This is what happens to an aluminum block when it hits...

[ElliotSmith]

This is what happen to an aluminum block when a 0.5 ounce piece of plastic hits it at a speed 15,000mph in space.

That's some serious impact! Just imagine what a heavier object could do traveling at the same speed.

 

[DaveC426913]

I have seen this image - and its claim - dozens of times over the last year. I have yet to find a reliable source of its authenticity.

This is a test, done here on Earth, under optimal conditions, not an actual impact in space.

"An anonymous user on Reddit, who apparently works in the aerospace field, posted an image of what a 1/2oz of space debris can do to a block of solid aluminum. This test was done by a light-gas gun in close quarters and shows how much damage even a tiny amount of space debris can do: "
https://bigthink.com/news/heres-the-damage-a-tiny-speck-of-space-debris-can-do-at-15000mphBTW, because of the lens, the pic looks darned impressive, but the crater is (only) 5 inches deep. That makes it about 10 inches across.

 

[Vanadium 50]

This is a test, done here on Earth, under optimal conditions, not an actual impact in space.

My first question was "why would anyone want to launch an aluminum block?"

 

[Bystander]

Kinetic kill is kinetic kill, roadkill is roadkill, ... So...?

 

[ElliotSmith]

Even tiny objects that weigh hardly anything can become extremely powerful projectiles at hypervelocity.

That half-ounce piece of plastic probably packed a many times more kinetic energy than a bullet fired from a 50-caliber rifle.

 

[Choppy]

So it turns out the way to defeat the Borg was a 0.5 ounce piece of plastic traveling at 15,000 mph.

Who knew?

 

[gleem]

The article referenced states that the damage was done by an object the size and weight of a pencil eraser. It may be the size of a pencil eraser but at 0.5 oz or 14.2 grams its mass is close to a 0.45 ACP (automatic colt pistol) bullet at 15 grams. Bang.

 

[berkeman]

My first question was "why would anyone want to launch an aluminum block?"

Ask Elon...

 

[HankDorsett]

Electromagnetic railgun?

 

[DaveC426913]

Electromagnetic railgun?

No. "Light-gas gun".
Whatever that is.

 

[HankDorsett]

earlier today I saw a meme with the same image that stated it was aluminum on the ISS that was hit by plastic. You got to love social media.

 

[yelelafella]

No way!
The damage is proportional to the Kinetic energy imparted:
KE = 1/2 m v2...
so i ran the numbers & unfort the Physics doesn't add up.
(NB: 15000mph = 6705.6 meters/sec)
KE = 1/2 x 0.014kg x (6705 x 6705)
= 1/2 x 0.014 x 44 957 025
= 1/2 x 629 398.35
= 314 699 Joules
So it's only:
314.699kJ = 75.3 calories = 0.0875 Kilowatt Hours or
in other words; enough energy to run your 1000W (1kW) radiator
for 0.0875 of an hour...5.25mins
(or for comparison: 564 calories in a Big Mac... so about 1/8th of a burger)
I severely doubt that is enough energy
to spiflicate a solid block of Aluminium like that!

 

[Frabjous]

Amusingly, you defend against these threats by using Whipple Shields which are essentially thin sheets of spaced armor. The basic idea is that the first layer does so much damage to the projectile that the next layer is able to stop the debris. On the other hand, a rifle bullet, which is slower and is consequently damaged less, would penetrate easily.

 

[Frabjous]

No way!
The damage is proportional to the Kinetic energy imparted:
KE = 1/2 m v2...
so i ran the numbers & unfort the Physics doesn't add up.
(NB: 15000mph = 6705.6 meters/sec)
KE = 1/2 x 0.014kg x (6705 x 6705)
= 1/2 x 0.014 x 44 957 025
= 1/2 x 629 398.35
= 314 699 Joules
So it's only:
314.699kJ = 75.3 calories = 0.0875 Kilowatt Hours or
in other words; enough energy to run your 1000W (1kW) radiator
for 0.0875 of an hour...5.25mins
(or for comparison: 564 calories in a Big Mac... so about 1/8th of a burger)
I severely doubt that is enough energy
to spiflicate a solid block of Aluminium like that!

You are thinking about this wrong. 315 kJ corresponds to .16 lbs of tnt. It is a lot of energy.

 

[Tom.G]

A bit of a units (math?) error there.
315 kJ ≈ 75 300 calories.
(food calories are actually kilocalories)

Density of Aluminum: 2.7g/cc

Specific Heat of Aluminum: 0.89J/g
Melting point of Aluminum: 660C
(660 - 20) * 0.89 = 570J/g

Heat of fusion for Aluminum: 380J/g
315 000/(570 + 380) = 332g (or 123cc) of Aluminum is liquified

Heat of vaporization for Aluminum: 11 370J/g
315 000/(570 + 380 + 11 370) = 25.6g (or 9.5cc) of Aluminum is vaporized

Cheers,
Tom
(Yup, I'm bored tonite! )

 

[Frabjous]

25.6g (or 9.5cc) of Aluminum is vaporized

Before anyone asks, melt and vaporization are a small percentage of crater volume. Most of it is from deformation and failure.

