JANUS: first images taken in space

Last week, when Juice was about 8 million km from Earth, engineers switched the JANUS optical camera instrument on for the first time. Unlike the RPWI sensors mounted on booms far from Juice’s main body, JANUS is fixed to an optical bench; this means that it is kept stable when pointing towards its targets – like using a tripod here on Earth. JANUS also points in the same direction as Juice’s other ‘remote sensing’ instruments.

At Jupiter, the JANUS camera will take images in 13 different colours, from violet light to near infrared. These images will allow scientists to investigate the moons Ganymede, Callisto and Europa, including studying whether life could exist below their icy crusts. JANUS will also collect data on other parts of the Jovian system, including the intense volcanic activity on Io, the many smaller moons, and Jupiter’s faint ring system. Last but not least, JANUS will image processes taking place in Jupiter’s atmosphere.

During last week’s commissioning, a full hardware check was undertaken, with all subsystems activated and monitored. The performance of the instrument was checked by taking images of stars.

“The acquired data demonstrate that everything was nominal. After this intense on-ground session, we can say: we have a (fully commissioned) instrument!” says Pasquale Palumbo (IAPS-INAF), principal investigator of JANUS.

For more details see the website of the Italian National Institute for Astrophysics.