For decades, space agencies have relied on astronauts to take precarious and time-consuming spacewalks, but today, space station operators are increasingly turning to robots to perform tasks in orbit.

Why it matters: Using robots instead of astronauts for routine spacewalks would make spaceflight safer and more efficient, experts say, freeing up humans to only take walks in space during an emergency or for delicate experiments in microgravity.

Driving the news: Astronauts on the International Space Station are in the midst of a marathon 10 spacewalks focusing on station upkeep and repairs to a science instrument.

• Ground controllers were able to use robotics to help set up some activities ahead of the spacewalks, making them easier for astronauts to perform.
• But even with that robotic help, these spacewalks have taken dozens of hours of planning and training and represent one of the most dangerous activities astronauts can perform in space.

Details: The Dextre robotic tool — which comes equipped with 2 arms and 4 tool holders — on the outside of the ISS was used to loosen bolts before astronauts stepped out on their first walk in the series this month.

• In the future, robotic tools could also take the place of astronauts in constructing stations while in orbit and inspecting components of those stations once built, aerospace engineer Ella Atkins of the University of Michigan and IEEE told Axios via email.
• Humanoid robots in the vein of NASA's Robonaut might be able to take even more of that responsibility off of the shoulders of astronauts.

What's next: NASA's small Gateway station around the Moon will be designed to minimize the number of spacewalks needed at any given time, making use of advances in robotics.

• And the Gateway will not be crewed year-round, making it more important that mission managers have robots at their service.
• "By designing your vehicle to favor the robot, chances are good that anything the robot can do, humans can do as well, whereas vice versa isn't always true," NASA's lead for robotics flight controllers Laura Lucier told Axios.

Yes, but: It's unlikely robots will fully take over all spacewalking operations, and there are other ways to reduce the number of spacewalks needed aboard orbiting outposts.

• Humans will be needed for excursions on the Moon or other bodies that are far less efficient with robots alone, such as collecting or examining rocks.
• Axiom Space — a company that plans to build a commercial space station — is putting many of its critical systems inside its station and will make use of robotics outside, reducing the need for frequent spacewalks, Axiom CEO Michael Suffredini told Axios.
• It's also possible that spacewalking will be a draw for people hoping to visit privately built space stations, Suffredini said, though it's not yet clear what kind of market those stations will have.

Go deeper: Alexei Leonov, Soviet cosmonaut and the first person to walk in space, dies at 85 (Washington Post)

The interstellar comet discovered in August looks very similar to comets originating in our own solar system, according to a new study in Nature Astronomy this week.

The big picture: Comet 2I/Borisov represents just the second known interstellar object to make its way through our solar system, and it's astronomers' best chance so far to study a piece of a distant star system at close range.

• Even if it does turn out that the comet is just like those native to our solar system, it will show astronomers that other planetary systems light-years from our own likely formed in similar ways.

What they found: Unlike the strange cigar shape of the first interstellar object — named 'Oumuamua and seen in 2017 — 2I/Borisov has a pronounced dust tail and a reddish color that can be compared to other comets, according to the study.

• "In combination with what we have learned from peculiar `Oumuamua, it tells us that there may be a lot of diversity in other planetary systems and the formation of minor bodies," Piotr Guzik, one of the authors of the new study, told Axios via email.
• The team began their observations of the comet on Sept. 10, using the Gemini North Telescope in Hawaii and the William Herschel Telescope in Spain.

"This is a quick first look at the object and is showing what everyone has seen who has been observing this," University of Hawaii astronomer Karen Meech, who did not take part in the study, told Axios via email.

What to watch: Astronomers will be keeping a close eye on 2I/Borisov as long as it's visible from Earth.

• An earlier study submitted to The Astrophysical Journal Letters found cyanogen, a common molecule in solar system comets, in 2I/Borisov's atmosphere.
• However, the comet still isn't in the perfect position to be able to get a good look at its chemical signature yet.
• As the object gets closer — with its closest flyby of the Sun expected in early December — scientists should be able to piece together the chemical makeup of the comet's atmosphere and figure out just how familiar or alien it really is.

A NASA satellite designed to investigate a critical layer of Earth's atmosphere launched to space last Thursday.

• The spacecraft — called the Ionospheric Connection Explorer (ICON) — is tasked with gathering data about the ionosphere in order to understand how the region affects satellites and people in space.

Why it matters: Scientists think the ionosphere can interfere with communications, expose astronauts to high radiation and even drag satellites down through the atmosphere earlier than expected when space weather hits.

• “ICON will be the first mission to simultaneously track what’s happening in Earth’s upper atmosphere and in space to see how the two interact, causing the kind of changes that can disrupt our communications systems," Nicola Fox, NASA's director for heliophysics, said in a statement.

Details: 3 of ICON's 4 instruments are designed to study airglow — bands of faint light created when neutral particles in the atmosphere are slammed by radiation from the sun, exciting the particles and causing them to emit light.

• Airglow is similar to the northern or southern lights, but instead of being relegated just to high latitudes, airglow instead appears all over the world.
• ICON data should help piece together how airglow works.
• The spacecraft's 4th instrument will measure the environment around ICON.

The bottom line: Space weather poses a major threat to people living in space and satellites in orbit, so the data ICON gathers about the way the ionosphere behaves is critical to help protect those assets and people in orbit.

The exquisite boredom of spacewalking (Marina Koren, The Atlantic)

Boeing to launch unpiloted Starliner test flight in December (Hanneke Weitering, Space.com)

China begins preparations for crucial Long March 5 rocket launch (Andrew Jones, Space News)

Satellite broadband's boom (Axios)

The eerie streaks within a crater on Mars show off the planet's strange, alien geology.

• The photo, taken by the Mars Reconnaissance Orbiter, shows lines left behind by material that has fallen down from the steep sides of the impact crater after it was formed.
• These kinds of streaks and craters are interesting for scientists because they expose Martian dirt that would usually be covered, allowing them to study new kinds of material from above.
• The orbiter has been circling Mars since 2006.