The Messenger from Afar

Non-Fiction - by Peter Jekel

Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying. Arthur C. Clarke

The Fermi Paradox resulting from a lunchtime muse by physicist Enrico Fermi in 1950 asks an essential question of the Universe. If there is intelligent life out there, where is it? Nary a peep through the Search for Extraterrestrial Life (SETI) project from anywhere in our vast Universe. Is no one out there? Are we alone?

Maybe it is because we just will not notice another race of aliens and let them slip by us. On October 19, 2017, the first known interstellar traveller entered our visual field with the aid of the Pan-STARRS telescope in Hawaii. As it entered our Solar System, the object, tumbling end over end, was actually accelerating. Scientists were puzzled. It flew into our Solar System and left again, 34 days later, the only natural object to do so up to that time. It came in at a blistering 87.7 kilometers per second as it approached perihelion of its tight orbit about the Sun. By comparison, Halley’s Comet, a famous regular visitor to our Solar System every 75 years, travels at around 45 kilometers per second. Once it reaches its origins in interstellar space sometime in the 25^th century, it will still be travelling at an equally impressive 26.3 kilometers per second.

It was a small object estimated to be between one hundred and one thousand meters in length with a thickness of only 35 to 167 meters. It was dark red in colour not unlike objects from the outer Solar System; however, upon reaching the Sun it showed none of the tell-tale signs of what astronomers first thought it was, an asteroid.

At first its red colour and varying brightness also pointed strongly to the possibility of it being an asteroid but that was dismissed; it did not fit the pattern of movement expected of an asteroid, moving at far too great a velocity. Its incredible speed was more highly suggestive of a comet, but it had no coma or tail.

It was neither but showed characteristics of both. Spectra from the Hale Telescope at the Palomar Observatory in California showed that the object’s red colour is not unlike comet nuclei or Trojans which are small space bodies that share the orbit of a larger object such as a moon or planet; it remains in a stable orbit about sixty degrees ahead or behind the main body. The William Herschel Telescope in the Canary Islands further showed that the object was featureless and again confirmed the red colouration much like objects from our own Kuiper Belt. At infrared wavelengths the object showed a spectrum similar to D-type asteroids found in the asteroid belt. A subsequent report on observations by the Spitzer Space Telescope recently retired on January 30, 2020, indicated that the object was at least ten times more shiny than a typical comet and unlike a comet it contains no water or ice, but is more likely made of metals or rock like an asteroid.

Finally it was identified as an interstellar object, the first of its kind discovered in our Solar System. It was named Oumuamua, Hawaiian for “a messenger from afar arriving first.” Officially it is called, 1I/2017 U1, an acronym for Interstellar Object Number One in 2017 by the International Astronomical Union.

Astronomers figured this out by looking at its eccentric orbit. Its orbital eccentricity was at 1.2, the highest of any object outside of an interstellar comet not discovered until August 2019, the 2I/Borisov; that comet showed all of the characteristics of a comet, unlike Oumuamua. All of the gravitational interactions of the objects in the Solar System including even possibly unknown objects could not account for the eccentricity; the eccentricity of greater than 1.0 meant that the object exceeded the Sun’s gravitational grip and therefore, the object must be interstellar in origin.

Calculations suggested that Oumuamua was coming from the direction of the Vega star in the constellation of Lyra. Calculations show that the object would take 300,000 years to reach our Solar System from there. Interestingly, Vega, a Main Sequence white star, was nowhere near that position 300,000 years ago so it is likely that Oumuamua has circulated the galaxy several times, adding to its age and mystery further.

The eerie resemblance to Arthur C. Clarke’s classic Rendezvous with Rama, suggested that there was a thought that it was an alien craft, perhaps abandoned, perhaps not. With this in mind, there were, at first, limited radio observations by the SETI Institute’s Allen Telescope Array in California. Nothing was detected. Later examination using the Breakthrough Listen hardware, part of SETI’s updated search at the Green Bank Telescope in West Virginia and the Parkes Telescope in New South Wales, Australia, revealed nothing unusual being emitted from the object. However, every radio scan is limited, even a broad range of bands is finite; something may be emitting outside that range and in spite of the relatively broad scan, it was finite in duration. In the case of the Green Bank survey, it lasted only six hours.

