Astronomy

Are interstellar meteorites more common on the moon's polar regions?

Are interstellar meteorites more common on the moon's polar regions?


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Given that the rocks of the solar system mostly travel on the disc, is there any considerable probability that impacts on the moon coming straight up and down can be interstellar rocks?

If axis-aligned meteorites are very rare, then perhaps there is a chance that a significant number of axis-aligned impacts come from interstellar objects.

It would be fun to search the polar regions of the moon for meteorite impacts that were axis aligned in the hope that the impactor would be interstellar. How unreasonable is it? If I put a square of foam on the moon for 20 years, and I checked afterwards which objects had hit the foam at high speed from an axis aligned vector, perhaps I could find a rock from elsewhere in the galaxy?


Asteroids found to be the Moon’s main ‘water supply’

An artist’s impression of NASA’s Lunar Reconnaissance Orbiter. Launched on 18 June 2009, the spacecraft is not only conducting a detailed mapping program to identify safe landing sites and locate potential resources on the Moon, but has also provided evidence for considerable quantities of water and hydroxyl groups in the near-surface lunar soil. Image credit: NASA. At the beginning of the space age, during the days of the Apollo program, scientists believed the Moon to be completely dry. At these earliest stages in satellite evolution, the absence of an atmosphere and the influence of solar radiation were thought enough to evaporate all volatile substances into space. However, in the 1990s, scientists obtained data from the Lunar Prospector probe that shook their confidence: the neutron current from the satellite surface was indicative of a larger fraction of hydrogen at the near-surface soil of some regions of the Moon, which one could interpret as a sign of the presence of water.

In order to explain how water could be kept on the Moon’s surface, scientists formulated a theory known as “cold traps.” The axis of the Moon’s rotation is nearly vertical, which is why in the polar regions there are craters with floors that are never exposed to sunlight. When comets consisting mostly of water ice fall, evaporated water can gravitate into those “traps” and remain there indefinitely, as solar rays do not evaporate it.

In recent years, lunar missions (the Indian Chandrayan probe, the American Lunar Reconnaissance Orbiter [LRO], data from the Cassini probe and Deep Impact) have brought scientists two pieces new information. The first is that there are indeed considerate quantities of water and hydroxyl groups in the near-surface soil on the Moon. The LCROSS experiment, in which a probe purposely crashed onto the Moon resulting in the release of a cloud of gas and dust that was later studied with the use of a spectrometer, directly confirmed the existence of water and other volatile substances. The second piece of new information came when the Russian LEND apparatus mounted on board LRO generated a map of water distribution on the Moon’s surface.

But this second piece has only partly proven their theory: the map of “cold traps” did not correspond to the map of water deposits. The scientists had to refine the theory, and the idea of “lunar congelation” was proposed. It allowed accepting that “survival” of water ice in the regions exposed to sunlight is possible under a soil blanket. It was also suggested that a substantial part of “water” seen by the probes is implanted solar wind: hydrogen atoms from solar wind react with oxygen atoms and form an unstable “dew” of water molecules and hydroxyl groups. Scientists left the possibility open that water could exist in a bound state, i.e. in hydrated minerals.

There was still the matter of determining how water had appeared on the Moon and how much of it there could be. At the same time, another issue may prove to be of practical importance in the coming years: if manned stations are to be constructed on the Moon in the nearest future, we should know what kind of resources we can count on, preferably before construction begins. Temperature of the surface around the southern pole of the Moon according to NASA’s Lunar Reconnaissance Orbiter data. Image credit: © NASA. Vladimir Svettsov and Valery Shuvalov, who have been researching the fall of comets and asteroids, including the computerised simulation of the Tunguska catastrophe as well as the Chelyabinsk meteorite fall, decided to develop the most probable mechanism of water delivery to the Moon and an approximate the “supply” volume. For this they used the SOVA algorithm, which they created themselves, for the computerised modelling of the fall of cosmic bodies onto the surface of the Moon. Each body had its own velocity and its own angle of fall. In particular, at the output, the model demonstrated the distribution of maximum temperatures when the falling body’s mass heated up during impact as well as its dynamic.

The scientists first decided to check whether the comets are able to fulfill the role of main “water suppliers.” The typical velocity of an ice comet ranges from 20 to 50 kilometres per second. The estimates suggested that such a high impact velocity causes from 95 to 99.9 percent of the water to evaporate into space beyond retrieve. There is a family of short-period comets whose velocity of fall is much lower &mdash 8-10 kilometres per second. Such short-period comets account for about 1.5 percent of lunar craters. Nevertheless, the simulation has shown that when these short-period comets do fall, almost all the water evaporates and less than 1 percent of it remains at the impact point.

