Let’s say an alien civilization made a spacecraft that, as luck would have it, matches the Voyager I piece for piece and gram for gram. How close would it have to get for any of our equipment to detect it?
Edited to add: it seems the craft is roughly the size of a subcompact car. Could our telescopes pick up a Honda Civic hatchback passing by between Mars and Jupiter?
What angle is it coming at? Most of our instruments are designed to pick up comets and asteroids not too far off the ecliptic plane.
Related:
~Max
And is it trying to be detected (by pointing a radio antenna at us, say)?
Good point. We’re still receiving intermittently from Voyager 1, at least as of last year, from outside the solar system.
~Max
If it isn’t radiating in a radio band where astronomy is typically done or has an extremely high albedo, the chances are practically nil.
Here is an image of the region where the Apollo 17 Lunar Module landed. Bragging rights to anyone who can actually find the descent stage of the lander and rover that are still there.
Stranger
Yeah, this is critical. The worst case is something coming at us from the other side of the solar system so that it approaches the sun and then comes out towards us. A small asteroid did exactly that last year, and was only detected a few hours before it hit the Earth’s atmosphere. Fortunately, it was fairly small, only about a meter across, and it burned up harmlessly in the atmosphere. But even a Honda-sized asteroid coming in from that direction is going to be difficult to detect.
Google’s bullshit generator thinks that the smallest asteroids that we have detected in the asteroid belt between Mars and Jupiter are about 10 meters in width. But if you actually click on the link where the bullshit machine got its info from, it actually says this:
So based on that, I would say that there’s very little chance of us picking up the Interstellar Honda.
I’m pretty sure Elon Musk’s Tesla Roadster still passes outside of Mars at some point. And it was just accidentally spotted by an automated telescope, two months ago. But I couldn’t tell you how far away it was at the time.
ETA:
According to this website, the Roadster is currently between Mars and Jupiter and,
A telescope about 56,161 ft (17,118 m) in diameter would be required to resolve the Upper stage from Earth. A smaller one could see him as an unresolved dot, about 108.0 ft (32.9 m) in diameter, in ideal conditions.
(n.b. the largest telescope on Earth is ~500m in diameter.)
~Max
I didn’t cheat, nor did I download and expand it. Just working from what zoom my browser window could do. I think they’re:
Very roughly 25% up from the bottom and 15% in from the right edge. There’s a triangular hump of the lighter gray rock at the left end of a series of several elliptical humps of similar color. The triangle has a faint oblong depression in it extending from near the leftmost corner rightwards to just past the center. With something sitting in that depression casting a distinct very dark shadow towards the ~8:00 o’clock direction. Which I take to be the descent module and its shadow.
From there there’s an anomalously bright white object roughly 80% that size about five shadow-diameters to the 6:30 o’clock direction. I take that to be the rover.
I suspect the shallow depression atop the triangular rise is the scoured area caused by the descent engine’s plume impinging on the surface during the landing.
I’ll either be right, or utterly full of shit. The latter would be a classic example of the “Face on Mars” fallacy: trying too hard to see what isn’t quite there.
The apoapsis of Martin Eberhard’s Tesla Roadster which was stolen by Elon Musk and later launched into space on a Falcon Heavy is just inside the aphelion of Mars. But its ephemerides are well known and the periapsis is actually slightly inside Earth orbit, so if the Earth happens to be fairly near during periapsis (which should be about once every three years, at least for another couple of decades) then it could easily be visible to a ground based telescope with sufficient resolution to find smaller Apollo Near Earth Asteroids and astronomers would know exactly where to look for it.
I hate to do a rug pull on you, but even Hubble doesn’t have resolving power to actually make out the features on the scale of the lander:
Stranger
And radiating with it.
An antenna (or camera) aimed at an observer is a good approximation of a black body when it’s not emitting.
Next up, I’ll find more faces on the Moon for you.
It was fun looking though. Not having any idea of the size of a pixel left a lot to the imagination. As in “all of it”.
Yeah, it is really easy to fool yourself into believing that you’ve found some image on a landscape; the human brain is really good at looking for patterns but also manages to create a lot of false positives when there is nothing to find. And for what it is worth, I see a ‘face’ in the lower right quadrant of the image with two big, dark eye sockets and a broad mottled nose, with a sort of bright ‘beauty mark’, like the detached skull of a dead Celestial that was long ago embedded in the Moon.
Stranger
Once seen, they cannot be unseen either.
???
That article is from 2006. As of 2023 Eberhard’s Tesla Roadster, the second one produced, is in his garage.
~Max
Amelia Earhart’s plane is clearly seen in that photo. We found it!
That article is incorrect. Musk took ownership of the second Tesla Roadster off the line (about which he has publicly boasted) even though Eberhard was guaranteed it through his severance agreement. Eberhard eventually got the fourth Roadster produced, which was damaged by a Tesla employee and then repaired. Musk has been pretty nasty toward Eberhard (and the other true cofounder, Marc Tarpenning), at one point claiming that they really had nothing to do with the vehicle that was actually produced as the Roadster and that he had also practically designed the production car himself. Musk himself got named as a cofounder in a court settlement after forcing Eberhard and Tarpenning out of their company even though he was only involved at the Series A funding round (about eight months after the company was incorporated) and then inserted himself into the company, making demands of implementing non-critical features such as an electronically actuated door handle that by most accounts delayed the release of the car by over a year. There is a well documented history of the litigation even if some of the specific details are of the “He said, she said” variety, and given what the public has seen of Musk’s behavior lately (and what I’ve seen for going on fifteen years of man-baby temper tantrums, SLAPP suits, and generally claiming credit for the hard work of others) I’m inclined to give more credence to Eberhard and Tarpenning who have both decided that living well is the best revenge versus Musk’s campaign of vengeance upon them as well as minor functionaries in the regulatory agencies that he is now trying so hard to dismantle.
A little taste of the true history of Elon Musk:
Stranger
Well, they picked up Elon Musk’s car and mistook it for an unknown asteroid until they matched the trajectory to the known debris. So apparently, yes.
Eta; this was mentioned, nvm
Small boys are perfectly capable of seeing drawings of naked people out as far that planet that’s just this side of Neptune.