Science
Japanese Astronaut's Space Boomerang Came Back
Posted by Gizmodo US Edition at 3:00 AM on March 22, 2008
Japan's Takao Doi has just checked out an aerodynamics conundrum we were all curious about: would a boomerang return when thrown in zero-G? World boomerang champion Yasuhiro Togai had asked him to find out, you see. So, taking time out from his work aboard the International Space Station, he gave it a whirl.
The answer: "I was very surprised and moved to see that it flew the same way it does on Earth," he apparently said during a chat to his wife. Sadly, NASA hasn't released a video yet.
Now, I can't exactly remember my boomerang physics, but I thought gravity was one of the balancing forces? I'm sure someone can set me straight in the comments.
Next up: juggling in space ... [AFP via Yahoo News]

Comments (AU Comments · US Comments)
There are currently no AU comments for this post.
klew
Posted 6:17 AM 22/3/08
Looks like NASA is looking into getting some of that Mythbusters money.
klew
Klappstuhl
Posted 6:17 AM 22/3/08
@papaguru: Well, there was a time when it cost less to shoot kangaroos into space then monkeys...
Klappstuhl
Amiash
Posted 6:17 AM 22/3/08
@dantaylor08: thank you i learned something today.
Amiash
Deoki
Posted 6:17 AM 22/3/08
I'm sure they threw it into the cold, dark space, and a friendly alien throw it right back!
Deoki
frndlybnny
Posted 6:17 AM 22/3/08
Dave and the Interplanetary Boomerangs would be an awesome band name.
frndlybnny
dantaylor08
Posted 6:17 AM 22/3/08
He didn't throw a returning boomerang - he threw a hunting boomerang. The reason a returning boomerang returns is because of the way the air reacts with it's wings (nothing do do with gravity).
dantaylor08
Amiash
Posted 6:17 AM 22/3/08
im imagining; if the boomerang was thrown in space, it'll just float and never come back.
Amiash
DWD
Posted 6:17 AM 22/3/08
@nutbastard:
It could be outside, ignoring gravity from planets and stars, it would just take a really really long time for it to come back since space isn't a perfect vacuum.
DWD
sqeakytoy of the apocalypse
Posted 6:17 AM 22/3/08
However, my point is that the only "real" (the minute amount of gravity being applied could probably be ignored for the discussion at hand) counterforce to the lift generated by the blades is going to be the aerodynamic resistance (drag) that the boomerang has on its own. With it's low mass, I would think that even a small amount of lift would send it to the ceiling. What am I missing? If the c/d of the boomerang is high enough to replace the force being applied by gravity, how could they work on earth?
With that said, however, I might be answering my own question. The mass of the boomerang is small enough that perhaps the force of gravity is insignificant enough to affect it's flight????
But that just doesn't seem right....
Lets se if we can get World Boomerang Champion Yasuhiro Togai to weigh in on the subject.
sqeakytoy of the apocalypse
se7a7n7
Posted 6:17 AM 22/3/08
What they don't tell you is that when in came back, it had crossed though an inter-dimensional portal - that went straight through HELL!
That's why they can't show you the video.
se7a7n7
shenanigans61
Posted 6:17 AM 22/3/08
@Claystil: Haha you might be right.
Now...space ping pong!
shenanigans61
Claystil
Posted 6:17 AM 22/3/08
@shenanigans61: Actually, I looked again at the photo and you can see that the boomerang is very tiny. Maybe the minute size of the thing combined with his skillz make the toss ISS compatable?
Claystil
bmoctta
Posted 6:17 AM 22/3/08
@yogibimbi: ROFL.
bmoctta
shenanigans61
Posted 6:17 AM 22/3/08
@TomXP411: Uh...wrong.
The lift on a heli's blades are symmetric so long as the helicopter is hovering. If one wants to induce forward movement, however, the lift needs to be asymetric. Along the lines of that, the asymmetry in the blade pitch needs to be 90* before the intended movement (for lack of better words). That is, in order to move forward (providing top-down view counter-clockwise rotation), the increase in pitch needs to be on the right side of the heli, rather than in the back, as you might think.
This is what you got confused on. Yes, the blades change pitch as they rotate due to the swash, but that's only to provide for movement, NOT steady hovering.
Continue...
shenanigans61
yogibimbi
Posted 6:17 AM 22/3/08
one occasion for humour lost in the illustration: The Japanese guy should say 'It wolks'...
yogibimbi
shenanigans61
Posted 6:17 AM 22/3/08
@Claystil: I was wondering the same thing. My vision of the space station is a bunch of tubes barely big enough to float through. Maybe I'm wrong?
shenanigans61
dallasmay2
Posted 6:17 AM 22/3/08
Oh come on guys... We all know that there is plety of Gravity from the earth on the ISS. How else would it stay in orbit. I would say that the gravity argument only works in inter planetary space where the gravitational force from the earth really is zero.
dallasmay2
maximumleo
Posted 6:17 AM 22/3/08
Space-H4x tbh
maximumleo
Evil_Snow_Man
Posted 6:17 AM 22/3/08
Why wouldn't it work? The forces that cause the boomerang to fly in a loop is the resistance of the atmosphere. Gravity just makes it fall down eventually...
