Sending a Spacecraft to the Interstellar Asteroid | Hacker News Reader

Sending a Spacecraft to the Interstellar Asteroid

arxiv.org

223 pointsDanielleMolloy73 comments

It’s okay, we can wait for the next one. They come in threes anyway. ;)

Unfortunately the biggest hurdle to such a mission would be aligning political will and agency goals on a short time frame. NASA plans thingsnon 5 and 10 year horizons, so sending this mission means delaying something already in progress, which jeopardizes that project as everyone who was working on it goes off to do other things :( Can it be reached by a nearly empty payload on a Falcon Heavy or BFR certification flight? Getting a fully private mission might be the only option.

Edit: just realized SpaceX might not be able to recover any stages from such a launch, so maybe not so enticing. With cross fueling they might get he first set of ejected stages though.

It's a good reason to push for more space telescopes.

I believe some day (probably after we start having regular interplanetary travel) we'll have robotic light recorders in space recording every bit of incoming extraterrestrial light, especially on the planetary plane. Then we'll be able to back up to view where objects like these entered the system, not just after they are detected. And perhaps just detect them when the are entering the system to give us as much lead time as possible.

> especially on the planetary plane

We do in fact already concentrate our efforts to look for objects near the ecliptic. It's the number one recommendation followed by amateur asteroid/comet discoverers. But actually, interstellar objects might be more uniformly distributed - even Oort cloud objects are supposedly non-aligned with the ecliptic. If anything, I'd expect interstellar objects to be slightly more likely to come from directions roughly along the galactic plane.

I am curious if anyone is actually thinking about this problem in terms of technology required that currently does or does not exist, particularity in tech needed to store such vasts amount of data, unimaginably high resolution sensors, etc. It sounds like a fun project to be part of really.

A space telescope isn’t fast enough. That’s why there is LSST.

See: https://neocam.ipac.caltech.edu

"especially on the planetary plane" is a great algorithm for missing asteroids like this one.

> Can it be reached by a nearly empty payload on a Falcon Heavy or BFR certification flight?

Not even close. I don't think it's sunk into most hobbyists just how ridiculously fast ʻOumuamua is going. The fact that it came in at such a deep hyperbolic trajectory means that it's substantially faster relative to us than literally anything we have ever seen in the solar system before. Catching up to it in a human lifetime is a more demanding mission than anything we have ever done before, by a factor of at least two. It's honestly outside what traditional rocketry can do, to put a probe on it we would likely have to try something exotic like sun-diving solar sails, laser sail propulsion or at least nuclear electric propulsion.

Are you sure? I believe this is travelling at 26 km/s heliocentric dv while the sunscraper comet was blazing at 600 km/s. So it's not the fastest thing observed in the solar system, by a long shot.

Voyaver 1 is going 17 km/s so it's not like it's ridiculously out of reach... And we launched that one a while ago.

And remember, when people who say things like "NASA needs decades to plan these things," Korolev got out of the gulag in 1945, fresh and ready to work with almost all of his teeth missing and a jaw broken so badly he could not turn his head, it took him 15 years to: develop the first ICBM, first satellite in orbit, and the first sattelite around the moon, as well as the first object to impact the moon.

Without his engineering expertise he would have rotted to death (based on false accusations) in the gulag.

Voyager 1 was launched a long time ago and has roughly 75% the dv that Oumaumua has. It is very doable. We just need to demand it.

The caveat to Voyager 1 is that it was launched during an ideal window and performed a pair of gravity-assist slingshot maneuvers, and took 30 years to do it. That is right out of the question as far as this intercept is concerned. It's direct-ascent or bust.

There is no chance of accelerating anything with any substantial mass to that velocity. Hence me plugging starshot - the only chance of us catching up to it with anything at this point is for it to be fairyweight or atomically powered.

The object has already slingshotted, we're mostly boned at this point. Unless we act now, with a cunning plan, we will never learn anything about this object in particular. Even still, we really can't put much onto any hypothetical probe.

You could put more smaller upper stages to some big rockets. And finally tank the spacecraft itself with a lot of hydrazine so it can fo course corrections later.

There is another option though. There's a tanker version of Musk's BFR being designed for filling up Mars bound rockets or propellant depots in low earth orbit. You could instead refill the tanker or two or three and stage them. Or use the Mars bound stage.

We don't need something with substantial mass though. We could send a really minimal probe with no landing capability to take close up images.

what about Starshot probes?

TBF, if it did work, I could almost see Elon going "fuck it" and bumping the next SpaceX launch in favor of boosting a cubesat out there.

First we’d need to have a deep space planetary observation probe with a high dV propulsion system, an RTG and TWTA backed high gain antenna. Chucking a standard cubesat at it would be no more use than launching a washing machine. At this point the probe wouldn’t catch up with it until it’s at least as far away as Voyager is now.

Hah I was going to see if anyone immediately thought of the reference of which you referred to.

it's rama everybody.

