Hello everyone.

Did you guys know that some satellites are not only for radio signals, but also for measurements about the Earth's nature?

Actually, there are various satellites and related missions (so-called projects) in the world, including NASA and JAXA.

Moreover, as long as you have a personal computer, you can view the observation data. You do not have to be a researcher.

This article introduces the satellites we were able to identify at the time of this writing, both domestic and international!

Remote sensing technology can utilize data collected by earth observation satellites. This technology is used in a variety of fields, including mapping, urban planning, agriculture, and disaster monitoring. 

For example,

Agriculture: We use observation data from earth observation satellites to monitor the growth of crops and conduct appropriate cultivation management,

Urban Planning: It is also possible to monitor the expansion of the city and the construction of buildings, and to use this information for urban planning,

Disaster Situation Assessment: Assess damage in the event of a disaster and provide prompt relief

are some of the examples of a product that can be used in this way.

　So here you go.

To begin with, there are three types of satellites.

Satellites are classified according to various purposes, but can generally be divided into three main types:

Observation satellites (resource exploration satellites):

These satellites are used for resource exploration, Earth observation, and weather observation. These satellites observe the Earth's atmosphere and surface and collect images and data. They are used to study the Earth's environment, weather, and topography.

Communication Satellite:

Communications satellites are used primarily for communication and broadcasting purposes. These satellites work in conjunction with the Earth's telecommunications network to enable communications such as telephone, Internet, and television broadcasting. They provide information transmission and reception over a wide area of the globe.

Navigation Satellite:

This type of satellite is primarily used to provide positional information and timing; systems such as GPS and GLONASS use navigation satellites to provide location information on the earth. These are used in aviation, navigation, automotive, and surveying.

Each of these satellites serves a different purpose and contributes to a wide range of activities that affect many aspects of humanity.

The first of these is the first in this article.observation satellitewill be focused.

Why observation from the sky?

Observing from the sky has several advantages.

Extensive observations:

 Satellites can observe a wide area of the Earth's surface from a high vantage point. This allows them to efficiently cover vast areas and monitor multiple regions simultaneously.

Ease of access: 

Observations can be made in remote areas and in harsh natural environments that are difficult to access from the ground. Examples include mountainous regions and tropical rainforests.

Routine observations: 

Satellites can observe the same areas on a regular basis. This allows us to track seasonal and long-term changes.

Consistent data: 

Satellites collect data under constant observation conditions. This provides a consistent data set.

Multi-wavelength observations:

 Satellites can capture electromagnetic waves at a wide range of wavelengths, from visible light to infrared and microwaves. This makes it possible to capture specific characteristics of the earth's surface and atmosphere.

Real-time information: 

Data from satellites is provided in real time or near real time, helping to provide rapid information for disaster monitoring and emergency response.

Airborne observations are an effective means of obtaining information across various regions of the globe and are one of the most important methods of environmental monitoring and Earth observation.

demerit

Remote sensing technology is a powerful tool that can efficiently survey and analyze a wide range of natural resources, but it also has several disadvantages. Below is a detailed description of the disadvantages of remote sensing technology, with comparisons to other methods.

 data constrain

• Weather effects: Data acquisition may be limited by weather conditions such as clouds and rain. Optical sensors are particularly vulnerable to weather conditions and may not acquire sufficient data in cloudy or rainy weather.
• Data volume: The amount of data acquired through remote sensing is enormous and can be time consuming to process and analyze. High-performance computer systems are required, especially when analyzing a wide range of data.

Difficulty of interpretation

• Expertise Needed: Correct interpretation of remote sensing imagery requires expertise in image processing and geographic information systems (GIS).
• Presence of ambiguity: Remote sensing images do not necessarily directly represent the condition of the object. Interpreting images requires field surveys and comparisons with other data.
• Incomplete information: Remote sensing techniques may only be able to obtain surface information on an object. To understand underground resources and internal structures, it is necessary to combine this technology with other survey methods. For example, groundwater, which is invisible above ground.

Costs

• Sensor cost: High-performance sensors are expensive and cost a lot of money to install and maintain. It is currently difficult to fly by ourselves, so we can only obtain information from satellites that already exist.

