Venus Archives

February 15, 2018February 15, 2018 by Matt Williams

What are the Chances Musk’s Space Tesla is Going to Crash Into Venus or Earth?

StarMan drives his Tesla to space. Credit: SpaceX

On February 6th, 2018, SpaceX successfully launched its Falcon Heavy rocket into orbit. This was a momentous occasion for the private aerospace company and represented a major breakthrough for spaceflight. Not only is the Falcon Heavy the most powerful rocket currently in service, it is also the first heavy launch vehicle that relies on reusable boosters (two of which were successfully retrieved after the launch).

Equally interesting was the rocket’s cargo, which consisted of Musk’s cherry-red Tesla Roadster with a spacesuit in the driver’s seat. According to Musk, this vehicle and its “pilot” (Starman), will eventually achieve a Hohmann Transfer Orbit with Mars and remain there for up to a billion years. However, according to a new study, there’s a small chance that the Roadster will collide with Venus or Earth instead in a few eons.

The study which raises this possibility recently appeared online under the title “The random walk of cars and their collision probabilities with planets.” The study was conducted by Hanno Rein, an assistant professor at the University of Toronto; Daniel Tamayo, a postdoctoral fellow with the Center for Planetary Sciences (CPS) and the Canadian Institute for Theoretical Astrophysics (CITA); and David Vokrouhlick of the Institute of Astronomy at Charles University in Prague.

*Elon Musk’s Tesla Roadster being loaded aboard the Falcon Heavy’s payload capsule. Credit: SpaceX*

As we indicated in a previous post, Musk’s original flight plan has the potential to place the Roadster into a stable orbit around Mars… after a fashion. According to Max Fagin, an aerospace engineer from Colorado and a space camp alumni, the Roadster will get close enough to Mars to establish an orbit by October of 2018. However, this orbit would not rule out close encounters with Earth over the course of the next few million years.

For the sake of their study, Rein and his colleagues considered how such close encounters might alter the Roadster’s orbit in that time. Using data from NASA’s HORIZONS interface to determine the initial positions of all Solar planets and the Roadster, the team calculated the likelihood of future close encounters between the vehicle and the terrestrial planets, and how likely a resulting collision would be.

As they indicated, the Roadster bears some similarities to Near-Earth Asteroids (NEAs) and ejecta from the Earth-Moon system. In short, NEAs permeate the inner Solar System, regularly crossing the orbits of terrestrial planets and experiencing close encounters with them (resulting in the occasional collision). In addition, ejecta from the Earth and Moon also experience close encounters with the terrestrial planets and collide with them.

However, the Tesla Roadster is unique in two key respects: For one, it originated from Earth rather than being pulled from the Asteroid Belt into the inner Solar System by strong resonances. Second, it had a higher ejection velocity when it left Earth, which tends to result in fewer impacts. “Given the peculiar initial conditions and even stranger object, it therefore remains an interesting question to probe its dynamics and eventual fate,” they claim.

The Falcon Heavy Rocket being fired up at launch site LC-39A at NASA’s Kennedy Space Center in Cape Canaveral, Florida. Image: SpaceX — *The Falcon Heavy Rocket being fired up at launch site LC-39A at NASA’s Kennedy Space Center in Cape Canaveral, Florida. Credit: SpaceX*

Another challenge was how the probability of an impact will change drastically over time. While the chance of a collision can be ruled out in the short run (i.e. the next few years), the Roadster’s chaotic orbit is difficult to predict over the course of subsequent close encounters. As such, the team performed a statistical calculation to see how the orbit and velocity of the Roadster would change over time. As they state in their study:

“Given that the Tesla was launched from Earth, the two objects have intersecting orbits and repeatedly undergo close encounters. The bodies reach the same orbital longitude on their synodic timescale of ~2.8 yrs.”

They began by considering how the Roadster’s orbit would evolve over the course of its next 48 orbits, which would encompass the next 1000 years. They then expanded the analysis to consider long-term evolution, which encompassed 240 orbits over the course of the next 3.5 million years. What they found was that on a million-year timescale, the orbit of the Roadster remains in a region dominated by close encounters with Earth.

However, over time, their simulations show that the Roadster will experience changes in eccentricity due to resonant and secular effects. This will result in interactions more frequent interactions between the Roadster and Venus over time, and close encounters with Mars becoming possible. Over long enough timescales, the team even anticipates that interactions with Mercury’s orbit will be possible (though unlikely).

Don't Panic StarMan, Don't Panic. Credit: SpaceX — *Don’t Panic StarMan, Don’t Panic. Credit: SpaceX*

In the end, their simulations revealed that over the course of a million years and beyond, the probability of a collision with a terrestrial planet is unlikely, but not impossible. And while the odds are slim, they favor an eventual collision with Earth. Or as they put it:

“Although there were several close encounters with Mars in our simulations, none of them resulted in a physical collision. We find that there is a ~6% chance that the Tesla will collide with Earth and a ~2.5% chance that it will collide with Venus within the next 1 Myr. The collision rate goes down slightly with time. After 3 Myr the probability of a collision with Earth is ~11%. We observed only one collision with the Sun within 3 Myr.”