We don't suspect that interstellar asteroids are particularly rare. The best course of action would be to beef up the Earth-based telescope observation network so that we can discover future ones further out. As a side effect we'd get much better forewarning of potentially life-endangering near-Earth adteorids as well.

Once you have better lead time on an asteroid, and catch it coming rather than going, it's easier to intercept.

What is interesting about this one is it’s shape, otherwise I don’t think there’s be much interest in such a mission vs waiting for the next one (since there could be as many as 3 a day if our models are correct).

What process other than aliens creates a kilometers long rotating cylinder? It probably IS a natural process, don’t get me wrong, but we haven’t a f$&@ing clue what that might be which makes it really interesting to study.

Passing at great speed very close to a star? Outer shell or entire thing becomes superheated and malleable. Extreme tidal forces as the object passes the star and gets churned through the high gravity stretch it out. What if it passed close to something super dense, like a black hole, allowing the stresses of tidal force as it whipped around it to melt the rock on their own leaving it to fly away, pulled long and cooling in the cold of dead space.

I don't know how likely such things are, but I don't imagine it takes intelligence to make a long space rock.

To make a long one without breaking it into multiple objects is very unlikely. This thing isn't composed of silly putty -- rocks and metals tend to be brittle and break rather than "stretch out".

Not if they are melted, or softened. It might have taken millions of close orbits around a hot body for that shape to form.

Which also might be why it was ejected and made it to our solar system. The energy in its orbit might have been really high on a close approach to a star and a slight deviation flung it out of that system.

A highly eccentric orbit would have a close approach around a star, and then have it rapidly cool as it traveled away from the star. Repeat millions of times. Would make for a nice orbital, thermal and materials science simulation.

True, but on astronomical scales, unlikely events happen all the time.

The shape doesn’t seem all that incomprehensible to me. Just look at the great variety of rocks we find lying about the Earth. The universe is a big, violent, energetic place, with countless opportunites for rock to be squashed, worn, melted, smashed and congealed into any conceivable shape. I can totally imagine this being a shard ejected from a collision of two larger objects.

As I understand the elongated shape has only been determined based on the light curve. I'm guessing this assumes no big changes in albedo along the surface. It might actually be a much more round object with one light and one dark side. Iapetus is an example of an object with such coloration.

There's also the fact that it seems to be doing a swing-by on the Sun. To pass fairly close to the Earth. But of course, that's why we detected it. Perhaps that are many that we don't detect. Maybe some very fast ones from Sagittarius A* ;)

Given 3-a-year assumption, I wonder what the probability is of one, by chance, getting a gravity boost like that to swing right by earth.

To me, that implies more than three per year. Or real-time targeting.

The cylinder might be interstellar FedEx. It could be completely unmanned and just heading out to some previously surveyed world somewhere to robotically terraform it. This might be a project that could take 100s of years.

Whether by chance or by design, the fact that it has the rough shape of a boat or rocket weakly suggests that it passed through a thicker medium than empty space. But it came through alone; collisions would have fragmented it.

I am an astro-noob. But are you suggesting for example that it might have passed through a gas giant?

Not specially. I imagine a lot of these wanderers of all shapes might exist. Statistically, that we have only seen one with such an unusual shape demands explanation.

One possible reason would be that more conventional shapes are somehow hampered in their travels. My thesis is that a torpedo shape is relatively advantageous to objects traversing a fluid medium. I have no idea what fluid that might be.

Could it be a fragment from a collision of two larger rocky asteroids?

It could be but what collision would output a fragment of this size and shape? Maybe a supermassive one between two large planets

> Once you have better lead time on an asteroid, and catch it coming rather than going, it's easier to intercept.

This will lead to a very high speed impact (in the order of 60 km/s) or more likely a high speed miss. Or require years of lead time to get the interceptor there after one orbit around the sun.

A high speed impact might still be interesting if there are enough scientific instruments to look at the debris. However, that needs a very very precise aim.

A much easier scenario is to catch it on the outbound leg like the paper suggests.

Detect it coming rather than going, not impact it head-on. The more lead time you have the better (lower dv) an intercept course you can undertake.

Oh that makes sense. Although this one was detected while still incoming towards perihelion (right?), but not by much.

Spotting one of these a few years in advance is the dream of many astronomers.

No, this one was detected well after perihelion, and even after its closest approach to the Earth too (so if it'd been on a collision course we wouldn't have detected it in time even). See here: http://www.ifa.hawaii.edu/info/press-releases/interstellar/i...

Now this is what I'm talking about! Really cool stuff!

I think this was kind of a wake up call that we don't have any kind of rapid-response system ready and waiting to intercept interstellar objects. Even if we don't get this one, we should damn sure be ready for the next one.

I briefly worked with members of the planetary defense scientific community, the folk thinking up ideas to defend the Earth from asteroids. This would be great opportunity for them to demonstrate their technology, if they had ever received any funding.

I was thinking about this earlier - what could we have done better to intercept this one? Because that's the only way we'll catch the next one...

