Establishing Strategic Asteroid Resource Exploration Using a Combination of Small Spacecraft Solutions and Solar Sailing

Physical interaction with small solar system bodies (SSSB) for sampling has become the prime enabler for front-line planetary science related to SSSBs, propagating into solar system science towards interstellar objects, exoplanet and stellar formation research. [1,2,3] However, not every SSSB mission can take risks of extremely close approach, and heritage spacecraft to be re-used may not be designed with sampling in mind. Thus, risk takers that build a bridge to the surface at low resources cost may be of interest for near-term and future missions.    

Physical contact is also key for planetary defense (PD) and in-situ resource utilization (ISRU). From the seminal 1980 Alvarez paper on impact-triggered global extinction events to the 0.5 MtTNT Chelyabinsk airburst of 2013, the political mandate to discover, track and understand the population of potentially hazardous objects (PHO) was created and implemented, first in the U.S., now increasingly also in Europe. Within another decade, DART, the first PD test mission was built and successfully flown by NASA to perform a kinetic impact on Dimorphos. [4] ESA is following up with Hera, an impact effects assessment mission to the (65803) Didymos system to be launched later this year. [5]

Following a brief rush of interest in SSSB mining specifically for platinum-group metals and water, we now see the beginning of sustained long-term interest in SSSB resources as a potential major source of bulk materials for heavy or distant space-based infrastructures. [6]

The prerequisite for any such undertakings is scientific understanding of all relevant SSSB properties, including composition, surface and interior structure, and thermal properties. Although patterns appear, a comprehensive and detailed SSSB classification still has to evolve, with each investigated asteroid displaying its own uniqueness. In particular, geotechnical and interior structure aspects are little understood. This requires a much broader and more in-depth characterization effort for and by the ‘asteroid user communities’ – planetary science, planetary defense, planetary resources, and planetary infrastructures.

The close Earth encounter of (99942) Apophis on Friday, April 13^th, 2029 offers many scientific exploration, interaction and responsive mission implementation exercise opportunities that will also deeply inform PD and ISRU development. A small flotilla of planetary science missions led by OSIRIS-APEX and RAMSES is set to rendezvous with Apophis around the close encounter. It can include sample-return because of a fast, low ∆v return trajectory opportunity which we propose to take advantage of by the APOphiS SUrface sampler, APOSSUM, a small carry-on sample-return spacecraft (Hilchenbach et al., this conference) with a compelling science case including investigations into the recent LL chondrite parent body disruption (Stenzel et al., this conference).

An ideal complement for the orbiters OSIRIS-APEX and RAMSES as well as APOSSUM would be the deployment of MASCOT@Apophis nano-landers, derivatives of the shoebox-sized Mobile Asteroid Surface scCOuT deployed by the JAXA Hayabusa2 mission to carbonaceous NEA (162173) Ryugu. [7-12] MASCOTs are compatible also with small interplanetary missions designed for carry-along- or piggy-back launch accommodation, such as APOSSUM. After the initial scouting phase, the unique mobility mechanism and the addition of photovoltaic power enable long-lived missions that can traverse a SSSB’s surface by hopping from location to location. Many mission-specific MASCOT derivatives have been explored, such as the MASCOT2 for ESA‘s AIM spacecraft, the precursor of Hera which is the basis for RAMSES, or the CALICUT for the CNSA ZhengHe mission concept. [13-15] A self-transferring, minimalistic nanolander for a complex binary asteroid system has also been studied in detail. [16,17]

Many near-Earth asteroids (NEA) have occasional close Earth encounters at a few lunar distances which enable the implementation of a short duration sample-return trajectory similar to those of APOSSUM. These could be provided rapidly, by ‘asteroid as a service’ spacecraft evolved from APOSSUM, augmented with a transfer stage for propulsion, and with MASCOTs to scout the surface ahead of the sampling operations and to provide high-resolution surface and interior context science.   

Further along, target-flexible Multiple NEA Rendezvous (MNR) missions can significantly expand the choice of SSSB targets accessible within a reasonable time. The DLR-ESTEC Gossamer Roadmap Science Working Groups have identified MNR as a mission class uniquely feasible with solar sail propulsion. [18-20] Integration of a shuttling sample-return lander similar in size to APOSSUM has been studied in detail jointly by DLR and JAXA for the Solar Power Sail long-duration mission design, OKEANOS. [21-24]

The performance of now-term technology, i.e., that which can be designed into flight hardware immediately, is sufficient to fly all these missions. The methods which led MASCOT within 2 years from funding acquisition to flight model on the spacecraft, such as Concurrent Engineering, Constraints-Driven Engineering and Concurrent Assembly Integration and Verification enable the agile implementation of responsive missions based on and designed for re-use. [25,26]

Mother Nature offered a rare opportunity 20 years ago with the discovery of Apophis on June 19^th, 2004, and its upcoming close encounter in 2029. It’s time to get up and go. [27]

[1] Tsuda et al., 2013, doi:10.1016/j.actaastro.2013.06.028, [2] Lauretta et al., 2017 doi:10.1007/s11214-017-0405-1, [3] Küppers et al, 2024, hou.usra.edu/meetings/apophis2024/pdf/2053.pdf, [4] Cheng et al. 2023, doi:10.1038/s41586-023-05878-z, [5] Michel et al., doi:10.3847/PSJ/ac6f52, [6] www.planetarysunshade.org/s/PSF-State-of-Space-Intl-Print-Version.pdf, [7] Ho et al, 2016, DOI:10.1007/s11214-016-0251-6, [8] Bibring et al., 2017, DOI:10.1007/s11214-017-0335-y, [9] Jaumann et al., 2016, DOI:10.1007/s11214-016-0263-2, [10] Grott et al., 2016, DOI:10.1007/s11214-016-0272-1, [11] Herčík et al., 2016, DOI:10.1007/s11214-016-0236-5, [12] Ho et al., 2021, doi:10.1016/j.pss.2021.105200, [13] Lange et al., 2018, doi:10.1016/j.actaastro.2018.05.013, [14] Hérique et al., 2019, doi:10.1016/j.actaastro.2018.03.058, [15] Ho et al., 2023, doi:10.1016/j.actaastro.2023.08.024, [16] Chand, 2020, elib.dlr.de/143958/, [17] Chand et al., IAC 2020, [18] Dachwald et al., 2014, doi:10.1007/978-3-642-34907-2_15, [19] McInnes et al., 2014, doi:10.1007/978-3-642-34907-2_16, [20] Macdonald et al., 2014, doi:10.1007/978-3-642-34907-2_17, [21] Mori et al., 2018, doi:10.2322/tastj.16.328, [22] Okada et al., 2018, doi:10.1016/j.pss.2018.06.020, [23] Grundmann et al., 2017, elib.dlr.de/118803/, [24] Grundmann et al., 2019, doi:10.1016/j.actaastro.2018.03.019, [25] Grimm et al., 2018, doi:10.1016/j.paerosci.2018.11.001, [26] Grimm & Hendrikse, 2019, doi:10.1016/j.mex.2019.08.010, [27] Caffey & Wiedlin, 1982.