"same happened to Beagle2 MARS disk like non motile robot. "
Beagle was a completely different kettle of fish.
It was chronically underfunded right up until after the last moment, which meant amongst other things that the airbags used were the same ones which had been used, tested and patched in earth's atmosphere and as such were overweight and full of water vapour.
They spent 6 weeks being baked in my employer's vacuum chambers and we were still sucking out water when they had to be shipped off for launch integration (there was so much water in the airbags initially that it damaged the vacuum pumps). Ideally they should have spent 3 months or more being dessicated and you NEVER EVER fly test articles (This is what killed Apollo 13 - the oxygen tank which exploded was used and damaged in tests performed in 1964).
The odds are pretty good that Beagle's airbag simply froze solid and never inflated properly (or ruptured during inflation)
The money that did show up was too late to get replacement airbags
Had Beagle been properly funded, it very likely would have worked - and it was so cheap/lightweight it would have been easy to build a dozen of the things and plonk 'em down across Mars. The concept is likely to be revisited in the future.
As for Philae, the gas thuster is an issue (the nitrogen probably froze) but the most lkely reason the harpoons "didn't work" is that by the time they fired, the lander was already several metres off the ground having bounced. An ion engine for soft(er) landing may have been a good idea but you can't go out and attach one now.
Given the microgravity environment I think I'd have opted for a net or some other form of wide-firing anchor and possible an unfurling solar panel but it's not my project and all that stuff adds launch mass/complexity, etc. Overengineering isn't usually an option for deepspace probes.
Biting the hand that feeds IT
