How long would it take us to detect a Deimos-like object moving towards Sol from Alpha Centauri

In a backstory for a potential videogame I'll likely never realize I've got the situation that a Deimos-like object... let's drop the facade here, the object is indeed Deimos, one of Mars' satellites, complete with:

• a large spacestation attached to it that originally was orbiting Mars on its own
• about 60-80 personnel aboard (engineers, scientists, military personnel; what you expect a team of astronauts from all major space agencies to be composed of)
• permanent living spaces, storage and laboratories dug into Deimos to shield against radiation
• telecom equipment that relied on relay satellites in orbit around the sun to communicate with earth; as well as long range sensor equipment
• half a dozen short range Mars-to-Orbit shuttles
• at least one or two Mars-to-Moon Transferships
• and loads over loads of fuel generated using the material available on Mars' surface and Deimos itself

Thanks to an alien artifact found on Deimos, the whole thing was instantaneously warped into orbit around a planet of similar mass as Mars, but in the Alpha Centauri system (presumably orbiting the whole thing at quite some distance). It kept its current speed and did not rotate or anything, it simply has been picked up at one point and set down at the other point so to say. It is also assumed that the personnel aboard the station does, if at all, only manage to reproduce the effect and land in the same orbit they're already at (they do not manage to set any new coordinates).

The year all of this happens is about 2050, humanity has established a permanent base on the earthward-side of the Moon complete with a beanstalk dangling into Eart-Luna-L1 for easy transport of material off Luna.

Technologywise we haven't made any big leaps other than presumably quadrupled current processing powers of computers and more or less improved ion-drives to a point where the transittime between Luna and Mars takes about 18 months on average. Chemical propulsion and rockets are still a thing and used to get stuff off Mars and Earth.

Question: Assuming it takes the team aboard Deimos a Month or so to puzzle out where they are and where Sol is; they immediately make about converting the shuttles and docked ships into an array of thrusters and head off towards Sol.

How long does it take anyone at Sol to make out the object moving towards us?

Assume them to try everything imaginable in their position, e.g.:

• trying to increase the albedo of their space object
• try positioning themselves between one of the stars of Alpha Centauri and Sol (so they created a 'shadow')
• reworking their comms and sensoring equipment into equipment more suited for absurdly-long-range-comms

Addendum: Facts assembled from what I (assume to) know:

• EM-Waves take about 4.4 light years (that's distance, cut the 'light' for time) from Alpha Centauri to Sol; same the other way around
• even using directed beams the signal would most likely be dispersed and interrupted by space-factors along the way, making it difficult even detecting a simple morse S.O.S. (... _ _ _ ...)
• the albedo of Deimos itself is approx 0.068; I have no idea if covering the surface of Deimos with solar panels will increase or decrease this number

posted almost 9 years ago

dot_Sp0T‭

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