DLR Orbital Hub – A Modular Concept for Affordable Post-ISS Human Spaceflight

Source: DLR

The International Space Station (ISS) has been a remarkable achievement in space exploration and scientific research. However, its operational lifetime is limited, with an expected decommissioning in the 2030. In 2017, Engineers at the German Aerospace Center (DLR) proposed an innovative modular concept called the Orbital Hub to meet this need. This article provides an overview of the concept.

Overview of the Orbital Hub

The Orbital Hub consists of two complementary elements. The Base Platform provides basic functionality for long-term human habitation and research. This includes living quarters, laboratories, environmental control systems, and docking ports. It is designed to support a permanent crew of 3 astronauts.

The second element is the Free Flyer, an uncrewed autonomous research platform optimized for microgravity experiments. It provides expanded capabilities beyond the Base Platform. The Free Flyer operates independently but can dock with the Base Platform periodically for servicing and maintenance.

This modular approach allows the crewed and uncrewed sections to be decoupled. The lack of crew on the Free Flyer minimizes perturbations, creating a higher quality microgravity environment critical for certain experiments. It also enables flexible pointing options like Earth observation and deep space telescopes.

Incorporating Lessons from the ISS

The Orbital Hub design builds upon experience and lessons learned from the ISS program. For example, new operational concepts reduce the need for crew maintenance activities. The station aims to avoid regular extravehicular activities (EVAs), relying instead on robotics and autonomous systems. This improves safety and decreases costs associated with EVAs. The overall modular architecture and standards like the International Docking System also streamline operations compared to the ISS.

Technical Details and Design

Detailed technical design of the two elements was done via concurrent engineering studies. The Base Platform has an initial estimated mass of 63 tonnes, about 15% of the ISS mass. It provides 30 kW of power with a permanent crew of 3. The Free Flyer has a mass of 25 tonnes and power of 27 kW. It provides a pressurized laboratory and external unpressurized platform for diverse payloads.

User Applications and Payloads

The Orbital Hub aims to appeal to both scientific and commercial users with its capabilities. The Base Platform focuses on human physiology research and technology demonstrations. The Free Flyer enables microgravity materials science, Earth/space observations, and technology tests. Frequent payload exchanges are intended to support a variety of users.

Launch and Assembly Sequence

The Orbital Hub would be constructed over multiple launches. The Free Flyer is launched first, followed by the Base Platform modules. The Free Flyer provides maneuvering capability to rendezvous and assemble the full station. No astronaut involvement is needed until the Base Platform is completely operational.

International Partnership Approach

While the Orbital Hub could have been an ESA-led program, international partnership was envisioned to provide funding, technical capabilities, and operational expertise. This cooperative approach builds on the successful ISS model. Both existing and new space agencies could contribute based on their interests.

Outlook for Realization

The estimated cost for Orbital Hub development, in 2017, was 2.8 billion Euros over several years. DLR planned to further refine the concept through additional analyses, trade studies, and prototyping of key systems. The goal was to position the Orbital Hub as a viable post-ISS human spaceflight program. No updates are available regarding the current status of the concept.

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