On October 19, 2017, the first interstellar object ever detected flew past the Earth at the exit of the Solar System. Less than two years later, a second object was detected, an easily identifiable interstellar comet called 2I / Borisov.
The appearance of these two objects verified a previous theoretical work that concluded that interstellar objects (ISO) regularly enter our solar system.
The question of how often this happens has been the subject of considerable research since then. According to a new study led by researchers in the Interstellar Initiative (i4is), about seven ISOs enter our solar system each year and follow predictable orbits while they are here.
This research could allow us to send a spacecraft to meet one of these objects in the near future.
The research describing these discoveries was done by several researchers from i4is, a non-profit organization dedicated to making interstellar flight in the very near future.
They were joined by researchers from the Florida Institute of Technology, Harvard’s Institute for Theory and Computing (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 triggered a revolution in astronomy and the study of celestial objects. Not only was this an object that formed in another star system, but its arrival and detection involved 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 on a regular basis.
In addition to being an i4is physicist (and lead author of the study), Marshall Eubanks is a chief scientist at Space Initiatives Inc. and CEO of Asteroid Initiatives LLC. As Universe Today said in an email, the discovery of ‘Oumuamua and 2I / Borisov is significant in a way that cannot be underestimated:
“[J]proving that it exists, it has had a profound impact, creating a field of study almost out of nowhere (an area that funding authorities are just beginning to recognize). Interstellar objects give us the opportunity to study and, in the future, literally reach exobodies decades before the earliest possible missions even to the nearest stars, such as Proxima Centauri. “
This has led to several mission proposals that could meet future ISOs that have been observed passing through our system. One such proposal was Project Lyra, which i4is researchers shared in a 2017 study (with the support of Asteroid Initiatives LLC).
There is also the ESA Comet Interceptor mission, which it plans to launch in 2029 to meet with a long-range comet.
“We started working on potential missions for interstellar objects in 2017, immediately after the discovery of ‘Oumuamua’, and we initially focused on tracking that specific object, unlike Seligman and Laughlin, who focused on ISOs that would could be discovered in the future, ”said Eubanks.
“The Comet Interceptor mission would fall into a similar category (build and wait).”
Given that ISOs have formed in another stellar system, the possibility of studying them closely would give scientists a perspective on the conditions that are present there. In fact, the study of ISOs is the best thing for sending interstellar probes to neighboring stellar systems.
Of course, any such mission involves a lot of technical challenges, not to mention the need for prior warning. As Eubanks explained:
“There are two basic types of missions here – plan and wait or launch and wait missions, such as ESA Comet Interceptor and follow-up missions, such as needed to reach 1I / ‘Oumuamua. It is very unlikely that tracking missions will be able to meet a retreating ISO – they will certainly be limited to fast flybys. Meeting missions, missions to match speed and orbit or ISO landing, will need prior warning. “
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 known as the perihelion passage) and made a passage close to Earth.
Because of this, observers had only 11 days to make observations as they left the Solar System and were beyond the reach of their instruments.
The artist’s impression of 2I / Borisov beyond our solar system. (S. DagnelloNRAO / NSF / AUI)
In the case of 2I / Borisov, amateur astronomer and telescope maker Gennadiy Borisov saw him on August 30, 2019, about three months before he reached perihelion (December 8, 2019).
But for future missions to meet them, it is imperative that we 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 colleagues sought to place better constraints on these two variables. To do this, they began by considering how the speed of an interstellar object is influenced 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 are formed by stars and their planetary systems and that, after being on their own, they have the same galactic dynamics as stars. We use the two known ISOs, 1I / ‘Oumuamua and 2I / Borisov. , and the effectiveness of past and current astronomical surveys to estimate the number of these objects in the galaxy, as well as estimates of the stellar speed in the Gaia mission to estimate the speed at which we should expect. “
What they discovered was that in an average year, the solar system will be visited by up to seven ISOs that are asteroids. Meanwhile, objects such as 2I / Borisov (comets) would be rarer, appearing once every 10-20 years.
They also found that many of these objects were moving at higher speeds than ‘Oumuamua’ – which was moving at over 26 km / s before and after gaining momentum from the Sun.
Knowing these parameters will help scientists prepare for possible ISO mission missions, which Eubanks and colleagues addressed in more detail in a previous study – “Interstellar Now! Missions to Explore Nearly Objects Interstellar Objects ”.
As reported by Universe Today at the time of its launch, the study addressed a wider range of potential ISOs and the feasibility of achieving them.
In the meantime, this latest study provides basic information that will support the planning and implementation of these missions. In addition to ESA’s Project Lyra and Comet Interceptor, there are numerous proposals for spacecraft that could encounter interstellar objects (or even make interstellar travel on their own).
These include Project Dragonfly, a small spacecraft and laser spacecraft that was the subject of a conceptual design study hosted by the Interstellar Studies Initiative (i4iS) in 2013.
Another is Breakthrough Starshot, a concept presented by Yuri Milner and Breakthrough Initiatives that also requires a small spacecraft to be sent to Alpha Centauri using a light sail and a powerful laser matrix.
This proposal has been articulated in recent years by Prof. Abraham Loeb and Prof. Manasvi Lingam. While Leob is the founder of ITC and chair of the Starshot Advisory Committee, Lingham is a longtime ITC researcher and co-author of “Interstellar Now!” and this last work.
In addition to becoming interstellar, these concepts have been proposed as a possible way to “track objects” entering our solar system.
One way or another, we will soon reach other stellar systems! And knowing how to intercept and study the objects we periodically let go is a good way to start!
This article was originally published by Universe Today. Read the original article.