Our first visitor from the interstellar cosmos, even if it is not a version of Rama, is weird nonetheless. Firstly, the mere fact that it arrived here defied expectations. It was also larger than predicted. Its arrival tells us one thing for sure, that interstellar objects are more common than any models of our galaxy would have had us predict.

There is no photograph of the object due to its variable brightness as it rotated every 8.7 hours on its short axis and every 54.5 hours on its long axis. While most of the asteroids in our solar system rotate like this, it is hard to determine if Oumuamua’s spin is recent or has been that way since it left its home Solar System. Armed with this rotation information, astronomers were able conclude that the object is elongated with a length five to ten times its width. Most asteroids have a length/width ratio of three. It is very shiny, more than ten times that of any of the asteroids in our Solar System. The way that the light shone and waned, it was estimated that the object was around one hundred to four hundred meters in length. Taken together with its width, it appears very much like a disc shape.

Some astronomers have speculated that the object could have been ejected by a stellar system from a tidally destroyed planet. That is possible and would still make the object a rarity in our universe, but complications with the theory indicate that Oumuamua is disc-shaped rather than the resulting cigar shape of an object from a tidal disruption.

Another thought is that the object is an example of interstellar iceberg made of frozen hydrogen molecules instead of the more familiar water icebergs found on Earth. These objects form at a temperature very near absolute zero at -273 degrees Celsius in the interiors of interstellar clouds of molecular gases. Fits a lot of the criteria that would explain Oumuamua, but further study suggests that such icebergs would not survive the long journey through space.

The strangeness does not end there. The object’s trajectory deviated up to a tenth of a percent more than expected based on the gravitational influence of the Sun. Sounds small, but it is significant statistically. Then again comets do it all the time through outgassing as the surface of the comet heats up as it approaches the Sun; hence comets have a tail. There is one key difference; Oumuamua had no cometary tail. Some astronomers have stated that there could be enough outgassing without the gasses being detectable. One flaw in the hypothesis is that the outgassing, visible or not, would result in the object changing its rotation rapidly. The object never changed its spin.

It is like nothing we have seen before and defies some of the expected laws of physics if it was a natural body. Perhaps the source of the deviation in the trajectory was due to radiation pressure from the sun. However, for that to be an issue, the rock would have had to be less than a millimeter thick spanning at least twenty meters. Nothing natural fits this equation save a solar sail looking a lot like the Japanese mission, Interplanetary Kite-Craft Accelerated by Radiation of the Sun) IKAROS.

We are faced with the fact that perhaps we have been visited by an interstellar craft from another world in our galaxy. This has been suggested by Harvard astronomer, Ari Loeb and his postdoctoral student Shmuel Bialy.

Right now we cannot catch up with the rapidly moving object which is on a journey out of our Solar System to verify the theory, but that is not to say that sometime in the future, it will not be possible. We also have hope that the Large Synoptic Survey Telescope, now called the Vera C. Rubin Telescope being built in Chile-Vera C. Rubin was an American astronomer who calculated the rotation of galaxies-will become operational and will be sensitive enough to detect Oumuamua-like objects. If we do not see more, that means that the visitor was unique.

There has been suggestions to visit this strange world. The Initiative of Interstellar Studies launched what is known as Project Lyra to assess a visit to the strange object. Several options ranging from five to twenty five years have been suggested as options.

This is not the first time that an object in our Solar System has been thought to be an alien craft. One of the two tiny moons of Mars, Phobos, was an object of such speculation. In 1958, Russian astrophysicist Iosif Shklovsky, suggested that Phobos’ secular acceleration (the speeding up of an object in orbit about another, caused by a combination of gravity from other planet in the vicinity-Jupiter’s enormous pull would account for part of this-and tidal friction) in its orbit was due to its having a thin metal sheet opening up the idea of a thin metal structure. His calculations also deduced that to account for the secular acceleration that the object would have to be light; if it were hollow inside, it would fit this theory.

Several science fiction authors have written of the Martian moon as being an alien craft. Donald Wollheim’s Secret of the Martian Moons, suggests that both of the Martian moons, Phobos and Deimos are actually alien craft disguised as moons, built by humanoid aliens from the Vega star system, ironically the suggested origin of Oumuamua. Phobos the Robot Planet, by Paul Capon is about the moon being a giant computer that learns of humans via our radio broadcasts and kidnaps humans in UFOs to learn about human emotion. In Mission to the Heart Stars, by James Blish, a hollow Phobos is placed in Martian orbit to act as a receiver/transceiver to monitor Earth.