Given the Musk hoped that his Roadster would remain in orbit of Mars for one billion years, and that aliens might eventually find it, the prospect of it colliding with Earth or Venus is a bit of a letdown. Why bother sending such a unique payload into space if it’s just going to come back? Still, the odds that it will be drifting through space for millions of years remains a distinct possibility.

And if there are any worries that the Roadster will pose a threat to future missions or Earth itself, consider the message Starman was looking at during his ascent into space – Don’t Panic! Assuming humanity is even alive eons from now, the far greater danger will be that such an antique will burn up in our atmosphere. After millions of years, Starman is sure to be a big celebrity!

Further Reading: arXiv

December 8, 2017 by Matt Williams

Earth and Venus are the Same Size, so Why Doesn’t Venus Have a Magnetosphere? Maybe it Didn’t Get Smashed Hard Enough

At a closest average distance of 41 million km (25,476,219 mi), Venus is the closest planet to Earth. Credit: NASA/JPL/Magellan

For many reasons, Venus is sometimes referred to as “Earth’s Twin” (or “Sister Planet”, depending on who you ask). Like Earth, it is terrestrial (i.e. rocky) in nature, composed of silicate minerals and metals that are differentiated between an iron-nickel core and silicate mantle and crust. But when it comes to their respective atmospheres and magnetic fields, our two planets could not be more different.

For some time, astronomers have struggled to answer why Earth has a magnetic field (which allows it to retain a thick atmosphere) and Venus do not. According to a new study conducted by an international team of scientists, it may have something to do with a massive impact that occurred in the past. Since Venus appears to have never suffered such an impact, its never developed the dynamo needed to generate a magnetic field.

The study, titled “Formation, stratification, and mixing of the cores of Earth and Venus“, recently appeared in the scientific journal Earth and Science Planetary Letters. The study was led by Seth A. Jacobson of Northwestern University, and included members from the Observatory de la Côte d’Azur, the University of Bayreuth, the Tokyo Institute of Technology, and the Carnegie Institution of Washington.

The Earth's layers, showing the Inner and Outer Core, the Mantle, and Crust. Credit: discovermagazine.com — *The Earth’s layers, showing the Inner and Outer Core, the Mantle, and Crust. Credit: discovermagazine.com*

For the sake of their study, Jacobson and his colleagues began considering how terrestrial planets form in the first place. According to the most widely-accepted models of planet formation, terrestrial planets are not formed in a single stage, but from a series of accretion events characterized by collisions with planetesimals and planetary embryos – most of which have cores of their own.

Recent studies on high-pressure mineral physics and on orbital dynamics have also indicated that planetary cores develop a stratified structure as they accrete. The reason for this has to do with how a higher abundance of light elements are incorporated in with liquid metal during the process, which would then sink to form the core of the planet as temperatures and pressure increased.

Such a stratified core would be incapable of convection, which is believed to be what allows for Earth’s magnetic field. What’s more, such models are incompatible with seismological studies that indicate that Earth’s core consists mostly of iron and nickel, while approximately 10% of its weight is made up of light elements – such as silicon, oxygen, sulfur, and others. It’s outer core is similarly homogeneous, and composed of much the same elements.

As Dr. Jacobson explained to Universe Today via email:

“The terrestrial planets grew from a sequence of accretionary (impact) events, so the core also grew in a multi-stage fashion. Multi-stage core formation creates a layered stably stratified density structure in the core because light elements are increasingly incorporated in later core additions. Light elements like O, Si, and S increasingly partition into core forming liquids during core formation when pressures and temperatures are higher, so later core forming events incorporate more of these elements into the core because the Earth is bigger and pressures and temperatures are therefore higher.

“This establishes a stable stratification which prevents a long-lasting geodynamo and a planetary magnetic field. This is our hypothesis for Venus. In the case of Earth, we think the Moon-forming impact was violent enough to mechanically mix the core of the Earth and allow a long-lasting geodynamo to generate today’s planetary magnetic field.”

To add to this state of confusion, paleomagnetic studies have been conducted that indicate that Earth’s magnetic field has existed for at least 4.2 billion years (roughly 340 million years after it formed). As such, the question naturally arises as to what could account for the current state of convection and how it came about. For the sake of their study, Jacobson and his team considering the possibility that a massive impact could account for this. As Jacobson indicated:

“Energetic impacts mechanically mix the core and so can destroy stable stratification. Stable stratification prevents convection which inhibits a geodynamo. Removing the stratification allows the dynamo to operate.”

Basically, the energy of this impact would have shaken up the core, creating a single homogeneous region within which a long-lasting geodynamo could operate. Given the age of Earth’s magnetic field, this is consistent with the Theia impact theory, where a Mars-sized object is believed to have collided with Earth 4.51 billion years ago and led to the formation of the Earth-Moon system.

This impact could have caused Earth’s core to go from being stratified to homogeneous, and over the course of the next 300 million years, pressure and temperature conditions could have caused it to differentiate between a solid inner core and liquid outer core. Thanks to rotation in the outer core, the result was a dynamo effect that protected our atmosphere as it formed.

