Much of what scientists know about Earth, climate change and the how global warming is affecting our planet can be gleaned from satellites in orbit.
NASA has announced it has selected four new proposed missions, which will each receive $5 million to conduct a one-year mission concept study.
The missions are tasked with helping scientists better understand the effects of climate change in relation to greenhouse gases, the ozone layer, ocean currents and melting ice and glaciers.
See more pictures of Earth from space
The proposed studies are part of NASA's Earth System Explorers Program for space missions that enable scientific observations of Earth.
NASA currently has over two dozen Earth-observing satellites and instruments in orbit, and these four new missions could be the latest additions to the 'Earth observatory'.
The proposals will receive $5 million each for a one-year mission concept study, after which NASA will choose two proposals to go forward, with launches expected in 2030 and 2032.
Total mission cost cap is $310 million for each chosen investigation.
"The proposals represent another example of NASA’s holistic approach to studying our home planet," says Nicky Fox, associate administrator, Science Mission Directorate at NASA Headquarters in Washington.
"As we continue to confront our changing climate, and its impacts on humans and our environment, the need for data and scientific research could not be greater."
NASA's four new Earth-observing proposals
The Stratosphere Troposphere Response using Infrared Vertically-Resolved Light Explorer (STRIVE)
STRIVE's goal would be analysing Earth's upper troposphere to the mesosphere and gaining daily insight into temperature, atmospheric elements and aerosol properties.
The mission also seeks to measure vertical profiles of ozone and trace gasses needed to monitor and understand the recovery of the ozone layer – another identified NASA Earth sciences target.
Ocean Dynamics and Surface Exchange with the Atmosphere (ODYSEA)
A satellite to measure ocean surface currents and winds to improve scientists' understanding of interactions between the air and sea.
It would look at processes within sea surface currents and how they affect weather, climate, marine ecosystems and human wellbeing.
Earth Dynamics Geodetic Explorer (EDGE)
This satellite would be tasked with studying the 3D structure of ecosystems on Earth and the surface topography of glaciers, ice sheets and sea ice, particularly in how they're changing over time.
The mission would be a continuation of measurements currently undertaken from space by ICESat-2 and GEDI (Global Ecosystem Dynamics Investigation).
The Carbon Investigation (Carbon-I)
What is the quantity of greenhouse gases in the atmosphere and how does this change over time?
That would be the task of this mission, to reveal the sources of natural emissions and those caused by human activity.
It would provide global coverage to help better understand the carbon cycle and the global methane budget.
