
Ask HN: GPS for Mars - ddalex
Since inception, the GPS and similar GNSSes proved invaluable in orientation and advanced navigation here on Earth. It seems to me that in order to successfully send humans to Mars, you need to have reliable infrastructure.<p>A GNSS network that doubles as communication network based on an array of low-flying satellites seems an obvious step to me - people landing there would have access to unlimited-range comms, and precise navigation techniques. But nobody talks about this.<p>What would be the tech and economical problems in starting to build the digital infrastructure on Mars?
======
gvb
The problems are economical and priorities.

The cost per pound to put satellites into orbit is large. There are lots of
arguments on _how_ large, but there is no question that it _is_ large.[1]

The priority problem is that unlimited comms and convenient navigation are
only useful after a _lot_ of other things become a reality.

Unlimited range comms will only be useful when moving about the surface is
(relatively) fast and (relatively) unlimited. Navigation is the same - it is
only necessary when you get beyond visual range.

Navigation can be done using (a) eyeballs, (b) inertial navigation and (c) the
stars. Eyeballs are good for short distances. Inertial navigation is good for
moderate distances. Stars are good for very long distances. Navigation is best
done in layers: inertial (and/or stars) to get you close enough for eyeballs
to work.

GPS on the earth is (historically) a very new way of navigating. It is very
convenient, very accurate, and can be used with almost zero knowledge and
skill, but it is not necessary. Navigating using the stars has been used for
thousands of years. Over time, improvements to time measurement, mathematics,
angle measurement (sextant), and star mapping made the navigation more
accurate.

You only need inertial / star accuracy to a few miles - visual range - in
order to successfully get to a destination. After all, Mark Watney was able to
navigate successfully to the MAV using just Phobos and his eyeballs. ;-)

[1] Ref:
[https://www.reddit.com/r/Mars/comments/42rs7k/cost_per_pound...](https://www.reddit.com/r/Mars/comments/42rs7k/cost_per_pound_to_mars/)

