Conference Agenda

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In recent years, spaceborne imaging spectroscopy has made significant progress. The field has evolved from a limited range of instruments and data offer to a broad selection of missions simultaneously acquiring quality data, both in terms of spectral resolution and signal-to-noise-ratio. The spectral information provided by these missions is playing an increasingly important role in our understanding of the Earth’s surface and its dynamic processes, in monitoring the environment and in managing the Earth’s resources.

DESIS, launched in June 2018, was the mission that inaugurated this new era, followed by the missions GF-5 (2018), PRISMA (2019), HISUI (2019), EnMAP (2022) and EMIT (2022). Today, DESIS has been in operation for more than 5 years and has acquired by May 2024 over 330.000 images of the Earth. Together with the other imaging spectroscopy missions in orbit, a huge image archive has been created covering many areas multiple times by several instruments.

In this presentation, the status of the mission and data access in general will be explained. DESIS, a pushbroom imaging spectrometer that operates in the VNIR range (400 – 1000 nm), uses narrow (2.55 nm) spectral sampling. The spatial resolution is 30 m and the swath width is 30 km while the swath length varies, depending on the planned acquisitions. Users obtain DESIS products processed to different levels and with different processing options. Level 1B products (L1B) correspond to radiometric Top of Atmosphere (TOA) at sensor geometry radiances. Level 1C (L1C) are L1B products that are ortho-rectified. Finally, Level 2A (L2A) are atmospherically corrected orthorectified TOA radiances, providing finally Bottom of Atmosphere (BOA) reflectances.

A new data access point has been developed to enable the download of mass data in particular, which is often required for the integration of such data into artificial intelligence and deep learning algorithms. It enables a simple data selection process that include not just DESIS data but also EnMAP and other satellite data available at the DLR GeoService. Furthermore, DESIS data are in the process of getting the CEOS analysis ready data status. DESIS products are being used by a growing user community in a wide range of applications. The large number of DESIS products enables the development of applications that need to be trained on large volumes of data or data acquired under different observation conditions. The huge DESIS data archive is a suitable data source for developing scientific and commercial applications.

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The German hyperspectral satellite EnMAP is now more than 2 years in orbit and is acquiring data at an increasing pace. Users feedback, as collected during these years at conferences and workshops dedicated to hyperspectral imagery, is extremely positive: the EnMAP HSI instrument generates data of quality beyond expectations.

Thanks to the experience gained during the time of operations, the team of the Ground Segment, supported by the Space Segment and in collaboration with the Science Segment, gradually enhanced the Missions proficiency. They implemented new features and fine-tuned the observing strategy, thus optimizing the exploitation of the satellite capabilities. Moreover, they further developed the processing pipeline, thus improving the quality of the derived products.

We will give an overview of the status of operations, also including some statistics concerning users and acquired data. We will focus in particular on the EnMAP observation planning strategy, which includes user requests, background and foreground missions. That way we will provide the background information needed for a fruitful discussion about possible synergies with other missions.

NASA's Earth Surface Mineral Dust Source Investigation (EMIT) is an imaging spectrometer operating in the Visible-Shortwave Infrared (VSWIR) from 3800-2500 nm. Since its installation on the International Space Station in 2022, it has been acquiring tens of thousands of data cubes globally covering a wide range of natural environments. This talk describes some data analysis lessons learned over the course of EMIT operations. We will discuss technical achievements, including on-orbit FPA alignment and the high stability, uniformity, and SNR of the EMIT optical design. We will also discuss early indication of performance for different processing steps in the EMIT science data analysis system. Of particular interest is the use of vicarious calibration rather than onboard calibrators to achieve the required levels of reflectance accuracy. We will draw out implications of these findings for future missions like SBG, which will borrow many aspects of the EMIT processing chain and concept of operations. We will also describe areas where improvement is still needed, such as EMIT's onboard cloud screening algorithms, and in outreach to the potential user community. EMIT's two years on orbit provide valuable insights into the capabilities and challenges of operating a modern, high performance imaging spectrometer in a global mission.

The NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission launched from Kennedy Space Center in the early morning of February 8, 2024. Just 63 days later, data from NASA’s newest Earth-observing satellite became available to the public. These data will extend and improve upon NASA’s 20+ years of global satellite observation of our living oceans, atmospheric aerosols, and cloud and initiate an advanced set of climate-relevant data records. PACE’s primary instrument is a global spectrometer that spans the ultraviolet to near-infrared region in 2.5 nm steps and also includes seven discrete shortwave infrared bands from 940 to 2260 nm. This leap in technology will enable improved understanding of aquatic ecosystems and biogeochemistry, as well as provide new information on phytoplankton community composition and improved detection of algal blooms. The PACE payload is complemented by two small multi-angle polarimeters with spectral ranges that span the visible to near infrared spectral region, both of which will significantly improve aerosol and hydrosol characterizations and provide opportunities for novel ocean color atmospheric correction. In the months since launch and initial data release, the PACE Project applied instrument temporal and system vicarious calibrations, pursued cross-instrument comparisons, conducted performance assessments, explored synergies with other missions, and released advanced science data products. In parallel, the PACE Validation Science Team left for the field and the Post-launch Airborne eXperiment (PACE-PAX) executed its mission. And, most importantly, preliminary science results were realized. Here, we present a snapshot of these activities and their impacts and outcomes, encompassing the first half+ year of the PACE mission.

