Buzz Aldrin Finally Told the Truth about the Moon Landing – "We Didn’t Go There" (VIDEO)
Nasa has recently announced US$600,000 (£495,000) in funding for a study into the feasibility of sending swarms of miniature swimming robots (known as independent micro-swimmers) to explore oceans beneath the icy shells of our Solar System’s many "ocean worlds". But don’t imagine metal humanoids swimming frog-like underwater. They will probably be simple, triangular wedges.
Pluto is one example of a likely ocean world. But the worlds with oceans nearest to the surface, making them the most accessible, are Europa, a moon of Jupiter, and Enceladus, a moon of Saturn.
ife inside ocean worlds
These oceans are of interest to scientists not just because they contain so much liquid water (Europa’s ocean probably has about twice as much water as the whole of Earth’s oceans), but because chemical interactions between rock and the ocean water could support life. In fact, the environment in these oceans may be very similar to that on Earth at the time life began.
These are environments where water that has seeped into the rock of the ocean floor becomes hot and chemically enriched – water that is then expelled back into the ocean. Microbes can feed off this chemical energy, and can in turn be eaten by larger organisms. No sunlight or atmosphere is actually needed. Many warm, rocky structures of this sort, known as "hydrothermal vents", have been documented on Earth’s ocean floors since they were discovered in 1977. In these locations, the local food web is indeed supported by chemosynthesis (energy from chemical reactions) rather than photosynthesis (energy from sunlight).In most of our Solar System’s ocean worlds, the energy that heats their rocky interiors and prevents the oceans from freezing all the way to the base comes principally from tides. This is in contrast to the largely radioactive heating of the Earth’s interior. But the chemistry of the water-rock interactions is similar.
Enceladus’s ocean has already been sampled by flying the Cassini spacecraft through plumes of ice crystals that erupt through cracks in the ice. And there are hopes that Nasa’s Europa Clipper mission may find similar plumes to sample when it begins a series of close Europa flybys in 2030. However, getting inside the ocean to go exploring would potentially be much more informative than merely sniffing at a freeze-dried sample
In the Swim
This is where the sensing with independent micro-swimmers (Swim) concept comes. The idea is to land on Europa or Enceladus (which would be neither cheap nor easy) at a place where the ice is relatively thin (not yet located) and use a radioactively heated probe to melt a 25cm-wide hole through to the ocean – located hundreds or thousands of metres below.
Once there, it would release up to about four dozen 12cm long, wedge-shaped micro-swimmers to go exploring. Their endurance would be much less than that of the 3.6m long autonomous underwater vehicle famously named Boaty McBoatface, with a range of 2,000km that has already achieved a cruise of more than 100km below the Antarctic ice.At this stage, Swim is merely one of five "phase 2 studies" into a range of "advanced concepts" funded in the 2022 round of Nasa’s . So there are still long odds against Swim becoming a reality, and no complete mission has been scoped out or funded.
The micro-swimmers would communicate with the probe acoustically (through sound waves), and the probe would send its data via cable to the lander on the surface. The study will trial prototypes in a test tank with all subsystems integrated.
Each micro-swimmer could explore maybe only tens of metres away from the probe, limited by their battery power and the range of their acoustic data link, but by acting as a flock they could map changes (in time or location) in temperature and salinity. They may even be able to measure changes in the cloudiness of the water, which could indicate the direction towards the nearest hydrothermal vent.
Power limitations of the micro-swimmers may mean that none could carry cameras (these would need their own light source) or sensors that could specifically sniff out organic molecules, though. But at this stage, nothing is ruled out.
I think finding signs of hydrothermal vents is a long shot, however. The ocean floor would, after all, be many kilometres below the micro-swimmer’s release point. But, to be fair, pinpointing vents is not explicitly suggested in the Swim proposal. To locate and examine the vents themselves, we probably do need Boaty McBoatface in space. That said, Swim would be a good start.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Astronomers estimate that our galaxy has about one exoplanet for every star. Of course, some stars have many planets, such as our Sun, which has eight. And some stars have none. However, if a star lives long enough, planet formation appears to be the rule rather than the exception.
That doesn’t mean astronomers will be able to map all of those billions of stars. The number of exoplanets that have been measured or counted in some way is much smaller.
