121
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A starship is traveling at 0.9c and collides with a small rock. Will it leave a clean hole through, or will more happen?
@Hobbes answered this in a comment.
Your final guess
Will it collide with enough energy to initiate fusion with the atoms of the hull?
is correct.
See the first XKCD What-If comic, "Relativistic ...
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83
votes
Time at 1 g acceleration to travel 100 000 light years
Nonrelativistic solution
The variables used will be
$x$ for the distance travelled
$v$ for velocity
$a$ for acceleration ($1~\mathrm{g}$)
$t$ for the time
$c$ for the speed of light.
Non braking
...
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38
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Is it possible to create a relativistic space probe going at least 0.1c with present day technology?
I'm showing the calculations for Russell Borogove's excellent answer.
You've asked to accelerate an object to 0.1 times the speed of light. Mathematically, $$\left( \frac{\Delta v}{c} \right) = 0.1$$...
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35
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A starship is traveling at 0.9c and collides with a small rock. Will it leave a clean hole through, or will more happen?
I answer this question from a purely structural-mechanical point of view, i.e. not considering fusion as discussed in Dan Pichelman's answer.
Will it create a football sized hole through the ship ...
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35
votes
Accepted
Is it possible to create a relativistic space probe going at least 0.1c with present day technology?
No.
10% of the speed of light is about 30,000,000 m/s. Our fastest space probe to date, New Horizons, left Earth at less than 1/1000 of that speed. With a large propellant tank and a high-efficiency ...
- 167k
28
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Is it possible to create a relativistic space probe going at least 0.1c with present day technology?
Breakthrough Starshot claims to be capable of attaining 0.15c to 0.2c. But, the concept is based on a swarm of tiny probes (centimeter scale). They would be propelled by a "ground-based" laser; no on-...
- 17.4k
26
votes
A starship is traveling at 0.9c and collides with a small rock. Will it leave a clean hole through, or will more happen?
Let us consider a 10 kg rock with a $0.1\,\mathrm{m}^2$ cross-sectional area. Further let’s assume that we are lucky and the rock passes only through one wall of the spaceship (say $3\,\mathrm{mm}$ of ...
- 19.4k
15
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Is it possible to create a relativistic space probe going at least 0.1c with present day technology?
Yes, with nuclear pulse propulsion.
The fastest manmade object is a "hubcap" that was used to cover a nuclear blast testing site, which was clocked at 125,000 miles per hour. With a ...
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11
votes
Accepted
At what speed does it seem like you are going lightspeed due to time dilation?
Clarifying the question (I hope): your spaceship leaves point A, accelerates up to some relativistic speed relative to A, coasts for a while, then decelerates to rest at some point B. A and B are at ...
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11
votes
Accepted
To what percentage of the speed of light you need to accelerate to get artificial gravity at 1g?
The speed of the craft is not a factor in the acceleration felt by the passengers.
If the craft accelerates at 1 g, 1 g is what the passengers will feel, from the moment that the acceleration starts.
...
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10
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A starship is traveling at 0.9c and collides with a small rock. Will it leave a clean hole through, or will more happen?
Probably the spaceship is destroyed.
The big problem is that the energy of the rock-spaceship collision is large. So large that even if a trivial amount is deposited into the spaceship, the ship is ...
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9
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Is it possible to create a relativistic space probe going at least 0.1c with present day technology?
Given that rockets are clearly not cut for this, I find it rather weird that, despite a couple mentions in the comments, Breakthrough Starshot isn't getting more discussion here even though it was ...
- 438
7
votes
Accepted
Is there a maximum ISp?
A photon rocket should have a Ve of c, hence ~30 megasecond Isp. The rocket equation would be tricky to apply, of course -- if you have a magic matter-energy reaction that perfectly converts "fuel" ...
- 167k
7
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Achieving relativistic speeds with the use of lasers
For propulsion you have to think momentum rather than energy. In this case almost all of the optical energy output of the laser remains in the emitted photons. Whomever is unlucky enough to find ...
- 149k
6
votes
About non-FTL travel and realitivistic effect for a hard sci fi novel
The important thing to note here is that to say "it takes 8-9 years" doesn't make sense without specifying who it applies to. When relativistic effects start to apply, it's not the same in all ...
