Venus hides a wealth of information that could help us better understand Earth and exoplanets. NASA’s JPL is designing mission concepts to survive the planet’s extreme temperatures and atmospheric pressure. This image is a composite of data from NASA’s Magellan spacecraft and Pioneer Venus Orbiter.
Credits: NASA/JPL-Caltech
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Sue Smrekar really wants to go back to Venus. In her office at NASA’s Jet Propulsion Laboratory in Pasadena, California, the planetary scientist displays a 30-year-old image of Venus’ surface taken by the Magellan spacecraft, a reminder of how much time has passed since an American mission orbited the planet. The image reveals a hellish landscape: a young surface with more volcanoes than any other body in the solar system, gigantic rifts, towering mountain belts and temperatures hot enough to melt lead.
Now superheated by greenhouse gases, Venus’ climate was once more similar to Earth’s, with a shallow ocean’s worth of water. It may even have subduction zones like Earth, areas where the planet’s crust sinks back into rock closer to the core of the planet.
“Venus is like the control case for Earth,” said Smrekar. “We believe they started out with the same composition, the same water and carbon dioxide. And they’ve gone down two completely different paths. So why? What are the key forces responsible for the differences?”
Smrekar works with the Venus Exploration Analysis Group (VEXAG), a coalition of scientists and engineers investigating ways to revisit the planet that Magellan mapped so many decades ago. Though their approaches vary, the group agrees that Venus could tell us something vitally important about our planet: what happened to the superheated climate of our planetary twin, and what does it mean for life on Earth?
Orbiters
Venus isn’t the closest planet to the Sun, but it is the hottest in our solar system. Between the intense heat (900 degrees Fahrenheit heat, or 480 degrees Celsius), the corrosive sulfuric clouds and a crushing atmosphere that is 90 times denser than Earth’s, landing a spacecraft there is incredibly challenging. Of the nine Soviet probes that achieved the feat, none lasted longer than 127 minutes.
By studying this mysterious planet, scientists could learn a great deal more about exoplanets, as well as the past, present, and possible future of our own. This video unveils this world and calls on current and future scientists to explore its many features.
Credits: NASA’s Goddard Space Flight Center/David Ladd
From the relative safety of space, an orbiter could use radar and near-infrared spectroscopy to peer beneath the cloud layers, measure landscape changes over time, and determine whether or not the ground moves. It could look for indicators of past water as well as volcanic activity and other forces that may have shaped the planet.
Smrekar, who is working on an orbiter proposal called VERITAS, doesn’t think that Venus has plate tectonics the way Earth does. But she sees possible hints of subduction — what happens when two plates converge and one slides beneath the other. More data would help.
“We know very little about the composition of the surface of Venus,” she said. “We think that there are continents, like on Earth, which could have formed via past subduction. But we don’t have the information to really say that.”
The answers wouldn’t only deepen our understanding of why Venus and Earth are now so different; they could narrow down the conditions scientists would need in order to find an Earth-like planet elsewhere.
Hot Air Balloons
Orbiters aren’t the only means of studying Venus from above. JPL engineers Attila Komjathy and Siddharth Krishnamoorthy imagine an armada of hot air balloons that ride the gale-force winds in the upper levels of the Venusian atmosphere, where the temperatures are close to Earth’s.
“There is no commissioned mission for a balloon at Venus yet, but balloons are a great way to explore Venus because the atmosphere is so thick and the surface is so harsh,” said Krishnamoorthy. “The balloon is like the sweet spot, where you’re close enough to get a lot of important stuff out but you’re also in a much more benign environment where your sensors can actually last long enough to give you something meaningful.”
A team of JPL engineers tests whether a large balloon can measure earthquakes from the air. The team proposes to measure “venusqakes” from the temperate upper atmosphere of Venus, using an armada of balloons.
Credits: NASA/JPL-Caltech
The team would equip the balloons with seismometers sensitive enough to detect quakes on the planet below. On Earth, when the ground shakes, that motion ripples into the atmosphere as waves of infrasound (the opposite of ultrasound). Krishnamoorthy and Komjathy have demonstrated the technique is feasible using silver hot-air balloons, which measured weak signals above areas on Earth with tremors. And that’s not even with the benefit of Venus’s dense atmosphere, where the experiment would likely return even stronger results.
“If the ground moves a little bit, it shakes the air a lot more on Venus than it does on Earth,” Krishnamoorthy explained.
To get that seismic data, though, a balloon mission would need to contend with Venus’ hurricane-force winds. The ideal balloon, as determined by Venus Exploration Analysis Group, could control its movements in at least one direction. Krishnamoorthy and Komjathy’s team hasn’t gotten that far, but they have proposed a middle ground: having the balloons essentially ride the wind around the planet at a steady speed, sending their results back to an orbiter. It’s a start.
