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1.
When a satellite orbit decaying slowly under the action of air drag experiences 15th-order resonance with the Earth's gravitational field, so that the ground track repeats after 15 rev, the orbital eccentricity may suffer appreciable changes due to perturbations from the gravitational harmonics of order 15 and even degree (16, 18, 20…). In this paper the changes in eccentricity at resonance for six satellites in near-circular orbits at inclinations between 56 and 90° have been analysed to derive 11 pairs of equations linking the harmonic coefficients of order 15 and (even) degree l, in the usual notation. These equations (together with eight constraint equations) are solved to give: | 109 | 109 | | 16 | ?13.7 ± 1.3 | ?18.5 ± 2.7 | | 18 | ?42.3 ± 1.8 | ?34.7 ± 3.4 | | 20 | 10.5 ± 3.1 | 29.8 ± 5.2 | | 22 | ?8.6 ± 3.8 | ?20.2 ± 7.4 | 相似文献
2.
When a satellite orbit decaying slowly under the action of air drag experiences 15th-order resonance with the Earth's gravitational field, so that the ground track repeats after 15 rev, the orbital inclination suffers appreciable changes due to the perturbations from the harmonics in the geopotential of order 15 and odd degree (15,17,19 …). In this paper the changes in inclination at resonance of 11 satellites at inclinations between 30° and 90° have been analysed to determine values of the geopotential coefficients of order 15 and degree and in the usual notation. The recommended solution, going up to l = 31, is: | l | 109C?l,15 | 109S?l,15 | | 15 | ?21.5 ± 0.9 | ?8.4 ± 0.9 | | 17 | 4.4 ± 1.6 | 9.0 ± 1.5 | | 19 | ?15.6 ± 2.6 | ?14.1 ± 2.7 | | 21 | 10.4 ± 3.0 | 7.3 ± 3.5 | | 23 | 22.5 ± 2.8 | 1.2 ± 4.4 | | 25 | ?0.9 ± 4.7 | ?3.8 ± 5.3 | | 27 | ?11.2 ±3.3 | 9.1 ± 3.2 | | 29 | ?20.5 ± 5.4 | ?1.2 ± 6.1 | | 31 | 17.7 ± 6.6 | ?1.0 ± 7.1 | 相似文献
3.
The Earth's gravitational potential is now usually expressed in terms of a double series of tesseral harmonics with several hundred terms, up to order and degree at least 20. The harmonics of order 14 can be evaluated by analysing changes in satellite orbits which experience 14th-order resonance, when the track over the Earth repeats after 14 revolutions.In this paper we describe our first evaluation of individual 14th-order coefficients in the geopotential from analysis of the variations in inclination and eccentricity of satellite orbits passing through 14th-order resonance under the action of air drag. Using results from eleven satellites, we find the following values for normalized coefficients of harmonics of order 14 and degree l, C?l, 14 and S?l, 14, for l=14, 154. 22: | 109C? | 109S?l,14 | | - | - | - | | 14 | ?38.5 ±2.9 | ?7.8 ±2.2 | | 15 | 4.5 ±1.1 | ?23.8 ±0.3 | | 16 | ?22.3 ±3.6 | ?36.0 ±3.8 | | 17 | ?15.0 ±2.6 | 16.8 ±1.2 | | 18 | ?24.0±4.9 | ?3.2 ±3.7 | | 19 | ?1.6 ±2.8 | ?7.6 ±1.0 | | 20 | 8.8 ±5.8 | ?15.4 ±4.6 | | 21 | 18.2 ±3.6 | ?10.6 ±1.9 | | 22 | ?14.5 ±8.1 | 9.9 ±6.4 | 相似文献
4.
Explorer 1, 1958α, ths first U.S. artificial satellite, was launched on 1 February 1958 and remained in orbit for 12 years. In this paper theoretical curves have been fitted to the values of inclination, giving three values of the average atmospheric rotation rate at heights of 350–400 km, and latitudes 0–20°: | Feb 1958 to mid 1960 | 1.5 rev/day | | Mid 1960 to Dec 1967 | 1.2 rev/day | | Jan 1968 to Mar 1970 | 1.3 rev/day | 相似文献
5.
