Keith’s note: Larger image. Objects are to scale. But the way that this thing rotates might dictate a more prudent station keeping distance.
First Interstellar Asteroid `Oumuamua is Like Nothing Seen Before, ESO
“Observations from ESO’s Very Large Telescope in Chile and other observatories around the world show that this unique object was traveling through space for millions of years before its chance encounter with our star system. It appears to be a dark, reddish, highly-elongated rocky or high-metal-content object.”
First Known Interstellar Visitor Is an “Oddball”
“While study of ‘Oumuamua’s colors shows that this body shares characteristics with both Kuiper Belt objects and organic-rich comets and Trojan asteroids,” says Meech, “its orbital path says it comes from far beyond.”
An Interstellar Visitor Unmasked, IFA
“Originally denoted A/2017 U1 (with the A for “asteroid”), the body is now the first to receive an “I” (for interstellar) designation from the International Astronomical Union, which created the new category after the discovery. In addition, it has been officially given the name `Oumuamua.”
Solar System’s First Interstellar Visitor Dazzles Scientists, NASA
“The asteroid, named ‘Oumuamua by its discoverers, is up to one-quarter mile (400 meters) long and highly-elongated–perhaps 10 times as long as it is wide. That aspect ratio is greater than that of any asteroid or comet observed in our solar system to date.”

Biologist, Explorers Club Fellow, ex-NASA Space Biologist and Payload integrator, Editor of NASAWatch.com and Astrobiology.com, Lapsed climber, Explorer, Synaesthete, Former Challenger Center board member...

20 replies on “Rendezvous With `Oumuamua”

  1. I saw a piece estimating 10,000 interstellar objects in our solar system taking an average of 10 years to transit. I wonder what it would take actually to rendezvous with one of them? Probably a lot of delta-V, but we have some pretty big rockets coming online.

    1. “I wonder what it would take actually to rendezvous with one of them?”

      I wondered a similar thing, whether we could actually get some sort of probe to renedzvous with Oumuamua, I guess any probe would have to be be accelerated to a speed considerably greater than the 38.3Kps relative to the sun that Oumuamua is travelling to make some sort of flyby within a feasible timescale and with probably little option for gravity assists that would I should think be quite a formidable task. I wonder just what it would take to get some sort of cubesat sized probe (provided one could be magicked up from somewhere!) up to the kind of velocity needed? Of course then you have the problem that you would then be travelling so fast relative to Oumuamua that it would be literally blink and you’ll miss it.

      1. With improvements in our NEO monitoring spacecraft, which are needed anyway, it might be possible to spot incoming interstellar objects earlier, which would be essential to have any chance of a rendezvous. Not sure what plans exist for a new NEO monitoring spacecraft but considering the emphasis on “planetary defense” maybe Congress would be amenable. https://cneos.jpl.nasa.gov/

        1. I can’t see any NEO program a rendezvous much easier. The propulsive requirements are huge and made worse by both the likely (high) inclination and the really harsh constraints on launch windows to rendezvous with an object on a hyperbolic trajectory.

          But timing is the main problem. If memory serves, ‘Oumuamua will be crossing the orbit of Jupiter in May. That’s perihelion to 5 AU in eight months. A NEO program is likely to focus on, well, near Earth objects. I don’t think future efforts would be able to pick up something this size at 5 AU. So you’d be talking about throwing together the spacecraft on under eight months notice.

          1. I think the only way it would work would be to make a spacecraft now with very high propulsion and low weight. Something like the New Horizons spacecraft, which was the fastest thing ever launched from earth, but even lighter and faster. Then keep it in storage to be launched on short notice if a similar interstellar rock is discovered. Forget Oumuamua, that thing is long gone.

          2. sure. I can just hear the arguments now when the next object is spotted. “Is this the one?”, people will muse, realizing the Spaceship In A Closet might not be replaced.

          3. There have been suggestions of designing a CubeSat for a minimal survey of fresh (very long period) comet, and then keeping it on the shelf until one is discovered. The same logic works for flybys of interstellar objects. I don’t think anyone would worry about wasting a CubeSat on a potentially boring interstellar object, or think it would be might not be replaced for the next opportunity. And after five or ten years on the shelf, you might want to scrap and replace it anyway (since the state of the art would have improved.)