“We came to the conclusion that only a very small amount of water that arrives with a comet stays on the Moon, and from this decided to explore the possibility of an asteroid origin of lunar water,” Shuvalov says.

The scientists decided to take a closer look at asteroids and found that they consist of initially non-differentiated construction materials of the solar system and contain a rather considerable proportion of water. In particular, chondrite carbonaceous, the most common type of asteroids and meteorites, can contain up to 10 percent water.

However, water in chondrites is effectively protected: it is in a chemically bounded condition, and it is “blocked” in a crystal lattice of minerals. Water starts to seep out only when it is heated to 300-1200 degrees centigrade depending on the type of hydrous mineral. This means that it has the potential of remaining in the crater together with the asteroid.

The simulation has also revealed that when the velocity of fall is 14 kilometres per second and the angle of fall is 45 degrees, about half of the asteroid’s mass will never even reach the fusing temperature and remains in a solid state. One-third of all asteroids that fall on the Moon have a velocity of less than 14 kilometres per second just before impact. When this happens, the major part of the fallen body remains in the crater: 30-40 percent is left after an oblique impact, and 60-70 percent after a vertical one.

“We’ve concluded that the fall of asteroids containing water could generate “deposits” of chemically bounded water inside some lunar craters,” Shuvalov says. “The fall of one two-kilometre size asteroid with a rather high proportion of hydrated minerals could bring to the Moon more water than all of the comets that have fallen over billions of years,” he adds.

Calculations reveal that around 2 to 4.5 percent of lunar craters could contain considerable supplies of water in the form of hydrated minerals. They are stable enough to contain water even in areas exposed to the Sun.

“That is very important because the polar cold traps are not very convenient areas for the construction of lunar bases. There is a small amount of solar energy and it is difficult to organise radio communication and, lastly, there are dramatically low temperatures. The possibility of obtaining lunar water in regions exposed to the Sun could make the issue of satellite exploration much easier,” concluded the scientist.


Meteorite “Paris” Contains Similar Organics as the Interstellar Medium

A team of researchers from the Institute of Space Astrophysics (IAS / CNRS-Université Paris Sud) examining the meteorite “Paris”, was able to highlight the presence of organic components similar to those of the interstellar medium.

Fig.2: This photograph shows the Paris meteorite fusion crust (croute de fusion) formed during atmospheric entry partially oxidized (orange) traces (traces d’oxydation) and the interior well preserved meteorite (visible in the center) where you can see small white inclusions called chondrules (chondre). Image Credit: MNHN

The meteorite “Paris” is a carbonaceous chondrite 1 CM type 2 with two lithologies of which one is affected more than the other. This 1.2 kg meteorite was recently acquired by the Laboratory of Mineralogy and Cosmochemistry (LMCM / MNHN-CNRS).

Although the circumstances of the fall of “Paris” are unknown, it appears to have been remarkably preserved in the terrestrial environment and in particular as regards to its original organic matter. Indeed, organic materials similar to those observed in the interstellar medium have been highlighted.

Ten mg were provided by B. Zanda from the MNHN. Some samples of fifty microns were collected and analyzed by the SMIS (Microscopy and Spectroscopy in the Infrared using Synchrotron) of Synchrotron SOLEIL (CNRS-CEA) which, due to its high brightness coupled with a spatial resolution that can go up to 6 microns, allowed us to detect small inclusions rich in organic matter with spectroscopic signatures in the infrared absolutely similar to those observed in some molecular clouds in the interstellar medium.

Fig.2: Comparison of IR spectra of a fragment of Paris (frag2) than GCS3 sources and SgrA * in the region 3.4μm (upper panel) and the region around 6 microns (lower panel in which the arrows indicate common bands in the spectrum of Paris and in the interstellar medium). Image Credit: CNRS


Figure 2 compares the infrared signatures of a fragment of “Paris” (named frag2) with those of two infrared sources — protostellar objects that form stars and planetary systems — in the direction of the galactic center, SgrA*, obtained by the Short Wavelength Spectrometer (SWS) satellite ISO (Infrared Space Observatory) in the region of 3.4 microns (top figure) and in the region of around 6 microns (bottom figure).

This new discovery allows reopening the debate on primitive chemicals in certain meteorites and the role of chemical processes in molecular clouds, needed for the production of large quantities of organic material from abiotic origins and the transition into the prebiotic chemistry in the Solar System objects such as the Earth.


Deep space exploration

Samples from these cold traps could tell us more about how the Moon, and even Earth, got its water, Hayne said, perhaps providing evidence of water delivered by asteroids, comets and the solar wind.

Jacob Bleacher, chief exploration scientist for NASA's Human Exploration and Operations Mission Directorate, said it was crucial to find out more about where the water came from and how accessible it is.

