the existence of target asteroids

[NirViaje]

1.3AU

A near-Earth object (NEO) is any small Solar System body whose orbit can bring it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU).[2] If a NEO's orbit crosses the Earth's and the object is larger than 140 meters (460 ft) across, it is considered a potentially hazardous object (PHO).[3] Most known PHOs and NEOs are asteroids, but a small fraction are comets.[1]

Absolute Magnitude

An asteroid’s absolute magnitude is the visual magnitude an observer would record if the asteroid were placed 1 Astronomical Unit (au) away, and 1 au from the Sun and at a zero phase angle.

The magnitude of an asteroid at zero phase angle and at unit heliocentric and geocentric distances.

H is the absolute magnitude of the asteroid (represents the intrinsic brightness for example in the V band) is the distance between the asteroid and Earth (or the observer) r is the distance from the asteroid and the Sun is the angle between the lines of sight to Earth and the Sun as seen from the asteroid. is a phase function that depends on the movements of the NEO

Target asteroids

An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions. An asteroid family is a more specific term than asteroid group whose members, while sharing some broad orbital characteristics, may be otherwise unrelated to each other. https://en.wikipedia.org/wiki/Asteroid_family

• JPL NEO Earth Close Approaches Data
• JPL Small-Body Mission-Design Tool
• Planetary Radar Science Group of Arecibo Observatory
• 1986 DB, Amor | 1986 EB (3554 Amun)
• The composition of M-type asteroids II- Synthesis of spectroscopic and radar observations, J.R. Neeley e al., Icarus, 2014

Impact crater

https://github.com/ExponentialDeepSpace/exponentialdeepspace.github.io/issues/3#issuecomment-450642387

Detect

小龙哈勃: 6.5米镜，用他们所用的宽带测光，1%精度的话，到21等左右应该是可以的。就目前观测到NEO的星等分布来看，估计绝对星等在23等左右吧。

2米估计到19等。

• https://en.wikipedia.org/wiki/Las_Cumbres_Observatory
• http://www.chilescope.com/services-and-pricing/service-description/
• The Mission Accessible Near-Earth Objects Survey (MANOS)

asime-2018/pdfs/elvis.pdf, Harvard-Smithsonian Center for Astrophysics

• http://geophy.uni.lu/users/tonie.vandam/asime-2018/presentations/elvis.pdf.gz

Spectrum

• http://www.hayabusa2.jaxa.jp/en/enjoy/material/factsheet/FactSheet_en_v2.31s.pdf

• [Evaporating planetesimals, Nature, Sept28 2017](http://sims.ess.ucla.edu/eyoung/reprints/Young_2017_NV.pdf
• https://en.wikipedia.org/wiki/Planetesimal

[NirViaje]

Asteroid Detection

Methodology

• Update to Determine the Feasibility of Enhancing the Search and Characterization of NEOs, NASA, 2017
• Keck asteroid retrieval feasibility
  • http://www.kiss.caltech.edu/study/asteroid/asteroid_final_report.pdf
  • http://kiss.caltech.edu/final_reports/ARM_final_report_techdev.pdf
  • http://kiss.caltech.edu/programs.html#asteroid

How to find metal-rich asteroids https://arxiv.org/abs/1403.6346

How Many Ore-Bearing Asteroids? https://arxiv.org/abs/1312.4450

Observation Resource

Ground

• 4.6亿美元 8米口径 巡天专用 数据公开，2019年投入使用 Large Synoptic Survey Telescope, Slide

Space

• Hubble_Space_Telescope
• https://en.wikipedia.org/wiki/Near_Earth_Object_Surveillance_Satellite
  • http://www.asc-csa.gc.ca/eng/satellites/neossat/default.asp
  • https://earth.esa.int/web/eoportal/satellite-missions/n/neossat a Canadian microsatellite using a 15-cm aperture f/5.88 Maksutov telescope (similar to that on the MOST spacecraft), with 3-axis stabilisation giving a pointing stability of ~2 arcseconds in a ~100 second exposure.
• Planetary Resources, Arkyd-6, 3~5um, sensitive to the presence of water and hydrated minerals
  • LWIR or MWIR Infrared Imaging: Which is best for your application

