What should you do if an errant piece of space junk lands in your yard or crushes your two-car garage? And who is legally on the hook for damages to your property or person?

It's an astronomically unlikely occurrence, but it happened at least once. In March, a piece of the International Space Station tore through the roof of a home in Naples, Florida, and narrowly missed homeowner Alejandro Otero's 19-year-old son.

"We weren't sure if there had been an earthquake or what," Otero reported. "When [my son] saw the hole coming through the house, he realized something fell through." After some sleuthing, experts determined the mystery object, about the size of a soda can, was a battery pallet from the International Space Station.

Who's responsible for falling space junk?

The aftermath of the incident raises some interesting questions, the most immediate being: How dangerous is it? Determining this should be the first thing you do in the astonishingly unlikely event that some space junk hits your house. The Oteros followed sensible space-junk protocol and contacted their local sheriff after the incident. Eventually, NASA determined that this piece of space junk wasn't toxic or radioactive, but you never know, so exercise extreme caution. Don't put your lips on it.

The second question is more complex: who is responsible for the estimated $15,000 in damage to the Oteros' property, and any emotional and mental anguish the Oteros suffered as a result of the incident?

The first payee is likely to be their insurance company, so if this happens to you, give them a call. Homeowner's insurance policies generally cover property damage from anything that falls from outer space, manmade or natural. Responsibility for damages above what your insurance covers, and for non-property claims like emotional distress, has a more complicated answer—you'll need to hire a lawyer to sort that out.

According to the United Nations' Office of Outer Space Affairs' 1967 Outer Space Treaty and the 1972 Liability Convention, the government of the country where a launch took place is responsible for the financial compensation for any space junk damage from that launch, no matter what other country it might land in, even if a private company launched the satellite.

If the debris had landed in another country, the liability would be clear under the UN rules, but this was NASA junk that landed domestically, so international law no longer applies, according to space law expert Mark Sundahl.

"It becomes a domestic legal issue," Sundahl told NPR. "A homeowner would have to bring a tort action against the federal government."

According to the family's lawyer, the Oteros have filed a claim with NASA. A spokesperson for the space agency said NASA won't comment on a pending claim, so stay tuned as this unique case works its way through the legal system.

Who owns the space debris that lands on your property?

You might think that the Oteros would get to keep the space junk that fell into their home—what a conversation piece, right?—but the rule of "finders keepers" doesn't apply here. The debris belongs to NASA and it has already retrieved it.

If a meteorite or asteroid lands on your house, it's a different story. In that case, the law is clear in the U.S.: you own it in all ways. You (well, you and your insurance company) are responsible for any damages, and you get to keep your space rock. Just be careful the meteor isn't full of invasive alien plant matter so you don't end up like Stephen King in Creepshow.

Who is responsible for damages if a flying saucer crashes into your house?

If a flying saucer or other interstellar alien spacecraft crashes through your roof, you would probably have a valid claim with your insurance company. Policies cover damage from falling "spacecraft," which presumably includes flying saucers.

It's unlikely you would be able to collect anything above whatever homeowner's insurance coverage you carry though; suing Gleepzorp from Romula V would probably be impossible: "As far as I know, only human beings, and those specifically granted personhood status by state legislatures or other laws, are subject to being parties to a lawsuit," Chicago-based attorney Wesley Johnson told me. (Full disclosure: Wesley is my brother—I'm embarrassed to contact an attorney I'm not related to with this question.)

"Space aliens would probably be judgment-proof anyway, as they don't have any money, at least money that could be exchanged for U.S. money," Johnson added, displaying impressive patience.