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1.
Spectrum–Röntgen–Gamma (SRG) is a space observatory designed to observe astrophysical objects in the X-ray range of the electromagnetic spectrum. SRG is planned to be launched in 2019 by a Proton-M launch vehicle with a DM3 upper stage. The spacecraft will be delivered to an orbit around the Sun–Earth collinear libration point L2 located at a distance of ~1.5 million km from the Earth. Although the SRG launch scheme has already been determined at present, in this paper we consider an alternative spacecraft transfer scenario using a lunar gravity-assist maneuver. The proposed scenario allows a oneimpulse transfer from a low Earth orbit to a small-amplitude orbit around the libration point to be performed while fulfilling the technical constraints and the scientific requirements of the mission. 相似文献
2.
The possibility of investigating the sky region near the Galactic center with instruments of the INTEGRAL orbital astrophysical gamma-ray observatory by the method of its occultation by the Earth and the Moon is considered. Existing engineering constraints on the observing conditions, such as the admissible orientation of the INTEGRAL satellite relative to the direction to the Sun and the performance of measurements only outside the Earth??s radiation belts, are taken into account. Long time intervals during which the lunar occultation center passes at angular distances of less than 2° from the Galactic center have been found. Such events occur under the adopted constraints two or three times per year without any correction of the INTEGRAL satellite orbit. The orbit can be corrected to reduce the angular distance between the Moon and the Galactic center in occultation events. The required velocity impulses do not exceed several meters per second. The possibility of the Galactic center being occulted by the Earth has been analyzed. In this case, to perform measurements, the admissible (in radiation exposure) height of the working segment of the orbit should be reduced to 25 000 km, which can be problematic. At the same time, part of the Galaxy??s equatorial region is shadowed by the Earth for a time long enough to carry out the corresponding experiments. 相似文献
3.
Eismont N. A. Zasova L. V. Simonov A. V. Kovalenko I. D. Gorinov D. A. Abbakumov A. S. Bober S. A. 《Solar System Research》2019,53(7):578-585
Solar System Research - The article describes the trajectory scenario for the Venera-D mission. The main aspects of optimal launch dates are considered. A scenario, which enables insertion of an... 相似文献
4.
D. W. Dunham H. J. Reitsema E. Lu R. Arentz R. Linfield C. Chapman R. Farquhar A. A. Ledkov N. A. Eismont E. Chumachenko 《Solar System Research》2013,47(4):315-324
The atmospheric detonation of a 17 m-asteroid above Chelyabinsk, Russia on 2013 February 15 shows that even small asteroids can cause extensive damage. Earth-based telescopes have found smaller harmless objects, such as 2008 TC3, a 4 m-asteroid that was discovered 20h before it exploded over northeastern Sudan (Jenniskens, 2009). 2008 TC3 remains the only asteroid discovered before it hit Earth because it approached Earth from the night side, where it was observed by large telescopes searching for near-Earth objects (NEO’s). The larger object that exploded over Chelyabinsk approached Earth from the day side, from too close to the Sun to be detected from Earth. A sizeable telescope in an orbit about the Sun-Earth L1 (SE-L1) libration point could find objects like the “Chelyabinsk” asteroid approaching approximately from the line of sight to the Sun about a day before Earth closest approach. Such a system would have the astrometric accuracy needed to determine the time and impact zone for a NEO on a collision course. This would give at least several hours, and usually 2–4 days, to take protective measures, rather than the approximately two-minute interval between the flash and shock wave arrival that occurred in Chelyabinsk. A perhaps even more important reason for providing warning of these events, even smaller harmless ones that explode high in the atmosphere with the force of an atomic bomb, is to prevent mistaking such an event for a nuclear attack that could trigger a devastating nuclear war. A concept using a space telescope similar to that needed for an SE-L1 monitoring satellite, is already conceived by the B612 Foundation, whose planned Sentinel Space Telescope could find nearly all 140 m and larger NEO’s, including those in orbits mostly inside the Earth’s orbit that are hard to find with Earth-based telescopes, from a Venus-like orbit (Lu, 2013). Few modifications would be needed to the Sentinel Space Telescope to operate in a SE-L1 orbit, 0.01 AU from Earth towards the Sun, to find most asteroids larger than about 5 meters that approach the Earth from the solar direction. The spacecraft would scan 165 square degrees of the sky around the Earth every hour, finding asteroids when they are brightest (small phase angle) as they approach Earth. We will undertake Monte Carlo studies to see what fraction of asteroids 5 m and larger approaching from the Sun might be found by such a mission, and how much warning time might typically be expected. Also, we will check the overall coverage for all Earth-approaching NEO’s, including ground-based observations and observations by the recently-launched NEOSSat, which may best fill any gaps in coverage between that provided by an SE-L1 telescope and ground-based surveys. Many of the objects as large as 50 m, like the one that created Meteor Crater in Arizona, will not be found by current NEO surveys, while they would usually be seen by this possible mission even if they approached from the direction of the Sun. We should give better warning for future “Bolts out of the blue.” 相似文献
5.