*Artist’s concept of a collision between proto-Earth and Theia, believed to happened 4.5 billion years ago. Credit: NASA*

The seeds of this theory were presented last year at the 47th Lunar and Planetary Science Conference in The Woodlands, Texas. During a presentation titled “Dynamical Mixing of Planetary Cores by Giant Impacts“, Dr. Miki Nakajima of Caltech – one of the co-authors on this latest study – and David J. Stevenson of the Carnegie Institution of Washington. At the time, they indicated that the stratification of Earth’s core may have been reset by the same impact that formed the Moon.

It was Nakajima and Stevenson’s study that showed how the most violent impacts could stir the core of planets late in their accretion. Building on this, Jacobson and the other co-authors applied models of how Earth and Venus accreted from a disk of solids and gas about a proto-Sun. They also applied calculations of how Earth and Venus grew, based on the chemistry of the mantle and core of each planet through each accretion event.

The significance of this study, in terms of how it relates to the evolution of Earth and the emergence of life, cannot be understated. If Earth’s magnetosphere is the result of a late energetic impact, then such impacts could very well be the difference between our planet being habitable or being either too cold and arid (like Mars) or too hot and hellish (like Venus). As Jacobson concluded:

“Planetary magnetic fields shield planets and life on the planet from harmful cosmic radiation. If a late, violent and giant impact is necessary for a planetary magnetic field then such an impact may be necessary for life.”

Looking beyond our Solar System, this paper also has implications in the study of extra-solar planets. Here too, the difference between a planet being habitable or not may come down to high-energy impacts being a part of the system’s early history. In the future, when studying extra-solar planets and looking for signs of habitability, scientists may very well be forced to ask one simple question: “Was it hit hard enough?”

Further Reading: Earth Science and Planetary Letters

November 9, 2017November 10, 2017 by Matt Williams

Building Electronics That Can Work on Venus

Artist's impression of the surface of Venus, showing its lightning storms and a volcano in the distance. Credit and ©: European Space Agency/J. Whatmore

The weather on Venus is like something out of Dante’s Inferno. The average surface temperature – 737 K (462 °C; 864 °F) – is hot enough to melt lead and the atmospheric pressure is 92 times that of Earth’s at sea level (9.2 MPa). For this reason, very few robotic missions have ever made it to the surface of Venus, and those that have did not last long – ranging from about 20 minutes to just over two hours.

Hence why NASA, with an eye to future missions, is looking to create robotic missions and components that can survive inside Venus’ atmosphere for prolonged periods of time. These include the next-generation electronics that researchers from NASA Glenn Research Center (GRC) recently unveiled. These electronics would allow a lander to explore Venus surface for weeks, months, or even years.

In the past, landers developed by the Soviets and NASA to explore Venus – as part of the Venera and Mariner programs, respectively – relied on standard electronics, which were based on silicon semiconductors. These are simply not capable of operating in the temperature and pressure conditions that exist on the surface of Venus, and therefore required that they have protective casings and cooling systems.

Naturally, it was only a matter of time before these protections failed and the probes stopped transmitting. The record was achieved by the Soviets with their Venera 13 probe, which transmitted for 127 minutes between its descent and landing. Looking ahead, NASA and other space agencies want to develop probes that can gather as much information as they can on Venus’s atmosphere, surface, and geological history before they time out.

To do this, a team from NASA’s GRC has been working to develop electronics that rely on silcon carbide (SiC) semiconductors, which would be capable of operating at or above Venus’ temperatures. Recently, the team conducted a demonstration using the world’s first moderately-complex SiC-based microcircuits, which consisted of tens or more transistors in the form of core digital logic circuits and analog operation amplifiers.

These circuits, which would be used throughout the electronic systems of a future mission, were able to operate for up to 4000 hours at temperatures of 500 °C (932 °F) – effectively demonstrated that they could survive in Venus-like conditions for prolonged periods. These tests took place in the Glenn Extreme Environments Rig (GEER), which simulated Venus’ surface conditions, including both the extreme temperature and high pressure.

Back in April of 2016, the GRC team tested a SiC 12-transistor ring oscillator using the GEER for a period of 521 hours (21.7 days). During the test, they raised they subjected the circuits to temperatures of up to 460 °C (860 °F), atmospheric pressures of 9.3 MPa and supercritical levels of CO² (and other trace gases). Throughout the entire process, the SiC oscillator showed good stability and kept functioning.

*SiC high-temperature electronics before and after testing in Venus surface conditions (rugged operation for extended durations). Credits: Marvin Smith/David Spry/NASA GRC*

This test was ended after 21 days due to scheduling reasons, and could have gone on much longer. Nevertheless, the duration constituted a significant world record, being orders of magnitude longer than any other demonstration or mission that has been conducted. Similar tests have shown that ring oscillator circuits can survive for thousands of hours at temperatures of 500 °C (932 °F) in Earth-air ambient conditions.

Such electronics constitute a major shift for NASA and space exploration, and would enable missions that were previously impossible. NASA’s Science Mission Direction (SMD) plans to incorporate SiC electronics on their Long-Life In-situ Solar System Explorer (LLISSE). A prototype is currently being developed for this low-cost concept, which would provide basic, but highly valuable scientific measures from the surface of Venus for months or longer.

Other plans to build a survivable Venus explorer include the Automaton Rover for Extreme Environments (AREE), a “steampunk rover” concept that relies on analog components rather than complex electronic systems. Whereas this concepts seeks to do away with electronics entirely to ensure a Venus mission could operate indefinitely, the new SiC electronics would allow more complex rovers to continue operating in extreme conditions.

