Hello there! So, let me tell you about Grace and Grace-FO. Grace stands for Gravity Recovery and Climate Experiment, and it is a very important NASA mission. Grace was launched into space in 2002, and it is made up of two satellites that orbit around the Earth.
What Grace does is measure changes in the Earth's gravity field. This might sound a bit complicated, but let me put it this way. Imagine you are playing with a ball in a pool. You might notice that when you move the ball, the water in the pool moves in a certain way. Well, Grace does the same thing with the Earth. It measures the way that the gravity field changes when things move around on the surface of the Earth.
Grace can tell us many things about our planet, like how much ice is melting in different parts of the world, or how much water is in the oceans. This helps us understand how our planet is changing over time, and how we can protect it.
Now, Grace-FO is a newer version of Grace that was launched in 2018. It stands for Grace Follow-On. Grace-FO is also made up of two satellites that orbit the Earth, just like Grace. The difference is that Grace-FO has some new technology that makes it even better at measuring changes in the gravity field.
Grace and Grace-FO are like two friends that work together to tell us important things about the Earth. And just like how friends help each other, Grace and Grace-FO are helping us better understand our planet so that we can take care of it.