Science and Power Platform, NEP
The concept of the Science and Power Platform, NEP, originated in the Mir-2 project, where a special truss was designed to carry an array of solar panels, power-generating concentrators, radiators and scientific payloads. The truss would extend symmetrically on both sides of the Mir-2's core module.
After Russian Mir-2 and NASA Freedom programs merged in 1993, NEP was reconfigured to meet goals of the new project. Original plans called for the NEP launch onboard Zenit booster, however, political problems between Russia and Ukraine, where Zenit was manufactured, prompted a switch to the US Space Shuttle in 1994.
This change would greatly facilitate the integration of the platform into the ISS, since no orbital tug would be required to maneuver NEP from the initial orbit to a rendezvous and docking with the station. The Space Shuttle would perform all the maneuvers and dock the platform to the station using its robotic arm.
In its original configuration, NEP consisted of three major elements:
At the time, the Space Shuttle docks NEP to the station its weight would be 15.6 tons, however, after the truss was equipped with all its payloads and hardware it would grow to 20 tons.
NEP development status
Russian space agency virtually stopped funding NEP in the first half of 1998, after paying for its initial development in 1996 and 1997. RKK Energia tried to continue NEP development on its own during 1999 and the beginning of 2000; however, had to stop the project at the point where considerable investment of funds was needed for further work.
As of January 2001, RKK Energia completed the assembly of two prototypes of the pressurized compartments - one for static and one for dynamic testing. Also, some parts for the flight version of the pressurized compartment have been produced.
All three copies of the structure connecting pressurized module with the main truss have been manufactured as well. All the elements for two prototypes of the main truss have been manufactured and currently TsSKB Progress in the city of Samara is conducting the integration of the static prototype of the truss with the goal of finishing the assembly by the end of the first quarter of 2001. The government does not fund this work.
RKK Energia also completed preliminary design of all major payloads and equipment for the NEP. RKK Energia subcontractors also manufactured prototypes of some systems; however, considerable investments are necessary before production of the flight hardware could be started.
Officially, NEP was scheduled for launch onboard US Space Shuttle in October 2002, during mission 9A.1, however, the financial problems have already pushed the project many months behind schedule.
Rosaviacosmos, reportedly allocated no funds for NEP development in 2001, so the development of the module as well as its launch date will likely continue to slip.
RKK Energia currently evaluates the proposals to scale down the NEP design to somewhat less ambitious configuration, which would be financially easier to implement. Skeptics say, however, that it given already manufactured hardware, it would be cheaper to complete the existing design than to develop the platform from scratch.
Without NEP, the Russian segment of the station, if ever build will have very limited energy capabilities provided primarily by the solar panels aboard the Zvezda Service Module. RKK Energia plans to deploy additional solar arrays onboard Zvezda, however they will provide only minuscule growth in the power supply to the Russian segment.
RKK Energia streamlines NEP design
In the effort to move forward stalled construction of the Russian segment of the ISS, RKK Energia made a decision to streamline the design of the NEP platform.
In the new configuration, NEP lost its pressurized section, as well as radiators and four out of eight solar panels. During the launch onboard the shuttle, NEP would be equipped with two solar panels, and two additional panels would be delivered and deployed later. All together, four panels would provide 25 kilowatt of electrical power, instead of 50 kilowatt, which would be provided with the previous configuration. Radiators would then be installed separately on individual modules.
As of 2001, the NEP platform was expected to be launched along with the Enterprise module on the same Shuttle mission (9A1) at the end of 2004. By 2004, the delivery of the NEP to the ISS was deferred to 2009 and the project was soon cancelled.
NEMs to replace NEP
Many functions of the NEP platform were transferred to a pair of NEM modules, whose development started in 2012. Both vehicles were to carry large solar panels and rotating mechanisms, whose development RKK Energia planned to sub-contract to ISS Reshetnev in Zheleznogorsk.
The isolated view of the Russian segment of the International Space Station with the NEP science and power platform seen at the top. Credit: RKK Energia