Later calculations challenged the claims of Shklovsky, based on more accurate observations; secular acceleration was due to tidal effects not considered earlier. The density of the moon also showed that it was actually a pile of rocks, verified by the Viking probes that reached Martian orbit in the 1970’s. All is not lost though, since the Mars Express has shown us that Phobos is not a solid rock or rocks, but instead readings indicate that there are voids, up to thirty percent being hollow.

While Rama may be the first book that comes to mind when we think of Oumuamua, there are others that have explored this possibility. Eon by Greg Bear is set against a backdrop of the year 2005, with the Soviet Union and the United States on the verge of nuclear war. Against this tense atmosphere, an asteroid is detected after a powerful energy burst outside the Solar System; the object moves into a highly eccentric Near Earth orbit. Both nations claim ownership of the object, dubbed “the Stone” by the Americans and “the Potato” by the Soviets.

In science fiction thriller, The Last Astronaut, by David Wellington, a huge alien object enters the Solar System, much like Rama. The object, like Rama and Oumuamua makes no effort to communicate with Earth in spite of efforts to reach out. Very similar in theme to the more famous Rendezvous with Rama, but containing more horror elements.

Pushing Ice by Alastair Reynolds describes a mission to Saturn when Janus, a moon of Saturn, deviates from its natural orbit and begins its acceleration out of the solar system. Upon approach to the now errant moon reveals it to be a camouflaged alien craft.

In David Brin’s Existence, there is a scene at the commencement of the novel, which describes the work of an orbital garbage collector; cleaning up the waste left in orbit about the Earth. During his routine work, he comes across an alien artifact. What follows is the response of the world to this unique find.

Some of these alien objects could be weapons as suggested by some writers. The original Star Trek series’ The Doomsday Machine by science fiction writer, Norman Spinrad, follows the Starship Enterprise in its efforts to disable an object that has already destroyed another starship and an entire planetary system. The object is theorized to be an ancient doomsday machine built by a long-dead alien civilization, now wandering the cosmos carrying out its deadly task, to destroy planetary systems.

Fred Saberhagen wrote a whole series of science fiction stories, The Berserker series, about doomsday machines left over from an ancient war between two alien civilizations; the machines have intelligence and range in size from a large asteroid down to a human size.

Whatever Oumuamua turns out to be, it is unusual. Wouldn’t it be amazing if it truly was an alien craft that made a brief visit to our corner of the universe? We may never know for sure unless one of the planned future expeditions comes to fruition. In the meantime, we can only dream of a rendezvous, not only with an alien craft, but a rendezvous with destiny.

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References:

Bailer-Jones, C et al. 2018. Plausible home stars of the interstellar object Oumuamua found in Gaia DR2. Astronomical Journal. 156(5):205.

Bannister, M. et al. 2017. Col-OSSOS: Colors of the Interstellar Planetesimal. 1I/2017 U1 in Context with the Solar System. The Astrophysical Journal Letters. 851(2):L38.

Belton, M. et al. 2018. The Excited Spin State of 1I/2017 U1 Oumuamua. The Astrophysical Journal Letters. 856(2):L21.

Bialy, S. and Loeb, A. 2018. Could Solar Radiation Explain Oumuamua’s Peculiar Acceleration? The Astrophysical Journal Letters. 868(1):L1.

Bolin, B. et al. 2017. APO Time Resolved Color Photometry of Highly-Elongated Interstellar Object 1I/’Oumuamua.’ The Astrophysical Journal Letters. 852(1):L2.

Cuk, M. 2018. 1I/Oumuamua as a Tidal Disruption Fragment From a Binary Star System. The Astrophysical Journal Letters. 852(1):L15.

de la Fuente, M. and de la Fuente, M. 2017. Pole, Pericenter, and Nodes of the Interstellar Minor Body A/2017 U1. Research Notes of the American Astronomical Society. 1(1):L5.

Drahus, M. et al. 2018. Tumbling motion of 1I/Oumuamua and its implications for the body’s distant past. Nature Astronomy. 2:407-412.

