High-grade, compact spectrometers for Earth observation from SmallSats

Abstract

The market for nano-and microsatellites is developing rapidly. There is a strong focus on 2D imaging of the Earth's surface, with limited possibilities to obtain spectral information. More demanding applications, such as monitoring trace gases, aerosols or water quality still require advanced imaging instruments, which are large, heavy and expensive. In recent years TNO has investigated and developed different innovative designs to realize advanced spectrometers for space applications in a more compact and cost-effective manner. This offers multiple advantages: a compact instrument can be flown on a much smaller platform (nano-or microsatellite); a low-cost instrument opens up the possibility to fly multiple instruments in a satellite constellation, improving both global coverage and temporal sampling (e.g. to study diurnal processes); a constellation of low-cost instruments may provide added value to the larger scientific and operational satellite missions (e.g. the Copernicus Sentinel missions); and a small, lightweight spectrometer can also be mounted easily on a high-altitude UAV (offering high spatial resolution). Last but not least, a low-cost instrument may allow to break through the 'cost spiral': lower cost will allow to take more risk and thus progress more quickly. This may lead to a much faster development cycle than customary for current Earth Observation instruments. To explore the potential of a constellation of low-cost instruments a consortium of Dutch partners was formed, which currently consists of Airbus Defence & Space Netherlands, ISISpace, S&T and TNO. In this paper we will illustrate this new design approach by using the most advanced design of a hyperspectral imaging spectrometer (named 'Spectrolite') as an example. We will discuss the different design and manufacturing techniques that were used to realize this compact and low-cost design. Laboratory tests as well as the first preliminary results of airborne measurements with the Spectrolite breadboard will be presented and discussed. The design of Spectrolite offers the flexibility to tune its performance (spectral range, spectral resolution) to a specific application. Thus, based on the same basic system design, Spectrolite offers a range of applications to different clients. To illustrate this, we will present a mission concept to monitor NO 2 concentrations over urban areas at high spatial resolution, based on a constellation of small satellites. A GROWING MARKET FOR NANO-AND MICROSATELLITESThe market for nano-and microsatellites is developing rapidly, largely driven by the continued interest of the commercial sector in nano-and microsatellite applications. The following observations are taken from the SpaceWorks 2016 Nano/Microsatellite Market Forecast 1 : • Projections based on announced and future plans of developers and programs indicate as many as 3,000 nano/microsatellites will require a launch from 2016 through 2022; • The commercial sector will contribute over 70% of future nano/microsatellites; • The commercial secto...

Development of the TANGO carbon instrument for greenhouse gas detection

“…The TANGO Carbon and Nitro instruments are members of the TNO Spectrolite family of imaging spectrometers. [2][3][4] These instruments are all-aluminium push broom spectrometers that provide high performance in a modest volume due to the use of freeform optics. The motivation to use the Spectrolite instrument as the baseline for TANGO is summarized below:…”

Development of spectrometers for the TANGO greenhouse gas monitoring missions

“…The imaging spectrometers used in TANGO-Carbon and TANGO-Nitro are of the TNO Spectrolite family of instruments [5][6][7] . These are all-aluminium push broom spectrometers that provide a high performance in a modest volume due to the use of free-form optics.…”

SmartAQnet: remote and in-situ sensing of urban air quality

“…Currently, more and more sensors on board of satellites are applied which are smaller, lighter, cheaper and more simply. This opens the door to a market for nano-and microsatellites which is developing rapidly (van der Wal et al, 2016) 5 . Now there is a strong focus on 2D imaging of the Earth's surface, and different innovative designs to realize advanced spectrometers for space applications in a more compact (volume of 10 x 20 x 20 cm 3 ) and cost-effective manner (van der Wal et al, 2016) 5 .…”

“…This opens the door to a market for nano-and microsatellites which is developing rapidly (van der Wal et al, 2016) 5 . Now there is a strong focus on 2D imaging of the Earth's surface, and different innovative designs to realize advanced spectrometers for space applications in a more compact (volume of 10 x 20 x 20 cm 3 ) and cost-effective manner (van der Wal et al, 2016) 5 . So, more and more satellite sensors operating in the Earth orbit are available which are the basis for high spatial-resolved information.…”