The Gaia Mission’s Science Operations are Over

ESA’s Milky Way-mapper Gaia has completed the sky-scanning phase of its mission, racking up more than three trillion observations of about two billion stars and other objects over the last decade to revolutionise our view of our home galaxy and cosmic neighbourhood.

The ESA has announced that Gaia’s primary mission is coming to an end. The spacecraft’s fuel is running low, and the sky-scanning phase of its mission is over. The ground-breaking mission has taken more than three trillion observations of two billion objects, mostly stars.

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Gaia Finds Hundreds of Asteroid Moons

This illustrates the orbits of more than 150,000 asteroids seen by Gaia as part of its data release 3. The orbits shown here extend from the inner solar system to the orbit of Jupiter. Courtesy ESA/Gaia/DPAC; CC BY-SA 3.0 IGO
This illustrates the orbits of more than 150,000 asteroids seen by Gaia as part of its data release 3. The orbits shown here extend from the inner solar system to the orbit of Jupiter. Courtesy ESA/Gaia/DPAC; CC BY-SA 3.0 IGO

The amazing Gaia mission to chart stars in the Milky Way Galaxy is also an expert asteroid hunter. Now, astronomers are reporting its success at spotting more moons of asteroids in our solar system. Once the Gaia data from its release 3 are confirmed, those observations will add 352 more binary asteroids to the known count. That nearly doubles the known number of asteroids with moons and previous Gaia data releases also revealed asteroids in its survey.

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Gaia Hit by a Micrometeoroid AND Caught in a Solar Storm

Artist impression of ESA's Gaia satellite observing the Milky Way. The background image of the sky is compiled from data from more than 1.8 billion stars. It shows the total brightness and colour of stars observed by Gaia
Artist impression of ESA's Gaia satellite observing the Milky Way (Credit : ESA/ATG medialab; Milky Way: ESA/Gaia/DPAC)

For over ten years, the ESA’s Gaia Observatory has monitored the proper motion, luminosity, temperature, and composition of over a billion stars throughout our Milky Way galaxy and beyond. This data will be used to construct the largest and most precise 3D map of the cosmos ever made and provide insight into the origins, structure, and evolutionary history of our galaxy. Unfortunately, this sophisticated astrometry telescope is positioned at the Sun-Earth L2 Lagrange Point, far beyond the protection of Earth’s atmosphere and magnetosphere.

As a result, Gaia has experienced two major hazards in recent months that could endanger the mission. These included a micrometeoroid impact in April that disrupted some of Gaia‘s very sensitive sensors. This was followed by a solar storm in May—the strongest in 20 years—that caused electrical problems for the mission. These two incidents could threaten Gaia‘s ability to continue mapping stars, planets, comets, asteroids, quasars, and other objects in the Universe until its planned completion date of 2025.

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Gaia is Now Finding Planets. Could it Find Another Earth?

Artist's impression of the ESA's Gaia Observatory. Credit: ESA

The ESA launched Gaia in 2013 with one overarching goal: to map more than one billion stars in the Milky Way. Its vast collection of data is frequently used in published research. Gaia is an ambitious mission, though it seldom makes headlines on its own.

But that could change.

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Variable Stars can Tell us Where and When to Search for Extraterrestrials

Artist’s impression of the Gaia spacecraft detecting artificial signals from a distant star system. In this synchronization scheme, the star system's inhabitants send the signal shortly after witnessing a supernova, which is also seen by telescopes on Earth. (Credit: Danielle Futselaar / Breakthrough Listen)

The European Space Agency’s Gaia Observatory has been operating steadily at the Earth-Sun L2 Lagrange Point for almost a decade. As an astrometry mission, Gaia aims to gather data on the positions, proper motion, and velocity of stars, exoplanets, and objects in the Milky Way and tens of thousands of neighboring galaxies. By the end of its primary mission (scheduled to end in 2025), Gaia will have observed an estimated 1 billion astronomical objects, leading to the creation of the most precise 3D space catalog ever made.

To date, the ESA has conducted three data releases from the Gaia mission, the latest (DR3) released in June 2022. In addition to the breakthroughs these releases have allowed, scientists are finding additional applications for this astrometric data. In a recent study, a team of astronomers suggested that the variable star catalog from the Gaia Data Release 3 could be used to assist in the Search for Extraterrestrial Intelligence (SETI). By synchronizing the search for transmissions with conspicuous events (like a supernova!), scientists could narrow the search for extraterrestrial transmissions.

