Sergei Ivanovich Ipatov (, born November 10, 1952, Moscow) is a Soviet, Russian, and American scientist, laureate of the F. A. Bredikhin Prize in astronomy of the Russian Academy of Sciences, Doctor of Physical and Mathematical Sciences. Asteroid 14360 Ipatov was named in his honor.
Early life Sergei Ivanovich Ipatov was born in Moscow, Soviet Union, on November 10, 1952.Ipatov’s biography at big biographical encyclopedia (in Russian). His parents were Ivan Iosifovich Ipatov (1927-2015), a сolonel, Ph.D., who was thedeputy head of a department in the V.V. Kuibyshev military academy and Alexandra Ivanovna Ipatova née Ropakova (1927-2010), a teacher of mathematics. His brother (Andrey Ivanovich Ipatov) is a professor, doctor of technical sciences. The wife of Sergei, Valentina Ivanovna Ipatova (Artioukhova), is a senior scientist, PhD, at the Lomonosov Moscow State University.Sergei Ipatov as Marquis Who's Who top scientist.S.I. Ipatov in the seventh edition of Millennium, A Marquis Who's Who Magazine.
In 1975, he graduated from the Faculty of Mechanics and Mathematics of the Lomonosov Moscow State University.
Career Between 1975 and 2003, Ipatov worked at the M.V. Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences (in the sector of RAS Academician T.M. Eneev at the department of Academician D.E. Okhotsimsky). In 1982 he became a candidate of physical and mathematical sciences (PhD), and in 1997 – a doctor of physical and mathematical sciences.S.I. Ipatov on the website of the V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry of Russian Academy of Sciences (in Russian) In 2001–2010 he worked at several scientific institutions in the United States: at the NASA's Goddard Space Flight Center (MD, USA), the University of Maryland (College Park, MD, USA), the Department of Terrestrial Magnetism of the Carnegie Institution for Science (now Earth and Planets Laboratory of Carnegie Science) (Washington, DC, US), the George Mason University (VA, US), and the Catholic University of America (Washington, DC, US). In 2011–2013 he worked in Qatar (Alsubai Establishment for Scientific Studies, Doha, Qatar). Since December 2013, he has been a lead scientist at the V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry of Russian Academy of Sciences.Sergei I. Ipatov's homepage
In 1990s Ipatov made several scientific visits (with duration from a month to six months) to Belgium, Germany, and the United States. In 1998 he delivered lectures at the astronomy department of the Faculty of Physics of Moscow State University. He worked part time at the Gubkin Russian State University of Oil and Gas (National Research University, Moscow, 2001–2002) and at the Space Research Institute of the Russian Academy of Sciences (Moscow, 2011–2017).
He is an authorList of publications by S.I. Ipatov in PublonsPublications by S.I. Ipatov with the ability to download most of the papers of about 80 papers in peer-reviewed scientific journals, about 120 papers in conference proceedings and books, and more than 300 conference abstracts. He published four books in Russian: "Migration of Celestial Bodies in the Solar System"Ipatov, S.I. (2000, 2021). Migration of celestial bodies in the solar system, Editorial URSS Publishing Company, Moscow, 320 p. DOI 10.17513/np.667. , (in Russian)., "Several notes about history of the USSR and Russia"Ipatov, S.I. (2025). Several notes about history of the USSR and Russia, Samprint, Moscow, 52 p. (in Russian)., "Formation and evolution of planetary systems"Ipatov, S.I. (2025). Formation and evolution of planetary systems, Samprint, Moscow, 132 p. DOI 10.17513/np.649. (in Russian). (the book contains 537 references, mainly in English, to publications by S.I. Ipatov), "My meetings with astronomers and other people"Ipatov, S.I. (2026). My meetings with astronomers and other people, Samprint, Moscow, 372 p. DOI 10.17513/np.668. (in Russian). (the book contains more than a thousand photos of scientists, including foreign scientists). The last two books contain a lot of text in English. Ipatov is a member of the editorial board of the scientific journal Solar System Research (since 2003), academician of the Russian Academy of Natural Sciences (section of physics, since 2000), a member of the Eurasian Astronomical Society (since 1995), European Astronomical Society (since 1995), American Astronomical Society (since 2002), International Astronomical Union (since 2003), American Geophysical Union (since 2006).