Deep space detector #25

• Hayabusa
• Hayabusa2
• Mars Cube One (MarCO), JPL, 2018
• Near-Earth Asteroid Scout, NASA, 2020
  • Near Earth Asteroid (NEA) Scout Solar Sail Implementation, slide, JPL, 2016
• Requirement
  • 磁特性
  • 导热率
  • Rotation, List of fast rotators (minor planets)
  • etc

Database and visualization

• Asterank
  • reference
• 3D Asteroid Catalogue
• Closest Approaches to the Earth by Minor Planets
• List of asteroid close approaches to Earth, Wikipedia

[NirViaje]

Asteroids Composition

Project+RAMA+NIAC+Phase+I+Final+Report, p25

• C型小行星：碳质球粒陨石，含水含有机物，榨干后的残渣含5到30%金属(铁镍球粒)。
• S型小行星：
• M型小行星：铁陨石，铁，10%镍, 1~10ppm铂，5%数量，光谱难以识别。
• A型小行星：橄榄铁陨石，约50%金属，某些样品有1000ppm铼，1/300数量，光谱特殊。

Asteroid Retrieval Feasibility Study, Keck Inst, 2012

• 魏德曼花紋 镍纹石是在熔点以下的温度均匀混合的铁和镍合金。在温度900到600 °C（与镍的含量相关），有两种镍含量不同的稳定合金：锥纹石的镍含量低（只有5%至15%的镍），镍纹石的镍含量高（可以高达50%）。八面体陨铁陨石的镍含量规范需要介于锥纹石和镍纹石之间，这会导致锥纹石在缓慢降温的条件下，锥纹石板会在镍纹石的晶格中沿着某一个晶轴平面的方向成长。 由于以极端缓慢的速率冷却（经历数百万年），镍铁晶体在固体内增长的长度只有几釐米。这种花纹的存在是材料来自外太空的证明，可以很容易的确定一小块的碎片是否陨石的一角。
• 八面体陨铁 在锥纹石和镍纹石的片状结构间的空隙，经常可以找到称为合纹石的微细混合物。一种铁镍磷化物，磷铁石，经常出现在镍-铁陨石中，还有镍-铁-钴、碳化钙、钴碳铁陨石、石墨和陨硫铁都会呈现几个釐米大的圆角结节 [1]。
• 陨硫铁 在地球自然的矿物中也可以找到陨硫铁，但在陨石中，特别是来自月球和火星的陨石，更为丰富。在2013年2月15日袭击俄罗斯的陨石标本中发现的矿物之一就是陨硫铁[4]。阿波罗、维京人、火卫一的太空探测器都已经证实陨硫铁存在于这些天体上。硫的同位素在陨石和地球上矿物的相对强度是相当确定的，因此代亚布罗峡谷陨石被选为国际的硫同位素比例的标准。

https://en.wikipedia.org/wiki/Iron_meteorite#Chemical_classification In 2006 iron meteorites were classified into 13 groups (one for uncategorized irons):[2]

