This is the sound of Sputnik, the very first artificial satellite, launched by the Soviet Union in 1957.
In 2018, SpaceX launched Elon Musk’s Tesla Roadster into an orbit around the sun.
Sputnik fell back down to earth just a few months after it’s launch, and Elon’s Tesla
is now just an uncontrollable piece of space debris.
LUKE SKYWALKER: What a piece of junk
There are around 1,700 operational satellites currently orbiting earth and beyond that we
still communicate with.
But how exactly do we communicate with objects in space?
In this video, we’re going to look at the different ways that we communicate with objects,
all the way from low Earth orbiting satellites to deep space probes at the edge of our solar system.
We’re also going to talk about the equipment that’s used and how the capability of that
equipment has to grow, in order to deal with the increasing amount of data we are collecting
from our solar system.
Say you wanted to send a command to a satellite placed in a geostationary orbit 36,000km above the Earth.
Firstly, the command gets converted into a radio wave which is a type of electromagnetic
radiation that travels at 300,000 kilometers per second, the speed of light.
Once the command is converted into a signal, a ground station antenna will then transmit
that signal towards the Satellite which will use it’s very sensitive antenna to receive the signal.
Then, the onboard systems will convert that signal into code which the onboard computers can understand.
Most satellites will have an uplink and a downlink to allow the Satellite to send data back to Earth.
In 1962, NASA realized that it would need a brand new communications system for the Apollo missions.
Not only would the Apollo missions be going much further than any previous missions,
they would also be communicating with 3 astronauts working in 2 different spacecraft as well
as sending telemetry and live television images back to Earth.
They developed a system called “Unified S-band” which could send: telemetry, command,
voice and television data using different frequencies but combined into a single antenna.
This system would communicate with the Apollo spacecraft via fixed ground stations placed around the Earth.
This would allow mission control to have continuous communication with the astronauts during the
mission apart from when the spacecraft curved around the far side of the moon, where the
signal would be lost until they reappeared on the other side 40 minutes later.
During this time, the astronauts had to fire up the engines in a critical maneuver to make
sure they reappeared on the other side of the moon.
If the crew had a successful burn, it would set them on the expected trajectory, meaning
Mission Control knew exactly when they would regain communication with the Apollo 8 crew.
HOUSTON: Apollo 8, Houston over. Apollo 8, Houston over.
APOLLO 8: Houston, this is Apollo 8.
Of course, this loss of signal can also happen to satellites orbiting Earth when the transmitter
has no clear path to the satellite.
To get around this, NASA set up the Space Network, which uses satellites in geostationary
orbits to relay data from other satellites to fixed ground stations.
This provides continuous global coverage for all Earth orbits.
The Space Network may cover satellites in Earth’s orbit, but what about satellites
that are much further away?
The furthest distance a satellite can orbit the Earth before the gravitational force of
the Sun equals that of the Earth is around 1.5million kilometres.
But what about satellites that are BILLIONS of kilometres away?
The furthest man-made object from Earth is the Voyager 1 space probe.
It was launched in 1977 to study the outer solar system.
It is currently 20 BILLION kilometres away from Earth and travelling at 62,000km/h.
The transmitters used by the Space Network aren’t powerful enough to reach and receive
data from deep space satellites.
For satellites this far away, we need something called the Deep Space Network in order to communicate.
The Deep Space Network consists of antenna complexes at three locations around the world
in: America, Spain and Australia.
These facilities are equally spaced 120 degrees apart on Earth.
Each complex has a 70 meter antenna as well as two smaller high efficiency antennas.
Satellites close to Earth typically use low gain antennas which spread their signals in
every direction making it relatively easy to them pick them up here on Earth.
Satellites in deep space use high gain antennas which focus their radiowaves to achieve a
much stronger signal strength once it reaches Earth.
The demands placed on deep space communication systems are continuously increasing.
As of March 2016, the Mars Reconnaissance Orbiter had returned more than 300 terabits*
of data, and as we continue to launch more and more satellites into deep space,
NASA estimates that our space communications capability will need to grow by a factor of 10 in the next decade.
So, as we continue to look further into space, it’s good to know that the brave little
spacecrafts that we send out to the edges of our solar system are able to talk back
to us and tell us what it’s like out there.
If you have any questions be sure to leave them in the comments below and make sure you’re
subscribed so you can join the discussion as we continue to learn more about all things space.
Thank you very much for watching and I’ll see you in the next video.