Interstellar object

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2I/Borisov comet, the second confirmed interstellar object, photographed in late-2019 beside a distant galaxy Comet 2I Borisov and Distant Galaxy in November 2019.tif
2I/Borisov comet, the second confirmed interstellar object, photographed in late-2019 beside a distant galaxy

An interstellar object is an astronomical object (such as an asteroid, a comet, or a rogue planet, but not a star or stellar remnant) in interstellar space that is not gravitationally bound to a star. This term can also be applied to an object that is on an interstellar trajectory but is temporarily passing close to a star, such as certain asteroids and comets (including exoasteroids exocomets [1] [2] ). In the latter case, the object may be called an interstellar interloper. [3]

Contents

The first interstellar objects discovered were rogue planets, planets ejected from their original stellar system (e.g., OTS 44 or Cha 110913−773444), though they are difficult to distinguish from sub-brown dwarfs, planet-mass objects that formed in interstellar space as stars do.

The first interstellar object which was discovered traveling through the Solar System was 1I/ʻOumuamua in 2017. The second was 2I/Borisov in 2019. They both possess significant hyperbolic excess velocity, indicating they did not originate in the Solar System. The discovery of ʻOumuamua inspired the tentative identification of CNEOS 2014-01-08, also known as the Manus Island fireball, as an interstellar object that impacted the Earth by astronomers Amir Siraj and Avi Loeb in 2019. [4] This was supported by the U.S. Space Command in 2022 based on the object's velocity relative to the Sun, [5] [6] [7] [8] [9] [10] In May 2023, astronomers reported the possible capture of other interstellar objects in Near Earth Orbit (NEO) over the years. [11] [12] however, NASA and Other astronomers doubt this, [13] [14] [15] [16] [17] [18] and still other experts found Earth-related explanations for the purported meteorite impact instead. [19]

The interstellar objects were once bound to a host star and have become unbound since. Different processes can cause planets and smaller objects (planetesimals) to become unbound from their host star. [20]

Nomenclature

With the first discovery of an interstellar object in the Solar System, the IAU has proposed a new series of small-body designations for interstellar objects, the I numbers, similar to the comet numbering system. The Minor Planet Center will assign the numbers. Provisional designations for interstellar objects will be handled using the C/ or A/ prefix (comet or asteroid), as appropriate. [21]

Overview

Interstellar velocity inbound ()
ObjectVelocity
C/2012 S1 (ISON)
(weakly hyperbolic
Oort Cloud comet)		0.2 km/s
0.04 au/yr [22]
Voyager 1
(For comparison)		16.9 km/s
3.57 au/yr [23]
1I/2017 U1 (ʻOumuamua) 26.33 km/s
5.55 au/yr [24]
2I/Borisov 32.1 km/s
6.77 au/yr [25]
2014Jan08 bolide
(in peer review,
no widespread consensus)		43.8 km/s
9.24 au/yr [26]

Astronomers estimate that several interstellar objects of extrasolar origin (like ʻOumuamua) pass inside the orbit of Earth each year, [27] and that 10,000 are passing inside the orbit of Neptune on any given day. [28]

Interstellar comets occasionally pass through the inner Solar System [1] and approach with random velocities, mostly from the direction of the constellation Hercules because the Solar System is moving in that direction, called the solar apex. [29] Until the discovery of 'Oumuamua, the fact that no comet with a speed greater than the Sun's escape velocity [30] had been observed was used to place upper limits to their density in interstellar space. A paper by Torbett indicated that the density was no more than 1013 (10 trillion) comets per cubic parsec. [31] Other analyses, of data from LINEAR, set the upper limit at 4.5×10−4/AU 3, or 1012 (1 trillion) comets per cubic parsec. [2] A more recent estimate by David C. Jewitt and colleagues, following the detection of 'Oumuamua, predicts that "The steady-state population of similar, ~100 m scale interstellar objects inside the orbit of Neptune is ~1×104, each with a residence time of ~10 years." [32]

Current models of Oort cloud formation predict that more comets are ejected into interstellar space than are retained in the Oort cloud, with estimates varying from 3 to 100 times as many. [2] Other simulations suggest that 90–99% of comets are ejected. [33] There is no reason to believe comets formed in other star systems would not be similarly scattered. [1] Amir Siraj and Avi Loeb demonstrated that the Oort Cloud could have been formed from ejected planetesimals from other stars in the Sun's birth cluster. [34] [35] [36] Both researchers proposed a search for ʻOumuamua-like objects which are trapped in the Solar System as a result of losing orbital energy through a close encounter with Jupiter. [37] [38]

It is possible for objects orbiting a star to be ejected due to interaction with a third massive body, thereby becoming interstellar objects. Such a process was initiated in the early 1980s when C/1980 E1, initially gravitationally bound to the Sun, passed near Jupiter and was accelerated sufficiently to reach escape velocity from the Solar System. This changed its orbit from elliptical to hyperbolic and made it the most eccentric known object at the time, with an eccentricity of 1.057. [39] It is heading for interstellar space.

Comet Machholz 1 (96P/Machholz) as viewed by STEREO-A (April 2007) 96P 20070403 000500 HI1A.png
Comet Machholz 1 (96P/Machholz) as viewed by STEREO-A (April 2007)

Due to present observational difficulties, an interstellar object can usually only be detected if it passes through the Solar System, where it can be distinguished by its strongly hyperbolic trajectory and hyperbolic excess velocity of more than a few km/s, proving that it is not gravitationally bound to the Sun. [2] [40] In contrast, gravitationally bound objects follow elliptic orbits around the Sun. (There are a few objects whose orbits are so close to parabolic that their gravitationally bound status is unclear.)

An interstellar comet can probably, on rare occasions, be captured into a heliocentric orbit while passing through the Solar System. Computer simulations show that Jupiter is the only planet massive enough to capture one, and that this can be expected to occur once every sixty million years. [31] Comets Machholz 1 and Hyakutake C/1996 B2 are possible examples of such comets. They have atypical chemical makeups for comets in the Solar System. [30] [41]

Recent research suggests that asteroid 514107 Kaʻepaokaʻawela may be a former interstellar object, captured some 4.5 billion years ago, as evidenced by its co-orbital motion with Jupiter and its retrograde orbit around the Sun. [42] In addition, comet C/2018 V1 (Machholz-Fujikawa-Iwamoto) has a significant probability (72.6%) of having an extrasolar provenance although an origin in the Oort cloud cannot be excluded. [43] Harvard astronomers suggest that matter—and potentially dormant spores—can be exchanged across vast distances. [44] The detection of ʻOumuamua crossing the inner Solar System confirms the possibility of a material link with exoplanetary systems.