Evil_Snow_Man
TomXP411
Posted 6:17 AM 22/3/08
Okay, let's not be jerks about it.
The answer is simple, but not obvious, and I can see why he was surprised that it worked. I've spent a lot of time studying flight, so I get why it works, but I had to think about it for a minute.
First off, let's look at a boomerang. It's basically wings, attached together asymmetrically. By spinning the boomerang as you throw it, you cause it to fly much like a helicopter blade.
Now the thing to understand about helicopter blades is that their lift is asymmetrical: the forward moving blade provides more lift than the backward moving blade. This would cause the helicopter to roll to one side if the rotor wasn't specially designed to counter this problem: the blades actually change their pitch as they rotate.
The boomerang, on the other hand, doesn't correct like this, so it will start to roll to the right as it flies. This rolling action causes the boomerang to fly in a big circle, eventually returning back to the thrower. It's also held perpendicular to the ground when it's thrown, so it actually flies off to the left at first, not straight up. As it continues its flight, it will roll to the right, so that its curve straightens out, and if everything works, it reaches the thrower relatively level. Gravity isn't actually a major player anywhere along the line here; the boomerang's own inherent instability is what causes it to return to the thrower.
Now in zero-g, the same effect applies. The boomerang will move "up" (based on its own axis) as it moves forward. It will also start rolling right. As it flies up, the roll continues. Since there's no gravity to speak of, the boomerang will probably end up flying more of a corkscrew motion, but should eventually get back to where it started.
Left to its own devices in a room large enough, I'd bet that it would fly a distored figure-8 pattern, or most of one, before it ran out of momentum.
TomXP411
DragonleechMage
Posted 6:17 AM 22/3/08
There is a minute amount of gravity in space, which is kinda where the shapes of planets, stars, etc.. come from. This low amount would be enough to give it some stability.. or perhaps its the low amount that gives it perfect stability. Hmm....
DragonleechMage
Claystil
Posted 6:17 AM 22/3/08
@tegronin: You totes should have called this guy, you know, since the conclusion was so obvious. I mean, you could have saved him some time and fun.
I just can't imagine how a guy who has a Ph.d. in aerospace engineering, with specialties in populsion and microgravity aerospace technology wouldn't know these simple facts when you do!
Claystil
1stage
Posted 6:17 AM 22/3/08
T'wasn't a roo. T'was a wallerbee, mate.
1stage
Keebler
Posted 6:17 AM 22/3/08
@Milstar:
Interesting point... but true. I mean, you'd think that we'd all have heard something more on all the tests being done up there. Can anybody with more knowledge than I offer some examples of things that have been learned from hanging out in space other than how difficult it is to pee in zero g??
Keebler
sqeakytoy of the apocalypse
Posted 6:17 AM 22/3/08
@sqeakytoy of the apocalypse: Stupid lappy keyboard.... *vertically
sqeakytoy of the apocalypse
AlphaTeam
Posted 6:17 AM 22/3/08
@jetexas: He was testing it on Zero-G, not Zero everything.
AlphaTeam
zenpoet
Posted 6:17 AM 22/3/08
@papaguru: to hunt with the boomerang, silly.
zenpoet
tegronin
Posted 6:17 AM 22/3/08
obvioulsy we aren't fully utilizing the time of persons in space. maybe next time he can blog.
of course a boomerang would work in zero-g, as mentioned earlier it's an aerodynamic issue, not a gravitational issue.
he SHOULD try it on an EVA. maybe it'll come back once it reaches the edge of the universe, or maybe every 75 years like a certain comet.
tegronin
an1m3fr33k
Posted 6:17 AM 22/3/08
i'm amazed that that's what NASA is spending billions of dollars on... just in case we need to go hunting in Zero-G...
an1m3fr33k
sqeakytoy of the apocalypse
Posted 6:17 AM 22/3/08
@papaguru: Just look on the tax forms, they had it being deducted as entertainment
sqeakytoy of the apocalypse
sqeakytoy of the apocalypse
Posted 6:17 AM 22/3/08
I would have thought that without gravity to counteract the lift, the sucker wold have just shot to the ceiling... After all, it would pretty much have un-opposed forces, at least verticaly. Thrust and drag would balance, but lift with no weight...?
sqeakytoy of the apocalypse
papaguru
Posted 6:17 AM 22/3/08
Ehm... Why was there a live kangaroo up there in the first place?
papaguru
jetexas
Posted 6:17 AM 22/3/08
Of course it works in the freaking atmosphere of the space station. Try throwing it while on a space walk.