Landing Probes
Among the many challenges facing a Venus lander are those Sun-blocking clouds: Without sunlight, solar-power would be severely limited. But the planet is too hot for other power sources to survive. “Temperature-wise, it’s like being in your kitchen oven set to self-cleaning mode,” said JPL engineer Jeff Hall, who has worked on balloon and lander prototypes for Venus. “There really is nowhere else like that surface environment in the solar system.”
By default, a landing mission’s lifespan will be cut short by the spacecraft’s electronics starting to fail after a few hours. Hall says the amount of power required to run a refrigerator capable of protecting a spacecraft would require more batteries than a lander could carry.
Sue Smrekar, seen here at the 2018 media briefing before the landing of NASA’s Mars InSight, is a planetary scientist at NASA’s Jet Propulsion Laboratory. She believes exploring Venus will reveal important details about how rocky planets form and whether other planets are capable of supporting life.
Credits: NASA/JPL-Caltech
“There is no hope of refrigerating a lander to keep it cool,” he added. “All you can do is slow down the rate at which is destroys itself.”
NASA is interested in developing “hot technology” that can survive days, or even weeks, in extreme environments. Although Hall’s Venus lander concept didn’t make it to the next stage of the approval process, it did lead to his current Venus-related work: a heat-resistant drilling and sampling system that could take Venusian soil samples for analysis. Hall works with Honeybee Robotics to develop the next-generation electric motors that power drills in extreme conditions, while JPL engineer Joe Melko designs the pneumatic sampling system.
Together, they work with the prototypes in JPL’s steel-walled Large Venus Test Chamber, which mimics the conditions of the planet right down to an atmosphere that’s a suffocating 100% carbon dioxide. With each successful test, the teams bring humanity one step closer to pushing the boundaries of exploration on this most inhospitable planet.
For more information about Venus, visit:
https://solarsystem.nasa.gov/planets/venus
A proposal to float balloons in Venus’ atmosphere as if that were a new idea? Has NASA forgotten it’s own history along with everyone else? It’s been done….the Vega 1 and Vega 2 missions….a joint effort of NASA and the Soviets, arrived at Venus June 1985 (almost 35 years ago). A lander and a helium balloon each, the balloons floated at 34 miles above the surface, where the temperature is near room temperature, and survived about 4 earth days.
Venus has negligible magnetic field intensity and super hot climate. Earth has moderate magnetic field and a moderate climate. As the Earth’s magnetic field gets weaker climate warms and vice versa, i.e. there is a strong negative correlation as shown here
http://www.vukcevic.co.uk/CT4-GMF.htm
“Venus is like the control case for Earth,” said Smrekar. “We believe they started out with the same composition, the same water and carbon dioxide. And they’ve gone down two completely different paths. So why? What are the key forces responsible for the differences?”
Venus and Earth have nearly similar diameters, masses, and gravity, but that’s where the similarity ends. Venus also receives twice the solar radiation of Earth, so that it would be hotter than Earth even if its primordial atmosphere was similar to that of Earth.
I don’t believe that Venus “started out” with the same amount of water as on Earth. If the surface atmospheric pressure on Venus is 90 atmospheres (about 1323 psi), liquid water could exist at up to 580 F in equilibrium at that pressure, but if there was much less liquid water available on Venus than on Earth when Venus formed, it would have all evaporated if the surface temperature was above 580 F.
Water vapor is also a greenhouse gas (more so than CO2), so if the primordial high-pressure Venusian atmosphere contained a lot of water vapor, it could have trapped enough heat so that the Venusian atmosphere was too hot to condense water, even at high pressure. Without any rain to replenish it, a Venusian ocean could have evaporated away.
It is also a stretch to believe that Venus “started out with the same carbon dioxide” as Earth–it probably had much more carbon dioxide than Earth. Assuming a current concentration of 400 ppm, the partial pressure of CO2 at sea level on Earth is about 0.0059 psi. If the total pressure of the atmosphere on Venus is 1,323 psi, even 10% CO2 would be a partial pressure of 132 psi, or more than 22,000 times the value on Earth. Where would all that CO2 come from, if it wasn’t there to begin with?
The article also talks about “corrosive sulfurous clouds” in Venus’ atmosphere, whereas Earth’s atmosphere contains very little sulfur-containing gases. Since sulfur-containing gases (H2S, SO2, SO3) are toxic to life on Earth, if the primordial atmosphere of the Earth contained as much sulfur as that on Venus, life probably would not have developed on Earth.
Earth’s atmosphere is very unusual among the planets of the solar system, with 78% nitrogen, which is chemically and optically inert, and 21% oxygen, required to sustain life but also relatively transparent in the visible and infrared spectra. Most of the outer planets have atmospheres rich in methane and/or ammonia, with very little nitrogen or oxygen, while Venus’ atmosphere is rich in CO2 and sulfurous gases. The Earth’s distance from the sun, combined with the greenhouse effect from water vapor, enable it to have large amounts of liquid water at the surface, for which the outer planets are too cold (water would freeze), and Venus and Mercury are too hot.
