7. December 2016

BIROS demon­strates au­tonomous ren­dezvous in space us­ing on­ly im­age da­ta

This im­age was ac­quired at a dis­tance of 67 me­tres from the cube pi­cosatel­lite
Image 1/2, Credit: DLR (CC-BY 3.0).

This image was acquired at a distance of 67 metres from the cube picosatellite

This im­age was ac­quired at a dis­tance of 67 me­tres from the cube pi­cosatel­lite, which has an edge length of just 10 cen­time­tres. The pi­cosatel­lite is re­flect­ing sun­light, which makes it seem ex­treme­ly bright. The satel­lite and its two an­ten­nas are clear­ly vis­i­ble. While BIROS is ap­prox­i­mate­ly the size of a wash­ing ma­chine and weighs 130 kilo­grams, the pi­cosatel­lite it­self has an edge length of just 10 cen­time­tres.
Dis­tance be­tween the two satel­lites
Image 2/2, Credit: DLR (CC-BY 3.0).

Distance between the two satellites

The curve shows the dis­tance be­tween the two satel­lites over the course of the ex­per­i­ment. Here, the red de­notes the times and dis­tances at which it was pos­si­ble to ac­quire im­ages of the pi­cosatel­lite.

A cosmic game of cat and mouse

For the first time in the history of space exploration, scientists at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) have demonstrated in a real space experiment how a satellite can approach a counterpart by fully autonomously, making use of only optical or vision-based navigation. This highly sophisticated technology was demonstrated on the Earth observation satellite BIROS (Bi-spectral InfraRed Optical System) as part of the AVAN­TI experiment (Autonomous Visual Approach Navigation and Target Identification), during which the satellite was able to draw to within 50 metres of its target object.

BEESAT-4, a picosatellite dispatched by BIROS last September, was used as a target satellite in the experiment. "We have, for the first time ever, demonstrated how a satellite can autonomously recognise and approach a flying object without using GPS data from the target satellite or requiring commands from the control centre," says Thomas Terzibaschian from the DLR In­sti­tute of Op­ti­cal Sen­sor Sys­tems, confirming the experiment's success. BIROS was fitted with a spring-loaded deployer mechanism that ejected the picosatellite at a velocity of 1.5 metres per second. In addition, DLR scientists and engineers equipped the microsatellite BIROS with a propulsion system that enables the washing machine-sized, roughly 130-kilogram satellite to rapidly execute any slew manoeuvres. During the AVANTI experiment, BIROS learned how to specifically modify its trajectory and use a camera head of the star trackerto search for and 'keep an eye' on the picosatellite. Unlike in conventional orbital manoeuvres, the satellite did not receive any commands from the control centre in Oberpfaffenhofen, relying instead on the on board AVANTI experiment programs. Equipping satellites with this capability could become extremely important in the future, as it would allow them to detect and later capture old and inactive satellites and space debris.

Approach to almost 50 metres

"In the AVANTI experiment, we demonstrated for the first time that merely one passive camera is sufficient to enable the autonomous approach of one satellite toward a non-cooperative object," says Gabriella Gaias from Space Operations and Astronaut Training at DLR. The image data was used to identify the target satellite and monitor its position. This then enabled the calculation and execution of the thrust manoeuvre needed to complete the approach. All of the steps were fully autonomous and took place on board BIROS. During the experiment, BIROS approached its target cube satellite – which has an edge length of just 10 centimetres – to within 50 metres. "This distance was specified as a minimum threshold for security reasons as the satellite does not have any additional and redundant sensor systems that would enable precise measurement of the relative positions. We also had to allow for a certain inaccuracy of the control system," adds Gaias.

  • Melanie-Konstanze Wiese
    Cor­po­rate Com­mu­ni­ca­tions, Berlin, Neustre­litz, Dres­den, Je­na and Cot­tbus/Zit­tau
    Ger­man Aerospace Cen­ter (DLR)

    Pub­lic Af­fairs and Com­mu­ni­ca­tions
    Telephone: +49 30 67055-639
    Fax: +49 30 67055-102
    Rutherfordstraße 2
    12489 Berlin-Adlershof
  • Dr Gabriella Gaias
    Ger­man Aerospace Cen­ter (DLR)

    DLR Space Op­er­a­tions
    Telephone: +49 8153 28-1769
    Linder Höhe
    51147 Köln
  • Thomas Terzibaschian
    Ger­man Aerospace Cen­ter (DLR)

    DLR In­sti­tute of Op­ti­cal Sen­sor Sys­tems
    Telephone: +49 30 67055-586
    Linder Höhe
    51147 Köln

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