Interstellar visitors in the Solar System cover the whole range of sizes - from kilometer large objects down to submicron particles. Also, interstellar dust and meteoroids carry with them valuable information from their parent systems. Detection of these objects along the continuum of sizes is, however, not evident. Uncertain size-frequency distribution of interstellar visitors.jpg
Interstellar visitors in the Solar System cover the whole range of sizes – from kilometer large objects down to submicron particles. Also, interstellar dust and meteoroids carry with them valuable information from their parent systems. Detection of these objects along the continuum of sizes is, however, not evident.

Interstellar visitors in the Solar System cover the whole range of sizes – from kilometer large objects down to submicron particles. Also, interstellar dust and meteoroids carry with them valuable information from their parent systems. Detection of these objects along the continuum of sizes is, however, not evident (see Figure). [46] The smallest interstellar dust particles are filtered out of the solar system by electromagnetic forces, while the largest ones are too sparse to obtain good statistics from in situ spacecraft detectors. Discrimination between interstellar and interplanetary populations can be a challenge for intermediate (0.1–1 micrometer) sizes. These can vary widely in velocity and directionality. [47] The identification of interstellar meteoroids, observed in the Earth's atmosphere as meteors, is highly challenging and requires high accuracy measurements and appropriate error examinations. [48] Otherwise, measurement errors can transfer near-parabolic orbits over the parabolic limit and create an artificial population of hyperbolic particles, often interpreted as of interstellar origin. [46] Large interstellar visitors like asteroids and comets were detected the first time in the solar system in 2017 (1I/'Oumuamua) and 2019 (2I/Borisov) and are expected to be detected more frequently with new telescopes, e.g. the Vera Rubin Observatory. Amir Siraj and Avi Loeb have predicted that the Vera C. Rubin Observatory will be capable of detecting an anisotropy in the distribution of interstellar objects due to the Sun's motion relative to the Local Standard of Rest and identify the characteristic ejection speed of interstellar objects from their parent stars. [49] [50] [51]

In May 2023, astronomers reported the possible capture of other interstellar objects in Near Earth Orbit (NEO) over the years. [11] [12]

Confirmed objects

1I/2017 U1 (ʻOumuamua)

Path of the hyperbolic, extrasolar object `Oumuamua, the first confirmed interstellar object, discovered in 2017 Oumuamua-solar system 2018.png
Path of the hyperbolic, extrasolar object ʻOumuamua, the first confirmed interstellar object, discovered in 2017

A dim object was discovered on October 19, 2017, by the Pan-STARRS telescope, at an apparent magnitude of 20. The observations showed that it follows a strongly hyperbolic trajectory around the Sun at a speed greater than the solar escape velocity, in turn meaning that it is not gravitationally bound to the Solar System and likely to be an interstellar object. [52] It was initially named C/2017 U1 because it was assumed to be a comet, and was renamed to A/2017 U1 after no cometary activity was found on October 25. [53] [54] After its interstellar nature was confirmed, it was renamed to 1I/ʻOumuamua – "1" because it is the first such object to be discovered, "I" for interstellar, and "'Oumuamua" is a Hawaiian word meaning "a messenger from afar arriving first". [55]

The lack of cometary activity from ʻOumuamua suggests an origin from the inner regions of whatever stellar system it came from, losing all surface volatiles within the frost line, much like the rocky asteroids, extinct comets and damocloids we know from the Solar System. This is only a suggestion, as ʻOumuamua might very well have lost all surface volatiles to eons of cosmic radiation exposure in interstellar space, developing a thick crust layer after it was expelled from its parent system.

ʻOumuamua has an eccentricity of 1.199, which was the highest eccentricity ever observed for any non-artificial object in the Solar System by a wide margin prior to the discovery of comet 2I/Borisov in August 2019.

In September 2018, astronomers described several possible home star systems from which ʻOumuamua may have begun its interstellar journey. [56] [57]

2I/Borisov

The object was discovered on 30 August 2019 at MARGO, Nauchnyy, Crimea by Gennadiy Borisov using his custom-built 0.65-meter telescope. [58] On 13 September 2019, the Gran Telescopio Canarias obtained a low-resolution visible spectrum of 2I/Borisov that revealed that this object has a surface composition not too different from that found in typical Oort Cloud comets. [59] [60] [61] The IAU Working Group for Small Body Nomenclature kept the name Borisov, giving the comet the interstellar designation of 2I/Borisov. [62] On 12 March 2020, astronomers reported observational evidence of "ongoing nucleus fragmentation" from Borisov. [63]

Candidates

Comet Hyakutake (C/1996 B2) might be a former interstellar object captured by the Solar System Hyakutake Color.jpg
Comet Hyakutake (C/1996 B2) might be a former interstellar object captured by the Solar System

In 2007, Afanasiev et al. reported the likely detection of a multi-centimeter intergalactic meteor hitting the atmosphere above the Special Astrophysical Observatory of the Russian Academy of Sciences on July 28, 2006. [64]

In November 2018, Harvard astronomers Amir Siraj and Avi Loeb reported that there should be hundreds of 'Oumuamua-size interstellar objects in the Solar System, based on calculated orbital characteristics, and presented several centaur candidates such as 2017 SV13 and 2018 TL6. These are all orbiting the Sun, but may have been captured in the distant past. [65] Both researchers have proposed methods for increasing the discovery rate of interstellar objects that include stellar occultations, optical signatures from impacts with the moon or the Earth's atmosphere, and radio flares from collisions with neutron stars. [66] [67] [68] [69]

