In December 2020 Hayabusa2, a Japanese space mission, returned samples from an asteroid to Earth, landing them in the Australian outback. Now, imagine a scenario where the samples accidentally land on someone's private property. Is that person legally obligated to give back the samples?

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    Related: If a baseball lands in my yard is it legally mine?
    – feetwet
    Commented Dec 17, 2020 at 15:06
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    Didn't almost this exact scenario occur when they deorbited Skylab back in '79? In this case it was a NASA station, parts of which crashed into western Australia. NASA was fined for littering, not sure what ultimately happened to the debris... Commented Dec 17, 2020 at 19:27

7 Answers 7


You have to give them back

You don’t own other peoples stuff just because it’s on your property.

However, you may be entitled to salvage rights - that is, payment for recovery of the vessel.

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    – Pat W.
    Commented Dec 20, 2020 at 12:45

Is that person legally obligated to give back the samples?

If the samples are kept then there may be an offence of theft by finding

The finder of lost property acquires a possessory right by taking physical control of the property, but does not necessarily have ownership of the property. The finder must take reasonable steps to locate the owner.

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    While this is probably true, the linked article refers to the United States while the question is discussing a Japanese spacecraft landing in Australia.
    – Ramon Snir
    Commented Dec 17, 2020 at 23:00
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    The OP's imagined scenario (starting at the penultimate sentence) makes no reference to a location beyond "someone's private property" and versions of theft by finding are found in many jurisdictions, but I can't help it if Wikipedia doesn't have a comprehensive list of them :)
    – user35069
    Commented Dec 17, 2020 at 23:18
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    This is wrong... while the linked article is entitled "theft by finding in the United States," every single citation and source in the article comes from England. Its just a bad wikipedia article.
    – Bob
    Commented Dec 20, 2020 at 8:01

Agreement Governing the Activities of States on the Moon and Other Celestial Bodies (1979)

Any samples that are collected from space must be made available at earliest convenience to the scientific community.


Currently not a single nation that conducts its own missions in space has ratified the agreement.


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    Interesting, but citing a treaty that hasn't been ratified by any spacefaring nation doesn't answer the question at all. The list of laws/agreements that don't determine ownership of spacecraft/samples is endless. Commented Dec 18, 2020 at 15:10

Let's consider a more mundane but analogous situation. A car is driving on a road with items tied to the roof. One of these flies off and winds up on private property. The item remains the property of the driver (who we will call D) (assuming that it was D's property to start with.) The owner of the land where it fell (L) does not own the item. L must either return the item on demand, or permit D or D's agent to retrieve it. In many jurisdictions L must give notice to local officials of finding the item, or publish such a notice. If L takes possession and control without going through the proper process specified by local law, L is probably guilty of theft by finding or some similar offense.

The situation with the spacecraft is not really different, although there may be some special law that applies, in some jurisdictions. But in no case does L become the owner of the samples.

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    There is special law: the Outer Space Treaty, which almost every nation, including all the space-fairing ones, is a party to. Article VIII, in particular, applies here: to take your example, if a SpaceX upper stage falls off a truck into your yard, it needs to be returned to SpaceX, but if it deorbits and crashes in your back yard, that upper stage needs to be returned not to SpaceX, but to the US government.
    – Mark
    Commented Dec 17, 2020 at 21:47

I don't know what country you are in, maybe others have very different laws.

But here in the US, just because something belonging to another person is on your property doesn't make it yours. Suppose a friend comes to visit and show me his new laptop. Could I say that once he walks in the door of my house, is laptop is on my property, and so now it belongs to me? And if he parks his car in my driveway, that's on my property too, so now I can claim his car? No.

It occurs to me that this sometimes works in your favor. Says the neighbor's kid throws a baseball threw my window. I can demand that my neighbor pay to repair the window. Could he argue that the instant the baseball crossed the property line it was on my property, and therefore belonged to me, and so I cannot insist that he be responsible for damage that "my" baseball caused to my window?

@pete mentioned maritime law. I'm not sure if it applies, but if it does ... Maritime law makes a distinction between "jetsam" and "flotsam". If you deliberately throw something overboard, it is "jetsam" and anyone can pick it up and claim it. But if your ship sinks, anything that was on board at the time it sank is "flotsam" and still belongs to the original owner. This can be a big issue when a ship is in trouble and the crew are throwing cargo overboard to lighten the load: what they throw overboard is jetsam, what goes down with the ship is flotsam.

Anyway, the point is, if you deliberately throw something away, then anyone else can claim it. But if you just put something down for a moment and look away, that doesn't give others the right to take it. Like if you throw your old coat in the garbage it's not yours anymore. If someone wants to root through your garbage he can legally take it. But if you go to a restaurant and hang your coat on a coat rack while you eat, with every intention of coming back for it, someone else can't just take it.