It is extremely unlikely that Earth’s atmosphere could become like that of Venus, unless there was some catastrophic change in the Sun, which would cause it to emit more than twice as much radiation as it does now.
As the Sun grows in power over the coming billions of years, at the rate of one percent per 100 million years, Earth will probably enter a “moist greenhouse” phase, in which surface water evaporates into the atmosphere, increasing pressure, hence allowing water to stay liquid at higher temperature, but eventually wetting the stratosphere, where UV light will break down H2O into its atoms, with the hydrogen being lost to space.
This is probably what happened to Venus from the start, ie it never had liquid water, despite high atmospheric pressure. But even if there were briefly liquid water on its surface, conditions were too hot for life to get started, with or without sulfur compounds. Chemosynthesis of sulfur compounds by microbes on Earth predated photosynthesis.
Venus most likely did have water in its primordial air, but lost it via photodissociation.
Make that 110 million years.
Thank you! 10% more time before I have to start getting seriously worried…
PV=nRT explains the temp on Venus quite well. Thank you. Solve for T.
This is yet another exercise by NASA in Science Fiction, containing such gems as: “Now superheated by greenhouse gases, Venus’ climate was once more similar to Earth’s, with a shallow ocean’s worth of water. ” ? It is yet another effort to bolster the failing GHG Global Warming theory.
““Venus is like the control case for Earth,” said Smrekar. “We believe they started out with the same composition, the same water and carbon dioxide. And they’ve gone down two completely different paths. So why? What are the key forces responsible for the differences?””
Well… for a start let’s get rid of the “we believe” Across many years of interest I have yet to see ANY evidence to support the idea that Venus and Earth have ever been ‘twins’ – they share similar size and that’s it.
The lack of magnetic field for Venus (what is there is apparently generated by interactions between her ionosphere and the solar wind) has the interesting effect of demolishing one explanation for the lack of atmosphere on Mars. The solar wind is MUCH stronger for Venus and yet the lack of a strong mag field hasn’t caused Venus atmosphere to evaporate away into space.
But the elephant in the room is as obvious as the full moon in the night sky… OK, it’s the Moon. 😀 It is likely the interactions with the Moon have changed Earth’s atmosphere and allowed us to have something we can survive in.
Constant perturbation of the Earth’s oceans and crust would also have effects not seen on Venus.
And as a nice little aside, they still can’t really explain why the orbit of Venus is so circular. The implication from Occam is that Venus hasn’t been there long and the low probability of it somehow entering an orbit so perfect could easily lead to speculation about HOW it got there.
The orbit of the Sun and planets around the solar barycenter should have warped the orbit of Venus long ago if it has been there since year dot.
As for the ludicrous statements about the planet based on the tiny amount we have gleaned, they belong in the ‘pure speculation’ cupboard, rather than as a justification trotted out to organise yet more doomed missions to the planet. If they can’t do enough science to recognise the absurdity of trying to blame CO2 for the heat of Venus, they should not be designing the missions.
Both Venus and Earth have nearly circular orbits, although Venus’ is more so than Earth’s, which is closer to Jupiter. Mercury has a highly elliptical orbit because of the Sun, while Mars does thanks to Jupiter.
An interesting observation is that Venus’ core appears to show a p = −5 spin‐orbit resonance with the Earth. We’re pretty close, so no surprise if we have a gravitational effect on each other.
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009JE003370
IMO there is no reason to assume that Venus didn’t coalesce in its present position.
Let’s give Sue Smrekar her wish and send her to Venus.
Mars is cold because the amount of heat convected from its surface and radiated to outer space at higher altitude is relatively greater than Venus. The pressure at Venus’ surface is high enough that there is hardly any wind, while 3/4 of the way up, where density density is lower, wind speeds are hundreds of km/hr, also moving the Sun’s radiant energy up to high enough altitude to radiate the heat to space through the relatively thick Venusian atmosphere, compared to Mars.
Mars is cold because it is farther away – period.
Venus a control case for Earth? Who is trying to fool us right now? Venus is on average 108 Million km away from the Sun. Earth almost 150 Million km. You don’t think that an additional more than 40 Million km makes a difference? The effect of solar radiation decreases exponentially with additional distance. So venus always received a lot more solar energy than Earth did. That may have prevented microbial life from forming which in turn prevented CO2 from being stored in solids. The Venusian atmosphere is not subject to a greenhouse effect. Its subject to a lot more solar energy and has an atmosphere to spread it over the surface day and night. Mercury is closer still but has no atmosphere so it heats up on the dayside and freezes on the night side. Venus is not like Earth – and has never been.