Engineer Stealth Technology

BigDave
MemberDeaconSep-26-2016 5:32 PMI would like to start a Topic that i dont think has really been covered before? If it has then its a Topic that has had very little discussion!
Do the Engineers posses some kind of Stealth Technology?
I propose this because of the lack of interaction and findings that Mankind has with the Engineers and their remnants of Technology.
In Aliens we have to ask how does the company go to LV-426 and start up the Hadleys Hope Colony without detecting the Derelict.... We see it has not been completely covered from the events of Alien in the 2120's to when Hadleys hope was set up 30 years latter.
Then we have Alien.... how did the Nostromo not be able to detect anything until they had landed, we have to ask if it was not for picking up the Beacon Signal would their sensors had found the Derelict?
It goes further than that.... in Prometheus when they was preparing to land on LV-223 it was Holloway who noticed a valley that stuck out "God does not build in Straight Lines"
During the entering into the atmosphere they did not detect that on the surface there was Alien Ancient Cave-complexes that contained Outposts and Ships!
It was only the Pups that was mapping the complex internally which they did by using infa-red to ping off objects to then create a 3D representation of them... that they latter mapped the Juggernaught.
Then we have Alien Covenant.. where a Colony Ship arrives at uncharted Paradise and eventually discover that David 8 is the only sole occupant.... but this World is the World of the Engineers, how can one of the Cradles of their Society not have any remnants of their Architecture and Technology or the Juggernaught that David had taken from LV-223 to Paradise?
Even if we assume that Paradise those Engineers did not create or possess the Bio-Mechanical Giger Architecture/Material that the Juggernaught/Derelict and LV-223 Outposts had.... we can surely assume this race is as advanced enough to be able to build advanced buildings and ships... as how do the Engineers end up from Paradise... to seed Worlds on those Pebble Seeding Ships and to LV-223?
Does the Material they use have properties that act as some kind of Stealth Technology? or do they have some kind of Technology that acts as a Stealth/Cloaking device... something that electronically interferes with the ability to be detected?
In the case of LV-223 and LV-426 maybe it can be put down to their environments? or maybe interference caused by the Gas Giant they surround?
The Source did mention the Engineers can manipulate climates to bring on serve weather changes and climate changes that can have a detrimental effect.
I am sure in one of Spaight drafts i read that the Engineers have Technology that causes interference in the atmosphere that render detection of their outposts invisible to radar and scanners etc.
R.I.P Sox 01/01/2006 - 11/10/2017