Re: Image satellite

From: Leo Barhorst (
Date: Sun Mar 26 2000 - 11:37:56 PST

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    Compare it with the UME-1 and 2 sats; 76 -19 A and 78- 18 B resp.
    They are in a lower orbit but also have lomg antenna's.
    This is from's Mark Wade's Encyclopedia Astronautica.
    Other Designations: Japanese Ionosphere Sounding Satellite. Class: Earth.
    Type: Ionosphere. Nation: Japan. Total Length: 3.9 m. Maximum Diameter: 0.8
    m. Total Mass: 141 kg.
    JISS - national name "Ume". Spin-stabilized; Ionospheric Sounder, Radio
    Noise Receiver, Plasma Measuring Equipment, Ion Mass Spectrometer, and other
    instruments. The satellites were intended for regular observation of global
    distribution of critical frequencies of the ionosphere, and for utilization
    of the results of the observation for radio wave forecasts and warning
    necessary for effective operation of short-wave radio-communication. Shape:
    cylindrical, 3.9m diameter and 0.8m height. Expected life: probability of
    survival in 1.5 years was more than 70 percent.
    Although the antenna's are not mentioned, I know these sats have them. The
    cause the flashes we can measure.
    The orbit of UME-1 is around 1000 km at 69 deg; UME-2 is in an orbit
    980x1260 km at 69 deg.
    In PPAS you can see the flash periods. For UME-1 it is now 4.6 sec and for
    UME-2 it is 3.3 sec
    I suspect that 250 m long antenna's are quite well visible at perigee and
    even beyond.
    ----- Original Message ----- (part)
    From: Tony Beresford <>
    >  The IMAGE spacecraft has just been put into orbit.
    > What might make it visually interesting is that one experiment,
    > a 3Khz-3Mhz radio transmitter, has 4 radial 250m antennae,
    > (ony 0.3mm diameter though). Wonder how much sunglint
    > off them?. The Spin axis is perpindicular to orbit, and
    > the long antennae will hence be in the orbital plane.
    > Spin period 30 seconds.
    Leo Barhorst
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