So did I, and not just one layer, there can be multiple layers stacked on top of each other at different altitudes.
Only one? You should have many orbiting the Star System, fully manned.
How many times in the
24th century ALONE, has Earth been threatened with imminent doom?
Threats from inside and outside:
1) 2364 Parasitic Bugs try to take over StarFleet upper brass
2) 2367 Battle of Wolf 359 dealt a tremendously lopsided loss to StarFleet, waking them up that StarFleet ISN'T PREPARED for the worst case scenario. 39/40 Ships Destroyed (97.5% Ship Loss Rate) in one battle. 11,000 StarFleet officers killed or assimilated. We only got by because of William Riker & his crew got lucky and found the "Sleep Command" and triggered it with the help of a semi-resisting Assimilated Locutus (Captain JLP). This was a CRITICAL MOMENT in StarFleet history.
3) 2372 The Founders start the Dominion War by infiltrating the Klingon High Council and having them fight the Cardassians to the point that the Cardassians get beaten down so hard that they willingly join "The Dominion", which eventually leads to the very bloody Dominion War which ends in 2375.
4) 2373 Battle of Sector 001 - Borg tries to conquer Earth AGAIN, but has a backup plan to Time-Travel into the past should Plan-A fail, which it does, thanks to the USS Enterprise-E rallying the Federation Task Force.
"At least 20 ships" were destroyed out of "At least 30 ships", those aren't good survival odds for the Federation Task Force for the price of 1x Borg Cube.
- 2378 Voyager Returns and thanks to Future Admiral Janeway, a critical blow is dealt to "The Borg" thanks to the Neurolytic Pathogen.
5) 2379 Praetor Shinzon threatens to genocide earth by using a banned Thaloron Weapon on Earth. Luckily the USS Enterprise-E and 2x Valdore type Warbirds stop the Scimitar from accomplishing its goals and potentially starting another war and killing everybody on Earth.
6) 2385 Rogue Synths launch an attack on Utopia Planitia, Fleet Yards. Setting Mars Ablaze. UFP bans Synths and abandons it's rescue efforts for the Romulus System and the impending SuperNova. Commodore Oh was in a position to risk critical damage to StarFleet/Earth. The fact that she only cared about her role to exterminate Synthetic Life isn't comforting considering that StarFleet's highest level of security was infiltrated and we got lucky that nothing worse happened.
- 2399 Commodore Oh was discovered to be a Tal-Shiar / Zhat Vash Double-Agent Mole infiltrating the StarFleet and becomes the Director of Security. Her Zhat Vash faction is directly responsible for the Synth attaack on Utopia Planetia on Mars. This infiltration of the highest order will have ripples across StarFleet security. 92,143 dead on Mars. The Romulan Armada is halted and countless millions dies because of the Zhat Vash's action in it's belief that it needs to exterminate Synthetic Life at all costs, including risking the millions of lives of their own Romulan people and dooming them to death.
At least 6x major incidents in the latter half of the 24th century alone.
Not counting anything that happened in the earlier half of the 24th century that we don't know about.
And the Early 25th century had the Borg taking over StarFleet through subtle assimilation plot. One that got "BARELY" averted.
The borg also opened up a giant TransWarp Conduit that could've been a "Galactic Event" if Borg Queen Jurati wasn't there to stop it. We got VERY lucky that Admiral JLP was there to help negotiate that critical moment.
So that makes 8x major incidents in a relatively short 50 year-ish time span starting from the later half of 2360's.
That's alot of potentially "World Ending" or "Galactic Effecting" events.
If you design them correctly, it should be fine. IMO.
What you don't want is a AQS (Artificial Quantum Singularity) reactor. If that goes run-away, you have a Black-Hole on your planet with ALOT of matter to feed it.
That makes the M/A-M reactor look easy to tame in comparison.
The M/A-M reactor just needs it's A-M stream shut-off to prevent the reactor from going Nuclear.
There are enough safety systems that can be designed to force shut-off manually or automatically the feed in the M/A-M reactor chamber.
That's why you need to protect your local Stars from getting messed with, even the Stars in adjacent and nearby StarSystems need protection due to how wide of a disaster a SuperNova could affect your Star System.
Yes you can, protect yourself by having Orbital Defense Systems stationed around each star along with a Starbase and reaction force. The Changeling Bashir was easily stopped by people who were paying attention and chasing him down.
It's not impossible, just requires eternal vigilence. That's the price you pay from bad actors that are willing to go that far.
That sounds like a bomb designed to target non-human species, very speciest of humanity to pull such a action.
Depends on how much power you're providing to your Planetary Shield Grid.
Earth looks like it only has a single layer.
It doesn't look like it has multiple layers or redundant reactors.