Ever since the early days of space-flight, rocket launches have been a fascinating spectacle.
Up until recently, lift-off has usually been the most tense and exciting part of any launch.
But ever since SpaceX came along and started to re-use their rockets, the landing of the
Falcon 9 booster has become one of the most iconic shots in spaceflight,
that is, when we get to see it.
Sadly, when watching the SpaceX broadcast, the live video feed often cuts out just as
the rocket is coming into view, leaving us in suspense.
But why does this happen?
In this video we are going to look at how SpaceX broadcasts live video from their landing sites.
We’re also going to look at how the live feed is interrupted by the rocket and the
possible solutions that could be put in place to get around this problem.
When the Falcon 9 lands back on Earth, it will either land back near the launch site
or on a drone-ship placed hundreds of miles out in the ocean.
With the drone-ship being in such a remote location,
the live video feed has to be transmitted via satellite.
A large antenna on the drone-ship sends a directional signal towards the satellite which
will then transmit that footage back down to the broadcast team.
The signal from the drone-ship needs to be directional, in order for it to be strong
enough to reach the satellite.
The problem occurs when the rocket gets close to the drone-ship.
As it comes in for a landing, the rocket is slowed down using either 1 or 3 of it’s
Merlin engines each firing over 100,000lbs of thrust towards the surface of the drone-ship.
As the rocket gets closer to the drone-ship, the thrust from the engines start to shake
the drone-ship with such a high frequency that the video feed antenna loses lock with
the satellite, causing the video feed to cut out.
Once the rocket has landed and the vibrations have dissipated, the video feed should reappear.
During this period of time, the footage is recorded and will be sent back as soon as
the drone-ship regains connection with the satellite.
Not only does this ensure that the engineers can analyze each landing, it also means that
SpaceX can upload the footage after the broadcast for everyone else to watch.
There have been many solutions put forward to fix this issue.
One solution would be to have a similar ship placed a few hundred metres away from the
drone-ship with it’s own antenna to transmit the video feed.
This antenna ship would be unaffected by the vibrations but it would need to be connected
to the drone-ship using a very long video cable to receive the footage.
A way around this is to transmit the video feed from the drone-ship using a non directional
signal to the antenna ship, which would then transmit the video feed up to the satellite
without being interrupted by the rockets vibrations.
Although this may seem like a problem that SpaceX could easily fix, going through the
effort of adding more vessels to their recovery fleet doesn’t seem like it’s worth the
cost for just a few seconds of live video.
Even if we don’t get to see live footage of the landing, the footage is always recorded
and uploaded a few days later for all of us to see, even when the landing goes wrong.
So while it may be frustrating to lose the video feed right at the most exciting part
of each mission, it does seem like SpaceX do everything they can to eventually bring
us clear footage of each landing.
If you have any more questions on how SpaceX broadcast their launches
let me know in the comments below.
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Thank you very much for watching and I’ll see you in the next video.