The Week in Space and Physics: Cosmic Filaments
On a set of mysterious filaments, the new Moon race, Starliner and Earth's new moon
Some ten million stars lie within a parsec of the galactic centre. That’s a fantastic number, especially when you remember that only one star, the Sun, lies within a parsec of Earth. In the midst of those ten million stars, positioned in the very heart of the galaxy, is the supermassive black hole Sagittarius A*; itself weighing in at over four million solar masses.
Its presence adds an element of chaos to the already crowded core. Around it stars move at incredible speed, propelled forward by its intense gravitational field. Those that dare approach it, swinging past its event horizon, can reach speeds almost half that of light. Speeds so fast, indeed, that astronomers sometimes use them to test extreme theories of physics.
Arranged vertically above and below the black hole, as astronomers discovered in the 1980s, are long filaments of gas. These align along the magnetic field of the galaxy, sometimes stretching over one hundred light years in length. Where they come from is still unknown, but they appear to be highly magnetic. As particles accelerate through those magnetic fields they act as a kind of radio antenna, generating bursts of energy detectable from Earth.
Now, forty years after that discovery, astronomers have spotted a second set of filaments stretching around the black hole. Like the vertical filaments, these new filaments are aligned with the black hole. But instead of aligning vertically, they do so horizontally, pointing out into the plane of the galaxy. That’s puzzling, the study’s author Farhad Yusef-Zadeh says, as there is no magnetic field for them to align with. Theoretically, they should be scattered randomly, pointing in every direction conceivable.
Something, therefore, must have happened to align them with the black hole. In his paper Yusef-Zadeh speculates that our black hole passed through an active phase some six million years ago. As it did, it would have sent a wave of energy and gas flowing outwards through the galaxy. That would have exerted pressure, bringing the filaments into alignment; rather as ripples flowing through water align needles floating on the surface.
Black holes in other galaxies are known to show active phases. These are sometimes triggered by collisions between galaxies - a sudden flow of new material into a black hole can send bursts of energy and matter shooting out. But quite what would have triggered an active phase in Sagittarius A* a few million years ago remains mysterious. So too is the question of whether it has calmed down yet.
Indeed, some evidence hints that our black hole has seen recent signs of activity. One study speculates that it may have sent out a dramatic flare just two centuries ago - a flare that has left a fingerprint on nearby clouds of gas. That, along with the newly discovered filaments, suggests our black hole is worth keeping an eye on.
The New Moon Race
As America inches towards another Moon landing, China has been sketching out a lunar future of its own. For much of the past few years their focus has been on Chang’e, a set of robotic lunar missions that have demonstrated Chinese prowess in space. Over time, China has said, Chang’e will help build up a robotic base on the Moon.
In the past, China has implied that this base would pave the road towards human landings in the 2030s. Yet occasional hints have suggested China is looking to a more ambitious target of landing by 2030 - a goal that would put China in close competition with America. Last week China made that official, with a deputy director of China’s space agency announcing plans to reach the surface before the end of the decade.
America, by contrast, is targeting a moon landing by 2025. If they can do that, they will arrive well before the Chinese. Yet a 2025 landing looks increasingly unlikely, especially as NASA has never been given the funds needed to reach the Moon so quickly. Today, with landing systems and spacesuits yet to be tested, a landing in 2026 or 2027 looks far more reasonable. Further delay - which is also likely - could push that date towards the end of the decade.
NASA, however, is far more transparent than the Chinese space agency. Problems and delays with Artemis are visible for all to see, but those that afflict China’s moon program are far harder to divine. Indeed, China has not yet flown a rocket capable of sending astronauts to the Moon, and only recently started work on a Moon lander. Whether it is truly capable of a moon landing by 2030 is impossible to say.
Still, if China is serious about landing before 2030, the second half of this decade may see an escalating race between the superpowers. America surely has the lead - they have already flown a Moon rocket and a capsule, after all - but China seems intent on catching up fast. A new space race may just be kicking off.
Starliner Hits Turbulence
Nine years ago, NASA asked two companies to develop capsules capable of ferrying astronauts to the International Space Station. One of them, SpaceX, rose to the occasion magnificently. The Crew Dragon, their capsule, has now flown ten times; carrying seven NASA crews to the space station, as well as three private crews.
Yet the other, Boeing, has struggled to do as NASA asked. Though their Starliner capsule first flew in late 2019, its test flight was marred with difficulties. Software bugs placed it in the wrong orbit and left its fuel tanks exhausted. Though it did manage to return safely to Earth, later reports showed that critical bugs had to be fixed in order for it to do so.
A second test flight last year went more smoothly, and Boeing had expected to make a first crewed flight to the space station this summer. Unfortunately, Boeing last week announced an indefinite halt to those plans. The company said that two critical faults had been found, both of which must be resolved before the spacecraft can fly again.
One issue concerns the capsule’s parachutes, which have turned out to be more dangerous than expected. A second issue involves the tape used to wrap wire harnesses inside the capsule. This tape, it emerged, is flammable, and thus represents a safety hazard.
Neither of these issues seems unresolvable, but they will take time and effort to fix. Instead of flying this summer, as hoped, Starliner now looks unlikely to reach the space station before 2024, at the earliest.
Quasi Moon
In recent weeks astronomers have found a new “quasi” moon lingering around the Earth. The rock, which measures only fifteen meters across, follows a long looping orbit that sees it swing between the orbits of Mars and Venus.
As it does, the rock, named 2023 FW13, consistently circles the Earth, making it a kind of moon. To be clear, of course, this is not a moon like the Moon, but rather an asteroid that happens to circle the Earth during its annual voyage around the Sun. One other rock, dubbed Kamo’oalewa, is known to make a similar journey, though it does tend to stick much closer to Earth.
Calculations suggest 2023 FW13 has been shadowing the Earth for over two thousand years, and is likely to continue doing so for at least another millennium and a half. Eventually, and somewhat sadly, the gravitational pull of the other planets will drag it away from Earth, leaving it to voyage on alone.