2014 interstellar meteor

CNEOS 2014-01-08 (also known as Interstellar meteor 1; IM1), [70] [71] [72] a meteor with a mass of 0.46 tons and width of 0.45 m (1.5 ft), burned up in the Earth's atmosphere on January 8, 2014. [4] [10] A 2019 preprint suggested this meteor had been of interstellar origin. [73] [74] [6] [7] [9] It had a heliocentric speed of 60 km/s (37 mi/s) and an asymptotic speed of 42.1 ± 5.5 km/s (26.2 ± 3.4 mi/s), and it exploded at 17:05:34 UTC near Papua New Guinea at an altitude of 18.7 km (61,000 ft). [4] After declassifying the data in April 2022, [75] the U.S. Space Command, based on information collected from its planetary defense sensors, confirmed the velocity of the potential interstellar meteor. [8] [5] In 2023, The Galileo Project completed an expedition to retrieve small fragments of the apparently peculiar [76] [77] [78] meteor. [79] [78] Claims about their findings have been doubted by their peers according to a report in The New York Times . [80] Further related studies were reported on 1 September 2023. [81] [82]

Other astronomers doubt the interstellar origin because the meteoroid catalog used does not report uncertainties on the incoming velocity. [83] The validity of any single data point (especially for smaller meteoroids) remains questionable. In November 2022, a paper was published, claiming the anomalous properties (including its high strength and strongly hyperbolic trajectory) of CNEOS 2014-01-08 are better described as measurement error rather than genuine parameters. Successful retrieval of any meteoroid fragments is highly unlikely. [84] Common micrometeorites would be indistinguishable from one another.

2017 interstellar meteor

CNEOS 2017-03-09 (aka Interstellar meteor 2; IM2), [71] [72] a meteor with a mass of roughly 6.3 tons, burned up in the Earth's atmosphere on March 9, 2017. Similar to IM1, it has a high mechanical strength. [85] [71] In September 2022, astronomers Amir Siraj and Avi Loeb reported the discovery of a candidate interstellar meteor, CNEOS 2017-03-09, that impacted Earth in 2017 and is considered, based in part on the high material strength of the meteor, to be a possible interstellar object. [71] [72]

Hypothetical missions

With current space technology, close visits and orbital missions are challenging due to their high speeds, though not impossible. [86] [87]

The Initiative for Interstellar Studies (i4is) launched in 2017 Project Lyra to assess the feasibility of a mission to ʻOumuamua. [88] Several options for sending a spacecraft to ʻOumuamua within a time-frame of 5 to 25 years were suggested. [89] [90] One option is using first a Jupiter flyby followed by a close solar flyby at 3 solar radii (2.1×10^6 km; 1.3×10^6 mi) in order to take advantage of the Oberth effect. [91] Different mission durations and their velocity requirements were explored with respect to the launch date, assuming direct impulsive transfer to the intercept trajectory.

The Comet Interceptor spacecraft by ESA and JAXA, planned to launch in 2029, will be positioned at the Sun-Earth L2 point to wait for a suitable long-period comet to intercept and flyby for study. [92] In case that no suitable comet is identified during its 3-year wait, the spacecraft could be tasked to intercept an interstellar object in short notice, if reachable. [93]

See also

Related Research Articles

<span class="mw-page-title-main">Comet</span> Natural object in space that releases gas

A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or coma surrounding the nucleus, and sometimes a tail of gas and dust gas blown out from the coma. These phenomena are due to the effects of solar radiation and the outstreaming solar wind plasma acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch beyond one astronomical unit. If sufficiently close and bright, a comet may be seen from Earth without the aid of a telescope and can subtend an arc of up to 30° across the sky. Comets have been observed and recorded since ancient times by many cultures and religions.

<span class="mw-page-title-main">Near-Earth object</span> Small Solar System body with an orbit that can bring it close to Earth

A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun (perihelion) is less than 1.3 times the Earth–Sun distance. This definition applies to the object's orbit around the Sun, rather than its current position, thus an object with such an orbit is considered an NEO even at times when it is far from making a close approach of Earth. If an NEO's orbit crosses the Earth's orbit, and the object is larger than 140 meters (460 ft) across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but about 0.35% are comets.

<span class="mw-page-title-main">Oort cloud</span> Distant planetesimals in the Solar System

The Oort cloud, sometimes called the Öpik–Oort cloud, is theorized to be a vast cloud of icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 AU. The concept of such a cloud was proposed in 1950 by the Dutch astronomer Jan Oort, in whose honor the idea was named. Oort proposed that the bodies in this cloud replenish and keep constant the number of long-period comets entering the inner Solar System—where they are eventually consumed and destroyed during close approaches to the Sun.

<span class="mw-page-title-main">Solar System</span> The Sun and objects orbiting it

The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. It formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc. The Sun is a typical star that maintains a balanced equilibrium by the fusion of hydrogen into helium at its core, releasing this energy from its outer photosphere. Astronomers classify it as a G-type main-sequence star.

Damocloids are a class of minor planets such as 5335 Damocles and 1996 PW that have Halley-type or long-period highly eccentric orbits typical of periodic comets such as Halley's Comet, but without showing a cometary coma or tail. David Jewitt defines a damocloid as an object with a Jupiter Tisserand invariant (TJ) of 2 or less, while Akimasa Nakamura defines this group with the following orbital elements:

<span class="mw-page-title-main">Orbital eccentricity</span> Amount by which an orbit deviates from a perfect circle

In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit, and greater than 1 is a hyperbola. The term derives its name from the parameters of conic sections, as every Kepler orbit is a conic section. It is normally used for the isolated two-body problem, but extensions exist for objects following a rosette orbit through the Galaxy.

<span class="mw-page-title-main">Avi Loeb</span> Israeli-American theoretical physicist

Abraham "Avi" Loeb is an Israeli-American theoretical physicist who works on astrophysics and cosmology. Loeb is the Frank B. Baird Jr. Professor of Science at Harvard University, where since 2007 he has been Director of the Institute for Theory and Computation at the Center for Astrophysics. He chaired the Department of Astronomy from 2011 to 2020, and founded the Black Hole Initiative in 2016.

<span class="mw-page-title-main">C/1980 E1 (Bowell)</span> Hyperbolic comet

C/1980 E1 is a non-periodic comet discovered by Edward L. G. Bowell on 11 February 1980 and which came closest to the Sun (perihelion) in March 1982. It is leaving the Solar System on a hyperbolic trajectory due to a close approach to Jupiter. In the 43 years since its discovery only two objects with higher eccentricities have been identified, 1I/ʻOumuamua (1.2) and 2I/Borisov (3.35).

