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 SpaceX drone ship live video feed often cuts out just as the rocket is coming into view, leaving us in suspense.
But why does this happen?
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 kilometers out in the Atlantic 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 its 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 meters away from the drone ship with its 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 rocket’s 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.
Read how SpaceX lands its rockets autonomously on drone ship and on land here.