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A Direct Image of a Planet That’s Just Like Jupiter, Only Younger

Direct images of the extrasolar planet, AF Lep b (white spot around 10 o’clock), orbiting its host star (center) taken in Dec. 2021 and Feb. 2023 using the W. M. Keck Observatory’s 10-meter telescope in Hawai?i. (Credit: Kyle Franson, University of Texas at Austin/W. M. Keck Observatory)

In a recent study published in The Astrophysical Journal Letters, a team of astronomers used the W. M. Keck Observatory on Maunakea, Hawai?i Island to identify exoplanet, AF Lep b, which is three times the mass of Jupiter orbiting a Sun-sized star located approximately 87.5 light-years from Earth. What makes this discovery unique is AF Lep b is the first exoplanet discovered using a method called astrometry, which involves measuring unexpected, miniscule changes in the position of a star relative to nearby stars, which could indicate another object, an exoplanet, is causing gravitational tugs on its parent star.

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Astronomers Find a Sun-like Star Orbiting a Nearby Black Hole

Gaia BH1 is a Sun-like star co-orbiting with a black hole estimated at 10 times the Sun's mass. Credit: ESO/L. Calcada

In 1916, Karl Schwarzchild theorized the existence of black holes as a resolution to Einstein’s field equations for his Theory of General Relativity. By the mid-20th century, astronomers began detecting black holes for the first time using indirect methods, which consisted of observing their effects on surrounding objects and space. Since the 1980s, scientists have studied supermassive black holes (SMBHs), which reside at the center of most massive galaxies in the Universe. And by April 2019, the Event Horizon Telescope (EHT) collaboration released the first image ever taken of an SMBH.

These observations are an opportunity to test the laws of physics under the most extreme conditions and offer insights into the forces that shaped the Universe. According to a recent study, an international research team relied on data from the ESA’s Gaia Observatory to observe a Sun-like star with strange orbital characteristics. Due to the nature of its orbit, the team concluded that it must be part of a black hole binary system. This makes it the nearest black hole to our Solar System and implies the existence of a sizable population of dormant black holes in our galaxy.

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Gaia Could Detect Free-Floating Black Holes Passing Near Stars in the Milky Way

The thing with black holes is they’re hard to see. Typically we can only detect their presence when we can detect their gravitational pull. And if there are rogue black holes simply traveling throughout the galaxy and not tied to another luminous astronomical, it would be fiendishly hard to detect them. But now we have a new potential data set to do so.  

Gaia just released its massive 3rd data set that contains astrometry data for over 1.5 billion stars, about 1% of the total number of stars in the galaxy. According to a new paper by Jeff Andrews of the University of Florida and Northwestern University, it might be possible for Gaia to detect perturbances caused by a rogue black hole briefly interacting with one of the 1.5 billion stars in the catalog. Unfortunately, it’s just not very likely that any such interaction actually took place during Gaia’s observing time.

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The Closeby Habitable Exoplanet Survey (CHES) Could Detect Exoplanets Within a few Dozen Light-Years of Earth Using Astrometry

Artist's concept of Earth-like exoplanets, which (according to new research) need to strike the careful balance between water and landmass. Credit: NASA

As of this article’s writing, NASA has indicated that 5,030 extrasolar planets have been confirmed in 3,772 systems, with another 8,974 candidates awaiting confirmation. With next-generation instruments like the James Webb Space Telescope (JWST) coming online, the number and diversity of confirmed exoplanets are expected to grow exponentially. In particular, astronomers anticipate that the number of known terrestrial planets and Super-Earths will drastically increase.

In the coming years, the opportunities for exoplanet studies will increase considerably as thousands more are discovered using various methods. In a recent study, a team led by the Chinese Academy of Sciences (CAS) described a new space-telescope concept known as the Closeby Habitable Exoplanet Survey (CHES). This proposed observatory will search for Earth-like planets in the habitable zones (HZs) of Sun-like stars within approximately 33 light-years (10 parsecs) using a method known as micro-arcsecond relative astrometry.

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The First Rogue Black Hole has Been Discovered, and it’s Only 5,000 Light-Years Away

Microlensing strikes again.  Astronomers have been using the technique to detect everything from rogue planets to the most distant star ever seen.  Now, astronomers have officially found another elusive object that has long been theorized and that we first reported on back in 2009 but has never directly detected – a rogue black hole.

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