The orbit of Tansei 3rocket(1977-12B) has been determined at 47 epochs between 1 October 1977 and 19 March 1979 using over 1700 observations and the RAE orbit refinement program PROP6. The rate of change of the inclination was examined to evaluate values of the atmospheric rotation rate, Λ rev day ?1. Analysis yielded the value Λ = 1.1 ± 0.05 at height 315 ± 30 km, average conditions; or alternatively Λ = 1.1 ± 0.1 at height 347 ± 12 km, slight winter bias and Λ = 1.07 ± 0.1 at height 270 ± 18 km, average conditions, supplying further evidence of a decrease in rotation rates from the 1960s to the 1970s.Analysis of the inclination at 15th-order resonance yielded the lumped harmonic values for inclination 65.485°. 相似文献
6.
In the course of testing a 3-channel photon-counting, high-speed photometer, we observed DY Peg on three nights, 1980 September 18, 19, and November 15, and obtained 7 light maxima. Combining with results observed over the past 30 years, we re-calculated the formula for the maximum epoch to be and the period decay rate to be (3.1± 0.1) × 10 ?8yr ?1. 相似文献
8.
The influence of aerodynamic drag and the geopotential on the motion of the satellite 1964-52B is considered. A model of the atmosphere is adopted that allows for oblateness, and in which the density behaviour approximates to the observed diurnal variation. A differential equation governing the variation of the eccentricity, e, combining the effects of air drag with those of the Earth's gravitational field is given. This is solved numerically using as initial conditions 310 computed orbits of 1964-52B.The observed values of eccentricity are modified by the removal of perturbations due to luni-solar attraction, solid Earth and ocean tides, solar radiation pressure and low-order long-periodic tesseral harmonic perturbations. The method of removal of these effects is given in some detail. The behaviour of the orbital eccentricity predicted by the numerical solution is compared with the modified observed eccentricity to obtain values of atmospheric parameters at heights between 310 and 430 km. The daytime maximum of air density is found to be at 14.5 hours local time. Analysis of the eccentricity near 15th order resonance with the geopotential yielded values of four lumped geopotential harmonics of order 15, namely: , , , at inclination 98.68°. 相似文献
9.
In this paper we confirm an earlier finding that the reaction constitutes a major source of OI 6300 Å dayglow. The rate coefficient for this reaction is found to be consistent with an auroral result, namely k 1 ≈ 6 × 10 ?12cm3s?1. We correct an error in an earlier publication and demonstrate that reaction (1) is consistent with the laboratory determined quenching rate for the reaction where . Dissociative recombination of O +2 with electrons is found to be a major daytime source in summer above ～220 km. 相似文献
10.
The paper gives the results of detailed studies of the frequency spectra of the chain of the wave packets Fs( t) of geomagnetic pulsations PC-1 recorded at the Novolazarevskaya station. The bulk of the energy of Fs( t) is concentrated in the vicinity of the central frequencies of spectra—the carrier frequencies of the signals. The velocity of the flux of protons generating these signals correspond to them. The spectra of the signals have oscillations—“satellites” irregularly distributed in frequency. These satellites, as the authors believe, testify to the presence of the individual groups of protons of low concentration whose velocities vary within 10 3–10 4 km s ?1.Their energy is only of the order of 10 ?2–10 ?3 of the energy of the main proton flux. Clearly pronounced maxima on double and triple frequencies are detected. They show that the generation of pulsations PC-1 is accompanied by the generation on the overtones of wave packets called in this paper “two-fold” and “three-fold” pulsations PC-1. Intensive symmetrical satellites of a modulation character have been discovered on frequencies . Frequency differences correspond to them. The authors believe that the values of Δ? ±sK are resonance frequencies of the magnetospheric cavity in which geomagnetic pulsations PC-1 are generated. It is established that the values of Δ? ±sK coincide closely with the carrier frequencies of geomagnetic pulsations PC-3 and PC-4 generated in the magnetosphere. This leads to the conclusion that the resonance oscillations of the magnetospheric cavity are their source. Thus, the generation of geomagnetic pulsations of different types and resonance oscillations in the magnetosphere are integrated into a unified process. The importance of the results obtained and the necessity to check further their trustworthiness and universality, using experimental data gathered in different conditions, is stressed. 相似文献
11.
