The Week in Space and Physics: LIGO Restarts
On LIGO and gravitational waves, Blue Moon, a space tourism restart and a nearby supernova
From the beginning Newton had his doubts about gravity. How, he wondered, did the Earth hold the Moon, with no physical contact between them? How did gravity exert its pull, apparently invisibly, across the vast void of space? It was a great absurdity, he wrote, that his law of gravitation worked at all; a mystery for which he could famously propose no solution.
It took two centuries for physics to find an answer. Gravity, as Einstein formulated it, was a consequence of the interaction between matter and spacetime. The presence of matter distorts space and time and in turn, the theory goes, spacetime directs the movements of matter. Gravity, in effect, is how we perceive these distortions.
Yet Einstein’s theories went further. Taken to an extreme they predict bizarre things like black holes; patches of space so distorted they become isolated from the rest of the universe. They also imply the existence of gravitational waves, ripples in spacetime created by the movements of matter. Einstein was doubtful about both. Gravitational waves, he once argued, could not really be rippling across the cosmos.
On that he was wrong. In 2015 an experiment in America picked up an almost imperceptible fluctuation in a laser beam. It was, they later announced, the signature of a passing gravitational wave; a flutter caused by a slight expansion and contraction in the fabric of space as the wave swept through the Earth.
Its origin was traced to a cataclysmic collision between two black holes over one billion light years away. As the pair spiralled towards one another they distorted the space and time around them, sending waves echoing out across the cosmos. At the moment of collision the waves died away, as though a ringing gong had suddenly been silenced.
The experiment responsible for the discovery was LIGO, a facility specially built to search for such waves. Along with VIRGO, a similar experiment in Europe, LIGO has since made dozens of gravitational wave observations. Yet for the past three years the facility has been offline, awaiting planned upgrades.
With those improvements complete, researchers are now bringing the experiment back online. Over the next few years, they hope, LIGO will be able to spot smaller waves than ever before, giving us new insight into black holes, neutron stars and other ultradense objects.
Indeed, researchers expect to pick up signals from colliding black holes two or three times a week. Collaboration with other facilities in Europe, Japan and India should allow for triangulation of signals, a technique that means the precise origin of the waves can be found. That could open the doors to multi-messenger astronomy, in which researchers match gravitational wave observations with images captured by traditional telescopes.
Blue Origin Shoot for the Moon
NASA plans to land on the Moon in 2025. To do that, they’ll need a spacecraft cable of carrying astronauts back and forth from the lunar surface. In 2021 NASA chose SpaceX for this, selecting Starship as the lander for the first flights to the Moon.
SpaceX, though, was not the only contender. Blue Origin, a space company owned by Amazon founder Jeff Bezos, had also submitted a proposal to NASA, only to see it rejected. At the time, Blue Origin did not take the loss gracefully. They sued NASA, arguing the selection of SpaceX was unfair. Ultimately NASA won the case in court. Blue Origin, despite then offering NASA a huge discount, had no choice but to accept the outcome.
Two years later, however, and Blue Origin has found redemption of a kind. Though SpaceX has been confirmed for the first two human landings, Blue Origin has now been selected for the third landing, planned for 2029. The move comes after Blue Origin submitted a major rethink of their proposal, and after NASA stressed the need to have two options for the lander.
Blue Origin’s plan envisions placing a spacecraft, named Blue Moon, in orbit around the Moon. It will descend and ascend from the lunar surface as required and, as such, will be reused for many missions. To refuel Blue Moon after each mission, Blue Origin will partner with Lockheed Martin to build a fuel tug. This will carry fuel from the Earth to the Moon and handle the delicate task of deep space refuelling.
To do all this, Blue Origin must first perfect their New Glenn rocket. Despite initially planning for a launch in 2020, New Glenn still has not seen lift-off, nor made any attempt at doing so. Still, Blue Origin seems likely to succeed eventually, even if progress has been slower than expected. New Shephard rocket, their smaller suborbital rocket, has now flown over two dozen times, carrying several crews of astronauts on short trips to space.
A Space Tourism Reboot?
In 2021, as Virgin Galactic and Blue Origin took turns flying tourists to the edge of space, it looked like the dawn of space tourism was finally here. Yet in the two years since, space tourism has struggled to live up to that promise. Virgin Galactic has not flown a full mission since July 2021, and Blue Origin has been grounded since an aborted launch in September last year.
Shortly after their last flight in 2021, Virgin Galactic delayed the start of its commercial service. Upgrades and maintenance were needed on their spacecraft, they said at time. That work was supposed to be done by 2022, but the company was forced to delay things for far longer than planned. Last week, Last week, however, they made a sub-orbital test flight for the first time in almost two years.
An introduction of a commercial spaceflight service should now follow. First up is a crew of Italian Air Force specialists who have booked a dedicated flight for research purposes. Afterwards Virgin Galactic hopes to fly regularly, bringing vital income for a company that apparently lost five hundred million dollars last year.
SpaceX and Axiom, meanwhile, have continued developing their own brand of commercial spaceflight. Last week saw the Axiom-2 mission arrive at the International Space Station. The crew of four astronauts - two of which hail from Saudi Arabia - lifted off on a Falcon 9 rocket and travelled on SpaceX’s Dragon capsule to the space station. A third Axiom mission may take place later this year.
A Supernova in the Pinwheel Galaxy
A supernova erupted in the nearby Pinwheel Galaxy, otherwise known as M101. At a distance of twenty-one million light years, this is one of the closest supernova to have taken place in the last decade.
The initial discovery of the supernova was made by an amateur Japanese supernova hunter, Koichi Itagaki, on May 19. Automated telescope surveys, it was later found, had picked up the first traces of the supernova two days earlier. Astronomers may also have captured the doomed star in past images of the galaxy. Initial speculation focused on a star roughly fifteen times larger than the Sun.
The Pinwheel Galaxy makes a nice target for amateur astronomers, as it appears almost perfectly face-on from Earth. The new supernova is bright enough to be seen through small telescopes. Dozens of images comparing the galaxy before and after the appearance of the supernova have been shared online.
Blue Moon is arguably better suited to returning to the Moon than Starship's HLS. It is too bad that BO was so behind the curve in their initial proposal.