<span class="mw-page-title-main">Exocomet</span> Comet outside the Solar System

An exocomet, or extrasolar comet, is a comet outside the Solar System, which includes rogue comets and comets that orbit stars other than the Sun. The first exocomets were detected in 1987 around Beta Pictoris, a very young A-type main-sequence star. There are now a total of 27 stars around which exocomets have been observed or suspected.

<span class="mw-page-title-main">514107 Kaʻepaokaʻawela</span> Retrograde asteroid discovered in 2014

514107 Kaʻepaokaʻāwela, provisionally designated 2015 BZ509 and nicknamed Bee-Zed, is a small asteroid, approximately 3 km (2 mi) in diameter, in a resonant, co-orbital motion with Jupiter. It is an unusual minor planet in that its orbit is retrograde, which is opposite to the direction of most other bodies in the Solar System. It was discovered on 26 November 2014, by astronomers of the Pan-STARRS survey at Haleakala Observatory on the island of Maui, United States. Kaʻepaokaʻāwela is the first example of an asteroid in a 1:–1 resonance with any of the planets. This type of resonance had only been studied a few years before the object's discovery. One study suggests that it was an interstellar asteroid captured 4.5 billion years ago into an orbit around the Sun.

<span class="mw-page-title-main">ʻOumuamua</span> Interstellar object passed near Earth in 2017

ʻOumuamua is the first interstellar object detected passing through the Solar System. Formally designated 1I/2017 U1, it was discovered by Robert Weryk using the Pan-STARRS telescope at Haleakalā Observatory, Hawaii, on 19 October 2017, approximately 40 days after it passed its closest point to the Sun on 9 September. When it was first observed, it was about 33 million km from Earth and already heading away from the Sun.

A hyperbolic asteroid is any sort of asteroid or non-cometary astronomical object observed to have an orbit not bound to the Sun and will have an orbital eccentricity greater than 1 when near perihelion. Unlike hyperbolic comets, they have not been seen out-gassing light elements, and therefore have no cometary coma. Most of these objects will only be weakly hyperbolic and will not be of interstellar origin.

Project Lyra is a feasibility study of a mission to interstellar objects such as ʻOumuamua and 2I/Borisov, initiated on 30 October 2017 by the Initiative for Interstellar Studies (i4is). In January 2022, researchers proposed that a spacecraft launched from Earth could catch up to 'Oumuamua in 26 years for further close-up studies.

<span class="mw-page-title-main">C/2017 U7 (PanSTARRS)</span> Hyperbolic comet

C/2017 U7 (PanSTARRS) is a hyperbolic comet, first observed on 29 October 2017 by astronomers of the Pan-STARRS facility at Haleakala Observatory, Hawaii, United States when the object was 7.8 AU (1.2 billion km) from the Sun. Despite being discovered only 10 days after interstellar asteroid 1I/'Oumuamua, it was not announced until March 2018 as its orbit is not strongly hyperbolic beyond most Oort Cloud comets. Based on the absolute magnitude of 10.6, it may measure tens of kilometers in diameter. As of August 2018, there is only 1 hyperbolic asteroid known, ʻOumuamua, but hundreds of hyperbolic comets are known.

<span class="mw-page-title-main">C/2018 C2 (Lemmon)</span> Non-periodic comet

C/2018 C2 (Lemmon) is a hyperbolic comet. It was first observed on 5 February 2018 by the Mount Lemmon Survey conducted at the Mount Lemmon Observatory near Tucson, Arizona, in the United States. The discovery was announced on 4 March 2018 along with another hyperbolic object, A/2017 U7. Based on the absolute magnitude of 15.1, it may measure several kilometers in diameter. On 22 March 2018 it was determined to be a hyperbolic comet.

<span class="mw-page-title-main">2I/Borisov</span> Interstellar comet passing through the Solar System, discovered in 2019

2I/Borisov, originally designated C/2019 Q4 (Borisov), is the first observed rogue comet and the second observed interstellar interloper after ʻOumuamua. It was discovered by the Crimean amateur astronomer and telescope maker Gennadiy Borisov on 29 August 2019 UTC.

<i>Extraterrestrial: The First Sign of Intelligent Life Beyond Earth</i> 2021 popular science book by Avi Loeb

Extraterrestrial: The First Sign of Intelligent Life Beyond Earth is a popular science book written by American theoretical physicist and Harvard University astronomer Avi Loeb, published by Houghton Mifflin Harcourt on 26 January 2021.

CNEOS 2014-01-08, also known as Interstellar meteor 1 (IM1), was a 0.45 m (1.5 ft) meteor that impacted Earth on 8 January 2014 near the northeast coast of Papua New Guinea. It was claimed to be an interstellar object in a 2019 preprint by astronomers Amir Siraj and Avi Loeb, and this was published in 2022. This was supported by the U.S. Space Command in 2022 based on the object's velocity relative to the Sun. NASA and Other astronomers doubt this, and still other experts found Earth-related explanations for the purported meteorite impact instead.

<span class="mw-page-title-main">The Galileo Project</span> Search for extraterrestrial intelligence

The Galileo Project is an international scientific research project to search for extraterrestrial intelligence or extraterrestrial technology on and near Earth and to identify the nature of anomalous Unidentified Flying Objects/Unidentified Aerial Phenomena (UFOs/UAP).

Amir Siraj is an American astrophysicist, pianist, and science and music communicator.

