Chasing Oumuamua-unfortunately human technology is not up to the task


Expand / An illustration of a New Horizons spacecraft over an illustration of Oumuamua. Nothing is to scale.

European Southern Observatory / M. Kornmesser

Just over a month ago, an interstellar visitor now known as & # 39; Oumuamua pbaded 24 million kilometers from Earth. Now it is rapidly moving away from our planet at a speed of approximately 26 km / s. That is considerably faster than, for example, the Voyager 1 spacecraft, which plunges beyond the Solar System at a speed of 17 km / s.

The first interstellar object is doubly intriguing because humans have never been able to study something beyond the Solar System up close. In addition, recent observations have shown that Oumuamua has a reddish color, say astronomers, and an unexpected oblong shape, like that of a giant 400-meter-long cigar. Already, the object is fading from view, and we will never see it again as it recedes.

But, what if we could? NASA is building what will be the most powerful rocket in the world, the Space Launch System. Would you be able to launch a small probe to catch Oumuamua? Do we have any technology that can catch this interstellar intruder?

Catch Me If You Can

To find out, Ars turned to the Office of Advanced Concepts at NASA's Marshall Space Flight Center in Huntsville, Alabama. The office manager, Mark Rogers, spoke with Ars, as did one of his mission planners, Larry Kos. It turns out that they were also curious and had made some preliminary calculations about the possibility of intercepting Oumuamua.

The short answer is that, unfortunately, it is already too late with our existing technology. Although Oumuamua moves at a speed of 26 km / s, factoring in the velocity vector of the Earth, the delta-v between a spacecraft in Earth orbit and the object is closer to 60 km / s. " Chemical propulsion just does not close the case in this scenario," Rogers said. "It is not possible".

But, what if NASA had worked feverishly after detecting the object on October 19 and had already sent a probe into space? The problem with our primary propulsion methods is that, although chemical rockets are very good at getting things out of Earth's orbit, they are vehicles that consume a lot of gas in space. Most of our existing space propulsion systems rely on chemicals, and they need a large amount of fuel, often hydrogen, to move a spacecraft. In this case, Kos calculated the specific impulse needed to trap Oumuamua to approximately 450 seconds.

That's actually good news, since conventional rocket engines can reach that specific momentum level. But there is also bad news. Maintaining that specific momentum to reach Oumuamua would require a lot of fuel. How much? Well, according to Kos, NASA would need to launch the equivalent of about two International Space Stations, or about 800 tons, of fuel into Earth orbit. And with all that fuel, we could push a 10kg spacecraft – a GoPro with a rudimentary avionics – to reach Oumuamua over time.

Unfortunately, the first version of the Space Launch System rocket, although powerful, will only launch 70 tons. It should fly in 2020. A more powerful version, capable of lifting 130 tons, can be ready to fly by the end of the 2020s We simply do not have the capacity to release so much fuel now or in the near future.

Another option, if we had been able to see Oumuamua before, would have been to fly a spacecraft to the closest interception point, approximately 60 times the distance between Earth and the Moon. Unfortunately, Oumuamua was not found until five days after this close flyby. Due to the object's hyperbolic orbit, it did not move much crosswise with respect to the star background when it made its closest approach to the Sun on September 9 and then moved towards Earth.

Although astronomers think that such interstellar overflights are probably quite frequent and estimate that an interstellar object similar to Oumuamua pbades within the orbit of the Earth several times a year, such overflights are difficult to find. In other words, we would have to be very, very lucky to detect a similar interstellar object much earlier, and then we would have to have a spaceship on the platform and ready to go. (The average wait time for a NASA scientific mission, unfortunately, is five to seven years before launch.)

Future flybys

We've probably missed our chance with Oumuamua with technology current. But baduming that the Space Launch System – or some other reasonably powerful rocket, like the Falcon Heavy or the New Glenn Boosters – connect online in the next decade, we might be able to catch another interstellar object in a short time with a different medium of space propulsion?

Electric propulsion, which sips fuel compared to chemical rockets and uses solar cells and an ion propellant, would not require a large mbad of propellant to be launched into orbit. However, current systems do not have the ability to go fast enough, and even electric propulsion on a larger scale would take years to gain speed to match Oumuamu, and many more years to pursue it. In addition, the more our probe from the Sun reached us, the less solar energy would be able to collect.

  Nuclear engines would help. Some.

Nuclear engines would help. Some.


One response to this is nuclear thermal propulsion, said Rogers. A nuclear thermal engine, such as the NERVA project developed in the 1960s and early 1970s, may have barely enough energy to chase an object like Oumuamua with a 10-kg probe. But for this, we would need the Earth to travel more or less in the same direction as an interstellar object, and that is basically the luck of the draw. (Oh, and there's the fact that due to nuclear costs and concerns, NASA has not worked in depth on a nuclear engine since 1972)


One last chance to reach Oumuamua comes from the technology that is studied by the Breakthrough Starshot project, which is essentially a spacecraft on a gram-scale chip. This miniature technology would include cameras, photon propellers, power supply, navigation and communication equipment. And these chips would carry a light candle, with a series of lasers of Earth-based lasers in the 100GW range, providing the sail enough thrust for the ship to move at approximately 20 percent of the speed of light .

If it's that small, a 1-gram spacecraft could be launched in 2021, according to a recent document, it could reach Oumuamua in about seven years. That would be delicious, except for the fact that the tiny spacecraft does not yet exist, they rely on unproven miniaturization technologies, and no one has discovered the geopolitics of building an enormous series of Earth-oriented lasers aimed at space. 19659004] In short, Oumuamua can be lost forever. Maybe it will stimulate humans to climb into our space flight game so that we do not miss the next interstellar intruder.

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