"Water is extremely critical for deep space exploration. It's a resource of direct value for our astronauts," he told reporters, adding it was heavy and therefore expensive to take from Earth.

"Anytime we don't need to pack water for our trip, we have an opportunity to take other useful items with us, for instance payloads to do more science."

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Meteorite Chunk Contains Unexpected Evidence of Solid Interstellar Material Formed Before the Sun Was Born

Curious Marie comes from the Allende meteorite, which fell in northern Mexico in February 1969. The white, fuzzy-looking features in this fragment of Allende are calcium-aluminum-rich inclusions — some of the first solids to condense in the solar system. Credit: Chip Clark, Smithsonian Institution

‘Curious and Curiouser!’ – Meteorite Chunk Contains Unexpected Evidence of Presolar Grains

An unusual chunk in a meteorite may contain a surprising bit of space history, based on research from Washington University in St. Louis.

Presolar grains — tiny bits of solid interstellar material formed before the sun was born — are sometimes found in primitive meteorites. But a new analysis reveals evidence of presolar grains in part of a meteorite where they are not expected to be found.

“What is surprising is the fact that presolar grains are present,” said Olga Pravdivtseva, research associate professor of physics in Arts & Sciences and lead author of a paper published in Nature Astronomy. “Following our current understanding of solar system formation, presolar grains could not survive in the environment where these inclusions are formed.”

Curious Marie is a notable example of an “inclusion,” or a chunk within a meteorite, called a calcium-aluminum-rich inclusion (CAI). These objects, some of the first to have condensed in the solar nebula, help cosmochemists define the age of the solar system. This particular chunk of meteorite — from the collection of the Robert A. Pritzker Center for Meteoritics and Polar Studies at the Chicago Field Museum — was in the news once before, when scientists from the University of Chicago gave it its name to honor chemist Marie Curie.

Olga Pravdivtseva, research associate professor of physics in Arts & Sciences at Washington University in St. Louis, uses noble gas isotopes to study the formation and evolution of the early solar system. Pravdivtseva, a member of the McDonnell Center for the Space Sciences, is pictured in her laboratory in Compton Hall. Credit: Whitney Curtis/Washington University

For the new work, Pravdivtseva and her co-authors, including Sachiko Amari, research professor of physics at Washington University, used noble gas isotopic signatures to show that presolar silicon carbide (SiC) grains are present in Curious Marie.

That’s important because presolar grains are generally thought to be too fragile to have endured the high-temperature conditions that existed near the birth of our sun.

But not all CAIs were formed in quite the same way.

“The fact that SiC is present in refractory inclusions tells us about the environment in the solar nebula at the condensation of the first solid materials,” said Pravdivtseva, who is part of Washington University’s McDonnell Center for the Space Sciences. “The fact that SiC was not completely destroyed in Curious Marie can help us to understand this environment a little bit better.

“Many refractory inclusions were melted and lost all textural evidence of their condensation. But not all.”

Like solving a mystery

Pravdivtseva and her collaborators used two mass spectrometers built in-house at Washington University to make their observations. The university has a long history of using noble gas isotopes as tracers of various nuclear processes and is home to one of the best-equipped noble gas laboratories in the world. Still, this work was uniquely challenging.

The researchers had 20 mg of Curious Marie to work with, which is a relatively large sample from a cosmochemistry perspective. They heated it up incrementally, increasing temperature and measuring the composition of four different noble gases released at each of 17 temperature steps.

“Experimentally, it is an elegant work,” Pravdivtseva said. “And then we had a puzzle of noble gas isotopic signatures to untangle. For me, it is like solving a mystery.”

Others have looked for evidence of SiC in such calcium-aluminum-rich inclusions in meteorites using noble gases before, but Pravdivtseva’s team is the first to find it.

“It was beautiful when all noble gases pointed to the same source of the anomalies — SiC,” she said.

“Not only do we see SiC in the fine-grained CAIs, we see a population of small grains that formed at special conditions,” Pravdivtseva said. “This finding forces us to revise how we see the conditions in the early solar nebula.”

Reference: “Evidence of presolar SiC in the Allende Curious Marie calcium–aluminium-rich inclusion” by O. Pravdivtseva, F. L. H. Tissot, N. Dauphas and S. Amari, 27 January 2020, Nature Astronomy.
DOI: 10.1038/s41550-019-1000-z


Lunar resources

Scientists and space planners have long acknowledged that extended human residence on the Moon would be greatly aided by the use of local resources. This would avoid the high cost of lifting payloads against Earth’s strong gravity. Certainly, lunar soil could be used for shielding habitats against the radiation environment. More advanced uses of lunar resources are clearly possible, but how advantageous they would be is presently unknown. For example, most lunar rocks are about 40 percent oxygen, and chemical and electrochemical methods for extracting it have been demonstrated in laboratories. Nevertheless, significant engineering advances would be needed before the cost and difficulty of operating an industrial-scale mining and oxygen-production facility on the Moon could be estimated and its advantages over transporting oxygen from Earth could be evaluated. In the long run, however, some form of extractive industry on the Moon is likely, in part because launching fleets of large rockets continuously from Earth would be too costly and too polluting of the atmosphere.

