The mystery surrounding the unfortunate lost Malaysian Flight MH370 has caused some of the more astute reporters to ask questions about satellites. Specifically, were there any satellites over the area the airplane disappeared in? And if there were, would they, or could they have picked up anything to help find the missing airplane? Ultimately, can satellites help find lost aircraft?
The answer, unfortunately, is a wishy-washy “It depends.” As described in my Low Earth Orbit (LEO) satellite series, most LEO satellites are moving closely, and quickly, above the Earth. If any one of these are imagery satellites (and there are several), then maybe there’s a picture out there somewhere owned by one of the many satellite imagery companies. But since the satellites are so low, they don’t see much of the Earth except for the areas they are directly over, and for some satellites, a little to the side.
For this mystery and these LEO satellites it’s all about timing and interest. The timing part is: was the satellite over the area the airplane disappeared on, or around the time the airplane disappeared? And if it was, did someone think the area, where the airplane disappeared, was interesting enough to have the satellite take a picture of it? If so, then maybe there’s an airplane in that image somewhere. And there are quite a few imagery satellites, so maybe someone did think that area was interesting. But it would be an amazing coincidence.
For geosynchronous orbiting (GEO) satellites, the problem is different. Remember from the lesson series for GEO, the satellite has the possibility of seeing the whole disk of the Earth. That would be what’s called it’s Field of Regard (FOR). But if the satellite operators and designers have put a camera or some sort of sensor that can be focused on a particular part of the Earth, to the exclusion of the rest of the satellite’s FOR, then that would be it’s Field of View (FOV).
Some weather satellites have the ability to take a picture of the FOR–it’s also their FOV. But this means there won’t be much detail in the picture. The passenger jet would be, if they were lucky enough to get it, a speck hidden near some clouds. There may be satellites that can focus their FOV, giving better resolution. But the trade-off here is the focus is normally of a particular area of the Earth. So if the airplane’s disappearance occurred in an area the satellite’s sensor wasn’t focused on–well, there’s no way of knowing what happened outside of the satellite sensor’s FOV.
An example of a GEO satellite is one that’s a part of the Space Based Infrared System (SBIRS)/Defense Support Program (DSP) constellation. According to some reports, there was no explosion detected by these SBIRS/DSP “spy satellites.” Actually, the specific phrase the report highlights is, “National Technical Means (NTM),” which the post explains as meaning spy satellites.
But the NTM report could really mean several things. It could mean maybe the satellites were observing something else and not looking in the disappearance area (entirely possible, since no one who wasn’t on board the airplane was expecting its disappearance). It could mean there was something obscuring a possible explosion. It could mean the airplane’s explosion wasn’t intense enough. Or, it could mean there wasn’t an explosion at all.
That’s where it gets interesting, as INMARSAT is now saying the missing airplane’s signal kept “pinging” their satellite after it disappeared from radar. INMARSAT offers a few radio satellite communication safety packages for airplanes (you can read about those on their site, here). The fact they are giving out information that the missing airplane was talking to their satellite means Malaysian Airlines subscribed to one of those services. INMARSAT also owns several GEO communications satellites. It turns out possibly three of them might have had the aircraft in their communications FOR (maps of their coverage are here).
At least one of the satellites, the one covering the Pacific Ocean area, would probably have some issues, because the airplane was near the edge of its coverage. This means the radiowaves would be moving through lots of atmosphere between the airplane and that Pacific Ocean satellite. Now understand, I’m just guessing here, and you’re welcome to add in, if you wish. So that leaves a possible two INMARSAT satellites that would reasonably and fairly easily have been able to receive the airplane’s radio “ping.” And only one of those satellites uses “spot beams”–228 of them–which might be a way to figure out which direction the aircraft was heading. You can see a picture of the spot beam pattern here (it’s at the bottom of the linked page).
Spot beams are the communications satellite’s way of “aiming” and focusing a signal from the satellite to a receiver on or close to Earth–like the one hooked to an airplane antenna. The satellite antenna it would need to know when to switch to a different beam to maintain communications with the airplane. It would also need to know which beam to switch to. The spot beams are big–at least a few hundred miles wide.
Maybe INMARSAT has looked at this, and just can’t find the information (because it’s just not there or too obscured). Or maybe they’re still trying to figure it all out. But it does bring a different tone to the whole story (actually–it looks like they might have done that–look at the map on the New York Times story here).
Even if these big satellite operators can’t find the missing airplane, there’s the possibility you can. Once again, Tomnod has a crowdsourcing project for interested helpers and budding Geospatial analysts. Just go there to sign up, choose what to look for, and then start scouring the pages.