Beyond Venus, this new technology could also lead to new classes of probes capable of exploring within gas giants – i.e. Jupiter, Saturn, Uranus and Neptune – where temperature and pressure conditions have been prohibitive in the past. But a probe that relies on a hardened shell and SiC electronic circuits could very well penetrate deep into the interior of these planets and reveal startling new things about their atmospheres and magnetic fields.

*AREE is a clockwork rover inspired by mechanical computers. A JPL team is studying how this kind of rover could explore extreme environments, like the surface of Venus. Credit: NASA/JPL-Caltech*

The surface of Mercury could also be accessible to rovers and landers using this new technology – even the day-side, where temperatures reach a high of 700 K (427 °C; 800 °F). Here on Earth, there are plenty of extreme environments that could now be explored with the help of SiC circuits. For example, drones equipped with SiC electronics could monitor deep-sea oil drilling or explore deep into the Earth’s interior.

There are also commercial applications involving aeronautical engines and industrial processors, where extreme heat or pressure traditionally made electronic monitoring impossible. Now such systems could be made “smart”, where they are capable of monitoring themselves instead of relying on operators or human oversight.

With extreme circuits and (someday) extreme materials, just about any environment could be explored. Maybe even the interior of a star!

Further Reading: NASA

September 19, 2017 by Matt Williams

Venus Express Probe Reveals the Planet’s Mysterious Night Side

Artist's impression of the Venus Express spacecraft in orbit around Venus. Credit: ESA

Venus’ atmosphere is as mysterious as it is dense and scorching. For generations, scientists have sought to study it using ground-based telescopes, orbital missions, and the occasional atmospheric probe. And in 2006, the ESA’s Venus Express mission became the first probe to conduct long-term observations of the planet’s atmosphere, which revealed much about its dynamics.

Using this data, a team of international scientists – led by researchers from the Japan Aerospace and Exploration Agency (JAXA) – recently conducted a study that characterized the wind and upper cloud patterns on the night side of Venus. In addition to being the first of its kind, this study also revealed that the atmosphere behaves differently on the night side, which was unexpected.

The study, titled “Stationary Waves and Slowly Moving Features in the Night Upper Clouds of Venus“, recently appeared in the scientific journal Nature Astronomy. Led by Javier Peralta, the International Top Young Fellow of JAXA, the team consulted data obtained by Venus Express’ suite of scientific instruments in order to study the planet’s previously-unseen cloud types, morphologies, and dynamics.

Whereas plenty of studies have been conducted of Venus’ atmosphere from soace, this was the first time that a study was not focused on the dayside of the planet. As Dr. Peralta explained in an ESA press statement:

“This is the first time we’ve been able to characterize how the atmosphere circulates on the night side of Venus on a global scale. While the atmospheric circulation on the planet’s dayside has been extensively explored, there was still much to discover about the night side. We found that the cloud patterns there are different to those on the dayside, and influenced by Venus’ topography.“

Since the 1960s, astronomers have been aware that Venus’ atmosphere behaves much differently that those of other terrestrial planets. Whereas Earth and Mars have atmospheres that co-rotate at approximately the same speed as the planet, Venus’ atmosphere can reach speeds of more than 360 km/h (224 mph). So while the planet takes 243 days to rotate once on its axis, the atmosphere takes only 4 days.

This phenomena, known as “super-rotation”, essentially means that the atmosphere moves over 60 times faster than the planet itself. In addition, measurements in the past have shown that the fastest clouds are located at the upper cloud level, 65 to 72 km (40 to 45 mi) above the surface. Despite decades of study, atmospheric models have been unable to reproduce super-rotation, which indicated that some of the mechanics were unknown.

As such, Peralta and his international team – which included researchers from the Universidad del País Vasco in Spain, the University of Tokyo, the Kyoto Sangyo University, the Center for Astronomy and Astrophysics (ZAA) at Berlin Technical University, and the Institute of Astrophysics and Space Planetology in Rome – chose to look at the unexplored side to see what they could find. As he described it:

“We focused on the night side because it had been poorly explored; we can see the upper clouds on the planet’s night side via their thermal emission, but it’s been difficult to observe them properly because the contrast in our infrared images was too low to pick up enough detail.”

This consisted of observing Venus’ night side clouds with the probe’s Visible and Infrared Thermal Imaging Spectrometer (VIRTIS). The instrument gathered hundreds of images simultaneously and different wavelengths, which the team then combined to improve the visibility of the clouds. This allowed the team to see them properly for the first time, and also revealed some unexpected things about Venus’ night side atmosphere.

What they saw was that atmospheric rotation appeared to be more chaotic on the night side than what has been observed in the past on the dayside. The upper clouds also formed different shapes and morphologies – i.e. large, wavy, patchy, irregular and filament-like patterns – and were dominated by stationary waves, where two waves moving in opposite directions cancel each other out and create a static weather pattern.