The solar wind has implanted hydrogen, helium, and other elements in the surfaces of fine grains of lunar soil. Though their amounts are small—they constitute about 100 parts per million in the soil—they may someday serve as a resource. They are easily released by moderate heating, but large volumes of soil would need to be processed to obtain useful amounts of the desired materials. Helium-3, a helium isotope that is rare on Earth and that has been deposited on the Moon by the solar wind, has been proposed as a fuel for nuclear fusion reactors in the future.

One natural resource uniquely available on the Moon is its polar environment. Because the Moon’s axis is nearly perpendicular to the plane of the ecliptic, sunlight is always horizontal at the lunar poles, and certain areas, such as crater bottoms, exist in perpetual shadow. Under these conditions the surface may reach temperatures as low as 40 K (−388 °F, −233 °C). Water molecules are found in their strongest concentrations at the lunar poles. These cold traps have collected volatile substances, including water ice, over geologic time.

The Lunar Prospector spacecraft, which orbited the Moon for a year and a half, carried a neutron spectrometer to investigate the composition of the regolith within about a metre (three feet) of the surface. Neutrons originating underground owing to radioactivity and cosmic-ray bombardment interact with the nuclei of elements in the regolith en route to space, where they can be detected from orbit. A neutron loses more energy in an interaction with a light nucleus than with a heavy one, so the observed neutron spectrum can reveal whether light elements are present in the regolith. Lunar Prospector gave clear indications of light-element concentrations at both poles, interpreted as proof of excess hydrogen atoms. The existence of water ice at the Moon’s south pole was confirmed by the LCROSS spacecraft.

The lunar ice can serve as a source of rocket propellants when split into its hydrogen and oxygen components. From a longer-term perspective, however, the ice would better be regarded as a limited, recyclable resource for life support (in the form of drinking water and perhaps breathable oxygen).

Aside from the existence of water, the lunar polar regions still represent an important resource. Only there can be found not only continuous darkness but also continuous sunlight. A solar collector tracking the Sun from a high peak near a lunar pole could provide essentially uninterrupted heat and electric power. Also, the radiators required for eliminating waste heat could be positioned in areas of continuous darkness, where the heat could be dissipated into space.

The lunar poles also could serve as good sites for certain astronomical observations. To observe objects in the cosmos that radiate in the infrared and millimetre-wavelength regions of the spectrum, astronomers need telescopes and detectors that are cold enough to limit the interference generated by the instruments’ own heat (see infrared astronomy). To date, such telescopes launched into space have carried cryogenic coolants, which eventually run out. A telescope permanently sited in a lunar polar cold region and insulated from local heat sources might cool on its own to 40 K (−388 °F, −233 °C) or lower. Although such an instrument could observe less than half the sky—ideally, one would be placed at each lunar pole—it would enable uninterrupted viewing of any object above its horizon.


Where did all of Earth's craters go?

The main difference between the two is that Earth has processes that can erase almost all evidence of past impacts. The Moon does not. Pretty much any tiny dent made on the Moon’s surface is going to stay there.

Three processes help Earth keep its surface crater free. The first is called erosion. Earth has weather, water, and plants. These act together to break apart and wear down the ground. Eventually erosion can break a crater down to virtually nothing.

Lake Manicouagan, a ring-shaped lake in Quebec, Canada, is all that remains of a crater from a massive impact over 200 million years ago. Credit: NASA/GSFC/LaRC/JPL/MISR Team

Though they were made in 1971, these Apollo 14 astronauts' tracks were easily viewed from a NASA spacecraft in orbit around the moon in 2011 (tracks highlighted in yellow). Credit: NASA/LRO

The Moon has almost no erosion because it has no atmosphere. That means it has no wind, it has no weather, and it certainly has no plants. Almost nothing can remove marks on its surface once they are made. The dusty footsteps of astronauts who once walked on the Moon are still there today, and they aren’t going anywhere anytime soon.

The second thing is something called tectonics. Tectonics are processes that cause our planet’s surface to form new rocks, get rid of old rocks, and shift around over millions of years.

