OKEANOS – A Mission That Would Have Returned Samples From the Trojan Asteroids

By Andy Tomaswick

Published on November 26, 2024

OKEANOS Mission Concept
Concept images of the OKEANOS mission. Credit – Takao et al.

Getting a mission to the point of officially being accepted for launch is an ordeal. However, even when they aren’t selected for implementation, their ideas, and in some cases, their technologies, can live on in other missions. That was the case for the Oversize Kite-craft for Exploration and AstroNautics in the Outer Solar System (OKEANOS) project, originally planned as a Japanese Aerospace Exploration Agency (JAXA) mission. Despite not receiving funding to complete its entire mission, the project team released a paper that details the original plan for the mission, and some of those plans were incorporated into other missions that are still under development.

The Purpose of OKEANOS

The OKEANOS mission aimed to build on JAXA's successful Hayabusa-2 mission, which successfully returned samples from the asteroid Ryugu in 2020. Unlike Ryugu, which is a near-Earth asteroid, the Trojan asteroids reside at the Lagrange points of the Jupiter-Sun system, occupying stable positions in front of and behind Jupiter. These locations hold significant scientific interest, as the Trojan asteroids are thought to contain primordial material from the early solar system.

Scientists believe that these asteroids originated from the Kuiper belt but were gravitationally pulled closer to the Sun by the massive gas giants. Understanding the composition of these bodies could provide vital insights into the formation of the solar system and the building blocks of planetary bodies.

A solar panel, like the one shown in the video, would have been a key component of the OKEANOS missions. Credit – The Japan Times YouTube Channel

Technology and Design

Several innovative technologies were proposed for the OKEANOS mission. A notable highlight was a combination solar sail and ion drive system, referred to as the solar power sail. This technology was envisioned to harness solar energy while simultaneously providing propulsion capability. The solar sail would allow the spacecraft to utilize solar radiation pressure to propel itself through the vast distances of the solar system.

The OKEANOS mission would also utilize an ion engine, meaning that once the spacecraft reached its destination, it could rely on an ion propulsion system to make its maneuvering more efficient. This technology is essential considering the harsh environment and weak gravitational forces in the outer solar system.

The Role of the Lander

Upon reaching one of the Trojan asteroids, OKEANOS intended to deploy a lander capable of collecting samples directly from the surface of the asteroid. The operational challenge was substantial, as this would be the first attempt at landing on a Trojan asteroid and returning samples via a "mothership"—a spacecraft that would travel back to Earth with collected material. Previous missions like Philae, part of ESA's Rosetta mission that landed on Comet 67P/Churyumov–Gerasimenko, demonstrated some of the technical complexity involved, but returning astromaterials from a Trojan asteroid posed even more significant hurdles.

Lack of Funding and Future Implications

Despite the promise that the OKEANOS mission held, JAXA ultimately did not fully fund it. The project was sidelined due to budgetary constraints, with JAXA instead opting to pursue another mission known as LiteBIRD, intended to study the cosmic microwave background.

Nevertheless, many of the technical specifications and design methodologies initially developed for OKEANOS have found their way into future asteroid missions. Researchers expect that the advancements stemming from this project will influence how we approach outer solar system exploration and sample return missions in the years to come.

Comparative Missions and Future Directions

Lucy, a more recent NASA mission, launched in 2021, is designed to conduct flybys of the Trojan asteroids, offering remote observations but lacking the capability to land or return samples. Although Lucy does not fulfill the same scientific objectives as the OKEANOS mission, it symbolizes a growing interest in these unique classes of asteroids.

One of the lessons learned from the OKEANOS proposal is the importance of advancements in propulsion technology. Many of the challenges facing future missions could be alleviated by utilizing the sophisticated solar power sail and ion engine hybrid systems. With that said, as technology continues to advance and funding priorities shift, the opportunity for a dedicated Trojan asteroid sample return mission remains an enticing prospect for the scientific community.

Conclusion

References

  • Takao et al. – Sample return system of OKEANOS—the solar power sail for Jupiter Trojan exploration (available at ResearchGate)
  • Universe Today – Lucy Adds Another Asteroid to its Flyby List (available on Universe Today)
  • Universe Today – Separation Camera Takes Full Images and ‘Movie’ of IKAROS Solar Sail (available on Universe Today)
  • Universe Today – Tiny Fragments of a 4-Billion Year Old Asteroid Reveal Its History (available on Universe Today)
The link has been copied!