Triple F—a comet nucleus sample return mission

Abstract

The Triple F (Fresh From the Fridge) mission, a Comet Nucleus Sample Return, has been proposed to ESA's Cosmic Vision program. A sample return from a comet enables us to reach the ultimate goal of cometary research. Since comets are the least processed bodies in the solar system, the proposal goes far beyond cometary science topics (like the explanation of cometary activity) and delivers invaluable information about the formation of the solar system and the interstellar molecular cloud from which it formed.The proposed mission would extract three sample cores of the upper 50 cm from three locations on a cometary nucleus and return them cooled to Earth for analysis in the laboratory. The simple mission concept with a touch-andgo sampling by a single spacecraft was proposed as an M-class mission in collaboration with the Russian space agency ROSCOSMOS.

Past and Future Comet Missions

“…As (cryogenic) sample return remains the ultimate goal of comet exploration, a key technology requirement is the ability to land on the nucleus safely: either in a brief 'touch and go' maneuver, as used by the asteroid missions Hayabusa, Hayabusa 2 and OSIRIS-REx, and proposed at a comet by the Triple-F mission (Küppers et al 2009), or for a longer period of measurement/drilling. Landers also have a lot of potential to advance our knowledge of cometary activity, independent of any sample return attempt, through local measurements of the surface (micro-)physics, as was planned for Philae.…”

“…Drilling into the ice, and extracting an unaltered core, would be technically challenging. The SD2 drill on Philae was designed to reach a depth of 23 cm and retrieve material (but not an intact core) for composition analysis (Finzi et al 2007), while Triple-F proposed to extract 50 cm cores in touch-and-go landings (Küppers et al 2009). Neither of these has been successfully demonstrated at a comet; obtaining meters-long ice cores will require significant advances of these technologies, but may benefit from current developments for ocean world applications (Dachwald et al 2020).…”

“…There have been recent technological advances in cryogenic flight systems and instrumentation, as well as in cryogenic sample curation, handling, and analysis (Westphal et al 2021). Küppers et al (2009) proposed a passive system that would keep the sample below 133 K during cruise and 163 K during reentry, which would return a valuable sample at relatively low cost, even if some ices were lost. Bockelée-Morvan et al (2021) suggest that temperatures must be kept below 90 K, and pressure at 1 bar, to preserve most volatile ices (H 2 O, CO 2 , HCN).…”

AMBITION – comet nucleus cryogenic sample return

“…In Europe, numerous industrial studies have been performed, in particular during phase A studies at ESA of the MarcoPolo and MarcoPolo-R asteroid sample return projects [20] for the Cosmic Vision programme (2015-2025), including sampling tool technology and the re-entry capsule (e.g., heat shield material development, aerodynamic stability). The Triple-F mission, a Comet Nucleus Cryogenic Sample return, has also been proposed to the Cosmic Vision programme, in collaboration with the Russian space agency [125].…”

On the attempts to measure water (and other volatiles) directly at the surface of a comet

“…This craft was also implicated in the Deep Impact campaign, which saw a projectile directed at the surface of comet 9P/Tempel 1 in 2005 (with the subsequent impact plume being observed by the Deep Impact spacecraft itself), followed by a flyby in 2011 of Stardust (known by now as Stardust NExT) to observe the crater that had been formed on the comet's surface. An overview of the achievements of (most of) these missions can be found in, for instance, Kuppers et al [12].…”