The orbit of Cosmos 837 rocket (1976-62E) has been determined at 36 epochs between January and September 1978, using the RAE orbit refinement program PROP 6 with about 3000 observations. The inclination was 62.7° and the eccentricity 0.039. The orbital accuracy achieved was between 30m and 150m, both radial and crosstrack. The orbit was near 29:2 resonance in 1978 (exact resonance occurred on 14 May) and the values of orbital inclination obtained have been analysed to derive lumped 29th-order geopotential harmonic coefficients, namely: and . These will be used in future, when enough results at different inclinations have accumulated, to determine individual coefficients of order 29. The values of lumped harmonics obtained from analysis of the values of eccentricity were not well defined, because of the high correlations between them and the errors in removing the very large perturbation (31 km) due to odd zonal harmonics. 相似文献
12.
Measurements of N 2+ and supporting data made on the Atmosphere Explorer-C satellite in the ionosphere are used to study the charge exchange process The equality k = (5 ± 1.7) × 10 ?10cm 3s?1. This value lies close to the lower limit of experimental uncertainty of the rate coefficient determined in the laboratory. We have also investigated atomic oxygen quenching of O +( 2D) and find that the rate coefficient is 2 × 10 ?11 cm 3s ?1 to within approximately a factor of two. 相似文献
13.
The influence of aerodynamic drag and the geopotential on the motion of the satellite 1964-52B is considered. A model of the atmosphere is adopted that allows for oblateness, and in which the density behaviour approximates to the observed diurnal variation. A differential equation governing the variation of the orbital inclination combining the effects of air drag with those of the Earth's gravitational field is given.The 310 observed values of inclination are modified by the removal of perturbations due to luni-solar attraction, solid Earth and ocean tides, solar radiation pressure, low-order long-periodic tesseral harmonic perturbations and changes due to precession. The method of removal of these effects is given in some detail.The variations in inclination due to drag are analysed to give four values of the average atmospheric rotation rate at heights of 296–476 km at latitude 0–54°. These values are as expected from previous analyses.The analysis of the change in inclination due to solar radiation pressure shows that this rapidly tumbling cylindrical satellite may be considered as equivalent to a spherical satellite of a given area-to-mass ratio.Analysis of the inclination near 15:1 resonance with the geopotential yields values of lumped geopotential harmonics of order 15 and 30, namely, 相似文献
14.
The orbit of the satellite 1967-104B has been analysed as it passed through 29:2 resonance with the Earth's gravitational field between January 1977 and September 1978. From the changes in inclination and eccentricity the following lumped 29th-order geopotential harmonic coefficients were obtained: , , , , , . These values have been compared with existing comprehensive geopotential models: the best agreement is with the model of Rapp (1981). 相似文献
15.
Absolute spectrophotometry of Neptune from 3390 to 7800 Å, with spectral resolution of 10 Å in the interval 3390–6055 and 20 Å in the interval 6055–7800 Å, is reported. The results are compared with filter photometry ( Appleby, 1973; Wamsteker, 1973; Savage et al., 1980) and with synthetic spectra computed on the basis of a parameterization proposed by Podolak and Danielson (1977) for aerosol scattering and absorption. A CH 4/H 2 ratio of is derived for the convectively mixed part of Neptune's atmosphere, and constrains optical properties of hypothetical aerosol layers. 相似文献
16.
