Marco Polo (spacecraft)

Marco Polo was a proposed space mission studied between 2007 and 2010. It was for a near Earth asteroid sample return, and was considered for the ESA Cosmic Vision programme. It was rejected for fourth time in March 2015 for the "M" medium-class missions under Europe's "Cosmic Vision" programme.

Overview

It was a space mission aimed at visiting a small asteroid and returning a sample to Earth for analysis in laboratory. It was rejected for the program Cosmic Vision 2015-2025 of the European Space Agency (ESA) in June 2007 but selected for further assessment studies in November 2007. The in-situ investigation and sample analysis would allow to improve knowledge of the physical and chemical properties of a small Near-Earth object (NEO) which is believed to have kept the original composition of the solar nebula in which planet formed. Thus, it would provide some constraints to the models of planet formation and some information on how life may have been brought to Earth. Information on the physical structure would help defining efficient mitigation strategies against a potential threatening object.

Missions

Small bodies, as primitive leftover building blocks of the Solar System formation process, offer clues to the chemical mixture from which the planets formed some 4.6 billion years ago. Current exobiological scenarios for the origin of life invoke an exogenous delivery of organic matter to the early Earth: it has been proposed that carbonaceous chondrite matter (in the form of planetesimals or dust) could have brought these complex organic molecules capable of triggering the pre-biotic synthesis of biochemical compounds on the early Earth. Moreover, collisions of NEOs with Earth pose a finite hazard to life. For all these reasons, the exploration of such objects is particularly interesting and urgent.

Primary objective

The principal scientific objective of the Marco Polo mission is to return unaltered materials from a NEO. Marco Polo would to analyze the samples in a terrestrial laboratory, and to obtain measurements that cannot yet be performed from a robotic spacecraft (e.g. dating the major events in the history of a sample: laboratory techniques can determine the time interval between the end of nucleosynthesis and agglomeration, the duration of agglomeration, time of accumulation, crystallization age, the age of major heating and degassing events, the time of metamorphism, the time of aqueous alteration, and the duration of exposure to cosmic radiation).

Other objectives

The mission would allow to:

• Determine the physical and chemical properties of the target body, which are representative of the building blocks of the terrestrial planets.
• Identify the major events (e.g. agglomeration, heating, aqueous alteration, solar wind interactions …) which influenced the history of the target.
• Determine the elemental and mineralogical properties of the target body and their variations with geological context on the surface.
• Search for pre-solar material yet unknown in meteoritic samples.
• Investigate the nature and origin of organic compounds on the target body.
• Search for organic compounds which may shed light on the origin of pre-biotic molecules.
• Understand the role of minor body impacts in the origin and evolution of life on Earth.

This NEO sample return mission would take advantage of the heritage/expertise of several European (Huygens, Philae) and Japanese (Hayabusa) missions, allowing both parties to increase their technological capabilities and thus meet a challenging objective.

Near Earth Objects

Near Earth Objects (NEO) are among the most accessible bodies of the Solar System. A number of possible targets of high scientific interest has been selected and covers a wide spectrum of possible launch windows in the time span 2015-2019, namely:

• The C-type asteroid 1999 JU3, as a representative of the numerous primitive population of the C (carbonaceous) taxonomic type asteroids; another C-type asteroid may be considered, namely 1989 UQ.
• Asteroids which belong to the primitive D and T types, namely 2001 SG286 and 2001 SK162, respectively;
• The dormant comet 4015 Wilson–Harrington (1979 VA), which can provide insights on the unknown link between asteroids and comets;
• The primitive C-type double asteroid 1996 FG3, which can provide insight into binary formation processes.

Timeline

MarcoPolo's first rejection came in the competitions for the M1 and M2 missions, which will be launched in 2018 and 2020, respectively, MarcoPolo-R, as it was then renamed and re-submitted, then lost out in the M3 competition, which will be launched in 2024. The mission was then renamed and re-submitted as MarcoPolo-2D to compete for the M4 opportunity, but it was rejected in March 2015 at the first stage of the competition.

A baseline mission scenario to 1999 JU3 included a launch with a Soyuz-type launcher of a Mother Spacescraft (MSC) possibly carrying a lander, a sampling device, a re-entry capsule and scientific payloads. The lander would perform a soft landing, anchor to the asteroid surface, and make various in situ measurements of surface/subsurface materials near the sampling site. Samples would be collected with either one or complementary techniques. Once the sampling and in-situ measurements are completed, the MSC would start the return journey towards Earth and would release the capsule for the high-speed re-entry into Earth’s atmosphere. The capsule would be retrieved on ground at a low to mid latitude, uninhabited area, possibly in the northern hemisphere. After appropriate space quarantine and sterilization processes, samples would be taken out of the capsule in a dedicated sample curation facility to conduct initial sample characterization, prior to their distribution to designated scientists for detail analyses.

Payload

The MSC scientific payloads would include a high resolution imaging system, visible and infrared and mid spectrometers, a LIDAR, and a dust monitor. These instruments would be operated during the approach, hovering and descent phases for science purpose, for landing site selection and for spacecraft safety during near-surface manoeuvres. The Lander would have its own payload for the characterization of the in situ measurements (e.g., close-up camera, panoramic camera, electron microscope, X-ray diffractometer, volatile detector, microbalance, mass spectrometer). Instruments on the lander would be operated in-situ through automatic and/or Earth commanded sequences. These instruments would also allow to characterize location and surface environment on site of the sampling. The scientific objectives of the mission would be attained by the combination of the following characterisations with the analyses of the returned samples:

1. Morphological surface properties
2. Environment conditions (e.g. dust, gravity field)
3. Mass, volume and bulk density
4. Mineralogical composition
5. Surface (and possibly subsurface) mineralogy and thermophysical properties (thermal inertia, conductivity, diffusivity, cohesion of the materials)
6. Surface elemental composition and distribution
7. Overall internal structure properties
8. Global topography
9. Volatile abundance.

Key capabilities

The Marco Polo mission would contribute to:

• Testing new technology developments: re-entry capsule, sampling technique, on board artificial intelligence, telecommunication, in situ energy, planetary protection tools.
• Preparing the next generation of laboratory facilities for extraterrestrial sample analysis.
• Having a pathfinder for sample returns from high gravity bodies and later on for human missions that may use asteroid resources to facilitate human exploration and the development of space.

The Marco Polo proposal was supported by more than 400 scientists worldwide and was prepared by a joint European Japanese group.

This mission was in competition with a few other ones for the M1, M2, M3 and M4 missions. It was rejected all four times.

See also

• MarcoPolo-R, successor to Marco Polo, submitted to the M3 call
• Asteroid
• Near-Earth object
• 4015 Wilson–Harrington

External links

• Website of the Marco Polo Mission