The giant star…is waging a tug-of-war between gravity and radiation to avoid self-destruction. The star, called AG Carinae, is surrounded by an expanding shell of gas and dust — a nebula — that is shaped by the powerful winds of the star. The nebula is about five light-years wide, which equals the distance from here to our nearest star, Alpha Centauri.
The huge structure was created from one or more giant eruptions several thousand years ago. The star’s outer layers were blown into space, the expelled material amounting to roughly 10 times the mass of our Sun. These outbursts are typical in the life of a rare breed of star called a Luminous Blue Variable (LBV), a brief unstable phase in the short life of an ultra-bright, glamorous star that lives fast and dies young. These stars are among the most massive and brightest stars known. They live for only a few million years, compared to the roughly 10-billion-year lifetime of our own Sun. AG Carinae is a few million years old and resides 20,000 light-years away inside our Milky Way galaxy. The star’s expected lifetime is between 5 million and 6 million years.
Source/Credit: A NASA composite image of Uranus taken from Voyager 2 and the Hubble Space Telescope.
In an earlier posting, I highlighted some scientific papers calling for a return to Neptune rather than Uranus, in part because of Neptune’s moon Triton. But what is the argument for a mission to Uranus? Below I highlight one of the papers submitted to the Planetary Science and Astrobiology Decadal Survey 2023-2032 arguing the merits of a NASA mission to Uranus.
The large moons of Uranus are possible ocean worlds that exhibit a variety of surface features, hinting at endogenic geologic activity in the recent past. These moons are rich in water ice, as well as carbon-bearing and likely nitrogen-bearing constituents, which represent some of the key components for life as we know it. However, our understanding of Uranus and its moons is severely limited by the absence of data collected by an orbiting spacecraft…
An orbiter would vastly improve our understanding of these possible ocean worlds and allow us to assess the nature of water and organics in the Uranian system, thereby improving our knowledge of these moons’ astrobiological potential. A Flagship mission to Uranus can be carried out with existing chemical propulsion technology by making use of a Jupiter gravity assist in the 2030 – 2034 timeframe, leading to a flight time of only ~11 years, arriving in the early to mid 2040’s (outlined in the Ice Giants Pre-Decadal Survey Mission Study Report: https://www.lpi.usra.edu/icegiants/mission_study/Full-Report.pdf).
The five large moons discussed in the paper are Miranda, Ariel, Umbriel, Titania, and Oberon. Titania and Oberon where the first to be discovered back in 1787, followed by the later discoveries of Ariel, Umbriel, and Miranda (in that order). Unlike the moons of other planets, the moons of Uranus are named after magical spirits in English literature.
All of these ocean worlds have gained greater interest as we learn about the dynamics of life on of our own planet. As noted in an article in the MIT Technology Review:
It was once thought the solar system was probably a barren wasteland apart from Earth. Rocky neighbors were too dry and cold like Mars, or too hot and hellish like Venus. The other planets were gas giants, and life on those worlds or their satellite moons was basically inconceivable. Earth seemed to be a miracle of a miracle.
But life isn’t that simple. We now know that life on Earth is able to thrive in even the harshest, most brutal environments, in super cold and super dry conditions, depths of unimaginable pressures, and without the need to use sunlight as a source of energy. At the same time, our cursory understanding of these obscure worlds has expanded tremendously.
We have plenty of worlds to explore in our own solar system as other scientists continue their search for exoplanets and exomoons. The only question now is which local worlds will we visit in our next round of space missions.
Source/Credit: Yutu 2 rover on the dark side of the moon from the China National Space Administration.
As much as we talk about cooperation in space, it is always nice to be the first nation to pass a milestone, be it the first man on the Moon or the first probe of Pluto. The U.S. has plenty of great stories about space travel, as do the Russians, and now the Chinese are creating their own stories. For instance, China’s Yutu 2 rover was the first rover to explore the dark side of the Moon.
