B Mars Landing, How instantaneous communication was possible

[NTesla]

TL;DR Summary

It was incredible to watch it live from JPL feed. However, while watching the EDL (Entry Descent and Landing) phase, what I couldn't understand was how come they were relaying the EDL phase situation on a second by second basis as if it were instantaneous when it takes about 11 minutes for information to travel from Mars to Earth.

[Mod note: thread level changed to beginner.]

If someone understood it, then kindly explain..?

 

[Bandersnatch]

They were relaying it simultaneous with the signal being received, not with what was happening on the ground.

 

[Klystron]

When around the world news coverage initially became more common, some broadcasters such as PBS and NASA-TV distributed some real-time content complete with speed-of-light and processing delays. They filled the gaps with live commentary, near-time recorded content and 'stock' photographs. Broadcast journalists explained the inherent delays were left intact in an abundance of caution to avoid the appearance of manipulation of words and events and because near-time information processing was resource intensive: expensive and time consuming.

I recall watching events from Houston (manned space flight) and JPL (instrument packages) in a theater at Ames Research Center (ARC) with intense nuggets of information interspersed among periods of operators fidgeting over consoles. Even after reception, data processing required minutes to hours.

Commercial broadcasters recorded real-time events and remote interviews and spliced the sequences into a cohesive narrative that avoided dreaded "dead air". As technique and technology rapidly improved, spliced near-time narratives replaced transmission/reception gaps in real-time as if no delay existed.

Modern audiences expect coherent uninterrupted narratives. Current broadcasters comply. This comment ignores government regulations and injections of artistic content outside the scope of the original post.

https://sanfrancisco.cbslocal.com/2021/02/18/nasa-ames-mars-rover-perserverance-landing/

 

[sophiecentaur]

In actual fact, we have grown to accept delays in communications via the internet which are worse than what you can get when talking with the Moon. Conversations with TV reporters used not to suffer in this way when simple wires were used.
The NASA commentary on the recent landing never pointed out that ‘all this happened eleven minutes ago’. Most of the audience would not have considered it.
People love to watch a recording of yesterday’s Big Match and avoid the news and newspapers whilst they’re waiting. Folks are strange.

 

[SpaceJacob]

I agree that we all are accustomed to delays, so NASA relied on the time they received a signal from Mars, not the real time. Moreover, people who watch NASA's live streams are aware of how the Earth-Mars communication occurs, so they thought there's no need to explain how the delay is overcome.

 

[phinds]

Moreover, people who watch NASA's live streams are aware of how the Earth-Mars communication occurs...

Really? All of them?

 

[sophiecentaur]

Really? All of them?

Well, the ones that count! Definitely not the ones who could ever have believed in the moon Landing Conspiracy. EM waves behave very pedantically.

 

[SpaceJacob]

Really? All of them?

I suppose the majority of them. When you watch NASA's streams from time to time, like it or not, you start to understand how things in space work. I don't mean they all are experts, I mean they have at least a basic knowledge of it.

 

[phinds]

I suppose the majority of them. When you watch NASA's streams from time to time, like it or not, you start to understand how things in space work. I don't mean they all are experts, I mean they have at least a basic knowledge of it.

Yeah, I was thinking more of the casual observer, but I think you're right.

 

[russ_watters]

Yeah, I was thinking more of the casual observer, but I think you're right.

I would hope even the casual observers. The fact that they are largely autonomous should be one of the first things you learn about them. Their actions are pre-planned and they are otherwise robotic/autonomous in part due to the delay. Otherwise they could be using them in realtime, which would be more productive.

 

[sophiecentaur]

@russ_watters i think you are overestimating the “casual observer” here. I talk to (far from dim) people who hear me say facts like delays of several minutes yet totally dismiss the real consequences.
it’s easy to forget that many of us PF members are going through this sort of thought process on a daily basis. None of these things are needed in everyday life so your average member of the public easily slips into the ‘now equals now, everywhere’view of time.