Eismont N. A. Nazirov R. R. Fedyaev K. S. Zubko V. A. Belyaev A. A. Zasova L. V. Gorinov D. A. Simonov A. V. 《Astronomy Letters》2021,47(5):316-330
Astronomy Letters - We consider the concept of applying gravity assist maneuvers near Venus using resonant orbits with a period equal to the Venusian one. We show that the proposed operations based... 相似文献
6.
G. N. Zastenker E. Salerno F. Buehler P. Bochsler M. Bassi Yu. N. Agafonov N. A. Eismont V. V. Khrapchenkov H. Busemann 《Astrophysics》2002,45(2):131-142
One of the important problems in astrophysics is the determination of the abundances of the helium isotopes 3He and 4He in various regions of the universe, since those abundances can provide evidence of the intensities of various possible processes of the production and decay of light elements and can thereby reflect their history. In this paper we describe the procedure and results of the first determination by a direct method of the abundances of helium isotopes in the local interstellar medium surrounding the solar system. The experiment was carried out on the piloted MIR station by the prolonged exposure in open space of specimens of metallic foil with their subsequent return to earth and detailed laboratory mass-spectrometric analysis. As a result, we were able to obtain estimates of the 4He density (about 7.5·10-3 cm-3) and the 3He/4He isotopic ratio (about 1.7·10-4) for the local interst ellar medium. 相似文献
7.
Zasova L. V. Gorinov D. A. Eismont N. A. Kovalenko I. D. Abbakumov A. S. Bober S. A. 《Solar System Research》2019,53(7):506-510
Solar System Research - The paper focuses on a future mission to Venus, Venera-D, which is presently at the stage of defining the scientific objectives and shaping the preliminary mission... 相似文献
8.
N. A. Eismont M. N. Boyarskii A. A. Ledkov R. R. Nazirov D. W. Dunham B. M. Shustov 《Solar System Research》2013,47(4):325-333
In this paper, the method of changing the trajectories of hazardous asteroids with orbits known for some years to be on a possible collision course with the Earth is considered. The method relies on the use of small asteroids (asteroid-projectiles) directed at hazardous celestial bodies by giving the projectile a sufficiently small velocity impulse ensuring the Earth gravity assist. As a result, the asteroid-projectile vector can be controllably changed over a wide range. Apophis is considered as an example of the target asteroid. The technical feasibility of this method is discussed. It is noted that despite the potential use of this elegant method, its practical implementation requires further research and development. 相似文献
9.
F. BÜhler M.L. Bassi P. Bochsler O. Eugster E. Salerno G.N. Zastenker YU.N. Agafonov L.G. Gevorkov N.A. Eismont A.V. Prudkoglyad V.V. Khrapchenkov N.I. Shvets 《Astrophysics and Space Science》2000,274(1-2):19-24
For the first time, the method of collecting impinging atoms in pretreated foil surfaces during exposure from a spacecraft
allowed to detect in the laboratory, after retrieval of the foils,4He gas of interstellar origin in the expected concentration.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
A. V. Zakharov N. A. Eismont V. M. Gotlib V. M. Smirnov O. V. Yushkova V. N. Marchuk 《Solar System Research》2017,51(5):386-399
The opportunities to study Phobos’ internal structure provided by radio methods are considered in this paper. The necessity of these studies is related to solution of the problem of the origin of the Martian moons. Radiosounding is one of the most efficient methods of analyzing the internal structure of small space objects and, in particular, that of Phobos. The new Boomerang project planned according to the Federal Space Program of Russia for 2016—2025 within the Expedition-M program aimed at the exploration of Phobos and delivery of soil samples from its surface to the Earth, as well as the specifics of a ballistic scenario of this expedition, provide a unique opportunity to carry out radioscopy of this space object to discover the internal structure Phobos and to solve the key problem of its origin. The model of Phobos’ internal structure, radiosounding ballistic conditions, analysis of optimum frequency range of sounding, and key parameters of the device required for the experiment are considered in this paper. The significance of proposed studies and opportunities for their implementation are discussed. 相似文献