*Examples of new types of cloud morphology discovered on the night side of Venus thanks to Venus Express (ESA) and the infrared telescope IRTF (NASA). Credits: ESA/NASA/J. Peralta and R. Hueso.*

The 3D properties of these stationary waves were also obtained by combining VIRTIS data with radio-science data from the Venus Radio Science experiment (VeRa). Naturally, the team was surprised to find these kinds of atmospheric behaviors since they were inconsistent with what has been routinely observed on the dayside. Moreover, they contradict the best models for explaining the dynamics of Venus’ atmosphere.

Known as Global Circulation Models (GCMs), these models predict that on Venus, super-rotation would occur in much the same way on both the dayside and the night side. What’s more, they noticed that stationary waves on the night side appeared to coincide with high-elevation features. As Agustin Sánchez-Lavega, a researcher from the University del País Vasco and a co-author on the paper, explained:

“Stationary waves are probably what we’d call gravity waves–in other words, rising waves generated lower in Venus’ atmosphere that appear not to move with the planet’s rotation. These waves are concentrated over steep, mountainous areas of Venus; this suggests that the planet’s topography is affecting what happens way up above in the clouds.“

This is not the first time that scientists have spotted a possible link between Venus’ topography and its atmospheric motion. Last year, a team of European astronomers produced a study that showed how weather patterns and rising waves on the dayside appeared to be directly connected to topographical features. These findings were based on UV images taken by the Venus Monitoring Camera (VMC) on board the Venus Express.

*Schematic illustration of the proposed behaviour of gravity waves in the vicinity of mountainous terrain on Venus. Credit: ESA*

Finding something similar happening on the night side was something of a surprise, until they realized they weren’t the only ones to spot them. As Peralta indicated:

“It was an exciting moment when we realized that some of the cloud features in the VIRTIS images didn’t move along with the atmosphere. We had a long debate about whether the results were real–until we realised that another team, led by co-author Dr. Kouyama, had also independently discovered stationary clouds on the night side using NASA’s Infrared Telescope Facility (IRTF) in Hawaii! Our findings were confirmed when JAXA’s Akatsuki spacecraft was inserted into orbit around Venus and immediately spotted the biggest stationary wave ever observed in the Solar System on Venus’ dayside.“

These findings also challenge existing models of stationary waves, which are expected to form from the interaction of surface wind and high-elevation surface features. However, previous measurements conducted by the Soviet-era Venera landers have indicated that surface winds might too weak for this to happen on Venus. In addition, the southern hemisphere, which the team observed for their study, is quite low in elevation.

And as Ricardo Hueso of the University of the Basque Country (and a co-author on the paper) indicated, they did not detect corresponding stationary waves in the lower cloud levels. “We expected to find these waves in the lower levels because we see them in the upper levels, and we thought that they rose up through the cloud from the surface,” he said. “It’s an unexpected result for sure, and we’ll all need to revisit our models of Venus to explore its meaning.”

*Artist’s impression of Venus Express performing aerobreaking maneuvers in the planet’s atmosphere in June and July 2014. Credit: ESA–C. Carreau*

From this information, it seems that topography and elevation are linked when it comes to Venus’ atmospheric behavior, but not consistently. So the standing waves observed on Venus’ night side may be the result of some other undetected mechanism at work. Alas, it seems that Venus’ atmosphere – in particular, the key aspect of super-rotation – still has some mysteries for us.

The study also demonstrated the effectiveness of combining data from multiple sources to get a more detailed picture of a planet’s dynamics. With further improvements in instrumentation and data-sharing (and perhaps another mission or two to the surface) we can expect to get a clearer picture of what is powering Venus’ atmospheric dynamics before long.

With a little luck, there may yet come a day when we can model the atmosphere of Venus and predict its weather patterns as accurately as we do those of Earth.

Further Reading: ESA, Nature Astronomy

August 31, 2017August 31, 2017 by Matt Williams

NASA’s Plan to Explore Venus with a “SteamPunk” Rover

Venus is one hellish place! Aside from surface temperatures hot enough to melt lead – as high as 737 K (462 °C; 864 °F) – there’s also the sulfuric acid droplets and extreme pressure conditions (92 times that of Earth’s) to contend with! Because of these hostile conditions, exploring Venus’ surface and atmosphere has been an ongoing and significant challenge for space agencies.

Hence why NASA’s Jet Propulsion Laboratory (JPL) is looking at some truly innovative and unconventional ideas for future missions to Venus. One of them is the second-generation concept known as the Automaton Rover for Extreme Environments (AREE). By relying on clockwork mechanisms instead of electronics, this rover will be able to function on the surface of Venus for longer periods of time.

If deployed, this rover will build upon the accomplishments of the Soviet-era Venera and Vega programs, which were the only missions to ever successfully land on Venus’ hostile surface. Unfortunately, those probes that actually made it to the surface and landed safely only survived for 23 to 127 minutes before their electronics failed and they could no longer send back information.

*Artist’s impression of the AREE clockwork rover operating on the surface of Venus. Credit: NASA/JPL-Caltech*

This is the reality of operating machines on Venus, where the extreme temperatures will melt outer casings and sulfuric acid will corrode electronics. Hence why Jonathan Sauder, a mechatronics engineer at JPL, began tinkering with the idea of a clockwork rover. In this respect, he was inspired by mechanical computers, a time-honored concept that relies on levers and gears to make calculations rather than electronic components.

