduled from the Baikonur Cosmodrome in Kazakhstan, with liftoff set for 1728:48 GMT (1:28:48 p.m. EDT) with a Russian Earth observation satellite named Resurs P1.

Less than 90 minutes later, at 1854:03 GMT (2:54:03 p.m. EDT), another Soyuz booster will blast off from the European-run spaceport in French Guiana, carrying four broadband communications satellites for O3b Networks Ltd.

The Soyuz launch from French Guiana, a mission organized by French launch provider Arianespace, was supposed to take off Monday. But unfavorable winds over the launch base forced officials to delay the launch to Tuesday.

The missions will use a modernized version of the Soyuz rocket, whose derivatives have launched more than 1,800 times since the dawn of the Space Age. The Soyuz 2-1b rocket employed on both flights features an upgraded RD-0124 third stage engine and a digital flight control system, replacing antiquated components on previous Soyuz configurations.

The first Soyuz launch Tuesday will send into orbit a satellite to take high-resolution photos of Earth for environmental researchers working for the Russian government and international organizations, according to TsSKB Progress, builder of the Resurs P1 satellite.

The Russian government-owned spacecraft, which weighs about 14,500 pounds at the time of launch, will operate in a circular sun-synchronous orbit about 295 miles above Earth.

The digital camera on Resurs P1 will see objects smaller than 1 meter - about 3.3 feet - on the ground, capturing black-and-white and hyperspectral imagery for the Russian Ministry of Natural Resources, the Russian Ministry of Emergency Situations, the Russian Ministry of Transportation, the Russian Ministry of Agriculture, the Fishery Sector of Russia and international customers, according to Roscosmos, the Russian space agency.

Resurs P1 is the first craft in a new series of Russian civil remote sensing satellites, replacing a satellite launched in June 2006. Resurs P1 is designed for a five-year lifetime in space.

Later Tuesday, another Soyuz rocket will soar into space from the Guiana Space Center along the northeast coast of South America.

Four satellites for O3b Networks are mounted on a dispenser before attachment to a Soyuz rocket and Fregat upper stage. Credit: CNES/ESA/Arianespace

Flying east from the launch site - nestled in the jungle near the town of Sinnamary, French Guiana - the three-stage Soyuz rocket and a Fregat upper stage will boost four 1,543-pound satellites into orbit over the equator at an altitude of 4,865 miles.

The satellites were built by Thales Alenia Space of Italy and are owned by O3b Networks Ltd., a startup communications firm based in the Channel Islands. SES - one of the world's three largest commercial satellite operators - is the main shareholder in O3b Networks, which was founded in 2007 by high-tech entrepreneur Greg Wyler.

O3b stands for "Other 3 billion," referncing the company's goal of serving broadband Internet to the half of the global population without access to high-speed connectivity.

Google, Liberty Global, HSBC Principal Investments and other venture capital firms also invested in O3b, which says it has raised $1.3 billion to finance the construction and launch of its satellites and ground network until the company breaks even.

SES chief executive Romain Bausch said in May that O3b had a backlog of $750 million at the end of March after striking deals with regional telecom operators and the Royal Caribbean International cruise line.

O3b customers include maritime users, companies in the oil and gas exploration industry and government-controlled operators. With an operational orbit about 5,000 miles over the equator, the satellites will reach customers between 45 degrees north and 45 degrees south latitude.

The company says its system offers cost, capacity and latency advantages over terrestrial networks and satellites based in geostationary orbit 22,300 miles above Earth.

Four more O3b satellites are scheduled to launch on another Soyuz rocket in September, followed by another quartet of craft in 2014.