6 ms·

It kind of baffles me that today the best solution we have to the problem of navigation is still based on the concept of having satellites in the space. Is ther

by d33 9y ago

It kind of baffles me that today the best solution we have to the problem of navigation is still based on the concept of having satellites in the space. Is there an ELI5 answer to why we can't have a decent system of figuring out where we are on this planet without making any unstable additions to it?

Zeebrommer 9y ago
Well why do you think we should? I don't know of any positioning principles that do not rely on measuring the distance to some known reference -- be it a star, sattelite, ground station or your place of departure.
bicubic 9y ago
Because there is no cheaper solution that's reliable. I think when we figure out affordable global positioning without needing external infrastructure, we'll unlock a major technological milestone as a species. Right now you can do this for short periods of time with multi million dollar INS solutions which are used exclusively by the military. My guess is the answer will be in SLAM augmented with some other sources of data. See googles project tango.
jo909 9y ago
We can and we have with mobile networks and wifi positioning. That's just not accurate enough for many applications, and resolution varies a lot.
Gravityloss 9y ago
Pulsar navigation https://news.ycombinator.com/item?id=16131537 https://news.ycombinator.com/item?id=16131537 wonder if it could work on Earth too...
coin 9y ago
https://en.wikipedia.org/wiki/Inertial_navigation_system https://en.wikipedia.org/wiki/Inertial_navigation_system
marcosdumay 9y ago
I don't get what is so unstable about satellites. Anyway, if you want a global system with sub-meter accuracy, you will have to continuously adjust it. If you settle for ~100m accuracy, you can create something that will last for a long while without any intervention by using satellites.
stordoff 9y ago
I'm not sure there IS an alternative. Ultimately, knowing where you are is in comparison to some known location (even inertial navigation is based on knowing a starting location and tracking movement away from that). GPS "just" provides a set of globally-visible waypoints rather than having to map those that are only locally-visible ahead of time. In theory, I suppose you could use the movement of astronomical bodies to do the same, but making a portable device that can automatically detect (without necessarily LoS the sky) the relative positions of sufficient markers seems like a tough ask.

by d33 9y ago

Zeebrommer 9y ago

Well why do you think we should? I don't know of any positioning principles that do not rely on measuring the distance to some known reference -- be it a star, sattelite, ground station or your place of departure.

bicubic 9y ago

Because there is no cheaper solution that's reliable. I think when we figure out affordable global positioning without needing external infrastructure, we'll unlock a major technological milestone as a species. Right now you can do this for short periods of time with multi million dollar INS solutions which are used exclusively by the military. My guess is the answer will be in SLAM augmented with some other sources of data. See googles project tango.

jo909 9y ago

We can and we have with mobile networks and wifi positioning. That's just not accurate enough for many applications, and resolution varies a lot.

Gravityloss 9y ago

Pulsar navigation https://news.ycombinator.com/item?id=16131537 https://news.ycombinator.com/item?id=16131537 wonder if it could work on Earth too...

coin 9y ago

https://en.wikipedia.org/wiki/Inertial_navigation_system https://en.wikipedia.org/wiki/Inertial_navigation_system

marcosdumay 9y ago

I don't get what is so unstable about satellites. Anyway, if you want a global system with sub-meter accuracy, you will have to continuously adjust it. If you settle for ~100m accuracy, you can create something that will last for a long while without any intervention by using satellites.

stordoff 9y ago

I'm not sure there IS an alternative. Ultimately, knowing where you are is in comparison to some known location (even inertial navigation is based on knowing a starting location and tracking movement away from that). GPS "just" provides a set of globally-visible waypoints rather than having to map those that are only locally-visible ahead of time. In theory, I suppose you could use the movement of astronomical bodies to do the same, but making a portable device that can automatically detect (without necessarily LoS the sky) the relative positions of sufficient markers seems like a tough ask.