As of this writing, the total number of confirmed exoplanets stands at 5,108. Astronomers, on the other hand, are surprisingly good at figuring out what they can’t see. They are aware that their telescopes are insufficiently powerful or precise to detect the most elusive planets – those that are very small, very far from their stars, or orbit stars very far from Earth. And conversely, there are regions of space where astronomers are pretty confident they’ve found all the planets within a certain range.
By combining the knowledge of what they can see – the known exoplanets – with the knowledge of what they can’t see – the parts of space currently beyond our ability to investigate – astronomers end up at the approximation of one planet per star. Astronomers believe they have discovered the first extragalactic exoplanet beyond our own galaxy. The binary system M51-ULS-1, located 28 million light-years away near the heart of the Whirlpool Galaxy (M51), consists of either a neutron star or a black hole tangoing with a more typical companion star.
Astronomers used X-ray data rather than more traditional visual observations to locate the distant planet hidden in this system. "We are trying to open up a whole new arena for finding other worlds by searching for planet candidates at X-ray wavelengths, a strategy that makes it possible to discover them in other galaxies," said study lead Rosanne Di Stefano of the Harvard-Smithsonian Center for Astrophysics in a press release.The Whirlpool Galaxy (left) in X-ray and optical light. On the right is an artist’s concept of the M51-ULS-1 system with the neutron star or black hole syphoning material from its companion star. The planet is eclipsing the X-rays generated by the superheated material around the compact object.
X-ray: NASA/CXC/SAO/R. DiStefano, et al.; Optical: NASA/ESA/STScI/Grendler; Illustration: NASA/CXC/M.WeissThe new study,
which was published in Nature Astronomy, looked at three galaxies: M51, M101, and M104. Using the Chandra X-ray Observatory and the European Space Agency’s XMM-Newton, the team targeted more than 200 total star systems within these galaxies. They discovered only one exoplanet in all of those systems.So far, researchers have primarily used two methods to identify the over 4,000 confirmed exoplanets. The radial velocity method determines how much a star wobbles when an orbiting planet gently tugs on its stellar host. Even though stars have far more mass than the planets that orbit them, even a small planet can cause its star to move slightly, leaving an imprint in the star’s light.In contrast, the transit method takes advantage of a planet passing in front of its star. This temporarily dims the starlight by a noticeable amount. Even though planets are much smaller than stars, researchers can detect these delicate but detectable variations in brightness.
Although both the radial velocity and transit methods are clearly effective, they can only find planets up to about 3,000 light-years from Earth. That is still well within the bounds of our Milky Way galaxy, which spans approximately 100,000 light-years.
To find the first extragalactic planet,
scientists decided to look for passing planets within X-ray binaries. A white dwarf, neutron star, or black hole would pull material from a companion star in these systems. When this material collides with the exotic stellar remnant, it becomes superheated and emits X-rays.
Unlike optical light transits, where a relatively small planet only blocks a tiny amount of starlight, the area where X-rays are produced in such binary systems is small enough that even a planet can block a significant portion (if not all) of the X-ray light. This means that X-ray transits can be found at much greater distances than visual transits.
The black hole or neutron star
in the M51-ULS-1 system is closely orbited by a star 20 times the mass of the Sun. This makes the system one of the most visible X-ray binaries in M51. Using Chandra data, researchers discovered that the X-rays typically emitted by the system dropped to zero for 3 hours. The researchers believe that a Saturn-sized exoplanet is orbiting the compact object at a distance of 19.2 astronomical units (AU; where 1 AU is the average distance between Earth and the Sun). That is roughly twice the distance between Saturn and the Sun.
Of course, an exoplanet isn’t the only possibility for why the X-ray signal was disrupted. A cloud of dust passing in front of an X-ray source can also obscure it. The researchers did consider this explanation, too, but they ultimately concluded it was less likely than an exoplanet.
Unfortunately, it will take a long time to confirm the extragalactic detection. Because of its large orbit, the candidate will not pass in front of the source for another 70 years.
Rough past
If M51-ULS-1 is a planet, the Saturn-sized object has a turbulent past.
The presence of a neutron star or black hole indicates that the system once housed not only the current companion star, but also another dying star. This doomed star would have used up all of its fuel before exploding as a supernova, bathing any nearby planets in intense radiation.
And, because the system’s massive current companion star is still alive and well, it’s entirely possible that this extragalactic exoplanet will be forced to survive another destructive supernova in the future.
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