And dear captioner, the Japanese use boomerangs to kill whales, not roos.
jetexas
CColdsmoke
Posted 6:17 AM 22/3/08
Obviously, this proves that boomerangs were invented by aliens.
CColdsmoke
Milstar
Posted 6:17 AM 22/3/08
wow I'm totally suprised by this!
Oddly this is the only scientific experiment that Nasa has done (probably unoffically but oh well) in decades and billions spent later that I've had any interest in.
Milstar
Claystil
Posted 6:17 AM 22/3/08
how on space stations is there enough room for boomering tossing?
Claystil
tamoko
Posted 6:17 AM 22/3/08
@ILikeMacsWhatAboutIT: "No more yankie my wankie. The Donger need food...and a boomarang that apparently works in micro gravity.
tamoko
Player4
Posted 6:17 AM 22/3/08
I think gravity just makes it fall. It's aerodynamics that make it curve in the air, since there's still air for it's wings to push against it can curve it's flight path. Or something?
Player4
nutbastard
Posted 6:17 AM 22/3/08
Was this outside or inside? I'm guessing inside, since aerodynamics are responsible for giving wings lift, and a boomerang is just a wing (arguably 2 wings)
nutbastard
P3nnst8r
Posted 6:17 AM 22/3/08
Next: do Yo-Yos yo.
P3nnst8r
ideaman2020
Posted 6:17 AM 22/3/08
Juggling in space would work.
As long as it's the style of juggling where you're bouncing the balls off a wall [or floor or ceiling]...
ideaman2020
ILikeMacsWhatAboutIT
Posted 6:17 AM 22/3/08
When it came back, I'm sure he let out a Keanu in the Matrix "woah."
ILikeMacsWhatAboutIT
mrxcel
Posted 6:17 AM 22/3/08
X price?
mrxcel
Mandatory_Field
Posted 6:17 AM 22/3/08
Aerodynamics?
Mandatory_Field
Kiteaton
Posted 8:04 AM 22/3/08
@TomXP411: Heh. True, and the ISS and boomerang would have to be in the right place in their orbits for the locations to coincide so you could catch it.
Kiteaton
TomXP411
Posted 8:04 AM 22/3/08
@Kiteaton: That's a huge circle! You'd have to wait around for 100 minutes to catch it. ;)
TomXP411
TomXP411
Posted 8:04 AM 22/3/08
@shenanigans61: Who ever mentioned hovering? I was talking about forward flight.
Read up on "Mu ratio" and "Mu barrier". Cartercopter.com is a good place to start. HowStuffWorks also has a good explanation of the boomerang. Their assertion is that gyroscopic precession is why the boomerang turns, and it's a perfectly reasonable explanation.
Regardless, the point is that a boomerang's flight doesn't have as much to do with gravity as it does with the interaction of air and the boomerang's shape.
TomXP411
Kiteaton
Posted 8:04 AM 22/3/08
Boomerang physics: [entertainment.howstuffworks.com]
Boomerang flight path is circular through a combination of lift from the wing surfaces and precession. You throw it tilted at an angle when on Earth to direct some of the lift force in an upwards direction to counteract gravitational force. In zero-g (technically, microgravity) you wouldn't need this tilt and the boomerang would go in a neat circle. Cool... the experiment worked!
Thrown in the vacuum of space outside the ISS it would just spin off, and end up in a different orbit of its own around the Earth, depending on how much delta v you'd given it. Physics is cool :-)
Kiteaton
rrwakc
Posted 8:04 AM 22/3/08
OK. First if you made small boomerang out of thicker paper, it can have diameter of flight under 2m.
I think boomerang uses allso radial force, which is perpendicular to the boomerag which drags it towards the inside and vary regarding mass of the spinning object. while airodynamics gives it momentum.
P.S.
Boomerang is not used just for hunting it's sports discipline. and not all boomerangs have just 2 blades. ther ar many shapes of boomerangs (V(standarrd),Y(trick catch),U(long distance), and many others M,N)
rrwakc
The illest wind
Posted 9:54 AM 22/3/08
@an1m3fr33k: Actually, hunting boomerangs don't return.
The more you know.
The illest wind
Vagabum
Posted 11:35 AM 22/3/08
Does the thought of an astronaut testing a boomerang in space seem like the premise of a Far Side cartoon to anyone else? Maybe that's just me.
Boomerang test: check.
Next up, silly putty test...
Vagabum
aec007
Posted 2:52 PM 22/3/08
Juggling, boomerangs, yoyos....
Kid's stuff.
What I really want to know is:
- What happens if you rip a good fart and light it up in zero G.
