Hi, I'm Mauro and this is Steve from BT.
We are part of the BT Space Team. You probably see
space through the lens of science fiction movies like Star
Wars and Star Trek. But what about reality? What about
the 8,000 satellites that are orbiting
the planet right now as we speak. Whether these
are satellites that are tracking what's happening with climate change or
tracking what's happening in disaster or war
zones across the world or even allowing you to
see where your friends are on Snap Maps.
Or be able to connect people, devices and machines
everywhere across the world. Satellites play a
pivotal part in your day-to-day life. So what
we're going to do today is we're going to start 36,000 kilometers
away from the earth looking at geostationary satellites and
gradually move our way in until we get to drones
which are 120 meters above the Earth.
So now we're going to talk about orbits. And then we're going to look at
geostationary satellites and why they're important. So
Steve,
tell us about geostationary satellites.
Well, it will be good to define what an orbit is.
An orbit is a regular repeating path an object
in space takes around another object. So
assume on the one hand you have Earth and on
the other hand you have a satellite - an orbit
is the path the satellite takes around the Earth. Geostationary satellites
are orbiting around
the Earth at the same rate as the Earth is rotating
around its axis. So to a person standing on the Earth,
gestational satellites appears as if it's not moving.
Geostationary orbits are about 36,000
kilometers away.
So an average human-being is 170cm,
so if you stack 21 million people, which is
half of the people in England, the last person might be able
to touch a geosatellite. They are so far away that it provides
a massive coverage and you only need three of them to cover
the Earth. Historically, satellite communication started
with geostationary satellites and because they're
so far away the signals arrive quite weak
to the ground and you need massive antennas to
receive them. And they are typically used for satellite
TV broadcasts. And they
can also be used for communications, but you have very low
speed and very high latency. Well
signals take time to arrive at
the Earth.
So now we've heard a bit about geostationary satellites. Let's look
at mid-Earth orbit satellites and get closer to Earth and
understand why they're important in terms of things like Google Maps
and Snap Maps. Compared to
geostationary supplies that are 36,000 kilometers away, MEOs are
roughly about 20,000 kilometers away.
So which means that signals from MEO arrive to
Earth much quicker, much stronger, so you
get much better capacity from MEOs.
But it's only one problem though, MEOs unlike
GEOs would move around the Earth twice
in a day. For you to provide coverage continuously with
a MEO you will need a constellation made up of
many of these MEOs. That's where one of
its key application comes from which is the GPS
and the Snap Map that you talked about.
For a receiver to locate itself and figure
out where exactly it is on Earth it needs
to get signals from more than two or three
satellites, which is quite easily applicable
with a MEO given that you you need a constellation of them
to provide coverage. Other typical applications of MEO is
again, high speed
communication. Like I mentioned signals arrive quicker and
stronger, so you have much more capacity but
like GEO you still need specialised receivers
to receive signals from MEO.
Now some of you would have probably heard of Elon Musk
and you maybe even have seen his satellites
in the sky. So now we're going to look at what low
Earth orbit satellites do and why they're becoming more important. So
you might have picked up on the fact
that we are actually coming closer to Earth with
every orbit and every focus. LEO appears
to be the darling of the industry at the
moment. Again, similarly to to MEOs it's because
it's much closer at 1,200 kilometers
or thereabouts to Earth. So your signal arrives much
stronger compared to the other orbits, much
quicker as well. LEOs, again
require more satellites - it's much
closer so more gravitational pull so you need more force to
keep it in orbit. It means it has to be a bit faster in the
orbit. It orbits around the Earth in 120 minutes , so which
means a single LEO satellite would go around the Earth 12
times in a day. So you need hundreds of them in the
LEO constellation - in LEO orbit constellation, to provide
continuous coverage. There are many advantages and
there are similarly some disadvantages. One
is that your receivers would have
to deal with the fact that many satellites
will come in view, so it will have to worry about changing transmission
from one satellite to the other. But the advantage is
that the signals come strong enough that your receivers do not
have to be specialised, you can receive signals
from LEO to your smartphones.
So we're no longer in Earth orbit, we're now
in the atmosphere and we're going to look at high altitude pseudo satellites.
Again, coming much closer, high altitude
platforms are, if you like, really large
drones - imagine your Boeing 747 flying somewhere
in the Stratosphere. So
just above the Atmosphere at 20 kilometers. Much closer,
much higher capacity than you would get from a satellite
and much quicker in that case. So it's more
ideal for your online gaming
because you don't experience your buffering,
everything seems as if it's going fast. We
imagine that in the near future you're going to
have constellations of high altitude platforms
somewhere in the Stratosphere giving us coverage.
Now my teenage daughters love to
muck around with drones. So now we're going to look at what the
future for drones holds.
There are other many applications, many use cases
for drones. They can be flown
to an area where there's been disaster and there's no communication, so
you fly them to serve the area and then fly them
back when services have already been restored. Or even to
help emergency areas. The downside is that they have
limitations on the battery, how long they can fly, but the
flexibility is that you can fly one back quickly, change the battery and
fly it back. Again there are other applications, there are people
already looking at delivering medications to rural areas
or hard to reach areas and delivering that
quickly.
Well, thanks for that Steve, that was really really interesting.
Well, I hope that you know, you've come away from that understanding a
lot more about the importance that space plays in
our day-to-day lives. And you know what, it's going to get even more important
as space may be the place we need to go to solve
some of the biggest challenges that the planet is facing. For
example, there are start-ups out there now that are
looking to build satellites that can beam solar power
down from space. Start-ups that are looking to do manufacturing
of microchips in space, which will provide
much more energy efficient networks. So as
you think about your future careers and where you
might want to go, please consider space as an avenue
to explore. Thank you.