References

  1. 1 2 3 Valtonen, Mauri J.; Zheng, Jia-Qing; Mikkola, Seppo (March 1992). "Origin of oort cloud comets in the interstellar space". Celestial Mechanics and Dynamical Astronomy. 54 (1–3): 37–48. Bibcode:1992CeMDA..54...37V. doi:10.1007/BF00049542. S2CID   189826529.
  2. 1 2 3 4 Francis, Paul J. (2005-12-20). "The Demographics of Long-Period Comets". The Astrophysical Journal. 635 (2): 1348–1361. arXiv: astro-ph/0509074 . Bibcode:2005ApJ...635.1348F. doi:10.1086/497684. S2CID   12767774.
  3. ↑ Veras, Dimitri (13 April 2020). "Creating the first interstellar interloper". Nature Astronomy. 4 (9): 835–836. Bibcode:2020NatAs...4..835V. doi: 10.1038/s41550-020-1064-9 . ISSN   2397-3366.
  4. 1 2 3 Siraj, Amir; Loeb, Abraham (4 June 2019). "Discovery of a Meteor of Interstellar Origin". arXiv: 1904.07224 [astro-ph.EP].
  5. 1 2 United States Space Command (6 April 2022). "I had the pleasure of signing a memo with @ussfspoc's Chief Scientist, Dr. Mozer, to confirm that a previously-detected interstellar object was indeed an interstellar object, a confirmation that assisted the broader astronomical community". Twitter . Retrieved 12 April 2022.
  6. 1 2 Ferreira, Becky (7 April 2022). "Secret Government Info Confirms First Known Interstellar Object on Earth, Scientists Say – A small meteor that hit Earth in 2014 was from another star system, and may have left interstellar debris on the seafloor". Vice News . Retrieved 9 April 2022.
  7. 1 2 Wenz, John (11 April 2022). ""It Opens A New Frontier Where You're Using The Earth As A Fishing Net For These Objects." – Harvard Astronomer Believes An Interstellar Meteor (or Craft) Hit Earth In 2014". Inverse . Retrieved 11 April 2022.
  8. 1 2 Handal, Josh; Fox, Karen; Talbert, Tricia (8 April 2022). "U.S. Space Force Releases Decades of Bolide Data to NASA for Planetary Defense Studies". NASA . Retrieved 11 April 2022.
  9. 1 2 Siraj, Amir (12 April 2022). "Spy Satellites Confirmed Our Discovery of the First Meteor from beyond the Solar System - A high-speed fireball that struck Earth in 2014 looked to be interstellar in origin, but verifying this extraordinary claim required extraordinary cooperation from secretive defense programs". Scientific American . Retrieved 14 April 2022.
  10. 1 2 Roulette, Joey (15 April 2022). "Military Memo Deepens Possible Interstellar Meteor Mystery – The U.S. Space Command seemed to confirm a claim that a meteor from outside the solar system had entered Earth's atmosphere, but other scientists and NASA are still not convinced. (+ Comment)". The New York Times . Retrieved 15 April 2022.
  11. 1 2 Gough, Evan (18 May 2023). "A Few Interstellar Objects Have Probably Been Captured". Universe Today . Retrieved 19 May 2023.
  12. 1 2 Mukherjee, Diptajyoti; Siraj, Amir; Trac, Hy; Loeb, Abraham (2023). "Close Encounters of the Interstellar Kind: Exploring the Capture of Interstellar Objects in Near Earth Orbit". Monthly Notices of the Royal Astronomical Society. 525: 908–921. arXiv: 2305.08915 . doi: 10.1093/mnras/stad2317 .
  13. ↑ Vaubaillon, J. (October 2022). "Hyperbolic meteors: is CNEOS 2014-01-08 interstellar?". WGN, Journal of the International Meteor Organization. 50 (5): 140–143. arXiv: 2211.02305 . Bibcode:2022JIMO...50..140V.
  14. ↑ Brown, Peter G.; Borovička, Jiří (August 2023). "On the Proposed Interstellar Origin of the USG 20140108 Fireball". The Astrophysical Journal . 953 (2): 167. arXiv: 2306.14267 . Bibcode:2023ApJ...953..167B. doi: 10.3847/1538-4357/ace421 .
  15. ↑ Gallardo, Patricio A. (October 2023). "Anthropogenic Coal Ash as a Contaminant in a Micro-meteoritic Underwater Search". Research Notes of the AAS . 7 (10): 220. Bibcode:2023RNAAS...7..220G. doi: 10.3847/2515-5172/ad03f9 .
  16. ↑ Desch, Steve; Jackson, Alan (November 2023). "Critique of arXiv submission 2308.15623, "Discovery of Spherules of Likely Extrasolar Composition in the Pacific Ocean Site of the CNEOS 2014-01-08 (IM1) Bolide", by A. Loeb et al". arXiv: 2311.07699 [astro-ph.EP].
  17. ↑ Fernando, Benjamin; Mialle, Pierrick; et al. (March 2024). "Seismic and acoustic signals from the 2014 'Interstellar Meteor'". arXiv: 2403.03966 [astro-ph.EP].
  18. ↑ Desch, Steve (March 2024). "Be,La,U-rich spherules as microtektites of terrestrial laterites: What goes up must come down". arXiv: 2403.05161 [astro-ph.EP].
  19. ↑ Richtel, Matt (11 March 2024). "Surprise: An 'Extraterrestrial' Gadget Was Something More Familiar - In 2014 a fireball from outer space was posited to be an alien artifact. A recent study suggests otherwise". The New York Times . Archived from the original on 11 March 2024. Retrieved 11 March 2024.
  20. ↑ The ‘Oumuamua ISSI Team; Bannister, Michele T.; Bhandare, Asmita; Dybczyński, Piotr A.; Fitzsimmons, Alan; Guilbert-Lepoutre, Aurélie; Jedicke, Robert; Knight, Matthew M.; Meech, Karen J.; McNeill, Andrew; Pfalzner, Susanne; Raymond, Sean N.; Snodgrass, Colin; Trilling, David E.; Ye, Quanzhi (2019-07-01). "The natural history of 'Oumuamua". Nature Astronomy. 3 (7): 594–602. doi:10.1038/s41550-019-0816-x. ISSN   2397-3366.
  21. ↑ "MPEC 2017-V17: NEW DESIGNATION SCHEME FOR INTERSTELLAR OBJECTS". Minor Planet Center. 6 November 2017.