Because of tectonics, the surface of Earth is recycled many times throughout its long history. As a result, very few rocks on Earth are as old as the rocks on the Moon. The Moon has not had tectonics for billions of years. That’s a lot more time for craters to form and stay put.

The third thing is volcanism. Volcanic flows can cover up impact craters. This is a major way impact craters get covered up elsewhere in our solar system, but it is less important than the recycling of crust here on Earth. The Moon once had large volcanic flows way in the past that did cover up many of the bigger earlier impacts, but it has been without volcanism for around three billion years.


SOLAR SYSTEM | Meteorites

Cosmic ray exposure age:

the time spent as a metre-scale meteoroid orbiting the Sun. Cosmic rays react with some atoms in iron or stony meteoroids and the quantity of gases formed depends on the chemical nature of the meteoroid and the duration of exposure to cosmic rays in space. The most usual measurements are of the quantity of neon gas resulting from this cosmic ray exposure. The evidence suggests that few stony meteorites survive in space without further collisional destruction and pulverisation for more than 40 million years, but iron meteorites are more robust, surviving up to 1000 million years.


The molecules listed below were detected through astronomical spectroscopy. Their spectral features arise because molecules either absorb or emit a photon of light when they transition between two molecular energy levels. The energy (and thus the wavelength) of the photon matches the energy difference between the levels involved. Molecular electronic transitions occur when one of the molecule's electrons moves between molecular orbitals, producing a spectral line in the ultraviolet, optical or near-infrared parts of the electromagnetic spectrum. Alternatively, a vibrational transition transfers quanta of energy to (or from) vibrations of molecular bonds, producing signatures in the mid- or far-infrared. Gas-phase molecules also have quantised rotational levels, leading to transitions at microwave or radio wavelengths. [1]

Sometimes a transition can involve more than one of these types of energy level e.g. ro-vibrational spectroscopy changes both the rotational and vibrational energy level. Occasionally all three occur together, as in the Phillips band of C2 (diatomic carbon), in which an electronic transition produces a line in the near-infrared, which is then split into several vibronic bands by a simultaneous change in vibrational level, which in turn are split again into rotational branches. [2]

The spectrum of a particular molecule is governed by the selection rules of quantum chemistry and the molecular symmetry. Some molecules have simple spectra which are easy to identify, whilst others (even some small molecules) have extremely complex spectra with flux spread among many different lines, making them far harder to detect. [3] Interactions between the atomic nuclei and the electrons sometimes causes further hyperfine structure of the spectral lines. If the molecule exists in multiple isotopologues (versions containing different atomic isotopes), the spectrum is further complicated by isotope shifts.

Detection of a new interstellar or circumstellar molecule requires identifying a suitable astronomical object where it is likely to be present, then observing it with a telescope equipped with a spectrograph working at the required wavelength, spectral resolution and sensitivity. The first molecule detected in the interstellar medium was the methylidyne radical (CH • ) in 1937, through its strong electronic transition at 4300 angstroms (in the optical). [4] Advances in astronomical instrumentation have led to increasing numbers of new detections. From the 1950s onwards, radio astronomy began to dominate new detections, with sub-mm astronomy also becoming important from the 1990s. [3]

The inventory of detected molecules is highly biased towards certain types which are easier to detect e.g. radio astronomy is most sensitive to small linear molecules with a high molecular dipole. [3] The most common molecule in the Universe, H2 (molecular hydrogen) is completely invisible to radio telescopes because it has no dipole [3] its electronic transitions are too energetic for optical telescopes, so detection of H2 required ultraviolet observations with a sounding rocket. [5] Vibrational lines are often not specific to an individual molecule, allowing only the general class to be identified. For example, polycyclic aromatic hydrocarbons (PAHs) are known to be common in space due to their vibrational lines, which are widely observed in the mid-infrared, but it has not been possible to identify exactly which molecules are responsible. [6]

One of the richest sources for detecting interstellar molecules is Sagittarius B2 (Sgr B2), a giant molecular cloud near the centre of the Milky Way. About half of the molecules listed below were first found in Sgr B2, and many of the others have been subsequently detected there. [7] A rich source of circumstellar molecules is CW Leonis (also known as IRC +10216), a nearby carbon star, where about 50 molecules have been identified. [8] There is no clear boundary between interstellar and circumstellar media, so both are included in the tables below.