The orbit of TETR-3 (1971-83B), inclination: 33°, passed through resonance with 15th order geopotential terms in February 1972. The resonance caused the orbit inclination to increase by 0.015°. Analysis of 48 sets of mean Kepler elements for this satellite in 1971–1972 (across the resonance) has established the following strong constraint for high degree, 15th order gravitational terms (normalized): This result combined with previous results on high inclination 15th order and other resonant orbits suggests that the coefficients of the gravity field beyond the 15th degree are smaller than Kaula's rule ( ). 相似文献
17.
The odd zonal harmonics in the geopotential are the terms independent of longitude and antisymmetric about the Equator: they define the ‘pear-shape’ effect. The coeffecients J3, J5, J7,…of these harmonics have been evaluated by analysing the variations in eccentricity of 27 orbits covering wide range of inclinations. We use again most of the orbits from our previous (1969) evaluations, but we now have the advantage of 3 accurate orbits at inclinations between 60° and 66°, where the variations in eccentricity become very large, and 3 near-equatorial orbits, at inclinations between 3° and 15°, whereas previously there were none at inclinations lower than 28°. The new data lead to much more accurate and reliable values for the coeffecients. Our recommended set, which terminates at J17, is . With this new set of values the pear-shape tendency of the Earth amounts to 44.7 m at the poles, instead of the previous 40 m, though the new geoid is within 1 m of the old at latitudes away from the poles. 相似文献
18.
The photodissociation of water vapour in the mesosphere depends on the absorption of solar radiation in the region (175–200 nm) of the O 2 Schumann-Runge band system and also at H-Lyman alpha. The photodissociation products are OH + H, OH + H, O + 2H and H 2 + O at Lyman alpha; the percentages for these four channels are 70, 8, 12 and 10%, respectively, but OH + H is the only channel between 175 and 200 nm. Such proportions lead to a production of H atoms corresponding to practically the total photodissociation of H 2O, while the production of H 2 molecules is only 10% of the H 2O photodissociation by Lyman alpha.The photodissociation frequency (s ?1) at Lyman alpha can be expressed by a simple formula where F10.7 cm is the solar radioflux at 10.7 cm and N the total number of O 2 molecules (cm ?2), and when the following conventional value is accepted for the Lyman alpha solar irradiance at the top of the Earth's atmosphere ( ) qLyα,∞ = 3 × 10 11 photons cm ?2 s 1?.The photodissociation frequency for the Schumann-Runge band region is also given for mesospheric conditions by a simple formula where JSRB,∞(H 2O) = 1.2 × 10 ?6 and 1.4 × 10 ?6 s ?1 for quiet and active sun conditions, respectively.The precision of both formulae is good, with an uncertainty less than 10%, but their accuracy depends on the accuracy of observational and experimental parameters such as the absolute solar irradiances, the variable transmittance of O 2 and the H 2O effective absorption cross sections. The various uncertainties are discussed. As an example, the absolute values deduced from the above formulae could be decreased by about 25-20% if the possible minimum values of the solar irradiances were used. 相似文献
20.
Six times of maxima of the ultrashort-period cepheid variable EH Librae were measured in 1980 May to June and in 1981 January, with a three-channel photocounting high-speed photoelectric photometer. These, together with all the photoelectric times of maxima over the past 30 years, are used to re-examine the nature of the change of the period. We found that we can fix the times of maxima by the following formula where T0 = HJD 2433438.6088 and P0 = 0.0884132445 d represent the initial maximum epoch and the pulsation period, β = ?2.8 × 10 ?8/yr; A = 0.0015 d, P0 = 6251 d = 17.1 yr are the semi-amplitude and the period of the sine curve, and E is the number of periods elapsed since T0, and ( E0 = 70700).If we interpret this 17.1 year periodicity as a modulation of the phase of maximum by binary motion, then the semi-amplitude of the orbital radial velocity variation is K = 2 πasin i/ E0 = 0.45 km/s and the mass function is 相似文献
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