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Today, GPS and similar navigation systems use satellites in space
to help you navigate where you want to go here on Earth.
Tomorrow, these same satellites will transform navigation in space as well,
making life on Earth safer, healthier and more productive.
And they will even help navigate missions to the moon and spacecraft on the way to Mars!
This will be accomplished through international collaboration and a capability called the Space Service Volume.
Worldwide, there are four global navigation satellite systems
and two regional navigation satellite systems,
collectively known as GNSS.
These navigation constellations include the United States’ GPS, Russia’s GLONASS,
Europe’s Galileo, China’s BDS,
India’s NAVIC and Japan’s QZSS.
Individually, these constellations can significantly improve navigation
for spacecraft in low Earth orbit like the International Space Station
or Missions that measure climate change and map the Earth’s surface.
But for the spacecraft located in higher orbits
in a region we call the space service volume, navigation is more challenging.
The space service volume stretches from 3,000
to 36,000 kilometers above Earth. Most navigation
satellite orbits are inside this region and broadcast their signals
toward Earth. However, it is challenging for other satellites, like weather
or communications satellite, at the top of the space service volume to
to receive these signals. Users on the other side of the Earth receive weaker
signals from navigation satellites because of the longer travel distances.
Additionally, the Earth blocks most
of the navigation satellite signals.
In response, engineers have developed special technology to navigate with
weaker and fewer signals in view. But this does not overcome
all the challenges. Because users in low Earth orbit are below
the navigation satellites, the individual constellations can guarantee
lots of signals for missions like Space Station. In the upper
reaches of the space service volume, users receive significantly fewer
navigation signals and many times no signals at all.
If all navigation constellations are able to operate together,
signal reception dramatically improves with an average of four to 12 signals
in view and at least one signal continually. This is
critical to ensure navigation support 24/7/365.
This unified system is called the multi-GNSS
Space Service Volume. So how do we get all these constellations
working together? The International Committee on
the ICG, sponsored by the United Nations Office
of Outer Space Affairs, is leading collaborative efforts to ensure
that all these systems are interoperable through the creation of common definitions
and specifications. Operating together,
this combined system of navigation satellites will be transformational
for missions operating within and above the space service volume,
significantly improving navigation performance and enabling spacecraft to navigate
autonomously, without any direction from the ground.
This technology enables accurate pinpointing of extreme weather, like
flash floods, tornados and hurricanes, crucial for public safety
and more accurate weather prediction. It will fuel
future advancement in observing, communicating and working in space
even extending all the way out to the moon! Like GNSS
has transformed our lives on Earth, navigation in space will enable
scientists to devise exciting new missions, improving science and
enhancing our life on Earth. All via the multi-GNSS
space service volume.
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