A reentering spacecraft is similar to that of a meteor or small asteroid body with some notable differences. Many reports by local people, regardless of the country of origin, appear on YouTube or other public information source without basic critical pieces of information. While reentry of a spacecraft or piece of space debris can be quite startling and bright, it is possible that a piece or pieces of debris could survive this fiery process and be recovered.
The general public will likely not be able to tell the difference between a satellite reentry and that of a meteor. But the tell tale signs are there. A satellite will generally (but not always) be travelling from the north, or northwest, or west, or southwest or south in the opposing direction. The process will result in an initial slow appearance of a single bright object which will gradually break up into a number of fiery objects of varying brightnesses, some disappearing quickly with others surviving a lot longer.
News media may sometimes have advance knowledge and may publicize the possible reentry. The case of Cosmos 1220 on February 16, 2013 was one of those situations where this very large satellite was predicted to break up somewhere over the ocean. Instead its reentry was visible from a number of locations in Saudi Arabia. Within hours a number of separate videos from towns such as Mecca, Madina, Taif, Jiddah, and Hai’l. Some witnesses said it was moving from North to South.
In order to gather critical information that might aid in finding and recovering a piece of space debris, the following is needed from each observing location:
a. latitude and longitude of observer as derived from GPS or Google Earth
b. time (converted to GMT) of the observation; a description of how this time was obtained. For example, using a watch with a second hand, a clock on the wall, a calibrated time source.
c. direction of motion from beginning to end. It is important to know how the directions were obtained: using buildings as a reference, street layout, knowledge of the constellations, or guess work.
d. name(s) and email/phone of reporting observer(s)
e. description of what was seen including the presence of any sounds
f. astronomical experience (if any) of the reporting observer
g. degree of certainty or uncertainty in any of the information above
In most cases, it will not be possible to find any recoverable pieces. It is only in those exceptional cases where there are many reports along the entire reentry track as well as luck where one or more pieces may be found. Usually such debris is found within hours of its fall and only because someone was nearby and found it.
Space debris usually has a dozen or more fragments appearing along the trail, some appearing, then disappearing, others lasting along the entire flight path. The train of fragments may extend across the entire sky or vanish after 20 or 30 degrees. It depends on the location of the observer with respect to the reentry path. The amount of time spent in the sky could be from 20 seconds to 90 seconds, but this is just a guideline. Sonic booms are rarely heard.
For investigators with the skill, ability, resources and time to hunt for objects, the more reports with accurate details will enable the likelihood of recovery to occur. This is the same process that meteorite hunters might use to recover debris.
Fireballs that appear in the sky that are not space debris may come from any direction in the sky. Their speed is usually (but not always) faster than the slow moving train of space debris. They may break up into two or more noticeable fragments which travel in similar directions. The duration of such entries last anywhere from a second or two to perhaps 15 seconds. A smoke train may or may not be left in the sky and rarely a sonic boom might be heard.
Space debris crashing into the ground may sometimes do damage to buildings, vehicles and other structures. The impacts of a large object disintegrating into a number of smaller ones may pose more of a threat to an urban environment depending on the mass of each fragment and whether there is any potentially explosive or toxic material surviving. It is usually the large mass and velocity that would pose a threat to people or animals. But the rarity of such death or injury is such as to be miniscule based on the entire history of past reentries since the beginning of the space age in 1957.