  22. ↑ C/2012 S1 (ISON) had an epoch 1600 barycentric semi-major axis of −145127 and would have an inbound v_infinite of 0.2 km/s at 50000 au:
    v=42.1219 √1/50000 − 0.5/−145127
  23. ↑ Voyager Fast Facts
  24. ↑ Gray, Bill (26 October 2017). "Pseudo-MPEC for A/2017 U1 (FAQ File)". Project Pluto. Retrieved 26 October 2017.
  25. ↑ Gray, Bill. "FAQ for C/2019 Q4 (Borisov)". Project Pluto. Retrieved 2019-09-24.
  26. ↑ Siraj, Amir; Loeb, Abraham (2019). "Discovery of a Meteor of Interstellar Origin". arXiv: 1904.07224 [astro-ph.EP].
  27. ↑ "Interstellar Asteroid FAQs". NASA. 20 November 2017. Archived from the original on 18 December 2019. Retrieved 21 November 2017.
  28. ↑ Fraser, Wesley (11 February 2018). "The Sky at Night: The Mystery of ʻOumuamua" (Interview). Interviewed by Chris Lintott. BBC.
  29. ↑ Struve, Otto; Lynds, Beverly; Pillans, Helen (1959). Elementary Astronomy. New York: Oxford University Press. p. 150.
  30. 1 2 MacRobert, Alan (2008-12-02). "A Very Oddball Comet". Sky & Telescope. Archived from the original on 2008-12-07. Retrieved 2010-03-26.
  31. 1 2 Torbett, M. V. (July 1986). "Capture of 20 km/s approach velocity interstellar comets by three-body interactions in the planetary system". Astronomical Journal. 92: 171–175. Bibcode:1986AJ.....92..171T. doi: 10.1086/114148 .
  32. ↑ Jewitt, David; Luu, Jane; Rajagopal, Jayadev; Kotulla, Ralf; Ridgway, Susan; Liu, Wilson; Augusteijn, Thomas (2017). "Interstellar Interloper 1I/2017 U1: Observations from the NOT and WIYN Telescopes". The Astrophysical Journal. 850 (2): L36. arXiv: 1711.05687 . Bibcode:2017ApJ...850L..36J. doi: 10.3847/2041-8213/aa9b2f . S2CID   32684355.
  33. ↑ Choi, Charles Q. (2007-12-24). "The Enduring Mysteries of Comets". Space.com. Retrieved 2008-12-30.
  34. ↑ Siraj, Amir; Loeb, Abraham (2020-08-18). "The Case for an Early Solar Binary Companion". The Astrophysical Journal. 899 (2): L24. arXiv: 2007.10339 . Bibcode:2020ApJ...899L..24S. doi: 10.3847/2041-8213/abac66 . ISSN   2041-8213. S2CID   220665422.
  35. ↑ Carter, Jamie. "Was Our Sun A Twin? If So Then 'Planet 9' Could Be One Of Many Hidden Planets In Our Solar System". Forbes. Retrieved 2020-11-14.
  36. ↑ "Did the Sun have an early binary companion?". Cosmos Magazine. 2020-08-20. Archived from the original on 2020-11-16. Retrieved 2020-11-14.
  37. ↑ Siraj, Amir; Loeb, Abraham (2019). "Identifying Interstellar Objects Trapped in the Solar System through Their Orbital Paramteters". The Astrophysical Journal. 872 (1): L10. arXiv: 1811.09632 . Bibcode:2019ApJ...872L..10S. doi: 10.3847/2041-8213/ab042a . S2CID   119198820.
  38. ↑ Koren, Marina (23 January 2019). "When a Harvard Professor Talks About Aliens – News about extraterrestrial life sounds better coming from an expert at a high-prestige institution". The Atlantic . Retrieved 23 January 2019.
  39. ↑ "JPL Small-Body Database Browser: C/1980 E1 (Bowell)" (1986-12-02 last obs). Retrieved 2010-01-08.
  40. ↑ de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl; Aarseth, Sverre J. (6 February 2018). "Where the Solar system meets the solar neighbourhood: patterns in the distribution of radiants of observed hyperbolic minor bodies". Monthly Notices of the Royal Astronomical Society Letters. 476 (1): L1–L5. arXiv: 1802.00778 . Bibcode:2018MNRAS.476L...1D. doi: 10.1093/mnrasl/sly019 . S2CID   119405023.
  41. ↑ Mumma, M. J.; Disanti, M. A.; Russo, N. D.; Fomenkova, M.; Magee-Sauer, K.; Kaminski, C. D.; Xie, D. X. (1996). "Detection of Abundant Ethane and Methane, Along with Carbon Monoxide and Water, in Comet C/1996 B2 Hyakutake: Evidence for Interstellar Origin". Science. 272 (5266): 1310–1314. Bibcode:1996Sci...272.1310M. doi:10.1126/science.272.5266.1310. PMID   8650540. S2CID   27362518.
  42. ↑ Clery, Daniel (2018). "This asteroid came from another solar system—and it's here to stay". Science. doi:10.1126/science.aau2420.
  43. ↑ de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (11 October 2019). "Comet C/2018 V1 (Machholz-Fujikawa-Iwamoto): dislodged from the Oort Cloud or coming from interstellar space?". Monthly Notices of the Royal Astronomical Society . 489 (1): 951–961. arXiv: 1908.02666 . Bibcode:2019MNRAS.489..951D. doi: 10.1093/mnras/stz2229 . S2CID   199472877.
  44. ↑ Reuell, Peter (8 July 2019). "Harvard study suggests asteroids might play key role in spreading life". Harvard Gazette. Retrieved 29 September 2019.
  45. ↑ Hajdukova, Maria; Sterken, Veerle; Wiegert, Paul; Kornoš, Leonard (2020-11-01). "The challenge of identifying interstellar meteors". Planetary and Space Science. 192: 105060. Bibcode:2020P&SS..19205060H. doi: 10.1016/j.pss.2020.105060 . hdl: 20.500.11850/432235 . ISSN   0032-0633.
  46. 1 2 Hajdukova, M.; Sterken, V.; Wiegert, P.; Kornoš, L. (2020-11-01). "The challenge of identifying interstellar meteors". Planetary and Space Science. 192: 105060. Bibcode:2020P&SS..19205060H. doi: 10.1016/j.pss.2020.105060 . hdl: 20.500.11850/432235 . ISSN   0032-0633.
  47. ↑ Sterken, V. J.; Altobelli, N.; Kempf, S.; Schwehm, G.; Srama, R.; Grün, E. (2012-02-01). "The flow of interstellar dust into the solar system". Astronomy & Astrophysics. 538: A102. Bibcode:2012A&A...538A.102S. doi: 10.1051/0004-6361/201117119 . ISSN   0004-6361.
