Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 11
    Electronic Resource
    Electronic Resource
    First results from the Giotto Radio-Science Experiment (1986)
    [s.l.] : Nature Publishing Group
    Nature 321 (1986), S. 355-357 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The scientific objectives of the Giotto Radio-Science Experiment (GRE) are to determine the columnar electron content of comet Halley's ionosphere and the mass fluence of the cometary atmosphere1'2. For this purpose the radio signals from the Giotto spacecraft were used during the Halley encounter ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/321355a0
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Anisotropy and velocity of small-scale irregularities in the region of solar-wind acceleration (2000)
    Springer
    Astronomy reports 44 (2000), S. 634-640 
    Details
    ISSN: 1562-6881
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present the amplitude and frequency fluctuations of radio signals detected simultaneously at ground stations at Evpatoriya and Ussuri $$\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{l}$$ sk during experiments in which radio signals with wavelengths of 5, 8, and 32 cm emitted from the Venera-15 and Venera-16 spacecraft were transmitted through the solar plasma environment. Relations are obtained between the rates of amplitude scintillations (determined from the width of temporal spectra) and frequency scintillations (determined from the delay of the fluctuations between the ground stations), on the one hand, and the velocities of the solar wind and of wave-like density disturbances and the anisotropy of irregularities, on the other hand. Analysis shows that the transition of the solar-wind flow to a supersonic regime takes place at heliocentric distances of 10–15 solar radii (R s ) and that the flow becomes supersonic at distances exceeding 15R s . Solar-wind density inhomogeneities with scales of about 50 km are radially extended. For heliocentric distances from 10 to 20R s , the degree of extension is modest and, as a rule, does not exceed a factor of two.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1307557
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Coronal investigations with occulted spacecraft signals (1982)
    Springer
    Space science reviews 33 (1982), S. 99-126 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The radio telemetry links between Earth and a spacecraft near superior conjunction penetrate the corona at ranges well within the acceleration regime of the solar wind. Occultation experiments in the solar corona have been performed on many interplanetary missions beginning with the Mariner and Pioneer series and extending up to the more recent data on Helios, Viking, and Voyager. The changes in group and phase velocity of the radio signal are measured to determine the total electron content of the corona and its fluctuations. The broadening of the carrier signal may be used in combination with the electron content data to derive a solar wind velocity profile. The wave number spectrum of electron density fluctuations in the corona may be inferred from amplitude and phase scintillations of the received signal. Linearly polarized signals, which are rotated along the propagation path by the Faraday effect, can provide information on the coronal magnetic field and its variations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213250
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Radio occultation studies with Solar Corona Sounders (1995)
    Springer
    Space science reviews 72 (1995), S. 77-80 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Solar Corona Sounders (SCS), a mission designed to utilize the radio occultation technique for investigations of the inner heliosphere, was submitted to ESA in response to a call for new mission concepts. The SCS platforms are two small multifrequency transmitters placed at the “anti-Earth” position (superior solar conjunction) for continuous radio sounding of the solar corona. Appropriately specifying certain orbital elements for the heliocentric trajectories of the spacecraft, their radially-aligned positions as seen from Earth appear to circle the solar disk over the course of a year. The two radio sources would be most effectively positioned at apparent solar distances inside and outside the nominal solar wind critical point, respectively, e.g., at ∼3 R⊙ and ∼10 R⊙. Radio parameters to be measured using the linearly polarized, coherent dual-frequency links to ground include the group time delay, signal amplitude, the phase (Doppler) shift, linewidth, and Faraday rotation. The link frequencies for coronal sounding observations this close to the Sun could be the interplanetary standards at S-band (2.3 GHz) and X-band (8.4 GHz). These measurements are used to derive both mean values and fluctuation spectra of such coronal parameters as the electron density, the solar wind velocity, and the magnetic field. The geometry afforded by the two radio ray paths from the SCS transmitters would provide unprecedented observations of the radial evolution of dynamic coronal events such as coronal mass ejections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768757
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Galileo radio science investigations (1992)
    Springer
    Space science reviews 60 (1992), S. 565-590 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The radio science investigations planned for Galileo's 6-year flight to and 2-year orbit of Jupiter use as their instrument the dual-frequency radio system on the spacecraft operating in conjunction with various US and German tracking stations on Earth. The planned radio propagation experiments are based on measurements of absolute and differential propagation time delay, differential phase delay, Doppler shift, signal strength, and polarization. These measurements will be used to study: the atmospheric and ionospheric structure, constituents, and dynamics of Jupiter; the magnetic field of Jupiter; the diameter of Io, its ionospheric structure, and the distribution of plasma in the Io torus; the diameters of the other Galilean satellites, certain properties of their surfaces, and possibly their atmospheres and ionospheres; and the plasma dynamics and magnetic field of the solar corona. The spacecraft system used for these investigations is based on Voyager heritage but with several important additions and modifications that provide linear rather than circular polarization on the S-band downlink signal, the capability to receive X-band uplink signals, and a differential downlink ranging mode. Collaboration between the investigators and the space-craft communications engineers has resulted in the first highly-stable, dual-frequency, spacecraft radio system suitable for simultaneous measurements of all the parameters normally attributed to radio waves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216868
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...