• IAB
  • IA: Medium and coarse octahedrites, 6.4-8.7% Ni, 55-100 ppm Ga, 190-520 ppm Ge, 0.6-5.5 ppm Ir, Ge-Ni correlation negative.
  • IB: Ataxites and medium octahedrites, 8.7-25% Ni, 11-55 ppm Ga, 25-190 ppm Ge, 0.3-2 ppm Ir, Ge-Ni correlation negative.
• IC
• IIAB
  • IIA: Hexahedrites, 5.3-5.7% Ni, 57-62 ppm Ga, 170-185 ppm Ge, 2-60ppm Ir.
  • IIB: Coarsest octahedrites, 5.7-6.4% Ni, 446-59 pm Ga, 107-183 ppm Ge, 0.01-0.5 ppm Ir, Ge-Ni correlation negative.
• IIC: Plessitic octahedrites, 9.3-11.5% Ni, 37-39 ppm Ga, 88-114 ppm Ge, 4-11 ppm Ir, Ge-Ni correlation positive
• IID: Fine to medium octahedrites, 9.8-11.3%Ni, 70-83 ppm Ga, 82-98 ppm Ge, 3.5-18 ppm Ir, Ge-Ni correlation positive
• IIE: octahedrites of various coarseness, 7.5-9.7% Ni, 21-28 ppm Ga, 60-75 ppm Ge, 1-8 ppm Ir, Ge-Ni correlation absent
• IIIAB: Medium octahedrites, 7.1-10.5% Ni, 16-23 ppm Ga, 27-47 ppm Ge, 0.01-19 ppm Ir*
• IIICD: Ataxites to fine octahedrites, 10-23% Ni, 1.5-27 ppm Ga, 1.4-70 ppm Ge, 0.02-0.55 ppm Ir
• IIIE: Coarse octahedrites, 8.2-9.0% Ni, 17-19 ppm Ga, 3-37 ppm Ge, 0.05-6 ppm Ir, Ge-Ni correlation absent
• IIIF: Medium to coarse octahedrites, 6.8-7.8% Ni,6.3-7.2 ppm Ga, 0.7-1.1 ppm Ge, 1.3-7.9 ppm Ir, Ge-Ni correlation absent
• IVA: Fine octahedrites, 7.4-9.4% Ni, 1.6-2.4 ppm Ga, 0.09-0.14 ppm Ge, 0.4-4 ppm Ir, Ge-Ni correlation positive
• IVB: Ataxites, 16-26% Ni, 0.17-0.27 ppm Ga, 0,03-0,07 ppm Ge, 13-38 ppm Ir, Ge-Ni correlation positive
• Ungrouped meteorites. This is actually quite a large collection (about 15% of the total) of over 100 * meteorites that do not fit into any of the larger classes above, and come from about 50 distinct parent bodies.

Additional groups and grouplets are discussed in the scientific literature:

• IIG: Hexahedrites with coarse schreibersite. Meteoric iron has low nickel concentration.[18]

https://en.wikipedia.org/wiki/Sikhote-Alin_meteorite

Phosphorus is very common in meteorites, but in much greater concentrations than in steels. When the phosphorus level exceeds about 0.06 weight %, which is quite common in meteorites, phosphides are formed. They have a tetragonal type crystal structure with the general formula (Fe,Ni)3P but different morphologies are observed. Schreibersite is the name given to globular shaped phosphides in meteorites. Their size is a function of the phosphorous content. Schreibersite has a variable nickel content, depending upon the temperature at which they nucleated, from about 10 to 50% Ni. The higher nickel content particles tend to be smaller in size and they are more ductile than the larger, lower Ni particles, which are often cracked. https://vacaero.com/information-resources/metallography-with-george-vander-voort/1307-metallography-of-iron-nickel-meteorites-part-1-background.html

[NirViaje]

@emptymalei should we consider on the close approaching object?

• Closest Approaches to the Earth by Minor Planets
• List of asteroid close approaches to Earth, Wikipedia

Like the (29075) 1950 DA, the density >3.5 g/cm which people suggest it's metallic asteroid, with size of 1.39 km × 1.46 km × 1.07 km, close approach to earth in 0.0520726 AU on March 5, 2001.

Some of other objects a relative small though can be deployed as test bench.

btw, fyi - https://github.com/SoyGema/Deep_Asteroid

国内单位

• CAS
  • CAS 紫金山天文台 天体化学和行星科学实验室
• HIT
  • 哈工大计算机学院 太阳系小天体探测科学技术交流会 2018年7月30日至8月1日
  • Zhijun Zhao, Department National Key Lab of Robotics and Systems
• BIT
  • 北京理工大学 深空自主导航与控制实验室

Requirements

1. 面对太阳
2. 避开阴影
3. 焦点集中在自转轴极点
   • 可利用缓慢进动/其他自转减速机制 https://en.wikipedia.org/wiki/Yarkovsky_effect YORP effect, wikipedia

tho someone suggests it's D-type instead of M-type.