            Or, if the timing had a chance of working out, build a CubeSat _and_ a more capable spacecraft. Fly a CubeSat at every opportunity and safe the larger spacecraft for launch after you’ve seen the data from the CubeSat flyby.

          4. You’d definitely want something on the shelf and ready to fly within months of discovering a target. But I’m not convinced a rendezvous is the best option. Those propulsive requirements are huge. You can’t predict in advance which direction the target will be coming from, or how fast it will be going. That means you’d sacrifice lots of capability which may or may not be necessary. In addition, the whole time from rendezvous to end of mission (due to range from Earth and the Sun) is likely to be brief (six months? Less if it’s solar powered?)

            A close flyby is much, much easier and might be a better option. You might only get a couple of hours observing time within 100,000 km of the target. But you would get a vastly larger and more capable payload. That’s an interesting trade study: Which is better? Two months of data from a single instrument (almost certainly a camera, and perhaps not even a good one) or two hours with a suite of really good instruments?

            (Note, I mentioned 100,000 km because that was roughly the Cassini project’s threshold of interest distant icy satellite encounters. But the exact number depends on the instruments and goals.)

    2. The thing is moving at 25 km/s
      For reference, New Horizons is at 23 km/s with a Jovian assist.
      Given all we know, it’d be an extreme challenge and require a dedicated mission architecture that does not exist. It would also be the coolest thing EVER.

  2. The picture is just an artist’s impression. Other than the elongated shape, we do not know what it looks like. An alien artifact is unlikely, but not ruled out.

    1. Perhaps a defunct starship that suffered a massive systems failure? It reminds me more of that hulk artifact briefly glimpsed in Arthur C. Clarke’s “Islands in the Sky”.

  3. with dimensions like that, my uneducated mind immediately thought of a shard from an explosion or collision

  4. It’s worth noting that the shape may not be that extremely elongated. Since it isn’t resolved (and wasn’t observed from a variety of geometries), all they have is a light curve. It would take extreme variations, but if two region were much darker that the rest of the body, you’d get the same result. But that’s very rare (I think Iapetus is the only example in the solar system, and its brightness variations are hemispheric, with just one dark region.) The two regions would also have to be on opposite sides of the body. The paper itself notes this: “A roughly spherical object would require extreme variations of albedo to reproduce the range and sharp minima of the lightcurve but this is unlikely based on our current understanding of the surfaces of most asteroids in our solar system and the absence of any sign of volatiles.” Of course, anything in between (e.g. a 4:1 aspect ration and factor of two not ten albedo difference.)

    3. I had this idea too and found only one other post on Reddit and your post addressing this. Scientists assume it’s a rock, so they desperately look for an explanation how a simple rock can show this oscillating lightcurve. And then they come up with a very unlikely tumbling cigar. As much as we know, a ball with a black and a white area would present exactly the same lightcurve. And would be just as unlikely. Or, for that matter, something that really actively blinks / reflects light in a controlled matter and on purpose, like a garbage truck or an airplane. Scientists are jumping to conclusions instead of strictly separating facts from assumptions. So, maybe it’s a tumbling cigar and maybe not. We just don’t know anything about it besides the velocity, trajectory and the lightcurve. Anything more is guesswork and unserious science if not marked as such.

  5. I agree with Keith – they should’ve called it “Rama”. But perhaps it was a bunch of youngsters who had never even heard of Arthur C. Clarke?

    1. As soon as they decided it was asteroidal rather than cometary, the rules for naming asteroids applied. The discoverer gets to propose the name, and that suggestion is almost always approved. (Exceptions include things like living, political or religions figures, something obscene, etc.) You’re probably right: The discoverer may not have been a Arthur C. Clarke fan. Or maybe he didn’t want to give the tabloid press a chance for more alien spaceship stories.

    1. Not pictures. It’s already a few AU away and 400 meters isn’t very big at that distance. HST can manage about 10 to 20 kilometers resolution at 1 AU. And it’s likely to fade below HST detection limits by the end of the year. But unresolved spectra might be possible.

      Space Telescope Science Institute does reserve “Director’s Discretionary Time” for things like this. Some observing time isn’t allocated through the normal process and astronomers can request it to follow up on a new and/or time-critical discovery. (They also have time allocated to “snapshot” programs, things like, “if a nearby supernova is detected, I’d like ten orbits within a month of the discovery.” But I really doubt anyone thought to propose a snapshot program for an interstellar object.)

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