The earliest known example is the Antikythera mechanism, a device built by the ancient Greeks to predict astronomical phenomena. In 1642, French mathematician Blaise Pascal created what is considered to be the first mechanical calculator. Alternately known as the “Arithmetic Machine” and “Pascal Calculator“, Pascal is said to have invented this device to help his father reorganize the tax revenues for their province.

In the early 19th century, French weaver and merchant Joseph Marie Jacqaurd created the “Jacquard Loom“, a machine that relied on punch cards to turn out textiles in various patterns. And in 1822, English mathematician Charles Babbage began work on his “Difference Engine“, a machine that would automatically perform calculations and create error-free tables.

From these and other examples, Sauders and his team saw a possible solution to surviving Venus’ atmosphere. In essence, they proposed reverting back to an ancient practice of using analog gears to build a robot that could survive the most extreme environment within the Solar System. By relying on an entirely mechanical design and hardened metal structure, the AREE could theoretically survive for months or longer on Venus.

As Sauder explained in a recent NASA press statement:

“Venus is too inhospitable for kind of complex control systems you have on a Mars rover. But with a fully mechanical rover, you might be able to survive as long as a year.”

As a result, it would be able to send back far more information about Venus’ surface conditions and geological processes, which have remained something of a mystery for decades. These include (but are not limited to) why Venus has fewer volcanoes than Earth today – despite widespread evidence of volcanic activity early in its history – and the strange absorption patterns that have been seen in its upper atmosphere.

Sauder first proposed the concept back in 2015. In 2016, the concept was assessed as part of the NASA Innovative Advanced Concepts (NIAC) program, which opens itself to submissions every year for mission ideas. Along with twelve other proposals, AREE was selected for Phase I development and Sauder and his team were awarded $100,000 for a nine month period to assess the feasibility of their concept.

Beyond its processors, AREE would also rely on analog components for power. This would be necessary since solar cells cannot receive sunlight in Venus’ dense atmosphere. And a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG), which the Curiosity rover relies on for power, has complex electrical systems that would likely break down in Venus’s atmosphere.

A look inside the AREE rover (next to an astronaut for scale). Wind would be channeled through the rover’s body for primary power. Rotating targets on top could be “pinged” by radar, sending data as Morse code.Image Credit: NASA/JPL-Caltech

Mobility is another challenge, and one which Sauder and his team also looked to an old idea to address. Basically, Venus’ rocky, craters surface is full of unknowns and will likely be very difficult to navigate. Sauder and his team therefore looked to World War I-era tanks treads as a solution. These vehicles were slow and lumbering, but were designed to traverse the difficult terrain of No Man’s Land, which was characterized by trenches and craters.

Originally, Sauder’s was inspired by Dutch artist Theo Jansen’s “Strandbeests“, a series of wood and canvas “robots” that relied on wind-driven gears to power their legs and walk along beaches. In the same vein, Sauder considered building a spider-like robot that used spindly legs to get around. However, this seemed too unstable for Venus’ rocky terrain, and treads were favored instead.

For communications, AREE would rely on another time-honored technology – Morse Code. This would involve an orbiting spacecraft pinging the rover using radar, while the rover would communicate by reflecting radar signals off of properly-shaped targets. Thanks to a rotating shutter, which would be positioned in front of the radar target, the rover would be able to turn the signal on and off to simulate dots and dashes.

If successful, this rover would be the first mission since the Cold War to explore the surface of Venus. As Evan Hilgemann, a JPL engineer working on high temperature designs for AREE, explained:

“When you think of something as extreme as Venus, you want to think really out there. It’s an environment we don’t know much about beyond what we’ve seen in Soviet-era images.”

*Artist’s concept for the Automaton Rover for Extreme Environments (AREE). Credit: NASA/JPL*

Beyond Venus, such a probe would also be useful for exploring hostile environments on Mercury, within Jupiter’s radiation belt, interiors of gas giants, within volcanoes, and perhaps even the mantle of Earth. The AREE rover is currently in its second phase of NIAC development, and the team is working towards refining and prototyping parts of the concept.

In the future, Sauder and his team hope to expand the rover’s capabilities further and maybe equip it with a drill to collect geological samples. With the ability to function on the planet for up to a year, and the prospect of actual samples being obtained from the surface, scientists will be able to learn a great deal about Earth’s “Sister Planet”. This, in turn, could teach us much about the formation and evolution of rocky planets in our Solar System.

Be sure to check out this video of AREE concept, which features the team’s original spider-leg design:

Further Reading: NASA, NASA AREE

August 17, 2017 by Matt Williams

NASA Plans to Send CubeSat To Venus to Unlock Atmospheric Mystery

The cloud-enshrouded Venus appears featureless, as shown in this image taken by NASA’s MESSENGER mission. In ultraviolet, however, the planet takes on a completely different appearance as seen below. Credits: NASA

From space, Venus looks like a big, opaque ball. Thanks to its extremely dense atmosphere, which is primarily composed of carbon dioxide and nitrogen, it is impossible to view the surface using conventional methods. As a result, little was learned about its surface until the 20th century, thanks to development of radar, spectroscopic and ultraviolet survey techniques.