Monitoring atmospheric aerosols from space is crucial for understanding their spatial and temporal distribution, as well as their impact on climate, air quality and public health. In this context, while multispectral satellite data offer coarse but frequent observations, hyperspectral sensors capture a much finer spectral resolution, enabling detailed characterization of aerosols.

In this framework, the Italian Space Agency (ASI) is developing the MAIA/PLATiNO-2 mission, that is founded on the agreement with NASA which is providing the Multi-Angle Imager for Aerosols (MAIA) payload, that will be embarked on the ASI PLATiNO-2 satellite. The MAIA instrument includes a spectropolarimetric camera with 14 spectral bands (in UV-SWIR spectral range) and a two-axis gimbal, which enables observations from multiple view angles.

The MAIA/PLATiNO-2 mission will observe predetermined areas called Primary Target Areas, that have been selected around the world to include highly populated metropolitan areas, with a revisit of about 3-4 times per week. Moreover, Secondary Target Areas, with 1-3 observations per week, have been defined to extend the mission observations to additional areas of scientific interest.

The MAIA standard mission products will have a spatial resolution of 1 km and provides retrievals of Aerosol Optical Depth (AOD), including fractional AOD by shape, size, absorption and refractive index, as well as retrievals of different types of airborne Particulate Matter (PM).

On a parallel programme, ASI is developing a new “best-in-class” compact Hyperspectral payload, identified as PLATiNO-4 and implemented by Leonardo S.p.A., that exploits the heritage of the PRISMA instrument, launched by ASI in 2019.

The PLATiNO-4 imaging spectrometer is designed to measure the spectral signature across the wavelength range 400-2500 nm, with high spatial resolution (up to 20m of Ground Sampling Distance in SPOTLIGHT mode) and a high signal to noise ratio.

ASI will explore the exploitation of the synergy between these two novel missions, which will be launched between 2025 and 2026, to unlock new approaches for aerosol monitoring.

In the synergistic approaches MAIA multispectral data will provide the large-scale picture, in terms of AOD and PM observations and tracking, achieved thanks to the high revisit time. PLATiNO-4 data, as well as PRISMA and additional hyperspectral data from other missions, can be exploited to refine the MAIA observations by offering detailed spectral signatures for composition information over specific regions of interest, to improve the spatial resolution of the synergy products, as well as to retrieve additional PM and aerosol’s species.

The future ESA Earth Watch mission TRUTHS (Traceable Radiometry Underpinning Terrestrial- and Helio- Studies) will enhance by an order-of-magnitude our ability to estimate the spectrally resolved Earth Reflected Solar Radiation Budget through direct measurements of incoming and outgoing energy in the UV-VIS-NIR spectral domain (320-2400 nm with 2-6 nm spectral sampling). These observations at unprecedented accuracy (up to 0.3% uncertainty, k=2) will shorten the time to detect and disambiguate trends from natural variability in the Earth’s Climate system, and constitute unpredented radiometric calibration anchor to other missions.

Establishing an operational ‘metrology laboratory in space’ for the first time, TRUTHS is part of a new class of SI-Traceable satellites (SITSats), which are tying their observations to fully traceable SI standards.

TRUTHS is explicitly designed to re-calibrate itself in-orbit, to the Cryogenic Solar Absolute Radiometer (CSAR), as a primary standard of the international system of units (SI). TRUTHS will fly a push-broom high-resolution (50m) hyperspectral nadir imager (HIS) in a polar non-Sun-synchronous orbit with a 60-day repeat cycle. This orbit will guarantee regular simultaneous nadir observations with Low Earth Orbit (LEO) sensors and geostationary (GEO) missions at their subsatellite point. TRUTHS will acquire spectrally resolved measurements of the solar irradiance and of the lunar reflectance at unprecedented radiometric accuracy. This will considerably improve current Lunar irradiance modelling and overall directly benefit to EO missions relying on solar and lunar observations for their calibration.

TRUTHS can slew in orbit which will enable simultaneous off-nadir (or angled) observations, e.g. with missions in the GEO-ring, and will allow the characterisation of the top-of-atmosphere radiance and BRDF of invariant calibration targets. The SI traceability for other sensors can hence be achieved with TRUTHS fiducial reference data through direct intercalibration as well as by vicarious calibration. TRUTHS calibration anchors will improve other scientific and operational missions’s data and services. In particular, this will benefit to the institutional and commercial small-sat constellations which cannot rely on on-board calibration instrumentations.

TRUTHS is an ESA Earth Watch mission, currently in phase B2, seeded at NPL and developed by a large scientific team and an industrial consortia led by Airbus UK, with contributions in Switzerland, Czech Republic, Greece, Romania and Spain. The target launch date is 2030 with 5- to 8-year life-time.

We will present the mission status and design, the scientific objectives, and data products. We will illustrate the principles behind the unique calibration opportunities for other spectral imager missions.

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A compact, highly sensitive hyperspectral sensor to complement the revisit time of the Japanese hyperspectral sensor HISUI will be developed using the knowledge gained from HISUI. The spatial resolution is expected to be around 30 m, the wavelength range 400-1700 nm (optionally extended to 2300 nm), the wavelength resolution 10 nm (2 nm in high wavelength resolution mode), and the sensitivity is expected to be further improved by a multi-slit spectrometer. The demonstration flight is planned for 2027 with a 6U CubeSat. As a societal implementation, a constellation network of about 5-10 small satellites is intended for the late 2020s or early 2030s.

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