- Would you get actual propultion out of it compared to not lighting it up?
aec007
shenanigans61
Posted 2:52 PM 22/3/08
@TomXP411: Sorry, must've missed that in your post. I don't need to "read up" on anything. I've learned enough through physical interaction.
To say that a helicopter's blade's lift is asymetric is wrong, as proved by hovering. To say that the blade's pitch can change to cause symetric or asymetric lift is right.
shenanigans61
strider_mt2k
Posted 2:52 PM 22/3/08
Now we may never know if Bushmen can be trained to sort tiny screws in space...
strider_mt2k
TomXP411
Posted 4:25 PM 22/3/08
@shenanigans61: At low speeds (less than a significant fraction of the rotor tip speed), that's correct. But when the helicopter is moving forward as fast as the rotor is turning, what happens to the lift on the retreating blade?
*That's* the effect that makes a boomerang work.
TomXP411
TomXP411
Posted 4:25 PM 22/3/08
@aec007: Why has this particular post attracted so many infantile responses?
And if you want an actual answer: no. You need to direct the gases in one direction in order to get thrust. Lighting your own farts will just create a fireball that sits there.
TomXP411
csgoat
Posted 9:33 PM 22/3/08
we really need to look at the appropriate question. How did the boomerang get to space. If he made one, how did he make one in space? I call HOAX!!! Where did the boomerang come from? that is the true question
csgoat
Mr_LaZy
Posted 12:34 AM 23/3/08
I was watching something back then that explained the boomerang. I'm pretty sure you're right about the gravity. Gravity pulls its midpoint to a slant and basically flips it back upside down in the reverse motion to return it to you. Or something along those lines. Could it be true that we never even made it to SPACE!? CURSE YOU NASA!!!!
Mr_LaZy
entropyman
Posted 7:25 AM 23/3/08
why is anyone surprised? did we think that there was some magical gravitational pull on a boomerang when we throw it? If for some reason it didn't work that would mean that there was no air in the space capsule and that would be a serious problem for the astronauts.
entropyman
xanderjanz
Posted 3:44 PM 23/3/08
@aec007: I dont think you understand the idea behind rocket propultion and lighting it. Yes it would light, probably explosivly because I believe their is a higher ration of Oxygen in space station air. Also, you would get negligable propulsion because Rockets propel via balance of momentum. The light air shoots out the back really fast, so the heavy rocket moves forward not as fast in order to balance the net momentum.
xanderjanz
xanderjanz
Posted 3:44 PM 23/3/08
@csgoat: They get material shipments for food, water, and labs (like this) quite often. Thats why its an International station, even when one nation lowers support other countries like Japan, Russia, and others are still feeding them with stuff.
xanderjanz
xanderjanz
Posted 3:44 PM 23/3/08
@CColdsmoke: Ummmm What does working in space have to do with aliens? Aliens would have a homeworld too, which would have gravity.
And I think the reason it works has to do with the difference between orbit and weightlessness. When orbiting the earth on the the Space Station, Earths gravity is still quite strong, approx 75% of at surface. The reason it feels weightless is everything around is falling at the same rate, like of Disney's Tower of Terror how you can hold a penny and it floats when you fall. So gravity is still pulling on the boomorang. We would have to see it work further from the earth to see if gravity effects it.
xanderjanz
shenanigans61
Posted 5:19 PM 23/3/08
@TomXP411: I know that...and also that's the single biggest limiting factor in a heli's top speed. Retreating blade stall. Very, very bad effects.
shenanigans61
brian1cj
Posted 3:26 AM 24/3/08
So if a boomerang's flight pattern is the same in space, would it ever stop? Im no physics guy, but don't objects in motion stay in motion until acted upon by another force which is usually gravity? Since there is no gravity, would it just fly in a circle pattern forever or until it hit something?
brian1cj
yajusdono
Posted 5:29 PM 24/3/08
@brian1cj: Im sorry but for something to stay in motion has to have no force acting on it. However a boomerang had a constant force against it, its the air that it flys through. The air causes resistance as well as the lift that is needed for it to fly and eventually return to its source. The only way that i would continue forever would be in an absolute vaccum and nothing else to run into. No friction is what is needed, however in this type of situation the boomerang wouldnt act like a boomerang at all. It would just float straight in the direction it was tossed in.
yajusdono
Ben Zvan
Posted 8:14 AM 25/3/08
I would love to see what happened to a boomerang with in microgravity with nothing to hit. I would expect a very complex result rather than a figure eight or a circle. Get on that NASA!
The simple explanation for why it works is that it's in freefall when you throw it on earth too.
Ben Zvan
keith4298
Posted 3:32 AM 27/3/08
For the people that think that the upward force should make it hit the ceiling.....there is no up in zero G. The force would "push" it based on the axis it was thrown. And since it's assymetrical shape changes it's axis as it goes through the air....well, if you dont' get the rest, my explanation isn't going to help you.
keith4298