In October 2023, NASA launched its long-awaited on-again, off-again Psyche mission. The spacecraft is on its way to study the metal-rich asteroid 16-Psyche, an M-type asteroid that could be the remnant core of a planetesimal that suffered a collision long ago. But understanding the giant, metal-rich asteroid isn’t the Psyche mission’s only goal.
It’s also testing a new laser communication technology.
A few weeks ago, a team of scientists from Caltech announced that they had successfully transmitted energy from an orbiting satellite down to Earth. It wasn’t a lot of energy, but it showed that it was possible.
Eventually, we might be able to beam energy from solar satellites down to Earth, making solar energy available almost anywhere and helping combat climate change. But there’s another potential use: powering surface probes on Venus.
Every once in a while, the stars (or, in this case, satellites) align, and keen observers can receive an unexpected light show. That happened a few weeks ago at the Subaru telescope in Hawai’i. An eerie green laser seemingly appeared out of nowhere, as captured in a YouTube video uploaded to the telescope channel. Luckily, their source was no more ominous than a passing satellite, and with its video posted publicly, now everyone could enjoy the light show.
The vacuum of space isn’t really a vacuum. A vacuum is defined by Merriam-Webster as “a space absolutely devoid of matter.” However, even empty space has some matter in it. This matter, in the form of dust and gas, tends to collect into what are called molecular clouds. Without anything interfering with them they continue to float as a cloud.
When something happens to interrupt the balance of the molecular cloud, some of that dust and gas starts clumping together. As more and more of this dust and gas clump together gravity takes over and starts forming stars. One way that the balance of a molecular cloud can be interfered with is by a supernova remnant, the remains of an exploded star. Plasma jets, radiation, and other clouds can also interact with these clouds.
Galaxies don’t exist in a vacuum. Ok, maybe they do (mostly, since even interstellar space has some matter in it). But galaxies aren’t normally solitary objects. Multiple galaxies interacting gravitationally can form clusters. These clusters can interact with each other, forming superclusters. Our own galaxy is part of a group of galaxies called the Local Group. This Local Group is part of the Virgo Supercluster, which is in turn a part of a group of superclusters called the Laniakea Supercluster.
Mixed in with all of these galaxies is a lot of heat, with extremely high temperatures comparable to the core of our Sun, around 10 million Kelvin (27 million degrees Fahrenheit). This temperature is so hot that hydrogen atoms cannot exist, and instead of gas a plasma forms of protons and electrons. This is a problem for physicists though, who say it shouldn’t be that hot.
As Gianluca Gregori, a professor of physics at University of Oxford and one author of a new paper detailing an experiment to recreate the conditions inside a galaxy cluster, puts it: “The reason why the gas inside the galaxy cluster should have cooled down is simply due to the fact that the cluster has existed for a very long time (for a time which is comparable to the age of the Universe). So, if we assume thermal conduction works in the normal way, we would have expected the initial hot core to have dissipated its heat by now. But observations shows it has not.”
Between the exponential growth of the commercial space industry (aka. NewSpace) and missions planned for the Moon in this decade, it’s generally agreed that we are living in the “Space Age 2.0.” Even more ambitious are the proposals to send crewed missions to Mars in the next decade, which would see astronauts traveling beyond the Earth-Moon system for the first time. The challenge this represents has inspired many innovative new ideas for spacecraft, life-support systems, and propulsion.
In particular, missions planners and engineers are investigating Directed Energy (DE) propulsion, where laser arrays are used to accelerate light sails to relativistic speeds (a fraction of the speed of light). In a recent study, a team from UCLA explained how a fleet of tiny probes with light sails could be used to explore the Solar System. These probes would rely on a low-power laser array, thereby being more cost-effective than similar concepts but would be much faster than conventional rockets.
In some applications, bigger lasers mean better lasers. That is the case in astronomy, where lasers are used for everything from telescope calibration to satellite communication. The European Southern Observatory (ESO) and some of its commercial partners have developed a laser 3 times more powerful than the existing industry standard. With that increased power level, the new system has the potential to dramatically improve the way telescopes deal with one of the most fundamental problems in ground-based astronomy – atmospheric turbulence.
Solar sails have been receiving a lot of attention lately. In part that is due to a series of high profile missions that have successfully proven the concept. It’s also in part due to the high profile Breakthrough Starshot project, which is designing a solar sail powered mission to reach Alpha Centauri. But this versatile third propulsion system isn’t only useful for far flung adventures – it has advantages closer to home as well. A new paper by engineers at UCLA defines what those advantages are, and how we might be able to best utilize them.
Researchers at the Australian National University (ANU) are finding new uses for the laser-based technology that sharpens telescope imagery – called adaptive optics – and it just might help mitigate the world’s growing space debris problem. Purpose-built lasers could give derelict satellites a slight ‘push’ of photons, imparting just enough energy to change the debris’s orbit and prevent an impending collision.
If humans want to travel about the solar system, they’ll need to be able to communicate. As we look forward to crewed missions to the Moon and Mars, communication technology will pose a challenge we haven’t faced since the 1970s.