 

[256bits]

No. "Light-gas gun".
Whatever that is.

a giant spit-ball-machine using H2 OR He for propulsion

 

[Frabjous]

a giant spit-ball-machine using H2 OR He for propulsion

https://en.wikipedia.org/wiki/Light-gas_gun

 

[256bits]

No way!
The damage is proportional to the Kinetic energy imparted:
KE = 1/2 m v2...
so i ran the numbers & unfort the Physics doesn't add up.
(NB: 15000mph = 6705.6 meters/sec)
KE = 1/2 x 0.014kg x (6705 x 6705)
= 1/2 x 0.014 x 44 957 025
= 1/2 x 629 398.35
= 314 699 Joules
So it's only:
314.699kJ = 75.3 calories = 0.0875 Kilowatt Hours or
in other words; enough energy to run your 1000W (1kW) radiator
for 0.0875 of an hour...5.25mins
(or for comparison: 564 calories in a Big Mac... so about 1/8th of a burger)
I severely doubt that is enough energy
to spiflicate a solid block of Aluminium like that!

That's not all that was spificated.
The reddit poster doesn't know his conversions from metric to english
The crater is much more to be 5cm dia ( multipying by 2 doesn't give 10 inches )
Not so sure about the mass of the projectile, but it could be 14g

Anyways, find the volume of the crater, find the energy to melt that amount of Al, and your 315J should in the ballpark.

Before anyone asks, melt and vaporization are a small percentage of crater volume. Most of it is from deformation and failure.
@Frabjous I did say ballpark.

 

[gleem]

You are thinking about this wrong. 315 kJ corresponds to .16 lbs of tnt. It is a lot of energy.

To put it in perspective, TNT with a density of 1.65 gm/cc, for 75gms, is a cube about 3.5 cm on a side.

 

[jrmichler]

Some experimental data points:

Lead bullet at 1000 FPS on a solid steel plate splashes without denting the plate.

Lead bullet at 2000 FPS on a 2" thick solid steel plate makes a crater that my little finger tip fits into. And some of the lead splashes almost straight back. There are significant challenges making lead bullets work at that velocity, but handloaders like to do this sort of thing. Not me, but I was there.

It is easier to understand the dynamics of high speed impact if you assume that the projectile is a liquid, calculate the velocity pressure ($0.5 * \rho * V^2$), and compare to the compressive strength of the projectile.

 

[gleem]

They may have used Al for effect. Also, we do not know what alloy of Al was used. Even among Al alloys, there is a significant difference in strength. If they had used Stainless Steel for example the results would not have been as dramatic. SS has 3 to 4 times the tensile strength of Al alloys plus it is twice as dense and has a melting point twice that of Al. Anyway, it would be interesting to see what would have happened.

 

[Frabjous]

They may have used Al for effect. Also, we do not know what alloy of Al was used. Even among Al alloys, there is a significant difference in strength. If they had used Stainless Steel for example the results would not have been as dramatic. SS has 3 to 4 times the tensile strength of Al alloys plus it is twice as dense and has a melting point twice that of Al. Anyway, it would be interesting to see what would have happened.

I dug up a scaling law for geomaterials, (ρY³)^-.25, and it predicted a new crater volume equal to V₀/3.7. If one assumes that it retains the same shape, the new lengths are l₀/1.5.

 

[ElNochero]

So it turns out the way to defeat the Borg was a 0.5 ounce piece of plastic traveling at 15,000 mph.

Who knew?

View attachment 248756

Star Trek never touched on mass weapons, focusing primarily on energy weapons. However; Mass weapons can not only be destroyers of huge massive ships like what the Borg cube is supposed to be. They could also be planet destroyers. If we ever encountered another race is space. We would have to peacefully coexist, because they would undoubtedly be as familiar with mass weapons as we are and an all out war would mean mutually complete destruction.
On another note: This could be added to the long lists of possibilities, of why we have not seen evidence of other races. What if everytime 2 space faring races meet they completely destroy each other?

 

[Flyboy]

They may have used Al for effect. Also, we do not know what alloy of Al was used. Even among Al alloys, there is a significant difference in strength. If they had used Stainless Steel for example the results would not have been as dramatic. SS has 3 to 4 times the tensile strength of Al alloys plus it is twice as dense and has a melting point twice that of Al. Anyway, it would be interesting to see what would have happened.

Definitely late to the party, but I suspect the use of aluminum is because that's a very commonly used spaceframe material. Much of the ISS structure is aluminum alloys, iirc.