Suppose there was a nonzero chance, backed up by scientific evidence, that this 31/Atlas was an alien spacecraft. If so, would we have enough time, and technology, to get a probe to it to take pictures and gather other data? Or is it going to pass too far away and/or any mission to send a probe would take too long to plan and implement?
That sucker is moving fast! Mars to Venus in 30 days!
Never mind.
As you’ve probably read elsewhere, we’re way too late w way too little tech. Ask again in 10-20 years.
Better to slew the JWST or Hubble around to take a look.
We probably could catch up to it, with something with an ion engine. But it’d be tough.
To the extent that there is a “nonzero chance” of anything, 31/Atlas is definitely not an alien spacecraft surveilling human civilization on Earth. At 68.3 km/s speed at solar periapsis (more than twice Earth’s maximum orbital speed), there is no chance that we could launch a spacecraft that would intercept it before it would leave Sol’s sphere of influence. The amount of impulse required is well beyond what could be plausibly delivered by any existing or realistically proposed propulsion system.
Stranger
Also, its speed means that development time alone means that any “realistically proposed propulsion system” - or even an unrealistic proposed system - just wouldn’t be ready to be used in time. The thing is moving fast enough that such issues actually matter; we use what we have now, or we don’t use anything at all. And what we have now isn’t good enough.
I think that’s important to mention both because the lead time for developing even promising technology is often ignored, and because it’s unusual for astronomical issues to be so time-critical. But 31/Atlas is moving at a record-breaking velocity.
It should also be noted that 3i/ATLAS was basically on the other side of the Sun at closest approach to Earth and was moving at more than twice the orbital speed and doesn’t even cross the orbit of the Earth. So, even making best use of Earth’s momentum for the trajectory, an intercepting probe would somehow have to acquire >30 km/s of \Delta v and make the intercept somewhere beyond the orbit of Jupiter.
Here is an animation that shows the comet in relationship to the planets:
As for the thesis of 3i/ATLAS being an alien artifact:
Stranger
Minor nitpick, it’s 3I/ATLAS, not 31. As @Stranger_On_A_Train used in his post. And ATLAS is Asteroid Terrestrial-impact Last Alert System.
The “I” means it’s an interstellar object. This naming convention was created when the first interstellar object Omuamua was discovered (now named 1I/Omuamua). 3I/Atlas is only the third interstellar object ever discovered.
I know the ATLAS telescope discovered it, but what kind of tone deaf idiot names a swiftly moving rock in space after an acronym that partially stands for the words “terrestrial-impact”?
By convention, asteroids are named (given identifiers really) in part for the system that discovered it. It happens that ATLAS made the discovery. So they get the credit in the name.
Now ATLAS itself might have been given a less apocalyptic name, but it’s mission is exactly locating the no-shit dangerous ones on a last-chance basis. So sorta like those earthquake warning systems that go off about 5 seconds before the shaking starts; it’s not much warning, but may be enough to jump under a table before the ceiling comes down on you.
They could have named it after the person at ATLAS who first spotted it. (Unless that guy’s name is Bob Extinction)
Just heard about this for the first time in this thread. I’m surprised to see that an interstellar object is passing within the orbit of Mars. It apparently will pass relatively close to Mars and Jupiter. Earth will be on the other side of its orbit at closest approach.
With an estimated size of 1-10 km, if it did hit the Earth it would be an extinction-level event comparable to the asteroid that took out the dinosaurs 65 million years ago.
With its greater velocity (~58 km/sec) due to being an interstellar object it might even cause more damage. (The asteroid of 65 million years ago had an estimated velocity of 20 km/sec.)
Kinetic energy = 1/2 mv2. ~3x velocity → ~9x the KE per unit mass.
How Chicxulub’s mass compares to 3i/ATLAS is a different topic with large error bars.
No matter how the numbers work out it’d be a shitty day to be an Earthling, regardless of your location or species.
I remember reading about Omuamua. I don’t remember reading about a second. I guess it didn’t get as much coverage (that or I just missed it entirely).
The second was 2I/Borisov, discovered in 2019, about 2 years after Oumuamua. I don’t think it got as much press as Oumuamua.
But 3I/Atlas was totally expected, since the Ramans do everything in threes.
You could… get close. A Starship v3 in expendable config should be able to lift ~300 t to LEO. Orbital refilling would add 6 km/s to that.
Storable prop and a 66% staging mass ratio gets you about 3 km/s. So you build an absurdly multi-stage kick booster. 8 stages, each stack 1/3 the size of the last, starting with 200 t. Final stage is 120 kg with a 30 kg payload. That gets you to about 30 km/s. All with tech available within the next few years or off the shelf already. 30 kg isn’t much but you can do some interesting things with that.
I ain’t saying it’ll be easy, but key, it works in Kerbal Space Program.
You can squeeze a little bit more out if you put the Starship in an elliptical orbit and fill it there. But if too much more than 30 km/s is required, you’re outta luck. At least not without electric propulsion, but that’ll take forever (plus you need a nuclear reactor to make it practical).
The necessary \Delta v is significantly more than 30 km/s; I didn’t calculate how much because it would require working out the gravity loss on both the comet and probe where they achieve the same velocity (and there is also a lateral component because the probe starts out almost 2 AU perpendicular to the comet trajectory) but it’s probably closer to a total impulse equivalent to a \Delta v of 50 km/s (just gauging off of the orbital speed of Jupiter versus Earth).
I guarantee that staging doesn’t work like that with eight(!) stages, and 30 kg is just a little larger than a maximum weight of a 12U CubeSat. Since the probe would have to operate too far from the Sun to use solar and it isn’t large enough for a radioisotope thermoelectric generator (RTG), it would have to use betavoltaic ‘batteries’ charging a battery or capacitor bank to generate enough power to transmit information or run a low energy spectrometer, and frankly it probably wouldn’t provide better information than we can get from remote sensing.
Stranger
There’s no reason in principle why you can’t have unlimited stages, aside from the exponential growth with respect to the count. So somewhere in the ballpark of 8-10 is possible at least in principle. You wouldn’t have to design every component of every stage to be totally custom; engines and tankage could be somewhat shared across 2-3 stages, just increasing the count for the larger stages. A 4-2-1, 4-2-1, 2-1 sequence of propulsion units could allow you to design just 3 independent engine/tank combos.
Still, yeah, the power constraints mean fairly limited functionality. But you could probably pack a mass spectrometer on there and get some interesting info.
No way to hit 50 km/s on chemical propulsion, though, no matter how creative you get with staging.