PARIS — The German Aerospace Center, DLR, and satellite-builder Astrium signed a contract Aug. 30 for the construction of the TanDem-X radar Earth observation satellite, to be launched in 2009 as a companion satellite to the similar TerraSar-X spacecraft scheduled for launch in October.

The TanDem-X manufacturing contract is valued at 85 million euros ($110 million). DLR will be paying 56 million euros, with Astrium furnishing 26 million euros. The remaining 3 million euros will be financed from the sale of space on board the satellite for a secondary payload. DLR officials have estimated that the entire TanDem-X project, including launch and ground infrastructure, would cost about 145 million euros.

DLR will be responsible for deploying the satellite’s ground stations and will store data to be distributed free of charge to certain science and research users. Commercial imagery from TerraSar-X and TanDem-X will be distributed worldwide by Infoterra GmbH of Friedrichshafen, which like Astrium is owned by EADS Space.

DLR officials are leaning toward the inclusion of a laser communications terminal for the TanDem-X mission. It would be similar to the one to fly on TerraSar-X, but Rolf Werninghaus, DLR project manager, said a final decision on the laser communication option had not been made.

In an Aug. 30 interview, Werninghaus said TerraSar-X is still scheduled for an Oct. 31 launch aboard a Russian-Ukrainian Dnepr launch vehicle pending a final report on the causes of the July 26 Dnepr launch failure.

“We are expecting word from them in the coming days but as of now we are operating under the assumption that the launch remains on Oct. 31,” Werninghaus said. “Current preparations are to finish final acceptance reviews of TerraSar-X in time to ship it to Russia Sept. 27.”

ISC Kosmotras of Moscow, which operates the Dnepr rocket, said in an Aug. 15 statement that it expected to complete the retrieval of Dnepr components from the crash site not far from the Russian-run Baikonur Cosmodrome launch facility by the end of August, and to make its final report on the failure by the end of the month.

Dnepr is a converted SS-18 strategic missile that is launched from an underground silo. The July failure was its first failure in seven launches of satellites. Including its tests as a missile, Dnepr has been launched 160 times, Kosmotras said.

A preliminary investigation concluded that a hydraulic pump on the vehicle’s first-stage engine malfunctioned, causing the rocket to deviate from its flight path and forcing ground controllers to abort the mission. “The cause of the hydraulic valve malfunctioning has been found,” Kosmotras said, without providing details.

The synthetic-aperture radars aboard TerraSar-X and TanDem-X will be able to detect objects of 1 meter in diameter from their orbit at 514 kilometers in altitude. Stereo imaging using blended images from the two satellites will provide digital elevation models that Infoterra believes will have wide appeal among civil and military government agencies. TerraSar-X and TanDem-X were both developed as private-public partnerships, with operator Infoterra expected to generate sufficient commercial business to be able to finance successor satellites on its own.