JunoCam

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JunoCam image of Jupiter released by NASA on December 14, 2016[1]
JunoCam
JunoCam views of Jupiter, August 2016

JunoCam (or JCM) is the visible-light camera/telescope of the Juno Jupiter orbiter, a NASA space probe launched to the planet Jupiter on 5 August 2011. It was built by Malin Space Science Systems.[2] The telescope/camera has a field of view of 58 degrees with four filters (3 for visible light).[3] The camera is run by the JunoCam Digital Electronics Assembly (JDEA) also made by MSSS.[2] It takes a swath of imaging as the spacecraft rotates; the camera is fixed to the spacecraft so as it rotates, it gets one sweep of observation.[2]

JunoCam is not one of the probe's core scientific instruments; it was put on board primarily for public science and outreach, to increase public engagement, and all images will be available on NASA's website.[4][5] It is capable of being used for science, and does have some coordinated activities in regards to this, as well as to engage amateur and as well as professional infrared astronomers.[5]

In addition to visible light filters, it also has a near infrared filter to help detect clouds; a methane filter in addition the visible color filters.[6] The camera is a "push-broom" type imager, generating an image as the spacecraft turns.[6]

Due to telecommunications constraints, Juno will only be able to return about 40 megabytes of camera data during each 11-day orbital period. This downlink average data rate of around 325 bits per second will limit the number of images that are captured and transmitted during each orbit to somewhere between 10 and 100 depending on the compression level used.[7] This is comparable to the previous Galileo mission that orbited Jupiter, which captured thousands of images[8] despite its slow data rate of 1000 bits per second (at maximum compression levels) due to antenna problems that crippled its planned 135,000 bit-per-second communications link.

The primary observation target is planet Jupiter itself, although it is expected if all goes well should be able to capture some limited images of the Jupiter moons Metis and Adrastea.[5]

Design origins[edit]

The JunoCam physical and electronic interfaces are largely based on the MARDI instrument for the Mars Science Laboratory.[2] However, the housing and some aspects of the camera's inner mechanism have been modified to provide stable operation in the planet's comparatively intense radiation and magnetic field.[2] Part of its mission will be to provide close up views of Jupiter's polar region and lower-latitude cloud belts,[2] and at Juno's intended orbit the camera is able to take images at up to 15 kilometres (9.3 mi) per pixel resolution.[2] However, within one hour of closest approach to Jupiter it can take up to 3 kilometres (1.9 mi) pixel, thus exceeding the resolution of Cassini up to that that time on Saturn.[2]

Interfaces[edit]

The camera is run by the JunoCam Digital Electronics Assembly (JDEA) also made by MSSS.[2] The JunoCam is physically mounted to the body of the spacecraft, and moves with the spacecraft. The Voyager cameras (that also imaged Jupiter) were the only spacecraft cameras that were movable.

Specifications and mission[edit]

The camera and the mission are not designed to study the moons of Jupiter.[9] Only the poles and atmosphere of Jupiter will be imaged with high resolution. JunoCam has a field of view that is too wide to resolve any detail in the Jovian moons beyond 232 kilometers per pixel. Jupiter itself will only appear to be 75 pixels across from JunoCam when Juno reaches the furthest point of its orbit around the planet.[7] At its closest approaches JunoCam could achieve 15 km/pixel resolution from 4300 km, while Hubble has taken images of up to 119 km/pixel from 600 million km.[10]

The camera uses a Kodak image sensor, the KODAK KAI-2020, capable of color imaging at 1600 x 1200 pixels: less than 2 megapixels.[11] It has a field of view of 58 degrees with four filters (red, green, blue, and a methane band) to provide color imaging.[6] The low resolution, rigid mounting and lossy compression, applied before transmission makes it effectively the Juno "dashcam".

Despite the intense magnetosphere of Jupiter, the JunoCam is expected to be operational for at least the first eight orbits.[12]

Juno's planned orbit is highly elongated[9] and takes it close to the poles (within 4,300 kilometres (2,700 mi)), but then far beyond Callisto's orbit, the most distant Galilean moon.[9] This orbital design helps the spacecraft (and its complement of scientific instruments) avoid Jupiter's radiation belts, which have a record of damaging spacecraft electronics and solar panels.[9] The 'Juno Radiation Vault', with titanium walls, will also aid in protecting and shielding Juno's electronics.[13]

Jupiter – perijove pass as viewed by JunoCam.

Additional camera proposal[edit]

In 2005 the Italian Space Agency (ASI) proposed an additional visible light instrument "ItaCam", but instead they built a near-infrared camera/spectrometer, "Jovian Infrared Auroral Mapper" (JIRAM) and a Ka-band transponder.[9] ASI previously contributed a near-infrared instrument to the Cassini–Huygens Saturn probe.[9] The Ka-band instrument, KaTS, is a component of the Gravity Science experiment

See also[edit]

Other cameras manufactured by Malin Space Science Systems:

Other Juno instruments:

References[edit]

External links[edit]