The Week in Space and Physics: On The Edge of Stability
On the superheavy elements, a Moon rover cancelled, the most distant known ocean and Starliner.
The average atom of oganesson, the heaviest known element, falls apart in a little less than one one-thousandth of a second. It existed, if such a fleeting presence can really count as an existence, only in the aftermath of a violent collision between atoms of calcium and californium; an encounter arranged by physicists seeking the glory of ever heavier atoms.
Chemically speaking, oganesson lies at the end of the seventh row of the periodic table. Theoretically that makes it a noble gas, of the same group as neon, argon and krypton. In practice, oganesson seems to be nothing of the kind. As far as we can tell it is neither a gas - it is instead solid at room temperature - nor noble - it should instead be quite reactive. But we don’t really know, of course, since we’ve only ever made five atoms of the stuff.
As far as our experience actually goes, oganesson has more in common with the other superheavy elements. These, running from rutherfordium (element one-hundred-four) up to oganesson (element one-hundred-eighteen) are all unstable creatures, with only dubnium (one-hundred-five) lasting any sensible amount of time.
This instability is an inevitable consequence of their size. Each holds more than a hundred protons in their atomic nuclei, each of which is trying hard to repel all the others. In smaller atoms that repulsion is balanced by another force, the strong nuclear force, which pulls both neutrons and protons together. In the superheavy elements, however, the repulsive force far outweighs this strong force, and so the atoms must sooner or later split apart.
At some point, though, physicists believe an “island” of stability will emerge. Certain combinations of protons and neutrons should hold together better than others, and some estimates suggest the heaviest known atoms might be drawing close to a point where atoms are once again stable. The elements that belong to this island should, physicists think, last long enough for meaningful chemistry to occur.
Until recently, the search for these stable atoms has been hindered by experimental techniques. The heaviest known elements were made by smashing calcium atoms into other atoms, like californium. Yet oganesson is the heaviest atom that can be made by this approach, and it is not at all stable. To go further researchers must replace calcium with something else, but how to do that has, so far, been elusive.
Last week, however, researchers announced they’d created superheavy atoms with the use of titanium atoms in the place of calcium. So far this has merely recreated elements already made with other techniques, but it proves, for the first time, the viability of this new approach.
Researchers reckon this now opens the way to creating element one-hundred-twenty. If so, this would be the first element created on the eighth row of the periodic table, and one that should lie closer to the fabled island of stability. Getting there will be hard - it might take several years of work, the team behind the discovery said - but the island at last seems to be coming into sight.
Viper Cancelled
After spending close to half a billion dollars on a lunar rover, NASA this month abruptly cancelled the project. At blame, the agency said, was a price tag already far over the initial budget and a need to spend millions more on testing and operations. Instead of heading to the Moon, then, the rover may now be scrapped for parts.
The rover, named VIPER, was supposed to explore craters near the southern lunar pole. Water ice is thought to exist in the shadowed areas of those craters, and NASA wanted VIPER to find and extract some samples of it. In the future these ice reserves may act as a useful resource for astronauts. They could also offer insight into the origins of water on Earth and into the chemical makeup of the early Solar System.
Under original plans, VIPER should have reached the Moon in 2023. NASA wanted the rover to travel onboard a lander built by Astrobotic, one of several companies competing to put cargo on the lunar surface. Yet both the rover and the lander took longer to build than expected, and the landing date was delayed until 2025.
To make matters worse, Astrobotic’s first attempt to reach the Moon, made earlier this year, ended in disaster. A fuel leak appeared soon after it was launched, and instead of reaching the Moon the spacecraft was destroyed in the Earth’s atmosphere. Some of those involved in the project, according to an article in Nature, were sceptical of the company’s ability to land VIPER next year.
This is not the only recent NASA project to run into budget problems. Chandra, one of the world’s preeminent X-ray telescopes, is likely to shut down in the near future due to cuts in its funding. Dragonfly, a probe designed to fly across Saturn’s moon Titan, is facing delays after its projected price tag doubled. And the Mars Sample Return, a project to bring pristine samples of Martian rocks back to Earth, has been put on hold thanks to soaring costs.
Part of this is down to cuts in NASA’s overall budgets. But much is surely down to problems in the way the agency approaches and manages big scientific projects. Many of these are innovative, tackling things never done before, and are thus hard to budget properly. But at the same time, NASA’s recent moves have cut the output of some useful projects, while extending funding to others of questionable value. A rethink of priorities is sorely needed.
The Furthest Ocean
Seven years ago astronomers discovered a planet orbiting a small red star forty-nine light years away. It is, in many ways, an interesting planet. Its star is both old and cool, and seems to be rather calm, with few flares bursting out from its surface. The planet itself is larger than Earth, with a mass roughly five times greater. Though it is probably cooler than Earth, it should be warm enough to host liquid water.
A study last year found the density of the planet to be less than expected, given its size. That implied the planet was either a small gas giant, surrounded by a shell of hydrogen, or a vast water world, covered in a deep ocean of water.
Now, with the help of the James Webb telescope, researchers have taken a closer look at the planet’s atmosphere. It saw no sign of hydrogen, which almost certainly rules out the idea it is a small gas “giant”. But evidence of anything else was also weak. Most likely, they say, the planet has a nitrogen rich atmosphere along with an ocean, though they caution they still can’t be sure there is any atmosphere at all.
More observations will follow over the coming years, which should narrow down the possibilities. But if the ocean is confirmed then it really is an exciting discovery. It would be the first known ocean outside the solar system, and one of the only planets, aside from Earth, with a nitrogen-rich atmosphere. That makes this world worth studying.
Starliner - How Serious Are The Problems?
Boeing’s Starliner capsule remains docked at the space station, weeks after it should have returned to Earth. The two astronauts it took with it - Butch Wilmore and Sunita Williams - are still at the station, and have no clear date for when they might come home.
At blame are problems with Starliner’s thrusters. Specifically, the thrusters on the service module - a part of the spacecraft that is jettisoned before re-entry - appear to be faulty. Five of them failed as the capsule approached the station. NASA wants to fully understand the reasons why before they allow Starliner to depart and return to Earth.
Officially NASA is still confident the astronauts can return on Starliner. However, hints have emerged that the agency is exploring other options. This would probably include the astronauts coming back on SpaceX’s Dragon capsule instead, which could happen in the next few months. Such an outcome still seems unlikely, but it is significant that NASA is now taking the possibility seriously.
A really neat article collection!. That island of superheavy stability is exciting. Let's try sulfur. So is the planet! More woes in the budgets and hardware of Big Science. I miss the seventies and eighties! Viva cube sats!