The Week in Space and Physics: India on the Moon
On India's space program, the origin of magnetars, the search for Planet X and a cyberattack on America's telescopes
The last great age of lunar exploration came to an end half a century ago. It was an era marked by discovery and competition; a time in which bitter Cold War rivals used the Moon to prove their superiority by scientific might. Over the two decades it lasted, both the Soviets and the Americans sent dozens of orbiters, landers and astronauts, leaving behind flags and hauling back trophies in the form of dusty rocks.
Those days have long since passed. As the Cold War moved on, and eventually thawed, the Moon was neglected. Plans to build bases on the Moon came to naught, exploration all but ceased and astronauts never returned. Yet interest in the Moon has never quite died. Today, indeed, a new era of exploration seems to be unfolding, led not by America and Russia, but by two emerging powers in Asia.
Both India and China have, in recent years, sent a series of probes to the Moon, scanning its features from orbit. Both, now, have also reached its surface - becoming the only two nations in the last forty years to do so. As they go they are reawakening interest in our natural satellite; paving the path - one hopes - for a more sustained effort to move humanity beyond our planet.
The latest triumph, of course, belongs to India. Their Chandrayaan-3 mission last week touched down on the surface of the Moon, placing a lander in the region of the lunar south pole. An accompanying rover, Pragyaan, is now exploring the landing site - the most southerly point of the Moon yet visited by any nation.
Although Pragyaan carries tools to conduct geological studies, the main focus of the mission was to prove its ability to land. India’s last attempt - Chandrayaan-2 - crashed as it closed in on the surface, apparently experiencing software issues at a crucial stage.
Chandrayaan-3 has laid the ghosts of that failure to rest. It has also demonstrated India’s progress, and ability to learn, in space exploration. Indeed, India already has plans to send another, more capable, rover to the Moon - this time in collaboration with Japan - and has talked about sending probes to Mars and Venus within a decade. An Indian solar observatory, Aditya-L1, looks more certain, with a launch expected as soon as next week.
After robots, of course, questions will soon be asked about the potential for human landings. Yet unlike the other three powers to reach the Moon, India still has not put astronauts of its own into orbit. China, by contrast, already has a space station in orbit, and talks of sending humans to the Moon by the 2030s.
India’s astronaut program, named Gaganyaan, seems to have run into delays. Though a crewed flight was originally planned for 2021, problems with capsule parachutes have pushed that to 2025, at the earliest. A series of test flights should precede that, though whether they will fly next year, as hoped, remains to be seen. Still, India does seem likely to eventually succeed in their efforts. One day, indeed, we may well see Indian footsteps on the Moon.
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The Origin of the Magnetars
Among the two hundred billion stars that make up the Milky Way, just thirty are known to be magnetars. Each is a dense blob of material, compressing a mass equal to that of the entire Sun into a volume a mere twenty kilometers wide. From within erupt powerful magnetic fields so intense that atoms deform and the vacuum of space itself begins to distort.
These rare and bizarre objects are, naturally, the object of much study. They appear to be a type of neutron star, although ones with unusual magnetic properties. Like other neutron stars they are created when massive stars die, forming as their inner cores crush under tremendous pressures.
Most neutron stars, however, are not so magnetic. Partly that is because magnetars do not last long. Their intense magnetism seems to fade over a few thousand years, after which they look much like any other neutron star. Yet it also appears magnetars have a slightly different origin story, forming only when an already intensely magnetic star collapses.
Now, for the first time, astronomers have found a star that seems likely to collapse into a magnetar when it dies. The object, which sits some three thousand light years from Earth, is a Wolf-Rayet star, a rare kind of star that burns helium instead of hydrogen and glows incredibly brightly.
A recent examination, however, found that this star is intensely magnetic; perhaps the most magnetic large star ever found. It also appears to have an unusual history. After studying it, researchers think it probably formed when two smaller helium burning stars merged into one. That event could have created the strong magnetic fields now running through the star.
Eventually, they say, this star will collapse. When it does, it will form a neutron star with an even stronger magnetic field: creating a magnetar, in other words. This, then, gives us a first glimpse of the kinds of objects that later evolve into magnetars. Yet astronomers also acknowledge this is a highly unusual case. Other magnetars, they say, probably formed in different ways, though exactly how is still an open question.
The Search for Planet X
Does another planet lurk at the edge of the Solar System, hidden in the distant gloom? Speculation about such a world has been rife for decades, inspired by odd patterns in the orbits of distant asteroids. If it exists it is probably a large planet, perhaps ten times the size of Earth, lying many times further away than even Pluto.
Not everyone, however, is convinced that such a planet is necessary. The patterns in asteroid orbits are imagined, they say, and ruled out by more rigorous analysis. Others have pointed out that the effects of an extra planet should be felt more widely, since it should exert a slight pull on every other object in the solar system.
In a recent paper, a graduate student at the University of Pennsylvania took a closer look at those effects. Our interplanetary spacecraft, he says, should have been knocked slightly off course if an extra planet is out there. He reckons that if this planet is less than forty billion miles from the Sun - that’s to say, up to ten times more distant than Pluto - we would have spotted its impact on our spacecraft.
That seems to rule out some possibilities for the fabled Planet X. Yet the paper does note that a more distant planet could still exist, since its pull would be too small for us to have noticed. That, then, does not quite eliminate the prospect of another world in our solar system. Some calculations, indeed, have placed its possible orbit as far as one hundred billion miles from the Sun.
Top Telescopes Under Attack
Hackers seem to have struck many of America’s top telescopes, affecting the ability of astronomers to use them. According to a report in Science, ten telescopes in Hawaii and Chile have been attacked, halting observations for at least three weeks.
Because most telescopes are located in isolated regions, astronomers typically rely on computer systems to control them remotely. Yet at the start of August observatories reported cyberattacks on those systems, placing the telescopes in danger. To prevent damage, managers were forced to shut down the affected computer systems.
The reasons behind the attack seem unclear, or at least have not been publicly released. Worried astronomers, meanwhile, have been attempting to carry on work by visiting observatories in person - thus removing the need for remote access computer systems.
This, however, will not be sustainable for long. Instead astronomers will soon need to rethink the way they secure telescopes, while still allowing the data they collect to flow freely.
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