Available online at www.sciencedirect.com Advances in Space Research 50 (2012) 327–333 www.elsevier.com/locate/asr Proposal for a multiple-asteroid-flyby mission with sample return Dong Qiao ⇑, Pingyuan Cui, Hutao Cui Key Laboratory of Dynamics and Control of Flight Vehicle, Ministry of Education, School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China Received 22 November 2010; received in revised form 15 March 2012; accepted 13 April 2012 Available online 21 April 2012 Abstract Asteroid exploration provides a new approach to study the formation of the solar system and the planetary evolution. Choosing a suitable target and designing of feasible profile for asteroid mission are challenging due to constraints such as scientific value and tech- nical feasibility. This paper investigates a feasible mission scenario among the potential candidates of multiple flybys and sample return missions. First, a group of potential candidates are selected by considering the physical properties and accessibility of asteroids, for the sample return missions. Second, the feasible mission scenarios for multiple flybys and sample return missions to various spectral-type asteroids are investigated. We present the optimized design of preliminary interplanetary transfer trajectory for two kinds of missions. One is the single sample return mission to asteroids with various spectral types. The other is the multiple flybys and sample return mission to several asteroids. In order to find the optimal profiles, the planetary swing-by technique and Differential Evolution algorithm are used. Ó 2012 COSPAR. Published by Elsevier Ltd. All rights reserved. Keywords: Asteroid exploration; Multiple flybys; Sample return; Planetary swing-by; Differential Evolution algorithm 1. Introduction during the asteroid flyby and deliver the sample to the Earth. Morimoto et al. proposed two types of sample return Asteroid exploration provides a new approach to study missions and investigated the feasible mission scenarios the origin of the solar system and the formation of the plan- (Morimoto et al., 2004). Sears et al. introduced the Hera ets, because the asteroids hold key information for under- mission concept that involves multiple near-Earth asteroid standing these problems. They are often called the ‘‘fossil” sample return (Sears et al., 2004). Dachwald et al. investi- of the solar system. In the past, asteroid and comet missions gated the feasibility of multiple rendezvous and sample such as NEAR, Hayabusa, Deep Impact, ROSETTA, return missions to the near-Earth objects using solar sail- DAWN have been carried out, and gained plenty of valu- craft (Dachwald et al., 2006), and discussed main-belt aster- able experience and scientific data. With many new asteroid oid sample return missions by using the solar electric missions in various stages under development (Hayabusa II, propulsion (Dachwald et al., 2008). Don Quijote, Hera), our understanding of these celestial In this paper, we have primarily aimed this study at two bodies could be further improved in the future. aspects. On one hand, by considering physical properties, The sample return missions are able to obtain more phys- potential scientific value, and accessibility of asteroid, a ical details of the asteroids. Thus they attract more and more group of candidates are selected for the sample return mis- attention. Sukhanov et al. proposed main-belt asteroid sam- sions. On the other hand, we investigate the feasible mission ple return without landing on the asteroid (Sukhanov et al., scenarios for the sample return missions with multiple-aster- 2001). The proposed mission aims to collect the sample oids flybys. Two kinds of missions are considered: the single sample return missions to various spectral-type asteroids ⇑ Corresponding author. and the multiple-flybys and sample return missions to E-mail address: [email protected] (D. Qiao). several asteroids. 0273-1177/$36.00 Ó 2012 COSPAR. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.asr.2012.04.014 328 D. Qiao et al. / Advances in Space Research 50 (2012) 327–333 2. Target selection for sample return missions on basis of the radar observation data. Among the C-type asteroids, Nereus is a well-known asteroid and was selected It is generally believed that a large number of small as the target for NEAP missions. bodies including asteroids and comets were left over as D-type and P-type asteroids have low albedo and are remnants of the formation of the solar system. Asteroids redder than the C-type ones. Their properties are thought represent a large part of these primordial objects and reside to be of the most primitive origin. D-type asteroids such throughout the solar system since its formation. Therefore, as (3552) Don Quixote and 1997 SE5 show some charac- asteroid exploration, especially the sample return, can teristics of extinct comets (Hicks et al., 1998, 2000). From obtain more mineralogical composition details of asteroids the hazard assessment and the resource utilization points and greatly enhance our understanding