  48. ↑ Hajduková, Mária; Kornoš, Leonard (2020-10-01). "The influence of meteor measurement errors on the heliocentric orbits of meteoroids". Planetary and Space Science. 190: 104965. Bibcode:2020P&SS..19004965H. doi:10.1016/j.pss.2020.104965. ISSN   0032-0633. S2CID   224927095.
  49. ↑ Siraj, Amir; Loeb, Abraham (2020-10-29). "Observable Signatures of the Ejection Speed of Interstellar Objects from Their Birth Systems". The Astrophysical Journal. 903 (1): L20. arXiv: 2010.02214 . Bibcode:2020ApJ...903L..20S. doi: 10.3847/2041-8213/abc170 . ISSN   2041-8213. S2CID   222141714.
  50. ↑ Williams, Matt (2020-11-07). "Vera Rubin Should be Able to Detect a Couple of Interstellar Objects a Month". Universe Today. Retrieved 2020-11-14.
  51. ↑ Clery, Daniel (2021-07-26). "Project launched to look for extraterrestrial visitors to our Solar System". www.science.org. Retrieved 2021-10-22.
  52. ↑ "MPEC 2017-U181: COMET C/2017 U1 (PANSTARRS)". Minor Planet Center. Retrieved 25 October 2017.
  53. ↑ Meech, K. (25 October 2017). "Minor Planet Electronic Circular MPEC 2017-U183: A/2017 U1". Minor Planet Center.
  54. ↑ "We May Just Have Found An Object That Originated From Outside Our Solar System". IFLScience. October 26, 2017.
  55. ↑ "Aloha, 'Oumuamua! Scientists confirm that interstellar asteroid is a cosmic oddball". GeekWire. 20 November 2017.
  56. ↑ Feng, Fabo; Jones, Hugh R. A. (2018). "Plausible home stars of the interstellar object 'Oumuamua found in Gaia DR2". The Astronomical Journal. 156 (5): 205. arXiv: 1809.09009 . Bibcode:2018AJ....156..205B. doi: 10.3847/1538-3881/aae3eb . S2CID   119051284.
  57. ↑ 'Oumuamua Isn't from Our Solar System. Now We May Know Which Star It Came From
  58. ↑ King, Bob (11 September 2019). "Is Another Interstellar Visitor Headed Our Way?". Sky & Telescope . Retrieved 12 September 2019.
  59. ↑ "The Gran Telescopio Canarias (GTC) obtains the visible spectrum of C/2019 Q4 (Borisov), the first confirmed interstellar comet". Instituto Astrofisico de Canarias. 14 September 2019. Retrieved 2019-09-14.
  60. ↑ de León, Julia; Licandro, Javier; Serra-Ricart, Miquel; Cabrera-Lavers, Antonio; Font Serra, Joan; Scarpa, Riccardo; de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (19 September 2019). "Interstellar Visitors: A Physical Characterization of Comet C/2019 Q4 (Borisov) with OSIRIS at the 10.4 m GTC". Research Notes of the American Astronomical Society. 3 (9): 131. Bibcode:2019RNAAS...3..131D. doi: 10.3847/2515-5172/ab449c . S2CID   204193392.
  61. ↑ de León, J.; Licandro, J.; de la Fuente Marcos, C.; de la Fuente Marcos, R.; Lara, L. M.; Moreno, F.; Pinilla-Alonso, N.; Serra-Ricart, M.; De Prá, M.; Tozzi, G. P.; Souza-Feliciano, A. C.; Popescu, M.; Scarpa, R.; Font Serra, J.; Geier, S.; Lorenzi, V.; Harutyunyan, A.; Cabrera-Lavers, A. (30 April 2020). "Visible and near-infrared observations of interstellar comet 2I/Borisov with the 10.4-m GTC and the 3.6-m TNG telescopes". Monthly Notices of the Royal Astronomical Society . 495 (2): 2053–2062. arXiv: 2005.00786v1 . Bibcode:2020MNRAS.495.2053D. doi: 10.1093/mnras/staa1190 . S2CID   218486809.
  62. ↑ "MPEC 2019-S72: 2I/Borisov=C/2019 Q4 (Borisov)". Minor Planet Center. Retrieved 24 September 2019.
  63. ↑ Drahus, Michal; et al. (12 March 2020). "ATel#1349: Multiple Outbursts of Interstellar Comet 2I/Borisov". The Astronomer's Telegram . Retrieved 13 March 2020.
  64. ↑ Afanasiev, V. L.; Kalenichenko, V. V.; Karachentsev, I. D. (1 December 2007). "Detection of an intergalactic meteor particle with the 6-m telescope". Astrophysical Bulletin. 62 (4): 301–310. arXiv: 0712.1571 . Bibcode:2007AstBu..62..301A. doi:10.1134/S1990341307040013. ISSN   1990-3421. S2CID   16340731.
  65. ↑ Siraj, Amir; Loeb, Abraham (2019). "Identifying Interstellar Objects Trapped in the Solar System through Their Orbital Parameters". The Astrophysical Journal. 872 (1): L10. arXiv: 1811.09632 . Bibcode:2019ApJ...872L..10S. doi: 10.3847/2041-8213/ab042a . S2CID   119198820.
  66. ↑ Siraj, Amir; Loeb, Abraham (2020-02-26). "Detecting Interstellar Objects through Stellar Occultations". The Astrophysical Journal. 891 (1): L3. arXiv: 2001.02681 . Bibcode:2020ApJ...891L...3S. doi: 10.3847/2041-8213/ab74d9 . ISSN   2041-8213. S2CID   210116475.
  67. ↑ Siraj, Amir; Loeb, Abraham (2020-08-01). "A real-time search for interstellar impacts on the moon". Acta Astronautica. 173: 53–55. arXiv: 1908.08543 . Bibcode:2020AcAau.173...53S. doi:10.1016/j.actaastro.2020.04.006. ISSN   0094-5765. S2CID   201645069.
  68. ↑ Siraj, Amir; Loeb, Abraham (2019-09-19). "Radio Flares from Collisions of Neutron Stars with Interstellar Asteroids". Research Notes of the AAS. 3 (9): 130. arXiv: 1908.11440 . Bibcode:2019RNAAS...3..130S. doi: 10.3847/2515-5172/ab43de . ISSN   2515-5172. S2CID   201698501.
  69. ↑ August 2019, Mike Wall 30 (30 August 2019). "A Telescope Orbiting the Moon Could Spy 1 Interstellar Visitor Per Year". Space.com. Retrieved 2020-11-14.{{cite web}}: CS1 maint: numeric names: authors list (link)
