Ask any astronomer, and they will tell you that all of the planets in the Solar System (including those “dwarf planets”) have satellites, with the exception of Mercury and Venus. However, that is not entirely the case, as Venus has what is known as a “quasi-moon” – a large asteroid that orbits the planet but is not gravitationally bound to it. In 2002, astronomer Brian Skiff discovered this body using the Discovery Telescope at the Lowell Observatory (where Clyde Tombaugh discovered Pluto). Until recently, this object was known by its official designation, 2002VE68.
However, on February 5th, 2024, the International Astronomical Union (IAU) conferred a new name for the object: Zoozve. The name was announced in a bulletin (vol. 4, no. 5) issued by the IAU’s Working Group for Small Bodies Nomenclature (WGSBN). The IAU, which is responsible for naming celestial objects, traditionally prefers to assign names that come from mythological traditions to objects that cross Earth’s orbit. But in this case, the origins of Zoozve’s strange name are more of (to quote Bob Ross) a “happy accident,” where a children’s poster that showed the object led to a conversation and an official request.
Venus is only slightly smaller than the Earth, and so has enjoyed billions of years of a warm heart. But for this planet, sometimes called Earth’s sister, that heat has betrayed it. That planet is now wrapped in suffocating layers of a poisonous atmosphere made of carbon dioxide and sulfuric acid. The pressures on the surface reach almost 100 times the air pressure at Earth’s sea level. The average temperatures are over 700 degrees Fahrenheit, more than hot enough to melt lead, while the deepest valleys see records of over 900 degrees.
A recent study published in Astrobiology investigates the potential habitability in the clouds of Venus, specifically how amino acids, which are the building blocks of life, could survive in the sulfuric acid-rich upper atmosphere of Venus. This comes as the potential for life in Venus’ clouds has become a focal point of contention within the astrobiology community in the last few years. On Earth, concentrated sulfuric acid is known for its corrosivity towards metals and rocks and for absorbing water vapor. In Venus’ upper atmosphere, it forms from solar radiation interacting with sulfur dioxide, water vapor, and carbon dioxide.
In Dante Alighieri’s epic poem The Divine Comedy, the famous words “Abandon all hope, ye who enter here” adorn the gates of hell. Interestingly enough, Dante’s vision of hell is an apt description of what conditions are like on Venus. With an average temperature of 450 °C (842 °F), atmospheric pressures 92 times that of Earth, and clouds of sulfuric acid rain to boot, Venus is the most hostile environment in the Solar System. It is little wonder why space agencies, going all the way back to the beginning of the Space Age, have had such a hard time exploring Venus’ atmosphere.
Despite that, there are many proposals for missions that could survive Venus’ hellish environment long enough to accomplish a sample return mission. One such proposal, the Sample Return from the Surface of Venus, comes from aerospace engineer and author Geoffrey Landis and his colleagues at the NASA Glenn Research Center. Their proposed concept was selected for this year’s NASA Innovative Advanced Concepts (NIAC) program. It consists of a solar-powered aircraft that would fashion propellant directly from Venus’ atmosphere and deploy a sample-return rover to the surface.
When scientists detected phosphine in Venus’ atmosphere in 2020, it triggered renewed, animated discussions about Venus and its potential habitability. It would be weird if the detection didn’t generate interest since phosphine is a potential biomarker. So people were understandably curious. Unfortunately, further study couldn’t confirm its presence.
But even without phosphine, Venus’ atmosphere is full of chemical intrigue that hints at biological processes. Is it time to send an astrobiology mission to our hellish sister planet?
During the 1960s, the first robotic explorers began making flybys of Venus, including the Soviet Venera 1 and the Mariner 2 probes. These missions dispelled the popular myth that Venus was shrouded by dense rain clouds and had a tropical environment. Instead, these and subsequent missions revealed an extremely dense atmosphere predominantly composed of carbon dioxide. The few Venera landers that made it to the surface also confirmed that Venus is the hottest planet in the Solar System, with average temperatures of 464 °C (867 °F).
These findings drew attention to anthropogenic climate change and the possibility that something similar could happen on Earth. In a recent study, a team of astronomers from the University of Geneva (UNIGE) created the world’s first simulation of the entire greenhouse process that can turn a temperate planet suitable for Life into a hellish, hostile one. Their findings revealed that on Earth, a global average temperature rise of just a few tens of degrees (coupled with a slight rise in the Sun’s luminosity) would be sufficient to initiate this phenomenon and render our planet uninhabitable.
NASA is preparing to send humans back to the Moon with the Artemis missions in the next few years as part of the agency’s Moon to Mars Architecture with the long-term goal of landing humans on the Red Planet sometime in the 2030s or 2040s. But what about sending humans to other worlds of the Solar System? And, why not Venus? It’s closer to Earth than Mars by several tens of millions of kilometers, and despite its extremely harsh surface conditions, previous studies have suggested that life could exist in its clouds. In contrast, we have yet to find any signs of life anywhere on the Red Planet or in its thin atmosphere. So, should we send humans to Venus?
When spacecraft return to Earth, they don’t need to shed all their velocity by firing retro-rockets. Instead, they use the atmosphere as a brake to slow down for a soft landing. Every planet in the Solar System except Mercury has enough of an atmosphere to allow aerocapture maneuvers, and could allow high-speed exploration missions. A new paper looks at the different worlds and how a spacecraft must fly to take advantage of this “free lunch” to slow down at the destination.
Even though Venus is very similar to Earth in many ways, it’s a hell-world with a runaway greenhouse effect. It was assumed this was because it lacked plate tectonics like Earth to sequester carbon inside the planet. A new study suggests that the high nitrogen and argon in its atmosphere are evidence from outgassing when it had plate tectonics billions of years ago. This could mean that Venus was habitable for a long time before something went horribly wrong.
Seismology has been ubiquitous on Earth for decades, and missions such as InSight have recently provided the same data for the inside of Mars. Understanding a planet’s inner workings is key to understanding its geology and climate. However, the inner workings of Venus, arguably our closest sister planet, have remained a mystery. The sulfuric acid cloud and scorching surface temperatures probably don’t help. But Siddharth Krishnamoorthy from NASA’s Jet Propulsion Laboratory and Daniel Bowman of Sandia National Laboratory think they have a solution – use seismometers hanging from balloons.