Enriquez, J. 2018. Breakthrough Listen Observations of 1I/Oumuamua with the GBT. Research Notes of the American Astronomical Society. 2(1):9.

Feng, F. and Jones, H. 2017. Oumuamua as a messenger from the Local Association. The Astrophysical Journal Letters. 852(2):L27.

Fiekkoy, E. et al. 2019. The Interstellar Object Oumuamua as a Fractal Dust Aggregate. The Astrophysical Journal Letters. 885(2):L41.

Fitzsimmons, A. et al. 2018. Spectroscopy and thermal modelling of the first interstellar object 1I/2017 U1 Oumuamua. Nature Astronomy. 2:133-137..

Gaidos. E. et al. 2017. Origin of Interstellar Object A/2017 U1 in a Nearby Young Stellar Association? Research Notes of the American Astronomical Society. 1(1):13.

Hein, A. et al. 2019. Project Lyra: Sending a spacecraft to 1I/Oumuamua (former A/2017 U1), the interstellar asteroid. Acta Astronautica. 161:552-561.

Hibberd, A. et al. 2020. Project Lyra: Catching 1I/Oumuamua-Mission Opportunities After 2024. Acta Astronautica. 170:136-144.

Hoang, T. and Loeb, A. 2020. Destruction of the Molecular Hydrogen Ice and Implications for 1I/2017 (Oumuamua). The Astrophysical Journal Letters. 899(2):L23.

Jewitt, D. et al. 2017, Interstellar Interloper 1I/2017 U1: Observations from the NOT and WIYN Telescope. The Astrophysical Journal Letters. 850(2):L36.

Mashchenko, S. 2019. Modeling the light curve of Oumuamua: evidence for torque and disc-like shape. Monthly Notices of the Royal Astronomical Society. 489(3):3003-3021.

McNeill, A. et al. 2018. Constraints on the Density and Internal Strength of 1I/Oumuamua. The Astrophysical Journal Letters. 857(1):L1.

Meech, K. 2017. A brief visit from a red and extremely elongated interstellar asteroid. Nature. 552(7685):378-381.

Micheli, M. et al. 2018. Non-gravitational acceleration in the trajectory of 1I/2017/U1 (Oumuamua). Nature. 559:223-226.

Opik, E. 1964. Is Phobos Artificial? Irish Astronomical Journal. 6:281-283.

The Oumuamua ISSI Team. 2019. The natural history of Oumuamua. Nature Astronomy. 3(7):594-602.

Portegies-Zwart, S. et al. 2018. The origin of interstellar asteroidal objects like 1I/2017. Monthly Notices of the Royal Astronomical Society Letters. 479(1):L17-L21.

Pravec, P. et al. 2018. The tumbling rotational state of 1I/’Oumuamua’. Nature Astronomy. 2:383-386.

Seligman, D. and Laughlin, G. 2020. Evidence that 1I/2017 U1 (Oumuamua) was composed of molecular hydrogen ice. The Astrophysical Journal Letters. 896(1):L8.

Shilling, G. 1964. On exospheric drag as the cause of the supposed secular accelerations of Phobos. Journal of Geophysical Research. 69(9):1825-1829.

Shklovsky, I. and Sagan, C. 1966. Intelligent Life in the Universe. Bantam.

Trilling, D. et al. 2017. Implications for Planetary System Formation from Interstellar Object 1I/2017 U1 Oumuamua. The Astrophysical Journal Letters. 850(4):L38.

Trilling, D. et al. 2018. Spitzer Observations of Interstellar Object 1I/Oumuamua. The Astronomical Journal. 156(6):261.

Vinogradova, V. and Radzievskii, V. The Acceleration of the Martian Satellites and the Stabilization of Orbits of Artificial Earth Satellites. Soviet Astronomy. 9(2):334-339.

Wright, J. and Jones, H. 2018. On Distinguishing Interstellar Object Like Oumuamua From Products of Solar System Scattering. Research Notes of the American Astronomical Society. 1(1):38.

Ye, Q. and Zhang, Q. 2017. 1I/Oumuamua is Hot: Imaging, Spectroscopy and Search of Meteor Activity. The Astrophysical Journal Letters. 851(1):L5.

Zhang, Y. and Lin, D. 2020. Tidal fragmentation as the origin of 1I/2017 U1 (Oumuamua). Nature Astronomy. 4:852-860.