Main scientific interests and achievements Ipatov studied migration of bodies and planets in the forming Solar System and formation of planets and exoplanets. The studies were based on computer simulations of the evolution of disks of gravitating bodies combined at collisions. In particular, in 1991, before the Nice model, he publishedIpatov, S.I. (1991). “Evolution of initially highly eccentric orbits of the growing nuclei of the giant planets”. Soviet Astron. Letters. 17 (2): 113-119. for the first time that if the embryos of Uranus and Neptune were originally near the orbit of Saturn, then they could increase the semi-major axes of their orbits to their present values as a result of gravitational interactions with migrated planetesimals. The total mass of planetesimals ejected into hyperbolic orbits was several times higher than the mass of planetesimals that collided with forming giant planetsIpatov, S.I. (1993). “Migration of bodies in the accretion of planets”. Solar System Research. 27 (1): 65-79. The inner layers of every terrestrial planet can be accumulated mainly from material from the vicinity of this planet. The outer layers of the Earth and Venus could accumulate similar material from the feeding zone of the terrestrial planets. The Earth and Venus could accumulate most of the planetesimals from the zone at a distance of 0.7–1.1 AU from the Sun in less than 5 million years.Ipatov S.I. (2019). “Probabilities of collisions of planetesimals from different regions of the feeding zone of the terrestrial planets with the forming planets and the Moon”. Solar System Research. 53 (5): 332-361. arXiv:2003.11301. The formation of satellite systems of small bodies and the Earth-Moon system was studiedIpatov, S.I. (2010). “The angular momentum of two collided rarefied preplanetesimals and the formation of binaries”. Mon. Not. R. Astron. Soc. 403: 405-414. arXiv:0904.3529.Ipatov, S.I. (2017). “Formation of trans-Neptunian satellite systems at the stage of condensations”. Solar System Research. 51 (4): 294-314. arXiv:1801.05217.Ipatov, S.I. (2018). “Formation of embryos of the Earth and the Moon from the common rarefied condensation and the subsequent growth”. Solar System Research. 52 (5): 401-416. arXiv:2003.09925. for the model for which embryos of these celestial objects were formed as a result of the compression of a rarefied condensation formed as a result of the collision of two condensations at which it acquired the angular momentum needed for formation of a satellite system. The Moon embryo that formed as a result of compression of the condensation grew later mainly by accumulation of the material ejected from the Earth's embryo at its collisions with planetesimals.
Ipatov made computer simulations of migration of small bodies (asteroids, comets, trans-Neptunian objects, planetesimals, and bodies ejected from the terrestrial planets and the Moon). For example, in 1989, he showed for the first time that for the 5:2 resonance with Jupiter, the range of initial values of semi-major axes, eccentricities, and orbital inclinations at which test asteroids begin to cross the orbit of Mars in time of no more than 100 thousand years is close to the zone avoided by real asteroids.Ipatov, S.I. (1989). “Variations in orbital eccentricities of asteroids near the 2:5 resonance”. Soviet Astron. Letters. 15: 324-328.Ipatov, S.I. (1992). “Evolution of asteroidal orbits at the 5:2 resonance”. Icarus. 95 (1): 100-114. A small fraction of Jupiter-crossing objects can reach typical near-Earth objects' orbits and move in such orbits for millions of years. Although the fraction of such objects did not exceed a percent of the original objects, the contribution of such an object to the probability of collisions with the Earth could be greater than that of hundreds or even thousands of other objects with close initial orbits.Ipatov, S.I., Mather, J.C. (2004). “Migration of Jupiter-family comets and resonant asteroids to near-Earth space”. Annals of the New York Academy of Sciences. 1017: 46-65. arXiv: 0308448. Calculations showed that the amount of matter delivered to the Earth from beyond Jupiter's orbit could exceed the mass of the Earth's oceans if the mass of bodies in the feeding area of the giant planets was about 200 Earth's masses. The ratio of the mass of matter delivered from this region to a planet to the mass of the planet for Mars was about twice that for the Earth, and such ratios for Mercury and Venus were slightly larger than for the Earth. Bodies migrated from the zone of the outer asteroid belt could also deliver a considerable amount of water to the Earth and could be one of the sources of the late-heavy bombardment. Some papers on migration of small bodies were published in collaboration with Academician M.Ya. Marov. Based on the studies of lunar craters and the probabilities of collisions of near-Earth objects with the Earth, together with E.A. Feoktistova and V.V. Svetsov, he estimatedIpatov S.I., Feoktistova, E.A., Svetsov V.V. (2020). “Number of near-Earth objects and formation of lunar craters over the last billion years”. Solar System Research. 54 (5): 384-404. arXiv:2011.00361. the variations in the number of near-Earth objects over the last billion years, and also studied the depths of lunar craters in the region of the seas and continents.Feoktistova, E.A., Ipatov, S.I. (2021). “Depths of Copernican craters on lunar maria and highlands”. Earth, Moon, and Planets. 125, Article id. 1, 23 p. ArXiv: 2103.00291.
Together with John Mather, Ipatov numerically studied the migration of dust particles with initial velocities and positions the same as those of asteroids, trans-Neptunian objects and comets. The probabilities of collisions of dust particles of various masses with planets were calculated. Based on the results of studies of the migration of dust particles and observational data (for example, the spectra of dust particles of the zodiacal cloud), the fractions of the zodiacal dust produced by asteroids and comets, as well as the typical eccentricities of the zodiacal dust particles, were estimated.Ipatov, S.I., Kutyrev, A., Madsen, G.J., Mather, J.C., Moseley, S.H., Reynolds, R.J. (2008). “Dynamical zodiacal cloud models constrained by high resolution spectroscopy of the zodiacal light”. Icarus. 194 (2): 769-788. ArXiv:0711.349 4. In particular, it was concluded that cometary dust particles can play a dominant role in the zodiacal cloud. Migration of dust ejected from the terrestrial planets was also studied.