The discipline of astrochemistry includes understanding how these molecules form and explaining their abundances. The extremely low density of the interstellar medium is not conducive to the formation of molecules, making conventional gas-phase reactions between neutral species (atoms or molecules) inefficient. Many regions also have very low temperatures (typically 10 kelvin inside a molecular cloud), further reducing the reaction rates, or high ultraviolet radiation fields, which destroy molecules through photochemistry. [9] Explaining the observed abundances of interstellar molecules requires calculating the balance between formation and destruction rates using gas-phase ion chemistry (often driven by cosmic rays), surface chemistry on cosmic dust, radiative transfer including interstellar extinction, and sophisticated reaction networks. [10]

The following tables list molecules that have been detected in the interstellar medium or circumstellar matter, grouped by the number of component atoms. Neutral molecules and their molecular ions are listed in separate columns if there is no entry in the molecule column, only the ionized form has been detected. Designations (names of molecules) are those used in the scientific literature describing the detection if none was given that field is left empty. Mass is listed in atomic mass units. Deuterated molecules, which contain at least one deuterium ( 2 H) atom, have slightly different masses and are listed in a separate table. The total number of unique species, including distinct ionization states, is indicated in each section header.

Most of the molecules detected so far are organic. The only detected inorganic molecule with five or more atoms is SiH4. [11] Molecules larger than that all have at least one carbon atom, with no N−N or O−O bonds. [11]

Diatomic (43) Edit

Molecule Designation Mass Ions
AlCl Aluminium monochloride [13] [14] 62.5
AlF Aluminium monofluoride [13] [15] 46
AlO Aluminium monoxide [16] 43
Argonium [17] [18] 37 [note 1] ArH +
C2 Diatomic carbon [19] [20] 24
Fluoromethylidynium 31 CF + [21]
CH Methylidyne radical [22] [23] 13 CH + [24]
CN Cyano radical [13] [23] [25] [26] 26 CN + , [27] CN − [28]
CO Carbon monoxide [13] [29] [30] 28 CO + [31]
CP Carbon monophosphide [26] 43
CS Carbon monosulfide [13] 44
FeO Iron(II) oxide [32] 82
Helium hydride ion [33] [34] 5 HeH +
H2 Molecular hydrogen [5] 2
HCl Hydrogen chloride [35] 36.5 HCl + [36]
HF Hydrogen fluoride [37] 20
HO Hydroxyl radical [13] 17 OH + [38]
KCl Potassium chloride [13] [14] 75.5
NH Imidogen radical [39] [40] 15
N2 Molecular nitrogen [41] [42] 28
NO Nitric oxide [43] 30 NO + [27]
NS Nitrogen sulfide [13] 46
NaCl Sodium chloride [13] [14] 58.5
Magnesium monohydride cation 25.3 MgH + [27]
O2 Molecular oxygen [44] 32
PN Phosphorus mononitride [45] [46] 45
PO Phosphorus monoxide [47] 47
SH Sulfur monohydride [48] 33 SH + [49]
SO Sulfur monoxide [13] 48 SO + [24]
SiC Carborundum [13] [50] 40
SiN – [51] 42
SiO Silicon monoxide [13] 44
SiS Silicon monosulfide [13] 60
TiO Titanium(II) oxide [52] 63.9

Triatomic (44) Edit

Molecule Designation Mass Ions
AlNC Aluminium isocyanide [13] 53
AlOH Aluminium hydroxide [55] 44
C3 Tricarbon [56] [57] 36
C2H Ethynyl radical [13] [25] 25
CCN Cyanomethylidyne [58] 38
C2O Dicarbon monoxide [59] 40
C2S Thioxoethenylidene [60] 56
C2P — [61] 55
CO2 Carbon dioxide [62] 44
CaNC Calcium isocyanide [63] 92
FeCN Iron cyanide [64] 82
Protonated molecular hydrogen 3 H +
3 [53] [54]
H2C Methylene radical [65] 14
Chloronium 37.5 H2Cl + [66]
H2O Water [67] 18 H2O + [68]
HO2 Hydroperoxyl [69] 33
H2S Hydrogen sulfide [13] 34
HCN Hydrogen cyanide [13] [25] [70] 27
HNC Hydrogen isocyanide [71] [72] 27
HCO Formyl radical [73] 29 HCO + [24] [73] [74]
HCP Phosphaethyne [75] 44
HCS Thioformyl [76] 45 HCS + [24] [74]
Diazenylium [74] [24] [77] 29 HN +
2
HNO Nitroxyl [78] 31
Isoformyl 29 HOC + [25]
HSC Isothioformyl [76] 45
KCN Potassium cyanide [13] 65
MgCN Magnesium cyanide [13] 50
MgNC Magnesium isocyanide [13] 50
NH2 Amino radical [79] 16
N2O Nitrous oxide [80] 44
NaCN Sodium cyanide [13] 49
NaOH Sodium hydroxide [81] 40
OCS Carbonyl sulfide [82] 60
O3 Ozone [83] 48
SO2 Sulfur dioxide [13] [84] 64
c-SiC2 c-Silicon dicarbide [13] [50] 52
SiCSi Disilicon carbide [85] 68
SiCN Silicon carbonitride [86] 54
SiNC [87] 54
TiO2 Titanium dioxide [52] 79.9