Ethical Issues

• Privacy violation: Remote sensing technology can also acquire high-resolution images that can be used to identify individuals. As such, there are concerns about privacy violations.
• Military use: Remote sensing technology may also be used for military purposes. Regulations and ethical discussions on military use are needed.

A Simple Structure of Satellite Remote Sensing

Satellite remote sensing for environment-related observations of the Earth is a technology that uses satellite-based sensors to observe objects and environments on Earth. The mechanism varies depending on the satellite model, but can be summarized as follows:

Sensors: 

Sensors mounted on satellites receive electromagnetic radiation from the Earth's surface. These include various wavelengths of visible light, infrared, and microwaves.

The type of sensor changes the data that can be received, and consequently the environment-related items that can be taken as data will also change.

Radiation reflection and absorption:

 Objects such as the earth's surface, atmosphere, and vegetation reflect or absorb the received electromagnetic waves. This results in the appearance of different wavelength characteristics.

Receiving and Recording: 

Satellite sensors receive the reflected electromagnetic waves and record them. Depending on the amount and characteristics of the electromagnetic waves at each wavelength, data containing information about the object is obtained.

So far,This is Work performed by the satellite equipment itself.

The following is what various professional organizations do

Data Processing and Image Generation:.

 The received data is transmitted to a ground station or center for processing. This produces visual information such as images and maps.

Analysis and Applications: 

The data and images generated are analyzed and utilized in various fields such as environmental research, weather forecasting, agricultural management, and urban planning. This provides useful information for earth observation and environmental conservation.

Thus, satellite remote sensing is an important technology that provides a wide range of valuable data for earth observation and environmental monitoring.

The "analysis and application" part above can be done by anyone today, even if you no longer belong to a professional organization, thanks to the fact that much of the information infrastructure is becoming free.

Details will be described in the last section.

What to look for in an environmental resource survey

In environmental resource studies, it is also important to know "under what conditions" the data was obtained in order to understand the characteristics and causes of the data. If you don't know what to look for, you don't know what to judge.

What are the experts looking at, folks?

When using satellite data to identify water and environmental resources, it is important to focus on the following characteristics: - The location of the water resource

Spectral resolution:

 The ability to capture specific characteristics of water and land, covering a broad spectrum of visible, infrared, and microwave radiation.

Spatial resolution: 

The ability to capture details of the earth's surface at high resolution. Necessary to understand detailed topographic features such as water sources and precipitation distribution.

Re-observability: 

Frequency with which the same area can be observed many times in a short period of time. Necessary to understand seasonal and long-term changes.

Radiation correction capability 

The ability to compensate for atmospheric effects and provide accurate data. Especially important for accurate measurement of water reflectance and absorption.

Data Availability:

 Whether the data is readily available to users in terms of publicly available data, access methods, and analytical tools.

Temporal resolution: 

Ability to capture the speed and periodicity of change. Temporal resolution is important to capture rapid environmental change and seasonal variations.

Data Reliability and Accuracy 

The reliability and accuracy of observational data is essential for environmental research and policy making. It is necessary to ensure that reliable data is available.

The disadvantage of satellite data is that once a satellite breaks down while flying for some reason, it is impossible to get data, but the situation to take

Integration of multifaceted observation methods 

In addition to satellite data, more comprehensive information can be obtained by combining multiple methods, such as ground observations and model simulations.

Satellite data is very versatile as a 2-time use and very highly regarded as democratic data.

The ability to properly interpret observational data to understand environmental issues and propose solutions. It is important to know how to apply the information that the data holds to actual issues.

These capabilities will help in comprehensive understanding and use of the data.

Items that can be illustrated by environmental observations

The data that can be obtained with sensor bells is roughly the following image

Sensor Type	Types of electromagnetic waves	Data that can be obtained	Remarks
Optical Sensor	visible light	Land surface shape, land use, vegetation
Infrared Sensor	infra-red rays	Surface temperature, cloud cover, air pollution
Microwave sensors	Microwave	Shape of the land surface, forest conditions, sea level elevation	Not affected by clouds or rain
Synthetic Aperture Radar (SAR)	Microwave	Shape of the land surface, forest conditions, crustal deformation
Altimeter	Microwave	Surface elevation
Scatterometer	Microwave	Wind speed and direction
Air quality sensor	Ultraviolet, visible light, infrared	Concentrations of ozone, nitrogen dioxide, sulfur dioxide, etc. in the atmosphere

Specific Observation Satellites

CO2 Observation: Ibuki

We also found that the annual increase in the 2021 total atmospheric mean concentration of methane was the largest since 2011!