Maybe wide-field Hubble-equivalents in the LaGrange points of the outer planets to help spot them on the way in? Ideally larger satellites with 25/50/100 years of cryogens available for long-duration missions? Although past a certain point your cryogen consumption would be constant - you're not getting heat from Sol, you're getting heat from your detectors/equipment... so a sunshield is useless.

I went thru all Reddit posts and major conclusion was that it cannot be a spaceship - not because of its shape but rather because it was going much too slow.

Someone calculated with its current speed it needs 50,000 years to get to another star (thank you for correction). So no alien with technology to build something like that would want to ride at a "bicycle" speed.

Unless of course they slowed down to take a turn (using Suns gravity pull), just like riding 500HP car you slow down in the corners to leave them safely.

Edit: corrected, thank you friend.

Could be a derelict, though. Arguably, spaceship wrecks should be more numerous than spaceships themselves. After all, assuming alien spaceships have existed for a long time and have a relatively short operational time, they exist for much longer as a wreckage and are as such much more likely to be found in this form.

Just consider our own near-Earth space : there are many more space debris there than there are operational satellites.

Few people argued back and forth that it could be a used alien rocket booster.

>So no alien with technology to build something like that would want to ride at a "bicycle" speed.

I agree with this conclusion and I think it is of natural origin but that conclusion does rest on several assumptions.

1. That its current speed is the speed it was traveling at in the interstellar medium.

2. That some technological civilization would be unwilling to wait 50,000 years.

3. That it is working as intended, it may have been designed to go faster but something went wrong. Perhaps it was never intended to cross interstellar distances at all.

It probably takes 50,000 years to get to another star. At a speed of ~80 km/s it would take millions of years to get to another galaxy, although I don't believe its current velocity is high enough to escape Milky Way.

The escape velocity from the Milky Way at our position (about 30,000 light years from the center) is roughly 500 km/s, so yes, 80 km/s is well short of escape.

Does it make any sense to place a series of landers in solar orbit, waiting for short-lived opportunities like this? I don't think we'd save much on fuel since the orbits wouldn't be optimized for the target. However, it would require much less planning when opportunities arise, and wouldn't be as reliant on the political winds of the day.

I'd guess not, as the various components that make up probes are constantly improving. While it would be nice to have a 1990's era probe on hand to investigate this asteroid, I bet we can learn a lot more from modern sensors, and the electronics and comms will be more powerful and lighter.

Don't knock 90s technology: Hubble is still sending us gorgeous pictures of the universe...

As a sibling points out it is a justification for developing in space refueling and orbital fuel depots. Then you could just launch something out of the Earth gravity well, fully refuel it, and then send it on such a trajectory.

Or if we had moon/Mars colonies then we could use standby rockets from them - proximate to humans/resources so we can maintain them but much lower escape velocities.

Adding 4-5km/s dv probably makes intercept and slowdown impractical at interstellar speeds.

Just wait until there is a BFR supplied gas station in orbit for such an occasion.

You can ask questions to the authors of this paper here: https://fermatslibrary.com/arxiv_comments?url=https%3A%2F%2F...

We maybe can’t catch it or probe right now, but it wouldn’t be too hard to target variety of EM transmissions at it

That's pointless, EM is an outdated technology, nobody listens to it anymore.

geez, it was a(n interstellar) joke guys! the aliens might be using neutrinos or something!

"With the high approach speed a hyper-velocity impactor to produce a gas 'puff' to sample with a mass spectrometer could be the serious option to get in-situ data."

This seems to assume it could never be an artificially made object.

well the aliens can call our insurance agency if they don't like the dent we put in their ship.

Anything artificial that travelled interstellar distances must be robust enough to survive such impacts without damage.

Yes, but if it is artificial the owners might react differently to an intentional collision by another artificial craft than they would to a chance collision with a small asteroid even if no damage is done.

We'll beam a "no trespassing" warning, first.

Plot for a new movie.

Live action "The Dig" anyone?

Fun fact: “The Dig” was originally planned to be a Spielberg movie, but the cost of special effects made them change it into a Lucasarts Point-and-click adventure game instead.

If I'm remembering the right novel, that novel is surely in my top-5 literary disappointments.

Due to the endless complaints from environmentalists, the hyperspace express route crossing through Earth's solar system, as planned by the Vogons, has be postponed indefinitely. Travelers are advised to avoid the rather patchy B roads in the sector.

Of course, I get downvoted by interstellar motorists...

Don't bother. It's just a decoy.

What we really need to do is start combing the databases for anomalous X-ray flares so we can find any nearby Oasa emitters.

The problem is that unless you plan to crash into it you need to reach the same speed. Or use a rail-gun to shoot an anchor.

Or cast a net.

That was underwhelming. I’d much rather see NASA’s or SpaceX’s or Roskosmos’s take on this. AKA the entities that actually have the means to pull this off.

Reply on news.ycombinator.com