Space News & Blog Articles

Think about background radiation and most people immediately think of the cosmic background radiation and stories of pigeon excrement during its discovery. That’s for another day though. Turns out that the universe has several background radiations, such as infrared and even gravitational wave backgrounds. NASA’s New Horizons is far enough out of the Solar System now that it’s in the perfect place to measure the cosmic optical background (COB). Most of this light comes from the stars in galaxies, but astronomers have always wondered if there are other sources of light filling our night sky. New Horizons has an answer. No!

Ok lets talk pigeon excrement.  Back in 1965 two telecommunication engineers were exploring signal interference at the Bell Laboratory. Penzias and Wilson detected a faint ‘hum’ in all directions and initially put it down to pigeon excrement as they nested in the horn of the radio receiver. Instead, what they had discovered was the cosmic background radiation, the faint glow that permeates the entire universe and is the thermal radiation left over from the Big Bang. Studying it allows us to understand more about the Universe when it was 380,000 years old. 

In the late 80’s a different type of background radiation was detected; the infrared background radiation. It consists of the diffuse infrared glow that fills the universe coming from numerous sources throughout the history of the universe. It is mostly from thermal emissions from dust grains heated by stellar radiation. In addition to this is the gravity wave background although this has yet to be detected. 

Another hotly debated background is the cosmic optical background (COB), a diffuse light which originates from stars and galaxies and spans the whole of the visible spectrum. There has been gathering momentum in its study however with observations from Hubble Space Telescope and the Spitzer Infrared Telescope. The studies however revealed that a large contribution to a general background optical glow come from faint unresolved galaxies. The study of the COB allows us to explore the total energy output of the universe, about galaxy and star formation across the history of the cosmos. 

The detection of the COB is a challenging one however with Earth based instruments or even those in Earth orbit plagued by interference. The zodiacal light for example is the result of sunlight scattered by interplanetary dust, it is dominant in the inner solar system  and makes studies of the COB difficult. The New Horizon probe is ideally positioned out beyond the orbit of Pluto over 8 billion kilometres away from interference. On board New Horizons is the LORRI (Long Range Reconnaissance Imager) camera which was identified as an ideal platform to begin a search. 

The prospect of actually resolving the event horizon of black holes feels like the stuff of science fiction yet it is a reality. Already the Event Horizon Telescope (EHT) has resolved the horizon of the black holes at the centre of the Milky Way and M87. A team of astronomers are now looking to the next generation of the EHT which will work at multiple frequencies with more telescopes than EHT. A new paper suggests it may even be possible to capture the ring where light goes into orbit around the black hole at the centre of the Milky Way. 

Black holes are strange objects that are the powerhouses of many galactic phenomenon. They have a complex anatomy with a singularity at the centre, a point of infinite density where gravity is so intense that the laws of physics cease to work. Surrounding the singularity is the event horizon, the boundary beyond which, nothing, not even light can escape. Just outside the event horizon is the photon ring and it is here that light is bent into a circular orbit around the singularity. Further out than this is the accretion disk but the focus of the next generation Event Horizon Telescope will be the photon ring. 

The Event Horizon Telescope name is a little misleading for it is not one telescope but a global network of radio telescopes that work together to act as a virtual Earth-sized radio telescope. The technology that makes this happen is known as interferometry where the telescopes are all connected together. The very long baseline of the telescope or put more simply the fact it is virtually VERY big means it has incredible resolution capabilities allowing it to capture the event horizon around Sagittarius A at the centre of the Milky Way and also of the black hole at centre of M87.

The EHT was launched in 2009 but now attention is turning to the next generation. The addition of ten new dishes and a whole host of new technology will transform EHT. Modern high-speed data transfer protocols will speed up transfer times and the addition of new dishes and technology will mean EHT will be able to observe at 86, 230 and 345 GHz simultaneously. This allows for the utilisation of frequency phase transfer techniques where lower frequency data can be used to supplement higher frequency. Using this will mean integration times of minutes at 345 GHz rather than seconds opening up a whole universe of new observations such as, the photon rings of black holes. 

Studies of the supermassive black hole at the centre of M87 and Sagittarius A suggest a magnetically arrested accretion disk. In this accretion model, the accretion disk forms a series of irregular spiral streams and a vertical magnetic field, which is split into separate field lines, pokes through the accretion plane. As the disk rotates the material spirals inward, dragging the field lines and twist them around the axis of rotation leading to the formation of jets. These magnetically arrested disks exhibit symmetrically polarised synchrotron emissions which were used by a team of astronomers to study the detectability of the photon ring using next generation EHT.

The field of extrasolar planet studies has grown exponentially in the past twenty years. Thanks to missions like Kepler, the Transiting Exoplanet Survey Satellite (TESS), and other dedicated observatories, astronomers have confirmed 5,690 exoplanets in 4,243 star systems. With so many planets and systems available for study, scientists have been forced to reconsider many previously-held notions about planet formation and evolution and what conditions are necessary for life. In the latter case, scientists have been rethinking the concept of the Circumsolar Habitable Zone (CHZ).

By definition, a CHZ is the region around a star where an orbiting planet would be warm enough to maintain liquid water on its surface. As stars evolve with time, their radiance and heat will increase or decrease depending on their mass, altering the boundaries of the CHZ. In a recent study, a team of astronomers from the Italian National Institute of Astrophysics (INAF) considered how the evolution of stars affects their ultraviolet emissions. Since UV light seems important for the emergence of life as we know it, they considered how the evolution of a star’s Ultraviolet Habitable Zone (UHZ) and its CHZ could be intertwined.

