MSL Landing Timeline: What To Expect Tonight 140
An anonymous reader writes "When the Curiosity rover lands on Mars later tonight, it'll be executing a complex series of maneuvers. JPL will be relying on the Mars Odyssey orbiter to relay telemetry back to Earth in time-delayed real-time, and if all goes well, we'll be getting confirmation on the success (or failure) of each entry, descent, and landing phase, outlined in detail here."
Re:Not for any definition of "real time" that I kn (Score:5, Insightful)
Telemetry will be continuously relayed back to earth, true, but with not much less than about a 15 minute latency, owing to the fact that Mars roughly a quarter of a light-hour from earth right now.
That IS indeed real time. Relativity tells us nothing can have an effect here in less time. I don't know if you're trolling or just ignorant, but by your definition you can never look at the stars, galaxies or nebulae in the sky in real time either because they're all at varying distances and we're seeing light that originated anything from about 4 to several million years ago. With telescopes you can go back billions.
Re:Not for any definition of "real time" that I kn (Score:2, Insightful)
The single most important criteria for something to qualify as "real time" in data communications is low latency. 14 and a half minutes is not low.
Then by your definition NOTHING in space is real time. You look up into the sky and everything you're seeing is sending it's light to you from the past.
Re:Not for any definition of "real time" that I kn (Score:2, Insightful)
No, that's just your personal set of criteria that doesn't have anything to do with reality.
Real-Time is without artificial delay. Yes, there's 14 minutes actual delay, but it's not artificial, it is literally the fastest possible time.
If 14 minutes prevents it from being real time, then 14 seconds should too, as should 14 milliseconds, or 14 nanoseconds. All of them are arbitrary amounts of time, all of them are large amounts of latency relative to something.
Re:Not for any definition of "real time" that I kn (Score:5, Insightful)
Re:Not for any definition of "real time" that I kn (Score:4, Insightful)
Owing to the fact that we will know the lander has already reached the surface (in unknown condition) by the time we get the first signal it has entered the atmosphere
Relativity says that there is a 14 minute delay in *some* frames of reference. In other frames of reference, the delay is longer. For others (those occupied by the radio signal photons, for example), the landing events and our reception of the signals happen simultaneously.
Getting hung up over what you imagine is the "time delay" between two points in spacetime that are outside of each others' light cones is kind of pointless.