6
votes
Time at 1 g acceleration to travel 100 000 light years
Let's start by assuming you don't decelerate halfway. Work in units with $c=1$. With a constant acceleration of $a$, the rapidity $\phi=a\tau$ at a proper time $\tau$ after you start from rest, so $$\...
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6
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A laser can propel a spacecraft to 20% of light speed, time shorter on spacecraft?
If it took 10 years from our point of view, it would take 9.8 years from the point of view of the spacecraft travelling at 20% of the speed of light. So a little shorter, but not by much. A bigger ...
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6
votes
Accepted
"Oh-my-god" particle drive performance
Rocket equation starts with conservation of momentum:
$$\frac{dp}{dt} = m\frac{\partial v}{\partial t} + v\frac{\partial m}{\partial t}$$
But at such a high energy, the rest mass of the proton can ...
- 149k
5
votes
A starship is traveling at 0.9c and collides with a small rock. Will it leave a clean hole through, or will more happen?
On 0.9c, the kinetical energy of an 1g rock is $mc^2(\frac{1}{\sqrt{1-\frac{v^2}{c^2}}}-1)$ (ref).
Substituting 0.9c and 0.001kg, we get 116 TJ.
As a comparison, the Little Boy nuclear bomb released ...
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5
votes
Is it possible to create a relativistic space probe going at least 0.1c with present day technology?
New Horizons was the fastest man made object in space reaching 16.26 km/s after launch. After gravity assistance 23.3 km/s was reached later.
The speed of light is about 300,000 km/s. 0.001 c is 300 ...
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5
votes
How do you calculate the percentage of light-speed a ship with a certain delta-v can achieve, accounting for relativistic effects?
In the case where the spacecraft can achieve relativistic speeds and no gravity is involved, $\Delta v$ is actually $c$ times the maximal change of rapidity which can be achieved. So the maximal speed ...
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5
votes
Accepted
If Voyager 1 were to return to the Earth now, how much "younger" it would be than its replica displayed at JPL's Von Karman Auditorium?
Here is the plot of the speed of the Voyager (by its distance from the Sun):
Source: this question
We can assume an about $\rm{20 \frac{km}{s}}$ average speed, what is ${\rm \approx \frac{2}{30000} c}...
- 3,276
4
votes
Relativistic Rocket Equation
tldr; If $\Delta v>c$, its a reference frame issue. Use rapidity to calculate $\Delta v$ instead. If $v_e > c$, then there is no solution for the specified conditions, because the exhaust ...
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4
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A starship is traveling at 0.9c and collides with a small rock. Will it leave a clean hole through, or will more happen?
I think it's fair to say this is not really some thing we can describe with any confidence.
One thing is clear: the energies involved are stupendous, as @peterh points out, 1g of material at 0.9c is ...
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4
votes
Time at 1 g acceleration to travel 100 000 light years
Using this tool:
Observer time: 100001 years
Traveler time: 22.4 years
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4
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continuous acceleration in space
would the rocket keep accelerating to a faster and faster speed,
or is there a speed limit where acceleration stops
The rocket would keep accelerating and would get ever closer to the speed of ...
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3
votes
Is there a maximum ISp?
No. The number you gave is for a photon drive. However, if you throw particles out the back at relativistic velocity they weigh more than the fuel you drew from the tank. Since there's no limit on ...
- 11.5k
3
votes
Accepted
Relationship between propellant mass and thrust at relativistic speeds
From a pure physics perspective my thinking is that as the mass of the propellants increases with the speed of light their exit speed will drop but will produce the same amount of delta-v.
The mass ...
- 167k
3
votes
A starship is traveling at 0.9c and collides with a small rock. Will it leave a clean hole through, or will more happen?
I'd like to add onto Knudsen's answer, by stating that any such consideration of a fusion reaction has to factor in the the composition of both the rock and the spaceship (both its air and structural ...
3
votes
How are Experienced and Observed Mission Elapsed Times defined? (EMET & OMET)
How are EMET and OMET defined?
I understood the answer to be an example of what the timing on an interstellar mission would look like. In other words, the definitions of EMET and OMET are that answer....
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