Updated July 26 at 3:43 p.m. Eastern with additional information from DLR, and Aug. 2 with information from the German Federal Ministry of Defence.

WASHINGTON — Germany’s space agency, DLR, signed a delayed but long-expected contract with Bremen-based satellite manufacturer OHB Systems for an experimental telecommunications satellite that will be used in part by the Bundeswehr, Germany’s Federal Armed Forces.

The 310.5 million euro ($362.2 million) contract for the production and launch of the satellite, known as Heinrich Hertz, follows an 11 million euro contract to OHB in 2011, at which point the satellite was scheduled to launch in 2016. DLR and OHB said in June that they now anticipate launching the satellite in 2021.

In a July 20 interview with SpaceNews, Gerd Gruppe, a member of the DLR executive board, attributed the five-year delay in part to the mission concept changing during the early planning phase.

“With the German Ministry of Defense we started a public-public-partnership in order to try a new approach for both sides for realizing satellite projects. We solved a lot of issues which were not expected in the early days of this cooperation,” he said.

Heinrich Hertz will carry 20 or so technology experiments as well as a fully functioning Ku- and Ka-band military communications payload. The satellite’s Ku-band capacity is intended to replace some commercially sourced Ku-band, while adding new Ka-band capacity. A spokesperson for the German Federal Ministry of Defence on Aug. 2 declined to say how much commercial capacity would be replaced, saying only that Heinrich Hertz will be one of many capacity sources for the Bundeswehr, and “will complement existing capacities.”

“Another reason for part of the delay is the progress of the general development in industry we had to consider during our call of proposals,” Gruppe added.

Heinrich Hertz will use the SmallGEO satellite platform designed under the European Space Agency’s ARTES program. OHB’s first SmallGEO, the Hispasat-36W-1 satellite, launched in January on a Soyuz rocket. That satellite took seven years to build — substantially longer than what most commercial operators are willing to wait for a new spacecraft. OHB has stated its intent to rein in SmallGEO construction times to three years.

An Airbus protest over the Heinrich Hertz contract going to OHB last year further contributed to the delay.

Gruppe said no major changes have occurred with the satellite in the past few years.

DLR is responsible for Heinrich Hertz’s project planning and implementation. Germany’s Federal Ministry for Economic Affairs and Energy is financing the program.

Among the experiments on Heinrich Hertz will be several different propulsion systems.

“Heinrich Hertz is planned to use chemical and electric propulsion,” Gruppe said. “We want to test and operate the new electric [High Efficiency Multistage Plasma] thrusters for station keeping, which were developed for DLR. As backup we implement the electric [Hall-Effect Thrusters] thrusters for risk mitigation. The chemical propulsion will be used for orbit transfer and for station keeping, too.”

Gruppe said the satellite will test new antennas, flexible amplifiers, multiplexers, filters and onboard processing units. The satellite will also test new user equipment, including mobile antennas and modems, he said.

Heinrich Hertz’s communications payload showcases technology that can make satellites more adaptable to changing needs on the ground.

“Using a variety of flexible technologies, such as small on-board computers, it will be possible to continually reprogram the satellite from the ground station throughout its 15-year mission,” Heiko Ultes, DLR’s project manager for Heinrich Hertz, said in a June 28 statement. “This means that existing signal resources could be adapted efficiently to meet ever-changing demands. This effectively means that ‘Heinrich Hertz’ is ‘capable of learning’ throughout its life.”

OHB’s Heinrich Hertz contract includes the procurement of a launcher, as well as the construction of one main control center and one backup control center. The mission will also require 7-meter- and 13-meter-class ground station antennas.

Heinrich Hertz is named after the German physicist who first relayed electromagnetic waves in free space from a transmitter to a receiver in 1886. Gruppe said the satellite will not be used for any commercial services.