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NEOShield-2 Report Summary

Project ID: 640351
Funded under: H2020-EU.2.1.6.

Periodic Reporting for period 1 - NEOShield-2 (Science and Technology for Near-Earth Object Impact Prevention)

Reporting period: 2015-03-01 to 2016-03-31

Summary of the context and overall objectives of the project

(Note: Figure numbers refer to the image files uploaded to the "Publishable summary" section within the online "Periodic Reporting" module and are also provided in the core of the Periodic Report: Periodic Technical Report 1 ‒ Part B, section 6.4 "Images attached to the Summary for publication" on page 70.)

Collisions of celestial objects with the Earth have taken place frequently over geological history and major collisions of asteroids and comets with the Earth will continue to occur at irregular, unpredictable intervals in the future. As a result of modern observing techniques and directed efforts thousands of near-Earth objects (NEOs) have been discovered over the past 20 years and the reality of the impact hazard has been laid bare. Even relatively small impactors can cause considerable damage: the asteroid that exploded over the Russian city of Chelyabinsk in February 2013 had a diameter of only 18 m yet produced a blast wave that damaged buildings and caused injuries to some 1500 people (see uploaded Figure 1). The potentially devastating effects of an impact of a large asteroid or comet are now well recognized.
Asteroids and comets are considered to be remnant bodies from the epoch of planet formation. Planet embryos formed in the protoplanetary disk about 4.5 billion years ago via the accretion of dust grains and collisions with smaller bodies (planetesimals). A number of planet embryos succeeded in developing into the planets we observe today; the growth of other planet embryos and planetesimals was terminated by catastrophic collisions or a lack of material in their orbital zones to accrete. Most asteroids are thought to be the fragments of bodies that formed in the inner Solar System and were subsequently broken up in collisions.
As a result of collisions, subtle thermal effects and the very strong gravitational field of Jupiter, small main-belt asteroids can drift into certain orbital zones from which they may be ejected under the influence of Jupiter into the inner Solar System. The population of NEOs is thought to consist mainly of such objects, together with an unknown smaller number of old, inactive cometary nuclei. At the time of writing the number of known NEOs exceeds 14000 (; over 1600 of these are so-called potentially hazardous objects (PHOs), i.e. those having orbits that can bring them within 7.5 million kilometres of the Earth’s orbit and are large enough (diameter ≥ 100 m) to destroy a large city or urban area and kill millions of people if they were to impact the Earth. Smaller objects can also present a significant threat: the Chelyabinsk event is a very recent example (see above); a somewhat larger object caused the Tunguska event of 1908 in Siberia, in which an area of over 2000 square km was devastated and some 80 million trees felled. The Tunguska event is thought to have been due to the airburst of an object with a diameter of 30 - 50 m at a height of 5 - 10 km. The estimated impact frequency of NEOs on the Earth depends on size. The impact frequency increases with decreasing size due to the size distribution of the asteroid population: there are many more small objects than large ones. Current, albeit uncertain, statistical knowledge of the NEO size and orbital distributions indicates that NEOs with diameters of 50, 100, 300 m, for example, impact roughly every 1000, 10,000, and 70,000 years, respectively.
The known NEO population contains objects with a confusing variety of physical properties. Some NEOs are thought to be largely metallic, indicative of material of high density and strength, while some others are carbonaceous, of lower density, and less robust. A number of NEOs appear to be evolved cometary nuclei that are presumably porous and of low density but otherwise with essentially unknown physical characteristics. In terms of large-scale structure NEOs range from monolithic slabs to re-accumulated masses of collisional fragments (so-"

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The following is a brief description of highlights and results achieved so far from the technical and scientific work packages following the logical structure of the project: starting with the reference mission definition activities, the technical results from developing autonomous guidance, navigation, and control systems, the developed techniques for precise and rapid NEO orbit determination or the assessment of sample return technologies and development of a sampling device through target selection for deflection demonstration missions, to the results from the scientific work packages concerned with astronomical observations on multiple telescopes, the related data analysis, the derivation of NEO physical properties, modelling work and computer simulations, and finally the requirements for Future Research and International Actions.

