[ rain, thunder ]
[ thunder, music ]
[ bugs buzzing ] If we measure the Earth from the ground, we
can a get a good local picture of what is going around us.
But if we want to measure larger portions of the Earth, then we'll need to use
remote sensing. Remote
sensing measures the Earth and its features without making physical contact.
We can gather data from entire continents over longer time
periods so we can look at how the Earth is changing.
NASA uses specialized aircraft and sophisticated satellites to gather
data using both passive and active remote sensing methods.
Passive remote sensing measures the natural energy, or radiation, of the
Earth. Active remote sensing gathers data by actively sending
out signals that interact with the target of interest.
Using both active and passive remote sensing techniques, NASA can look at
soil moisture maps to monitor drought, estimate
snowpack in areas where snow is crucial for freshwater,
measure the change in ice sheets and sea level, tracking
storms that could impact human lives, and observing how
precipitation changes affect where we get our freshwater. The Global
Precipitation Measurement mission helps fill in the gaps where ground measurement
isn't enough. Places with rugged terrain can block the signals from ground
radars. The oceans are too vast to cover with enough
ships and measurement stations on the surface, and places
without the network of instruments needed to measure freshwater for people and agriculture.
We can then unify the measurements to create a consistent and
accurate picture no matter where we are. Because satellites get
more complete coverage than ground-based instruments, we can use remote sensing
to better see how the whole Earth is changing over time.
With a long data record we can make better predictions about the water cycle, the climate,
and the impact on humans. [ wind, thunder, rain ]
[ wind, debris flying ]
[ tree splitting, insects swarming ]
[ debris falling, bubbling, airplanes ]
[ music ]
By observing our Earth from above, we get a much better understanding of what is happening
on the surface, in the atmosphere,
underground, over the globe, and in our own
backyard. [ music ]