What ways would the scientific/military branch of a (preferably Western) government investigate a foreign object, which can't be moved, in or near a town populated with oblivious people without alerting their suspicion?
Come up with a cover story and evacuate the area.
- In large parts of Europe, this could be an unexploded WWII bomb of specially tricky manufacture, something like a Tallboy. The danger radius of those things is large enough to cover a wide evacuation and it would be understandable that the EOD guys work slowly. "We do not want to blow the thing in place, and the alternative is to dig it out very carefully."
- Declare that there is a lifestock or plant pest in the area. Nothing dangerous to humans, but the possible economic impact justifies a large quarantine zone. Think back to the avian influenza.
- Or just say "National Security" and refuse to tell details. The press will leap to all the wrong conclusions, possibly terror-related.
Build a tax inspectors' office on top of it. Easy way to keep the general population well clear of the area.
If you want to move lots of heavy equipment in and out then you could build a retail distribution warehouse over it, then nobody would question the trucks coming and going and such things are generically boring. Make sure your scientists work in blue overalls instead of white coats and it's unlikely anyone will notice anything.
You might have to advertise jobs at the place locally, interview a few people but not actually give anyone a position.
I think it depends on four (or more) parameters. Namely the size of the object, the location, the source and the potential risk.
The size, location and source are important. People might be able to see what is going on before the government can react. Their cover-up would then also need to explain what people have witnessed.
Here is a list of possible ideas. Their usefulness depends on the parameters.
They could claim that ...
- it is a meteorite or space debris that didn't fully burn during re-entry in the atmosphere
- it was a crashed sports aircraft
- it was a gas leak
- pest control is necessary for that area
- radioactive material from a defective radiotherapy source contaminated the area
- there was an outbreak of a disease that requires quarantine
- it is an artwork by a suddenly famous artist. To ensure that it is not damaged, access is highly restricted
- it is a fossile discovered during construction work
- it is part of a crime scene that has to be investigated
Hope that helps.
Gas leak, sewage leak, or water leak would provide a temporary soultion, but this isn't viable in the long term.
There's a better long-term story, depending on the natural resources of the area. Specifically, oil. In almost every country except the United States, the government owns all mineral rights (including oil), even if they don't own the land up top. And by owning the mineral rights normally they can gain access and control over the land up top by eminent domain.
The government just needs to create a story that surface oil was discovered which was highly usual given the local geography. Setting up for and then drilling an oil well is a multiyear process, and then even after drilling oil wells tend to provide oil for many years to come.
Eventually the government can roll this over form an extraction site to an office location because yada yada. The exact reason doesn't have to make complete sense, after all governments are known for making less-than-ideal choices.
What's more, is that oil is typically seen as an interest of national security, so especially in populated areas there would be additional security, which wouldn't really be questioned.
Typically while most western countries own the rights to the oil they do work through private companies, so the government will have to strong arm somebody private to this end.
Of course the above doesn't exactly work for the US, as citizens who own land own the oil under their land, and the US government can't force them off.
The object exists yet the inhabitants have no idea of its existence and importance, did I understand this right?
The government can just send agents disguised as tourists. Tourists are inconspicuous if they snoop around.
One downside could be that the agents' time there is by default limited before townsfolk turn suspicious. Another downside would be if the town isn't the kind of place that attracts tourists. Then they could stage some event, a distraction, to attract outsiders there. Say, a local festival suddenly gains national exposure via a viral video or a UFO has been sighted.
Another approach would be to investigate it openly, but under another pretense. Maybe your unmovable object is a hill that's been there ages. A nice story can be that the government agents are a bunch of geologists studying the rock layers because there used to be a lake there during Pangaea or that they discovered a new subspecies of moss and chose this hill to study it because it has the right conditions. The stories should be simple and imply something uninteresting, so they won't attract attention.
One of the important things would be for them to appear to pay attention to a much larger area than just the object itself, so no one would suspect there is anything interesting about it. If they're tourists they should talk to the locals and visit the whole town, if they're scientists they should focus on several areas, not just where the unmovable object resides and so on.
I say you should take into consideration how many people they need to send there, what kind of settlement it is(large towns are by default easier to receive new people), what kind of information they need to collect (if it's scientific measurements or local peoples' consultation is required), if a construction is required to be raised around the area (they could just pose as a real estate development firm or just a rich recluse, fence the area and build whatever they need) and build your story around these answers.
First off, I disagree with the "evacuate the area" answers because conspiracy theories are one of America's chief exports and there will always be pesky journalists, scientists, engineers, and Redditors that will try to get to the bottom of the mystery. The only way this would work is if there is some kind of detectable signal, such as EM interference, chemical traces, or radiation, which is often enough to deter people (and in the case of EM, can likely be jammed by the surrounding structure).
Anyway, it really depends on the size of the town.
If the town is small and remote, use eminent domain to purchase the area of the town for a large federal project, such as a government data center. Say the location is remote enough to be secure for national information security reasons and the to-and-from transportation system helps save the government a lot of money in the long run. Compensate the people of the town squarely, have them resettle in a nearby municipality, and tell everyone there and to be moved there that all of the new government employees will be spending their paychecks in the new town, so on top of a fat check, you will also be offering low-interest loans to spur small businesses that cater to the employees, who might even be working in the [Data Center] and not know it's a front! Locals will be happy to be making money and in time won't miss their old digs in the slightest.
The larger the town is, the harder this will be. In a medium-sized city (picking on St. Louis, Missouri for no reason in particular) you can't just expect everyone to up and move, and they will be highly suspicious of a big new building that could have just been built in the suburbs. So instead, partner with a private corporation or holding group to use eminent domain to purchase the necessary tract of land and build something big, like a convention center (which, incidentally, was how my grandfather was forced to sell his restaurant in Rochester, NY). People will grumble but come to accept it, and the flood of people coming in and out for legitimate reasons will keep people from suspecting anything fishy is going on.