of the planetary of view, M-type asteroids that may have high metallic con- formation and evolution process. tents by virtue of high radar albedo are perhaps the most Asteroids are categorized into many populations. Among practical interests among the NEAs (Tedesco et al., these populations, the Near-Earth Asteroids (NEAs), whose 1987). Two most notable asteroids among the M-type dynamic characteristics allow close approaches to our pla- NEAs are (3554) Amun and (6178) 1986DA. net, are gaining increasing attention. The attention to NEAs V-type asteroids are widely believed to be the fragments is due to not only their apparent scientific value and technical of the basaltic surface of the large main-belt asteroid 4 feasibility, but also their potential risk of collision with the Vesta, and are thought to be possible parent bodies of Earth. For selecting the target for an asteroid mission, it is the Howardite–Eucrite–Diogenite meteorites. Therefore, undoubted that the NEAs should take priority of the poten- V-type objects, such as (3361) Orpheus, (6489) Golevka, tial candidates. and (3908) Nyx, are also regarded as the primary targets. The NEA population consists of several sub-categories, E-type asteroids show appear both compositional and such as Atens, Apollos, Amors and Apohele. The Aten aster- dynamical relation to the Hungaria region (high incli- oids have a semimajor axis a less than that of the Earth and nation objects) of the inner asteroid belt (Gaffey et al., aphelia Q larger than Earth’s perihelion distance (a <1 1992). Among the E-type objects, (3103) Eger, 1989ML, AU, Q > 0.983 AU). The Apollo asteroids have a semi-ma- 1998WT24, and 1991VH are well known. jor axis greater than that of the Earth and perihelia q inside Q-type asteroids have spectra similar to that of the the aphelion distance of the Earth (a > 1AU, q < 1.017 ordinary-chondrite meteorites in laboratory (Bus et al., AU). The Amor asteroids are those with perihelia 2002). S-type asteroids have higher albedo and their approaching from outside of the orbit of our planet reddish spectrum are characterized in the near-infrared side (A > 1 AU, 1.017 < q < 1.3 AU). In addition, the Apo- by the absorption bands of pyroxene and olivine. The rela- hele (or Inner-Earth Objects, IEOs), whose orbits reside en- tion between these two types of asteroids and the ordinary- tirely inside that of the Earth (Q < 0.983 AU), has been chondrite meteorites has been debated for decades. The also proposed for one additional group of NEAs, although exploration and sample return of Q-type and S-type aster- in practice the Aten group could be extended to include oid can help solving the controversial problems. Among these objects. these Q-type and S-type objects, there are a quantity of The physical properties of asteroid, such as taxonomy, notable Q-type asteroids such as Akka, 1991VK, 1998PG, shapes, rotations, and optical properties, may provide and well-known S-type objects such as Toutatis, McAuliffe, important clues for the evolution of the planetary dynam- Seleucus, Geographos, Ivar, Anteros. ics, the origin of the solar system, and other significant In addition, other physical properties, such as the exotic topics. Among them, the taxonomic classifications and rotation states, the binary system, and the elongated shape, the mineralogical interpretations provide evidence for are also significant factors influencing scientific target selec- understanding the origin and the formation of the solar tion because these properties can help us understand some system. Almost all the taxonomic classes of the main-belt important problems, notwithstanding the fact that these asteroids are represented among the NEAs, including some properties alone are not sufficient to conclusively reveal peculiar types in the outer asteroid belt. The spectral type the origin of an individual NEA. For example, 1996FG3, and the mineralogical characterization may be extremely Dionysus, Didymos, and 1998PG show the double light- useful information for pinpointing source regions of NEAs curve binary. and their dynamical evolution. When selecting candidates for mission, the accessibility For instance, the low-albedo primitive C-type bodies of asteroids need to be considered, as it happens that some would represent samples of the pristine material character- objects are ‘‘the best candidates” from a scientific point of izing the outer main-belt asteroids. Among the C-type view but don’t satisfy the technical requirements. The mea- targets, we choose Wilson-Harrington, 1996 FG3, Nereus sure of accessibility is generally the minimum total velocity asteroids as candidates. Wilson-Harrington appears to be increments for two-impulse transfer to rendezvous with the consistent with the primitive solar-system materials pre- target body. In previous literature, some classical methods sumed to dominate in comets (Fernandez et al., 1997). for evaluating accessibility of asteroid, such as the Hoh- 1996 FG3 asteroid may be composed of the primitive mann transfer (Perozzi et al., 2001; Binzel et al.