Interestingly enough, when viewed in the ultraviolet band, Venus looks like a striped ball, with dark and light areas mingling next to one another. For decades, scientists have theorized that this is due to the presence of some kind of material in Venus’ cloud tops that absorbs light in the ultraviolet wavelength. In the coming years, NASA plans to send a CubeSat mission to Venus in the hopes of solving this enduring mystery.

The mission, known as the CubeSat UV Experiment (CUVE), recently received funding from the Planetary Science Deep Space SmallSat Studies (PSDS3) program, which is headquartered as NASA’s Goddard Space Flight Center. Once deployed, CUVE will determine the composition, chemistry, dynamics, and radiative transfer of Venus’ atmosphere using ultraviolet-sensitive instruments and a new carbon-nanotube light-gathering mirror.

*Ultraviolet image of Venus taken by NASA’s Pioneer-Venus Orbiter in 1979, lending Venus a striped, light and dark appearance. Credit: NASA*

The mission is being led by Valeria Cottini, a researcher from the University of Maryland who is also CUVE’s Principle Investigator (PI). In March of this year, NASA’s PSDS3 program selected it as one of 10 other studies designed to develop mission concepts using small satellites to investigate Venus, Earth’s moon, asteroids, Mars and the outer planets.

Venus is of particular interest to scientists, given the difficulties of exploring its thick and hazardous atmosphere. Despite the of NASA and other space agencies, what is causing the absorption of ultra-violet radiation in the planet’s cloud tops remains a mystery. In the past, observations have shown that half the solar energy the planet receives is absorbed in the ultraviolet band by the upper layer of its atmosphere – the level where sulfuric-acid clouds exist.

Other wavelengths are scattered or reflected into space, which is what gives the planet its yellowish, featureless appearance. Many theories have been advanced to explain the absorption of UV light, which include the possibility that an absorber is being transported from deeper in Venus’ atmosphere by convective processes. Once it reaches the cloud tops, this material would be dispersed by local winds, creating the streaky pattern of absorption.

The bright areas are therefore thought to correspond to regions that do not contain the absorber, while the dark areas do. As Cottini indicated in a recent NASA press release, a CubeSat mission would be ideal for investigating these possibilities:

“Since the maximum absorption of solar energy by Venus occurs in the ultraviolet, determining the nature, concentration, and distribution of the unknown absorber is fundamental. This is a highly-focused mission – perfect for a CubeSat application.”

*CubeSats being deployed from the International Space Station during Expedition 47. Image: NASA*

Such a mission would leverage recent improvements in miniaturization, which have allowed for the creation of smaller, box-sized satellites that can do the same jobs as larger ones. For its mission, CUVE would rely on a miniaturized ultraviolet camera and a miniature spectrometer (allowing for analysis of the atmosphere in multiple wavelengths) as well as miniaturized navigation, electronics, and flight software.

Another key component of the CUVE mission is the carbon nanotube mirror, which is part of a miniature telescope the team is hoping to include. This mirror, which was developed by Peter Chen (a contractor at NASA Goddard), is made by pouring a mixture of epoxy and carbon nanotubes into a mold. This mold is then heated to cure and harden the epoxy, and the mirror is coated with a reflective material of aluminum and silicon dioxide.

In addition to being lightweight and highly stable, this type of mirror is relatively easy to produce. Unlike conventional lenses, it does not require polishing (an expensive and time-consuming process) to remain effective. As Cottini indicated, these and other developments in CubeSat technology could facilitate low-cost missions capable of piggy-backing on existing missions throughout the Solar System.

“CUVE is a targeted mission, with a dedicated science payload and a compact bus to maximize flight opportunities such as a ride-share with another mission to Venus or to a different target,” she said. “CUVE would complement past, current, and future Venus missions and provide great science return at lower cost.”

*A cubesat structure, 1U in size. Credit: Wikipedia Commons/Svobodat*

The team anticipates that in the coming years, the probe will be sent to Venus as part of a larger mission’s secondary payload. Once it reaches Venus, it will be launched and assume a polar orbit around the planet. They estimate that it would take CUVE one-and-a-half years to reach its destination, and the probe would gather data for a period of about six months.

If successful, this mission could pave the way for other low-cost, lightweight satellites that are deployed to other Solar bodies as part of a larger exploration mission. Cottini and her colleagues will also be presenting their proposal for the CUVE satellite and mission at the 2017 European Planetary Science Congress, which is being held from September 17th – 22nd in Riga, Latvia.

Further Reading: NASA

June 9, 2017July 22, 2020 by Fraser Cain

Construction Tips from a Type 2 Engineer: Collaboration with Isaac Arthur

By popular request, Isaac Arthur and I have teamed up again to bring you a vision of the future of human space exploration. This time, we bring you practical construction tips from a pair of Type 2 Civilization engineers.

To make this collaboration even better, we’ve teamed up with two artists, Kevin Gill and Sergio Botero. They’re going to help create some special art, just for this episode, to help show what some of these megaprojects might look like.

Continue reading “Construction Tips from a Type 2 Engineer: Collaboration with Isaac Arthur”

May 31, 2017June 2, 2017 by Matt Williams

Researchers Think They Know Why Venus Doesn’t Have as Many Volcanoes as Earth

The surface of Venus has been a mystery to scientists ever since the Space Age began. Thanks to its dense atmosphere, its surface is inaccessible to direct observations. In terms of exploration, the only missions to penetrate the atmosphere or reach the surface were only able to transmit data back for a matter of hours. And what we have managed to learn over the years has served to deepen its mysteries as well.

