Tracking, or finding an aircraft over a large ocean area is still not possible. As this article says[1], "About 85,000 square kilometres of the 120,000 square kilometre search zone has been covered so far." But if you match that against the map of the search area, you will see that even that huge search area covers only a narrow strip of ocean.

The plane may be huge, but compared to the earth, it is very, very small.

[1] https://theconversation.com/two-years-on-since-flight-mh370-...

what makes it so difficult is it the underwater currents that carry the fragments below the sea? don't we have some xray view on our spy satellites?

Not entirely sure what you are asking, but A: No we have no xray view on spy satellites, and B: X-Rays can not go through water.

A: Is impossible - no satellite has enough energy to illuminate anything, they all use the sun for light and just take pictures.

B: Water blocks almost all forms of light, you need sonar to see anything under there.

Also, much of the MH370 search area includes some very rugged seafloor. If or when it sank, the wreckage may be located in the underwater equivalent of very mountainous terrain. Just like above water, it's a lot easier to find something in the desert (abyssal plain) than in the mountains. http://www.independent.co.uk/news/world/asia/missing-flight-...

While I appreciate your point A for optical wavelengths, space based radar is definitely a thing. Optical wavelengths are undoubtedly more popular however.

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

A: https://en.wikipedia.org/wiki/TOPAZ_nuclear_reactor

Weaponized, 1967-88: https://en.wikipedia.org/wiki/US-A

Which used a fast fission (!!!) reactor (i.e. not quite a nuclear kaboom operating mode).

More generally: https://en.wikipedia.org/wiki/Space-based_radar

"Although the test program was considered a success, no plans were pursued to fly any of the reactors."

Edit: I misunderstood the wiki article. Carry on.

That's just the TOPAZ-II model, the 2 of the earlier model flew, and 31 for the Soviet's military radar satellites.

That Russia was willing to work with us and share the TOPAZ-II is yet another sign of how much things changed after the Evil Empire fell.