*Reference Mission Definition & GNC Technology Validation I/F*
Based on existing mission designs, i.e. the NEOShield Kinetic Impactor deflection demonstration mission or the NEOTωIST Impactor only concept within NEOShield-2 the definition of reference mission and scenario requirements for targeted technology development for mitigation demonstration and sample return missions has been performed (refer to uploaded Figure 2 for the addressed mission scenarios). Two separate sets of reference mission descriptions and requirements have been documented in deliverables D3.1 "Reference mission definition: Mitigation Demonstration" and D3.2 "Reference mission definition: Sample Return". Both deliverables have been agreed within the consortium during the Reference Mission Definition and Requirement Review (MDRR) conducted within the first months of the project.
In subsequent activities the reference mission definitions are used to technically guide and validate against the technology development activities in WP4, 5, 6, 7 and 8 of the project. In context of the "GNC Technology Validation I/F" task, established to harmonize the undertaken technology development and verification/validation process for the different GNC missions as an independent validation instance towards the European Commission, numerous discussions interface and review meetings between all relevant parties have been held finally leading to a commonly established and agreed test plan.
The GNC validation and demonstration activities are decisive for raising the level of technology readiness of guidance, navigation and control techniques relevant for missions to NEOs to TRL 5-6, a prerequisite for conducting such missions in the future and for undertaking mitigation demonstrations. Validation and demonstration will occur through E2E GNC performance verification and validation definition and test plan (GNC E2E Performance Verification and Validation Plan, D3.3), monitoring of the GNC activities and TRL assessment. The proposed approach will be performed under the lead and guidance of GNC experts at ADS-DE who are however not involved in the respective GNC development for the specific missions. This is to secure the achievement of the targeted objective of significant rise of readiness level for enabling GNC technologies, whilst providing efficient coordination and guidance of the technical activities in a transparent and impartial manner.
In form of mini-project the novel deflection demonstration concept NEOTωIST has been introduced to explore a promising implementation option for a low-cost and high-value demonstration mission of the kinetic impactor concept (see uploaded Figure 3).
The mission rationale and its value proposition have been assessed during an organized workshop and its aftermath, as well as the derivation of observation requirements and therefore needed observation techniques. This is essential to perform in a next step high level concept trade-offs to consolidate the reference mission concept and to further examine the key technical challenges that must be resolved for successful mission development. This comprises the fo

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

We consider the main results from the NEOShield-2 project to be:
• Detailed definition of characteristic reference mission scenarios applicable to different NEO threat, deflection demonstration and in-situ characterization scenarios.
• Significant advances in development of autonomous guidance, navigation, and control systems as key technologies to explore and deflect NEOs. It allows for increased targeting accuracy and relative velocity of a kinetic impactor spacecraft into a small (e.g. 50-300m diameter) asteroid and facilitates approach/arrival including surface observation close to and landing onto low-gravity, irregularly shaped asteroids. A harmonized common approach for GNC validation and demonstration activities and transparent success criteria to raise & evaluate the level of technology readiness has been applied to all three GNC technology development scenarios.
• A novel low-cost kinetic impactor deflection demonstration concept called NEOTωIST, based on changing the spin rate of the NEO Itokawa. In its cheapest form, the concept requires only one spacecraft, the impactor, since the change in spin rate of the asteroid, and therefore the momentum transfer efficiency, can be measured via ground-based lightcurve observations. However, as the mission rationale and its value proposition assessment shows, the scientific value is largely increased by a small impact observing flyby module and CubeSat chasers for close-up ejecta cloud observations. Essential high level concept trade-offs to consolidate the technical concept and further examine the key technical challenges are ongoing.
• Improved techniques for NEO orbit determination allowing in short-term accurate quantification and validation of deflection attempts and its effects on the NEOs orbit also for deflection mission scenarios where no observations from Earth are possible.
• Identification of most promising sampling strategies as key aspect for all future sample-return missions targeting solar system bodies. Conducting an in depth analysis of existing and currently developed instruments suitable for NEO in-situ analysis and development including breadboard tests of a promising sampling device for the collection of material samples.
• The astronomical observations carried out by NEOShield-2 already more than doubled the available data for what concerns the surface composition (taxonomy) of small NEOs of most concern for mitigation/deflection purposes, and several objects of particular interest have been identified and/or studied in parallel. Moreover a number of observing runs are already foreseen for the next 1.5 years at several worldwide telescopes to continue our significant contribution to the physical characterisation of the NEO population leading to an increased list of suitable candidate targets for deflection test missions. Novel strategies are being developed by the related partners for the rotational and thermophysical modelling of extended samples of NEOs.
• The identification and characterization of several suitable target NEOs for exploration and mitigation/deflection (demonstration) missions on the basis of pre-computed trajectories is an ongoing process dynamically considering the list of known NEOs, which is enlarged by about 3-8 new objects per day (!) due to the respective rate of daily new NEO discoveries.
• Establishment of an online NEOShield-2 "NEO Properties Portal" (NEOPP, disseminating the data, tools and results produced by the project in open access to the public and supporting the observers as well as the mission analysts. The "NEO Properties Portal" contains observational data, derived physical properties, observation status & priority lists, and mission opportunities tables to suitable target NEOs for exploration and mitigation/deflection (demonstration) missions.
• An agreement to future migrate all data, made publicly available through the "NEO Properties Portal" internet server, to the

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