On October 19, 2017, the first interstellar object ever detected by Earth flew out of the solar system. Less than two years later, a second object was detected, an easily identifiable interstellar comet designated 2I / Borisov.
The appearance of these two objects corroborated earlier theoretical work that concluded that interstellar objects (ISOs) regularly enter our solar system.
The question of how often this happens has since been the subject of extensive research. According to a new study led by researchers at the Initiative for Interstellar Studies (i4is), about seven ISOs enter our solar system every year and follow predictable orbits while here.
This research could allow us to send a spacecraft to meet one of these objects in the near future.
The research describing these findings was conducted by multiple researchers from i4is, a non-profit organization dedicated to the realization of interstellar flights in the very near future.
They were joined by researchers from the Florida Institute of Technology, Harvard’s Institute for Theory and Computation (ITC), the University of Texas at Austin, the Technical University of Munich and the Observatoire de Paris.
‘Oumuamua through the William Herschel telescope. (Queen’s University Belfast / William Herschel Telescope)
The study of ‘Oumuamua in October 2017 caused a revolution in astronomy and the study of celestial objects. Not only was this an object that had formed in another galaxy, but its arrival and detection implied a large population of such objects.
The detection of 2I / Borisov in 2019 confirmed what many astronomers already suspected: that ISOs enter our solar system quite regularly.
Not only is Marshall Eubanks a physicist on the i4is (and the study’s lead author), he’s also the Chief Scientist of Space Initiatives Inc. and CEO of Asteroid Initiatives LLC. As he told Universe Today via email, the discovery of ‘Oumuamua and 2I / Borisov is significant in a way that cannot be underestimated:
[J]By proving that they exist, it has had a profound impact, creating an area of study almost from scratch (one that funding authorities are just starting to recognize). Interstellar objects allow us to study and literally touch exobodies in the future decades before the earliest possible missions to even the closest stars, such as Proxima Centauri. “
This led to multiple proposals for missions that could converge with future ISOs spotted by our system. One such proposal was Project Lyra, which researchers from the i4is shared in a 2017 study (with support from Asteroid Initiatives LLC).
There’s also ESA’s Comet Interceptor mission, which they plan to launch in 2029 to meet a long-lived comet.
“We started working on possible missions to interstellar objects in 2017, right after the discovery of ‘Oumuamua, and we initially focused more on chasing that particular object, unlike Seligman & Laughlin, which focused on ISOs that were used in the future could be discovered. ”said Eubanks.
“The Comet Interceptor mission would fall into a similar category (build-and-wait).”
Since ISOs were formed in another galaxy, the ability to study them up close would provide scientists with insight into the conditions that exist there. In fact, the study of ISOs is the second best way to send interstellar probes to neighboring galaxies.
Of course, any such mission presents many technical challenges, not to mention the need for advance warning. As Eubanks explained:
“There are two basic types of missions here – plan and wait, or start and wait, missions, such as the ESA Comet Interceptor, and chase missions, as required to reach 1I / ‘Oumuamua. Chase missions will be able to converge with one. retreating ISO – these will almost certainly be limited to fast flybys. Rendezvous missions, missions corresponding to speeds and orbiting around or landing the ISO, will need to be forewarned. “
To illustrate, when astronomers first became aware of ‘Oumuamua, it was only after the object had already made its closest approach to the sun (also called perihelion passage) and passed close to Earth.
Because of this, observers had only 11 days to conduct observations as it made its way out of the solar system and out of reach of their instruments.
Artist’s impression of 2I / Borisov outside our solar system. (S. DagnelloNRAO / NSF / AUI)
In the case of 2I / Borisov, amateur astronomer and telescope maker Gennadiy Borisov saw it on August 30, 2019, about three months before it reached perihelion (December 8, 2019).
But for future missions to meet them, it is imperative to know as much as possible about how often ISOs arrive and how fast they travel when they do.
For the sake of their study, Eubanks and his colleagues tried to impose better restrictions on these two variables. To do this, they began to consider how the speed of an interstellar object is affected by the local resting standard (LSR) – the average motion of stars, gas, and dust in the Milky Way near the sun:
“We assume that ISOs come from or formed with stars and their planetary systems, and that, after being alone, share the same galactic dynamics as stars. We use the two well-known ISOs, 1I / ‘Oumuamua and 2I / Borisov. ., and the efficiency of past and current astronomical studies to estimate the number of these objects in the galaxy, and stellar velocity estimates from the Gaia mission to estimate the velocity dispersion we can expect. “
What they found was that in an average year, the solar system would be visited by as many as seven asteroid-like ISOs. Meanwhile, objects like 2I / Borisov (comets) are said to be rarer, appearing about once every 10 to 20 years.
They further found that many of these objects would move at speeds higher than ‘Oumuamua’s – those traveling at over 16 mph before and after receiving a boost from the sun.
Knowing these parameters will help scientists prepare for possible encounter missions with ISOs, something Eubanks and his colleagues discussed in more detail in a previous study – “Interstellar Now! Missions to Explore Nearby Interstellar Objects”.
As Universe Today reported at the time of its release, the study covered a wider range of potential ISOs and the feasibility of achieving them.
Meanwhile, this latest study provides basic information that will support the planning and execution of these missions. In addition to Project Lyra and the ESA’s Comet Interceptor, there are numerous proposals for spacecraft that can meet interstellar objects (or even make the interstellar journey itself).
These include Project Dragonfly, a small spacecraft and laser sail that was the subject of a conceptual design study organized in 2013 by the Initiative for Interstellar Studies (i4iS).
Another is Breakthrough Starshot, a concept from Yuri Milner and Breakthrough Initiatives that also calls for a small spacecraft to be sent to Alpha Centauri using a light sail and a powerful laser array.
This proposal has been articulated in recent years by Prof. Abraham Loeb and Prof. Manasvi Lingam. While Leob is the founder of the ITC and chair of the Starshot Advisory Committee, Lingham is a longtime ITC researcher and co-author of the “Interstellar Now!” and this last article.
These concepts have not only been interstellar, but have also been presented as a possible way to “chase objects” entering our solar system.
Somehow we’ll be peaking at other galaxies soon! And knowing how to intercept and study the objects they periodically kick our way is a good way to start!
This article was originally published by Universe Today. Read the original article.