Four atoms (28) Edit

Molecule Designation Mass Ions
CH3 Methyl radical [89] 15
l-C3H Propynylidyne [13] [90] 37 l-C3H + [91]
c-C3H Cyclopropynylidyne [92] 37
C3N Cyanoethynyl [93] 50 C3N − [94]
C3O Tricarbon monoxide [90] 52
C3S Tricarbon sulfide [13] [60] 68
Hydronium 19 H3O + [95]
C2H2 Acetylene [96] 26
H2CN Methylene amidogen [97] 28 H2CN + [24]
H2CO Formaldehyde [88] 30
H2CS Thioformaldehyde [98] 46
HCCN — [99] 39
HCCO Ketenyl [100] 41
Protonated hydrogen cyanide 28 HCNH + [74]
Protonated carbon dioxide 45 HOCO + [101]
HCNO Fulminic acid [102] 43
HOCN Cyanic acid [103] 43
CNCN Isocyanogen [104] 52
HOOH Hydrogen peroxide [105] 34
HNCO Isocyanic acid [84] 43
HNCS Isothiocyanic acid [106] 59
NH3 Ammonia [13] [107] 17
HSCN Thiocyanic acid [108] 59
SiC3 Silicon tricarbide [13] 64
HMgNC Hydromagnesium isocyanide [109] 51.3
HNO2 Nitrous acid [110] 47

Five atoms (20) Edit

Molecule Designation Mass Ions
Ammonium ion [112] [113] 18 NH +
4
CH4 Methane [114] 16
CH3O Methoxy radical [115] 31
c-C3H2 Cyclopropenylidene [25] [116] [117] 38
l-H2C3 Propadienylidene [117] 38
H2CCN Cyanomethyl [118] 40
H2C2O Ketene [84] 42
H2CNH Methylenimine [119] 29
HNCNH Carbodiimide [120] 42
Protonated formaldehyde 31 H2COH + [121]
C4H Butadiynyl [13] 49 C4H − [122]
HC3N Cyanoacetylene [13] [25] [74] [123] [124] 51
HCC-NC Isocyanoacetylene [125] 51
HCOOH Formic acid [126] [123] 46
NH2CN Cyanamide [127] [128] 42
NH2OH Hydroxylamine [129] 37
Protonated cyanogen 53 NCCNH + [130]
HC(O)CN Cyanoformaldehyde [131] 55
C5 Linear C5 [132] 60
SiC4 Silicon-carbide cluster [50] 92
SiH4 Silane [133] 32

Six atoms (16) Edit

Molecule Designation Mass Ions
c-H2C3O Cyclopropenone [135] 54
E-HNCHCN E-Cyanomethanimine [136] 54
C2H4 Ethylene [137] 28
CH3CN Acetonitrile [84] [138] [139] 40
CH3NC Methyl isocyanide [138] 40
CH3OH Methanol [84] [140] 32
CH3SH Methanethiol [141] 48
l-H2C4 Diacetylene [13] [142] 50
Protonated cyanoacetylene 52 HC3NH + [74]
HCONH2 Formamide [134] 44
C5H Pentynylidyne [13] [60] 61
C5N Cyanobutadiynyl radical [143] 74
HC2CHO Propynal [144] 54
HC4N — [13] 63
CH2CNH Ketenimine [116] 40
C5S — [145] 92

Seven atoms (13) Edit

Molecule Designation Mass Ions
c-C2H4O Ethylene oxide [147] 44
CH3C2H Methylacetylene [25] 40
H3CNH2 Methylamine [148] 31
CH2CHCN Acrylonitrile [84] [138] 53
H2CHCOH Vinyl alcohol [146] 44
C6H Hexatriynyl radical [13] [60] 73 C6H − [117] [149]
HC4CN Cyanodiacetylene [84] [124] [138] 75
HC4NC Isocyanodiacetylene [150] 75
HC5O — [151] 77
CH3CHO Acetaldehyde [13] [147] 44
CH3NCO Methyl isocyanate [152] 57
HOCH2CN Glycolonitrile [153] 57

Eight atoms (12) Edit

Molecule Designation Mass
H3CC2CN Methylcyanoacetylene [155] 65
HC3H2CN Propargyl cyanide [156] 65
H2COHCHO Glycolaldehyde [157] 60
HCOOCH3 Methyl formate [84] [123] [157] 60
CH3COOH Acetic acid [154] 60
H2C6 Hexapentaenylidene [13] [142] 74
CH2CHCHO Propenal [116] 56
CH2CCHCN Cyanoallene [116] [155] 65
CH3CHNH Ethanimine [158] 43
C7H Heptatrienyl radical [159] 85
NH2CH2CN Aminoacetonitrile [160] 56
(NH2)2CO Urea [161] 60