A linchpin of the NASA moon effort is the Space Launch System, the Boeing-built mega-rocket that has been beset by years of delay and cost overruns that is finally set to make its maiden test flight in 2022.
The U.S., Russia, and China all have designs on the moon:
The U.S. moon program has been enlisting international partners in the form of the Artemis Accords, which now includes more than a dozen countries. But Russia and China, which are pursuing a lunar research station, are also seeking partners.
We already know that the U.S. hopes to have astronauts on the Moon in 2024, so what are the Russian and Chinese schedules for their projects? It appears the two nations are working on a joint lunar research base scheduled for the 2030s. However, not everyone is convinced this will happen. A Foreign Policy article, “A Chinese-Russian Moon Base? Not So Fast,”voiced skepticism that the two nations can generate sufficient funding, technological know-how, and political unity to pull off such a mission, citing earlier joint attempts, including a Martian mission:
In 2007, China and Russia signed an agreement for “joint Chinese-Russian exploration of Mars,” culminating in a 2011 launch of a Mars orbiter and landing craft. However, the Russian rocket malfunctioned, causing Russian and Chinese spacecraft to come crashing back down to Earth, an embarrassing conclusion to bothcountries’ first attempt to reach the red planet.
The two nations seems to be even more unified against the U.S. since this Foreign Policy article was published, so anything is possible. However, the U.S. did pretty well in the 1960s and 1970s after initially trailing the Russians, so my money is still on the U.S. in this latest race.
Source/Credit: Astronaut Leroy Chiao (right) attending a Red Square Memorial Ceremon in September 2004. Image from CNN.
As we await peace or war between Russia and Ukraine, US astronaut Leroy Chiao shared his thoughts about his cooperation with Russians at the International Space Station (ISS). He served as the copilot of a Russian Soyuz spacecraft to the ISS as well as the commander during Expedition 10. In his CNN editorial, he emphasizes the importance of continued cooperation at the station even when partners are on opposing sides during ongoing conflicts:
In the early 2000s, a few years after the Kosovo war, I started training for my ISS mission in Star City, outside of Moscow. Not long after I started training in Russia there were conflicts in and around the Balkans and I remember times when we would hear heavy Russian transport aircraft taking off all night from the air base next to us, bringing troops and materiel to the conflict zones. We Americans discussed these issues with our Russian friends in the training program and I learned one of the wonderful things about living in other worlds is you develop perspective. You don’t necessarily agree, but you can appreciate the viewpoints of the other side.
Let’s hope the two-nation relationship is not tested further in the weeks to come. I like the idea of international cooperation as well as maintaining healthy competition in the realm of space endeavors.
Source/Credit: Artist rendering of a candidate exoplanet orbiting Proxima Centauri from the ESO.
Earlier this month, astronomers utilizing the European Space Observatory’s (ESO) Very Large Telescope identified what appears to be a third exoplanet orbiting Proxima Centauri, the closest star to our solar system at about 4.2 light years away. The ESO press release shared the following details:
The newly discovered planet, named Proxima d, orbits Proxima Centauri at a distance of about four million kilometres, less than a tenth of Mercury’s distance from the Sun. It orbits between the star and the habitable zone — the area around a star where liquid water can exist at the surface of a planet — and takes just five days to complete one orbit around Proxima Centauri.
The star is already known to host two other planets: Proxima b, a planet with a mass comparable to that of Earth that orbits the star every 11 days and is within the habitable zone, and candidate Proxima c, which is on a longer five-year orbit around the star.
…At just a quarter of the mass of Earth, Proxima d is the lightest exoplanet ever measured using the radial velocity technique, surpassing a planet recently discovered in the L 98-59 planetary system. The technique works by picking up tiny wobbles in the motion of a star created by an orbiting planet’s gravitational pull. The effect of Proxima d’s gravity is so small that it only causes Proxima Centauri to move back and forth at around 40 centimetres per second (1.44 kilometres per hour).
It’s great to learn a little more about our nearest neighbor.