The research team was led by Riccardo Spinelli, an INAF researcher from the Palermo Astronomical Observatory. He was joined by astronomers from the National Institute of Nuclear Physics (INFN), the University of Insubria, and the Astronomical Observatory of Brera. Their paper, “The time evolution of the ultraviolet habitable zone,” recently appeared in the Monthly Notices of the Royal Astronomical Society: Letters.

This infographic compares the orbit of the planet around Proxima Centauri (Proxima b) with the same region of the Solar System. Credit: ESO

As Spinelli told Universe Today via email, the UHZ is the annular region around a star where a planet receives enough UV radiation to trigger the formation of RNA precursors but not so much that it destroys biomolecules. “This zone primarily depends on the star’s UV luminosity, which decreases over time,” he said. “As a result, the UV habitable zone is farther from the star during the early stages of the star’s evolution and gradually moves closer to the star as time progresses.”

On May 30th, the Mars Curiosity rover was just minding its own business exploring Gediz Vallis when it ran over a rock. Its wheel cracked the rock and voila! Pure elemental sulfur spilled out. The rover took a picture of the broken rock about a week later, marking the first time sulfur has been found in a pure form on Mars.

After Curiosity’s encounter with the broken rock and its pure sulfur innards, the rover trundled over to another rock, called “Mammoth Lakes” for a little drilling session. Before it left to explore other rocks, the rover managed to cut into that rock and take samples for further study to find out its chemical composition.

It’s not that sulfur isn’t prevalent on Mars. It is, but in different forms. The stuff is highly abundant in the Solar System, so this find isn’t as surprising as you’d think. However, Curiosity finding pure sulfur in the middle of broken rocks is a new experience in Mars exploration. So, of course, that’s raising questions about how it got there and its implications for habitable environments in Mars’s long history.

At the moment, the Curiosity rover is making its way through the Gediz Vallis. That’s a flow channel winding its way down a section of Mount Sharp (aka Aeolis Mons). That’s the central peak of Gale Crater. The rover has been heading up since 2014, charting different surface layers as it goes. Each layer was put down during a different era of Mars’s history. They could contain clues to the planet’s habitability in the past.

Fast-moving liquid water raged over the surface and carved Gediz. The floods carried a lot of rocks and sand and deposited them all along the way. Other piles of flood debris lie around the region, bearing witness to other ancient floods and landslides. “This was not a quiet period on Mars,” said Becky Williams, a scientist with the Planetary Science Institute in Tucson, Arizona, and the deputy principal investigator of the Mast Camera, or Mastcam on Curiosity. “There was an exciting amount of activity here. We’re looking at multiple flows down the channel, including energetic floods and boulder-rich flows.”

One of the challenges engineers face when developing technologies for use in space is that of different gravities. Mostly, engineers only have access to test beds that reflect either Earth’s normal gravity or, if they’re fortunate, the microgravity of the ISS. Designing and testing systems for the reduced, but not negligible, gravity on the Moon and Mars is much more difficult. But for some systems, it is essential. One such system is electrolysis, the process by which explorers will make oxygen for astronauts to breathe on a permanent Moon or Mars base, as well as critical ingredients like hydrogen for rocket fuel. To help steer the development of systems that will work in those conditions, a team of researchers led by computational physicist Dr. Paul Burke of the Johns Hopkins University Applied Physics Laboratory decided to turn to a favorite tool of scientists everywhere: models.

Before we explore the model, examining the problem they are trying to solve is helpful. Electrolysis immerses an electrode in a liquid and uses an electrical current and subsequent chemical reaction to split atoms apart. So, for example, if you put an electrode in water, it would separate that water into hydrogen and oxygen.

The problem comes from reduced gravity. As part of electrolysis, bubbles form on the surface of the electrode. On Earth, those bubbles typically detach and float to the surface, as the density difference between them and the remaining liquid forces them to.

However, in reduced gravity, the bubbles either take much longer to detach or don’t do so at all. This creates a buffer layer along the electrode’s length that decreases the electrolysis process’s efficiency, sometimes stalling it out entirely. Electrolysis isn’t the only fluidic process that has difficulty operating in reduced gravity environments – many ISS experiments also have trouble. This is partly due to a lack of complete understanding of how liquids operate in these environments – and that in itself is partly driven by a dearth of experimental data. 

Which is where the modeling comes in. Dr. Burke and his colleagues use a technique known as Computational Fluid Dynamics to attempt to mimic the forces the fluids will undergo in a reduced gravity environment while also understanding bubble formation.

Why July 2024 is a prime time to see distant Pluto before it fades from view.

Lots of the ‘wow factor’ in astronomy revolves around knowing just what you’re seeing. Sure, a quasar might be a faint +14th magnitude point of light seen at the eyepiece, but it’s also a powerful energy source from the ancient Universe, billions of light-years distant.

The same case is true for finding Pluto. Though its 0.1” disc won’t resolve into anything more than a speck in even the most powerful backyard telescope, knowing just what you’re seeing is part of the thrill of finding the distant world.

The good news is, Pluto reaches opposition for 2024 this week on July 23rd. This means it rises when the Sun sets, and is highest in the sky and well-placed for observation around midnight. 2024 sees Pluto loitering in the zodiacal constellation of Capricornus the Goat, just across the border from its former decade-long residence in Sagittarius.

Fun fact: on a leisurely 248-year orbit, Pluto has only moved from the constellation Gemini where it was first discovered by astronomer Clyde Tombaugh in 1930, to its present position.