Data from the Greenhouse Gases Observing Satellite (GOSAT) ("IBUKI"), which is operated by the National Institute for Environmental Studies and the Ministry of the Environment in collaboration with the Japan Aerospace Exploration Agency, revealed that the annual increase in the total atmospheric average concentration of methane in 2021 was the largest since observations began.

Although the cause of the recent increase in methane concentrations is not yet clear, the factors causing such an increase in concentrations may pose a major problem in forecasting future methane concentrations and checking the implementation status of emission reduction measures in each country under the Paris Agreement.

forestry observation

Forest observation, of course, also helps to understand the state of the environment.

Specific things to look at include the degree of deforestation.

Marine research: GRACE

An Earth observation satellite launched in 2002 by NASA of the U.S. and DLR of Germany. 2 satellites measured changes in the Earth's gravity field to determine the amount and movement of groundwater, ice sheets, and seawater. In resource exploration, they were able to determine the status of groundwater depletion and contamination.

• ALOS: An earth observation satellite launched by Japan's JAXA in 2006. Equipped with optical sensors and radar, it collected data on topography, vegetation, and soil. In resource exploration, it was able to estimate the distribution of groundwater, oil, metals, etc..
• Landsat: A series of earth observation satellites continuously launched by NASA and the USGS in the United States since 1972. Equipped with optical and thermal infrared sensors, they collected data such as the color and temperature of the earth's surface. In resource exploration, it was able to identify the types and distribution of minerals and rocks.

Water Resources Observation

There is also a great deal of personal interest in this area, you can check thisby clicking to see another articleThere are many things to look at.

And so much more to see!

The above are just a few examples of observations of the global environment.

There are cases where satellites that were not originally launched for Earth observation can be used for Earth observation, depending on how they are used! It might be interesting to check out various papers.

In addition, below are other pages where you can see remote sensing data in the global environment (global and Japanese companies)

• The Center for Environmental Remote Sensing Research (CEReS) at Chiba University collects, analyzes, and provides data from earth observation satellites as a joint use and joint research center in the field of environmental remote sensing of a national university corporation.Center for Environmental Remote Sensing Research, Chiba Universitythere you can browse our research results, latest newsletters, and more.
• The National Institute for Environmental Studies (NIES) develops and applies remote sensing technologies to solve environmental problems.Environmental Observatoryexplains the principles, types, and applications of remote sensing. Also,Statistical Analysis of Satellite Remote Sensing CO2 Observation Data Over Global and Australian CitiesThe results of this research have also been published.
• The Japan Meteorological Satellite Center (JMSC) receives, processes, and distributes data from meteorological satellites operated by the Japan Meteorological Agency.In JMSC Home Page,You can check the overview of meteorological satellites and how to view and apply for observation data at Also,in JMSC DatabaseYou can search and download images and numerical data from meteorological satellites at
• The Remote Sensing Technology Research Association of Japan (RESTEC), as the successor organization to the National Space Development Agency of Japan (NASDA), conducts research, development, and public awareness of Earth observation from space.RESTEC Home Pageintroduces basic knowledge of remote sensing, application examples, and education/training programs. In addition, [RESTEC's Data Service] provides information on how to purchase and use satellite data.

Let's try satellite data using Google Earth Engine!

Google Earth Engineallows anyone to analyze and visualize satellite imagery for free (up to a certain extent)!

At first, you may find it difficult because of all the unfamiliar things, but that is only in the beginning. But that's only in the beginning.

For detailed instructions, please look for Youtube or other technical professionals who have a lot of information on how to use the system!

Conclusion

As described above, the satellites that make possible the search for Earth's resources observe various aspects of the Earth and provide valuable information. This information is useful for the effective utilization and conservation of resources, and also contributes to our understanding of and countermeasures against global environmental changes and problems.

For otherArticles on Natural Resources,please click here!