  70. ↑ Pultarova, Tereza (3 November 2022). "Confirmed! A 2014 meteor is Earth's 1st known interstellar visitor - Interstellar space rocks might be falling to Earth every 10 years". Space.com . Retrieved 4 November 2022.
  71. 1 2 3 4 Siraj, Amir; Loeb, Avi (20 September 2022). "Interstellar Meteors are Outliers in Material Strength". The Astrophysical Journal. 941 (2): L28. arXiv: 2209.09905v1 . Bibcode:2022ApJ...941L..28S. doi: 10.3847/2041-8213/aca8a0 . S2CID   252407502.
  72. 1 2 3 Loeb, Avi (23 September 2022). "The discovery of a second interstellar meteor". TheDebrief.org. Retrieved 24 September 2022.
  73. ↑ Billings, Lee (23 April 2019). "Did a Meteor from Another Star Strike Earth in 2014? – Questionable data cloud the potential discovery of the first known interstellar fireball". Scientific American . Retrieved 12 April 2022.
  74. ↑ Choi, Charles Q. (16 April 2019). "The First Known Interstellar Meteor May Have Hit Earth in 2014 – The 3-foot-wide rock rock visited us three years before 'Oumuamua". Space.com . Retrieved 12 April 2022.
  75. ↑ Specktor, Brandon (11 April 2022). "An interstellar object exploded over Earth in 2014, declassified government data reveal – Classified data prevented scientists from verifying their discovery for 3 years". Live Science . Retrieved 12 April 2022.
  76. ↑ Loeb, Avi (18 April 2022). "The First Interstellar Meteor Had a Larger Material Strength Than Iron Meteorites". Medium. Retrieved 21 August 2022.
  77. ↑ Fuschetti, Ray; Johnson, Malcolm; Strader, Aaron. "Harvard Professor Believes Alien Tech Could Have Crashed Into Pacific Ocean — And He Wants to Find It". NBC Boston. Retrieved 2 September 2022.
  78. 1 2 Siraj, Amir; Loeb, Abraham; Gallaudet, Tim (5 August 2022). "An Ocean Expedition by the Galileo Project to Retrieve Fragments of the First Large Interstellar Meteor CNEOS 2014-01-08". arXiv: 2208.00092 [astro-ph.EP].
  79. ↑ Carter, Jamie (9 August 2022). "Astronomers plan to fish an interstellar meteorite out of the ocean using a massive magnet". livescience.com. Retrieved 21 August 2022.
  80. ↑ Miller, Katrina (24 July 2023). "Scientist's Deep Dive for Alien Life Leaves His Peers Dubious - Avi Loeb, a Harvard astrophysicist, says that material recovered from the seafloor could be from an extraterrestrial spacecraft. His peers are skeptical. + comment". The New York Times . Archived from the original on 25 July 2023. Retrieved 24 July 2023.
  81. ↑ McRae, Mike (1 September 2023). "Material Found in Ocean Is Not From This Solar System, Study Claims". Archived from the original on 1 September 2023. Retrieved 1 September 2023.
  82. ↑ Loeb, Avi; et al. (29 August 2023). "Discovery of Spherules of Likely Extrasolar Composition in the Pacific Ocean Site of the CNEOS 2014-01-08 (IM1) Bolide". arXiv: 2308.15623 .{{cite journal}}: Cite journal requires |journal= (help)
  83. ↑ Billings, Lee (2019-04-23). "Did a Meteor from Another Star Strike Earth in 2014". Scientific American . Retrieved 2019-04-23.
  84. ↑ Vaubaillon, J. (2022), "Hyperbolic meteors: is CNEOS 2014-01-08 interstellar?", WGN, 50 (5): 140, arXiv: 2211.02305 , Bibcode:2022JIMO...50..140V
  85. ↑ "Alien-Hunting Astronomer Says There May Be a Second Interstellar Object on Earth in New Study". Vice. Retrieved 3 November 2022.
  86. ↑ Seligman, Darryl; Laughlin, Gregory (12 April 2018). "The Feasibility and Benefits of in situ Exploration of ʻOumuamua-like Objects". The Astronomical Journal. 155 (5): 217. arXiv: 1803.07022 . Bibcode:2018AJ....155..217S. doi: 10.3847/1538-3881/aabd37 . S2CID   73656586.
  87. ↑ Ferreira, Becky (8 November 2022). "We Need to Intercept Our Next Interstellar Visitor to See If It's Artificial, Astronomers Say in New Study - A new study games out a mission to intercept an interstellar object in space and get a close-up look to see just what its made of". Vice . Retrieved 8 November 2022.
  88. ↑ "Project Lyra – A Mission to ʻOumuamua". Initiative for Interstellar Studies.
  89. ↑ Hein, Andreas M.; Perakis, Nikolaos; Eubanks, T. Marshall; Hibberd, Adam; Crowl, Adam; Hayward, Kieran; Kennedy, Robert G. III; Osborne, Richard (7 January 2019). "Project Lyra: Sending a spacecraft to 1I/'Oumuamua (former A/2017 U1), the interstellar asteroid". Acta Astronautica. 161: 552–561. arXiv: 1711.03155 . Bibcode:2017arXiv171103155H. doi:10.1016/j.actaastro.2018.12.042. S2CID   119474144.
  90. ↑ Hibberd, Adam; Hein, Andreas M.; Eubanks, T. Marshall (2020). "Project Lyra: Catching 1I/'Oumuamua – Mission Opportunities After 2024". Acta Astronautica. 170: 136–144. arXiv: 1902.04935 . Bibcode:2020AcAau.170..136H. doi:10.1016/j.actaastro.2020.01.018. S2CID   119078436.
  91. ↑ Hein, A.M.; Perakis, N.; Long, K.F.; Crowl, A.; Eubanks, M.; Kennedy, R.G. III; Osborne, R. (2017). "Project Lyra: Sending a Spacecraft to 1I/ʻOumuamua (former A/2017 U1), the Interstellar Asteroid". arXiv: 1711.03155 [physics.space-ph].
  92. ↑ "Ariel moves from blueprint to reality". ESA . 12 November 2020. Retrieved 12 November 2020.
  93. ↑ O'Callaghan, Jonathan (24 June 2019). "European Comet Interceptor Could Visit an Interstellar Object". Scientific American.
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