Part of the Oxford Instruments Group

Ground Based Optical Detector for Space Debris Tracking

Challenge Background

‘Space Debris’ defines the large array of debris in space that bears a potential collision threat to all space vehicles. The term encompasses ‘Orbital Debris’, referring to the huge amount of objects of varying sizes that is in orbit around the earth. Much of this orbital space junk is man-made, a by-product of more than 5000 space launches that have taken place since the 1960’s, and includes anything from rocket stages or defunct satellites, to small bits of metal or even flecks of paint. Orbital Debris is typically travelling at very fast speed, almost 7 times faster than a bullet, and even relatively small objects bear destructive capability. The scale of the problem is large, and it has been estimated that there are well in excess of half a million pieces of orbital debris that are greater than 1 cm diameter, with more than 29,000 pieces larger than 10 cm diameter.

There is increasing demand to detect and track orbital debris, even relatively small debris, given the destructive potential to current and future space missions. One of the leading methods to track orbital debris is through use of ground based optical telescopes, utilizing a high performance scientific digital camera at the focal plane. The detector must be highly photon sensitive, in order to detect signal from smaller debris, ideally whilst using sub-second exposure times. It must also have a large field of view in order to sample more of the sky, thus enhancing the statistics of detection. It is also advantageous that the camera can operate at up to several frames per second, thus enabling relatively fast moving objects to be tracked without motion blur effects.

Technology Solution

Scientific CMOS (sCMOS) camera technology is becoming increasingly recognised as the leading detector technology solution for ground based optical Space Debris Tracking. The high QE and low noise properties of sCMOS technology render it highly sensitive, without having to sacrifice frame rate (a common trade-off with CCD technology). Furthermore, the multiplexed readout architecture of sCMOS means that multi-megapixel devices are commonplace, meaning larger fields of view can be realised.

Andor Camera Solution for Space Debris Tracking

Andor strongly recommends the the Balor 17F-12 very large area sCMOS camera, Marana 4.2B-11 Back-illuminated sCMOS Camera and Neo 5.5 for Space Debris Detection and Tracking:

Debris Tracking Requirement Debris Tracking Solution: Marana 4.2B-11 & Balor 17F-12
Detect small and faint objects Both Balor and Marana achieve superb QE through low read noise and minimized vacuum cooled darkcurrent. Marana is further optimized for detection of the photon starved signal from small objects by virtue of having 95% QE.
Search more sky In this regard, Balor is unparalleled, offering a 16.9 Megapixel, 70mm diagonal sensor. However, Marana is the largest available back-illuminated sCMOS, combining a 4.2 Megapixel with 11 um pixel size, yielding a large 32mm diagonal sensor.
Track without blur Balor can blaze along in full resolution at up to 54 fps, in full 16-bit mode. Marana can also operate at up to 48 fps. Each solution can temporally over-sample even fast moving low earth orbit objects.
Accurate size assessment and light curves Both Balor and Marana can accurately measure the light curves of moving/rotating objects and quantify objects of varying sizes with photometric precision, due to multi-amplifier extended dynamic range technology combined with enhanced 99.7% quantitative linearity.
Low maintenance and minimal down time Balor and Marana are perfectly architected for sustained usage in remote observing locations. The vacuum sensor enclosure combined with shutter free operation provides the ultimate in performance longevity.

Date: November 2018

Author: Dr Andrew Dennis

Category: Solution Note

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