So if a satellite crash lands in your backyard, no, you can't claim it has yours. The space agency that launched it presumably has not given up claims to it. If it damages your property, you can sue them for the damages, but you can't take their property.

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    Even what you do with the garbage can change its legal status. If you wheel out the garbage to public roads to be collected, the police can go through it as evidence. If you leave it in the garage or a private part of the property, it is still private and that cannot be collected without a warrant. I don't remember enough about the case to find it, but I know this has happened before and evidence was thrown out because the police didn't get a warrant to go through someone's garbage on private property, on top of the blatant trespassing.
    – Nelson
    Commented Dec 19, 2020 at 7:38
  • @nelson I don't know the details of the law on that, but what you say makes logical sense to me. Until you actually take it to the place where the garbage collectors will pick it up, have you really thrown it away? If I put some junk in my garage, have I thrown it away, or am I still planning to sort through it and decide what to keep and what to discard?
    – Jay
    Commented Jan 27, 2021 at 15:44
  • ... I've had a few times that I've put furniture or old appliances out with the trash and scavengers have picked it up. I figure, good for them, if they get some use of it or can sell it for scrap and make a few bucks, better than it going to a landfill. But if someone broke into my garage and took something and I confronted him and he said, "Well, you dumped it in the garage, I thought you were throwing it away" ... no.
    – Jay
    Commented Jan 27, 2021 at 15:45

It's my understanding that spacecraft operate under maritime law.

What about claiming Salvage Rights?

The legal significance of salvage is that a successful salvor is entitled to a reward, which is a proportion of the total value of the ship and its cargo. The amount of the award is determined subsequently at a "hearing on the merits" by a maritime court in accordance with Articles 13 and 14 of the International Salvage Convention of 1989.

Suppose an unmanned sea vessel, remote controlled, or following a course programmed by computer, drifts accidentally into a harbour that is your private property, wouldn't you be allowed to claim a salvage fee for returning it? Shouldn't the same thing apply to a space vessel that lands on your property?

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    just.... under maritime law, the autonomous vessel is not salvage. It's still property, not salvage.
    – Trish
    Commented Dec 17, 2020 at 15:14
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    Well, yes. Salvage remains the property of the owner. The the person who recovers it must return it to the owner, but can claim a percentage of the value.
    – Pete
    Commented Dec 17, 2020 at 15:22
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    Maritime law would apply in navigable waters and possibly in outer space itself, but would not apply to something on land in the Australian outback merely because it was previously in outer space.
    – ohwilleke
    Commented Dec 17, 2020 at 19:20

The difference in the Skylab case and the Hayabusa2 is that the latter was a planned landing at Austrailia's Woomera Test range, which all suggestions seem to indicate that Japanese and Austraillian governments had negotiated the return of the capsule to the Japanese and the use of their military complex as a landing sight.

Skylab was not the case as the de-orbit was not planned and thus it's eventual crash sight in Western Australia was a bit of a surprise. While the crash was known as early as 1973 to happen, NASA was in the process of transitioning from the Apollo program to the Space Shuttle Program (STS) at this time and didn't have enough time for a mission to reactive Skylab and correct it's orbit. The orginal goal was for an early STS mission to do the job, but delays in the STS program prevented this. It would not be until a week prior to the crash that NASA could say for certain that it would crash within a specific time range, and much of the world was considered a possible target. There was a 1 in 152 chance the derbris would strike a population center of 100,000 people or more. NASA was able to partially guide Skylab and tried to strike a target 800 miles off the coast of Capetown, South Africa, but were off in their trajectory. Further complicating the matter was Skylab's slower than estimated burn up in the atmosphere on reentry.

The reported fine for littering was done more of a jest than actually any anger by the Australian government... in fact, the government of Australia never imposed the fine... it was the government of the town of Shire of Esperance, that imposed the A$400 fine on NASA... which wasn't paid until 2009 after a radio host in the U.S. raised the appropriate USD value to donate to paying the fine on NASA's behalf.

If you want a serious rule, this is actually a covered matter in International treaty, specifically the 1972 Space Liability Convention. To date, the only claim under this was made by Canada against the USSR after the NUCLEAR POWERED Kosmo 954 satellight crashed in the Northwest Territory of Canada. No one was injured but the nuclear core failed to properly eject (as it was designed to do so in the event of an emergency) and was never recovered in the debris. Canada claimed C$6,041,174.70 in damages but the USSR ended up paying only C$3 million for the incident. 96 nations of the world have signed the Convention, with a further 19 signing but not ratifying the convention. Of the non-signatory nations, the vast majority of these nations are in Africa, with a few in the Middle East and South East Asia, and one South American nation not party to the convention. All of North America, Europe, and Austrilia and New Zealand are covered.

  • no negotiation needed: Australia already was obligated to hand it back to Japan due to the Outer Space Treaty.
    – Trish
    Commented Feb 8, 2021 at 14:05

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