TanSat

TanSat (short for Carbon Dioxide Observation Satellite) is China’s first dedicated satellite for monitoring carbon dioxide (CO₂) levels in Earth’s atmosphere. It is part of China’s efforts to study and combat climate change through precise observation of greenhouse gas emissions and their global distribution.
Launched on 22 December 2016, TanSat marks a major milestone in China’s space-based Earth observation programme and contributes to international climate science by enhancing understanding of the carbon cycle and anthropogenic (human-caused) CO₂ emissions.

Background and Development

The TanSat project was developed under the leadership of the Ministry of Science and Technology (MOST) of China and managed by the Chinese Academy of Sciences (CAS). It was designed and built by the Institute of Atmospheric Physics (IAP) and the Shanghai Engineering Center for Microsatellites (SECM).
The satellite was launched aboard a Long March 2D rocket from the Jiuquan Satellite Launch Centre in Gansu Province. It became operational in 2017 after completing its in-orbit tests.
TanSat’s mission aligns with China’s commitment under global climate frameworks, including the Paris Agreement, to monitor and mitigate greenhouse gas emissions. It also complements similar international missions such as:

• NASA’s OCO-2 (Orbiting Carbon Observatory-2), and
• Japan’s GOSAT (Greenhouse Gases Observing Satellite).

Objectives of TanSat

The primary goal of TanSat is to monitor global atmospheric CO₂ concentrations and to help understand the sources (emissions) and sinks (absorption) of carbon dioxide.
Key Objectives Include:

• Measuring the spatial and temporal distribution of CO₂ in the atmosphere.
• Providing scientific data to improve global carbon cycle models.
• Supporting climate change research and carbon budgeting.
• Assisting in policy formulation related to emission reductions and environmental protection.
• Strengthening China’s capacity for independent environmental monitoring.

Technical Specifications

The sun-synchronous orbit allows TanSat to observe the same region under similar lighting conditions, ideal for consistent atmospheric measurements.

Instruments and Payloads

TanSat carries two major scientific instruments designed for high-precision CO₂ measurement and cloud/aerosol detection:

1. Carbon Dioxide Spectrometer (CDS):
   • Measures the absorption spectra of reflected sunlight in specific CO₂ and oxygen absorption bands.
   • Determines the column-averaged CO₂ concentration (XCO₂) in the atmosphere with high accuracy.
   • Operates in three narrow wavelength bands:
     • Oxygen A-band (0.76 µm)
     • Weak CO₂ band (1.61 µm)
     • Strong CO₂ band (2.06 µm)
2. Cloud and Aerosol Polarimetry Imager (CAPI):
   • Detects and measures clouds and aerosols that can affect CO₂ observations.
   • Operates in five spectral bands from visible to near-infrared wavelengths.
   • Provides data to correct atmospheric interference and enhance measurement precision.

These instruments work together to produce global CO₂ maps with an accuracy of better than 4 parts per million (ppm).

Scientific Objectives and Data Collection

TanSat observes sunlight reflected from Earth’s surface and measures how much light is absorbed by CO₂ molecules in the atmosphere. Using this data, scientists can:

• Estimate the density and distribution of CO₂ across regions and seasons.
• Identify major emission zones such as industrial regions and cities.
• Detect natural carbon sinks, including forests and oceans.
• Track seasonal and inter-annual variations in the carbon cycle.

Data from TanSat contribute to understanding how human and natural processes influence atmospheric CO₂ concentration, which is a critical component of global warming and climate change.

International Collaboration

TanSat’s mission enhances global collaboration in climate monitoring by complementing data from other international satellite programmes. It works in coordination with:

• NASA’s OCO-2 and OCO-3,
• Japan’s GOSAT and GOSAT-2,
• Europe’s Copernicus CO₂ Monitoring Mission (CO2M).

By sharing data and aligning methodologies, TanSat strengthens the Global Carbon Observation System, promoting transparency in emission tracking and scientific research.

Key Achievements

Since its deployment, TanSat has made several important contributions to atmospheric and climate science:

• First Global CO₂ Maps (2017): Produced China’s first global carbon dioxide distribution maps with high spatial resolution.
• Validation of Data: Cross-validated with NASA and JAXA satellite observations, confirming measurement accuracy.
• Identification of Emission Hotspots: Detected elevated CO₂ levels over major industrial and urban regions such as Eastern China, the U.S., and Europe.
• Seasonal Variation Analysis: Provided insights into how vegetation growth cycles and human activity affect atmospheric CO₂.
• Enhanced Climate Models: Data from TanSat have improved global carbon flux and climate simulation models used by Chinese and international researchers.

Successor Mission – TanSat-2

To further improve the accuracy and coverage of CO₂ monitoring, China is developing TanSat-2, an advanced version of the original satellite.
TanSat-2 Features:

• Enhanced spectral resolution and sensitivity.
• Ability to monitor multiple greenhouse gases, including methane (CH₄).
• Higher revisit frequency and improved calibration systems.
• Greater international data-sharing cooperation.

The follow-up mission will expand China’s role in global carbon observation and help achieve its national carbon neutrality goals by 2060.

Significance

The TanSat mission represents a major step in China’s scientific contribution to tackling global climate change. Its significance lies in:

• Providing independent, high-quality data on greenhouse gas emissions.
• Supporting national and international climate policies through reliable carbon accounting.
• Advancing Earth observation technology and atmospheric remote sensing capabilities.
• Strengthening the scientific basis for carbon neutrality strategies.