Nine atoms (10) Edit

Molecule Designation Mass Ions
CH3C4H Methyldiacetylene [162] 64
CH3OCH3 Dimethyl ether [163] 46
CH3CH2CN Propionitrile [13] [84] [138] 55
CH3CONH2 Acetamide [116] [134] [128] 59
CH3CH2OH Ethanol [164] 46
C8H Octatetraynyl radical [165] 97 C8H − [166] [167]
HC7N Cyanohexatriyne or Cyanotriacetylene [13] [107] [168] [169] 99
CH3CHCH2 Propylene (propene) [170] 42
CH3CH2SH Ethyl mercaptan [171] 62
CH3NHCHO N-methylformamide [128]

Ten or more atoms (17) Edit

Atoms Molecule Designation Mass Ions
10 (CH3)2CO Acetone [84] [172] 58
10 (CH2OH)2 Ethylene glycol [173] [174] 62
10 CH3CH2CHO Propanal [116] 58
10 CH3OCH2OH Methoxymethanol [175] 62
10 CH3C5N Methylcyanodiacetylene [116] 89
10 CH3CHCH2O Propylene oxide [176] 58
11 HC8CN Cyanotetraacetylene [13] [168] 123
11 C2H5OCHO Ethyl formate [177] 74
11 CH3COOCH3 Methyl acetate [178] 74
11 CH3C6H Methyltriacetylene [116] [162] 88
12 C6H6 Benzene [142] 78
12 C3H7CN n-Propyl cyanide [177] 69
12 (CH3)2CHCN iso-Propyl cyanide [179] [180] 69
13 C
6 H
5 CN
Benzonitrile [181] 104
13 HC10CN Cyanopentaacetylene [168] 147
60 C60 Buckminsterfullerene
(C60 fullerene) [182]
720 C +
60 [183] [184] [185]
70 C70 C70 fullerene [182] 840

These molecules all contain one or more deuterium atoms, a heavier isotope of hydrogen.

Atoms Molecule Designation
2 HD Hydrogen deuteride [186] [187]
3 H2D + , HD +
2
Trihydrogen cation [186] [187]
3 HDO, D2O Heavy water [188] [189]
3 DCN Hydrogen cyanide [190]
3 DCO Formyl radical [190]
3 DNC Hydrogen isocyanide [190]
3 N2D + — [190]
3 NHD, ND2 Amidogen [191]
4 NH2D, NHD2, ND3 Ammonia [187] [192] [193]
4 HDCO, D2CO Formaldehyde [187] [194]
4 DNCO Isocyanic acid [195]
5 NH3D + Ammonium ion [196] [197]
6 NH
2 CDO NHDCHO
Formamide [195]
7 CH2DCCH, CH3CCD Methylacetylene [198] [199]

Evidence for the existence of the following molecules has been reported in the scientific literature, but the detections are either described as tentative by the authors, or have been challenged by other researchers. They await independent confirmation.


The slow revolution

Together, the studies could help scientists start to piece together how the lunar water cycle works. Water on the moon comes from a few different sources. Some might arrive with meteorites that collide with the surface, but some also likely forms when hydrogen from the solar wind reacts with surface oxygen to form hydroxyl. Heat from the sun or micrometeorite impacts could cause hydroxyl molecules to collide to form H2O, Honniball says.

The heat from impactors such as micrometeorites could also melt some of the rocky surface and vaporize any water nearby. As the melt cools to glass, it could encapsulate the water vapors—and that may account for the watery signal Honniball and her team spotted.

But exactly how and where water moves around on the surface remains unknown. Meteorites could liberate some water from the surface, and the sun could also play a role in moving the water around, since the signal for water and hydroxyl weakens as the heat peaks in the lunar day, Sunshine says. "Do we really lose it, or does it go to some shadow zone?" she wonders. "These small scale cold traps could help us understand."

Scientists still have much to learn about lunar water, but some answers may be on the way. In 2022, NASA plans to send the Volatiles Investigating Polar Exploration Rover (VIPER) to the moon’s south pole to search for water ice. Further clues should come from the Lunar Compact Infrared Imaging System (L-CIRIS), also slated for a 2022 mission, Hayne says.

Scientists have speculated about the presence of water on the moon since at least the 1960s, but in the coming years, we should finally develop a full picture of where lunar water is hidden—and whether we could use it to aid future explorers.


Watch the video: Ιαπωνία: Μετεωρίτης έκανε τη νύχτα μέρα (June 2022).