[NirViaje]

Greenland large impact crater

Subsamples of all three glaciofluvial sediment samples were crushed in an agate mill and analyzed for major and trace elements, platinum-group elements (PGEs), and Au (Materials and Methods and data file S2). Two samples (HW12-2016 and HW13-2016) contain low concentrations of PGE, Au, and other siderophile elements that are consistent with bulk upper continental crust, so those two samples are believed to derive from local bedrock unaffected by the impact (figs. S1 and S3 and Supplementary Materials and Methods). In contrast, every tested subsample of the same sample that contained shocked quartz (HW21-2016) also contains elevated concentrations of Ni, Co, Cr, PGE, and Au, indicative of a relatively rare iron meteorite. PGE data for HW21-2016 produce prominent and consistent chondrite-normalized positive Rh and negative Pt anomalies (fig. S3), and metal ratios are unlike most typical terrestrial rocks that could potentially be local sources for these elevated PGE concentrations (e.g., komatiites, picrites, or high-Mg basalts). Rare sulfide-rich chromitites from the Bushveld Complex have similarly distinctive positive Rh anomalies, but even addition of this material cannot reproduce the observed Rh anomaly. Furthermore, weathering and dispersal of similar rocks would be expected to produce an abundance of Mg-rich and Ti-poor chromite, which is not observed in HW21-2016. The only two recovered spinels are one Cr-poor magnetite and one ilmenite, which have significantly lower MgO, Cr2O3, and NiO than spinels found in impact ejecta (13). Combinations of PGE ratios in HW21-2016 [e.g., (Rh/Pt)N >1.2, (Rh/Ru)N < 0.3, and (Pd/Pt)N > 2.5] effectively rule out terrestrial rocks and carbonaceous, ordinary, or enstatite chondrites as likely sources, whereas some iron meteorites contain high Rh and Pd concentrations. Modeling indicates that the best fit for the siderophile element data is a mixture between local crust and 0.01 to 0.05% of a component similar in composition to the strongly fractionated Duchesne (type IVA) iron meteorite (fig. S4).

• A large impact crater beneath Hiawatha Glacier in northwest Greenland, Kurt H. Kjær, 2018
• International Team, NASA Make Unexpected Discovery Under Greenland Ice
• Massive Crater Discovered under Greenland Ice, NASA Goddard Media Studios

Data from: https://upload.wikimedia.org/wikipedia/commons/c/cc/Earth_Impact_Database_world_map.svg Source file: https://docs.google.com/spreadsheets/d/1Mmrb0cHMbKHedO9-L5HUCojnRpjPJ5rpFcfmBTcAIHg/edit#gid=1571954926

Sudbury Basin

The large impact crater filled with magma containing nickel, copper, platinum, palladium, gold, and other metals. In 1856 while surveying a baseline westward from Lake Nipissing, provincial land surveyor Albert Salter located magnetic abnormalities in the area that were strongly suggestive of mineral deposits. The area was then examined by Alexander Murray of the Geological Survey of Canada, who confirmed "the presence of an immense mass of magnetic trap".

https://en.wikipedia.org/wiki/Sudbury_Basin#Modern_uses

[NirViaje]

• Radar observations and shape model of asteroid 16 Psyche, NASA, 2016

Radar observations indicate that Psyche has a fairly pure iron–nickel composition,[14][15] consistent with it having one of the highest radar albedos in the asteroid belt (0.37±0.09).[2] Psyche seems to have a surface that is 90% metallic (iron),[16] with small amounts – 6±1% – of orthopyroxene.[17][18]

• https://en.wikipedia.org/wiki/16_Psyche#Composition_and_origin