Xjyuk

I'm writing a soft scifi novel that has its fair share "fi" but every now and then I feel it important to acknowledge some "sci." In this scenario, a spaceship is in orbit and about to land on Earth. It's also in communication with Earth, and under observation. But some characters want to "abandon ship" and land on Earth undetected -- or at least have a head start before they're detected. I'd prefer not to use "cloaking" as an answer (though I'm not above that if it's the only option haha!) I was thinking they could board an escape pod and just "Indiana Jones" their way to Earth. But is this at all plausible in context of existing technology?

Edit: I was unclear about the nature of this spaceship. It's not alien tech; just super cutting edge (a cut above realistic, basically). There's wiggle room in it's capabilities, but I'd like to keep it as believable as possible.

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  Is the ship under observation for routine traffic control or other purposes?
  
  If people on Earth are serious about watching, and if they are already observing the ship, breaking contact will be difficult. Aircraft like the Cobra Ball or Cobra Eye might be deployed to fill gaps in the ground coverage.
  
  If it is routine, Earth might rely on secondary radar and transponder, and a non-transponding pod has much better chances.


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  Are Earth nations cooperating?
  
  Large parts of Earth are governed by nations without sophisticated air defenses.


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  Is the capsule stealthy or deliberately visible?
  
  An emergency escape capsule may be designed with colorful parachutes, automatic and redundant transponders, dye markers in case of water landing, etc.


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  Consider historical lost aircraft cases.
  Steve Fossett got lost in a small aircraft over the United States, a country with quite sophisticated air traffic control. MH370 was even larger, but over the ocean.
  
  On the other hand, a reentry with aerobraking means a visible trail. North Korean missile tests were visible to civilians in Japan.

Putting aside whether the "escape pod" has enough delta-V to break orbit, depending where they reenter it's very possible. I'd put the mother craft in a polar orbit, so they can reenter over the extreme southern Pacific, near the "pole of inaccessibility", and pass over Antarctica during the hottest part of the trip, then land in the extreme southern Atlantic near Elephant Island. With good timing (put the Pacific part during daylight, ideally near local noon), they might be visually seen by as few as several hundred people -- most of whom are in no position to immediately report the "bright meteor" passing near them.

No, not a convenient location, but one might be able to push it as far north as the Falklands (to have a nearby airport), since the last part of the landing isn't very visual -- land in the dark with a no-longer-meteoric spaceship, even large parachutes might go completely unnoticed.

It's going to be very difficult to remain undetected. In fact, it's possible to see the dragon space capsule, which a reasonable size for the escape capsule, with naked eyes alone. Amateur satellite trackers could very well see the separation or the fact that there are two objects where there is supposed to be one and report it on twitter. Military/traffic control space surveillance systems radars could also detect that there are two objects when there is supposed to be one and immediately call up the people aboard said spacecraft to ask them what's going on. A super cutting edge spacecraft or one with people on it is likely to be a prime target for space surveillance. Space surveillance is likely to become more important as space technology advances.

However, the US's current space surveillance network does not have extensive coverage though, there is minimal coverage in the southern hemisphere. A hand wave for detection by large government space surveillance radars is that they may not wish to reveal how good their radar systems are, so they may delay reporting of the separation. A bigger problem is keeping the escape pod separation secret from those onboard. This will create lots of sound and change the mass of spacecraft. The change in mass will be immediately apparent as soon as the spacecraft maneuvers.

There are other ways for the characters to abandon ship discreetly even if the escape pod is detected. One is to make an unscheduled delivery to earth. We may have some refrigerator fail necessitating an experiment or extremely valuable medicine to be returned to earth before it gets too hot. One of the spacecraft's engine's could have an 'accident' meaning the escape pod has to be ejected so that the spacecraft can safely land. The spacecraft may dispose of some garbage before landing using a now unnecessary escape pod.

If I remember my sci-fi correctly, I think one of the more accepted methods of doing this is using the 'hide a tree in a forest method'. In other words, just hide the escape pod within a meteor shower, and use atypical methods, such as deploying the equivalent of a BASE parachute at the last possible moment, or something of that nature.

One other way to get in undetected would be to shoot a great big empty escape pod slowly over an area that is heavily covered in radars, and then send a small pod down somewhere remote. The first escape pod would attract all the attention of the satellites and radars, and they might not notice a little tiny blip off in some dark corner.