For instance, for years, scientists have been aware of the fact that Venus experiences volcanic activity similar to Earth (as evidenced by lighting storms in its atmosphere), but very few volcanoes have been detected on its surface. But thanks to a new study from the School of Earth and Environmental Sciences (SEES) at the University of St. Andrews, we may be ready to put that particular mystery to bed.

The study was conducted by Dr. Sami Mikhail, a lecturer with the SEES, with the assistance of researchers from the University of Strasbourg. In examining Venus’ geological past, Mikhail and his colleagues sought to understand how it is that the most Earth-like planet in our Solar System could be considerably less geologically-active than Earth. According to their findings, the answer lies in the nature of Venus’ crust, which has a much higher plasticity.

*Image of the “pancake volcanoes” located in the Eistla region, taken by the Magellan space probe. Credit: NASA/JPL*

This is due to the intense heat on Venus’ surface, which averages at 737 K (462 °C; 864 °F) with very little variation between day and night or over the course of a year. Given that this heat is enough to melt lead, it has the effect of keeping Venus’ silicate crust in a softened and semi-viscous state. This prevents lava magmas from being able to move through cracks in the planets’ crust and form volcanoes (as they do on Earth).

In fact, since the crust is not particularly solid, cracks are unable to form in the crust at all, which causes magma to get stuck in the soft, malleable crust. This is also what prevents Venus from experiencing tectonic activity similar to what Earth experiences, where plates drift across the surface and collide, occasionally forcing magma up through vents. This cycle, it should be noted, is crucial to Earth’s carbon cycle and plays a vital role in Earth’s climate.

Not only do these findings explain one of the larger mysteries about Venus’ geological past, but they also are an important step towards differentiating between Earth and it’s “sister planet”. The implications of this goes far beyond the Solar System. As Dr. Mikhail said in a St. Andrews University press release:

“If we can understand how and why two, almost identical, planets became so very different, then we as geologists, can inform astronomers how humanity could find other habitable Earth-like planets, and avoid uninhabitable Earth-like planets that turn out to be more Venus-like which is a barren, hot, and hellish wasteland.”

*Volcanoes and lava flows on Venus. Credit: NASA/JPL*

In terms of size, composition, structure, chemistry, and its position within the Solar System (i.e. within the Sun’s habitable zone), Venus is the most-Earth like planet discovered to date. And yet, the fact that it is slightly closer to our Sun has resulted in it having a vastly different atmosphere and geological history. And these differences are what make it the hellish, uninhabitable place that is today.

Beyond our Solar System, astronomers have discovered thousands of exoplanets orbiting various types of stars. In some cases, where the planets exist close to their sun and are in possession of an atmosphere, the planets have been designated as being “Venus-like“. This naturally sets them apart from the planets that are of particular interest to exoplanet hunters – i.e. the “Earth-like” ones.

Knowing how and why these two very similar planets can differ so dramatically in terms of their geological and environmental conditions is therefore key to being able to tell the difference between planets that are conducive to life and hostile to life. That can only come in handy when we begin to study multiple-planet systems (such as the seven-planet system of TRAPPIST-1) more closely.

Further Reading: University of St. Andrews

April 19, 2017April 28, 2017 by Matt Williams

Here’s a Plan to Send a Spacecraft to Venus, and Make Venus Pay for It

Artist concept of Venus' surface. Credit: NASA)

In 2005, the Future In-Space Operations Working Group (FISOWG) was established with the help of NASA to assess how advances in spaceflight technologies could be used to facilitate missions back to the Moon and beyond. In 2006, the FISO Working Group also established the FISO Telecon Series to conduct outreach to the public and educate them on issues pertaining to spaceflight technology, engineering, and science.

Every week, the Telecon Series holds a seminar where experts are able to share the latest news and developments from their respective fields. On Wednesday, April 19th, in a seminar titled “An Air-Breathing Metal-Combustion Power Plant for Venus in situ Exploration“, NASA engineer Michael Paul presented a novel idea where existing technology could be used to make longer-duration missions to Venus.

To recap the history of Venus exploration, very few probes have ever been able to explore its atmosphere or surface for long. Not surprising, considering that the atmospheric pressure on Venus is 92 times what it is here on Earth at sea level. Not to mention the fact that Venus is also the hottest planet in the Solar System – with average surface temperatures of 737 K (462 °C; 863.6 °F).

*Although similar in size and composition to the Earth, Venus has an extremely dense atmosphere with clouds that produce sulfuric acid rain. Credit: NASA*

Hence why those few probes that actually explored the atmosphere and surface in detail – like the Soviet-era Venera probes and landers and NASA’s Pioneer Venus multiprobe – were only able to return data for a matter of hours. All other missions to Venus have either taken the form of orbiters or consisted of spacecraft conducting flybys while en route to other destinations.

Having worked in the fields of space exploration and aerospace engineering for 20 years, Michael Paul is well-versed in the challenges of mounting missions to other planets. During his time with the John Hopkins University Applied Physics Laboratory (JHUAPL), he contributed to NASA’s Contour and Stereo missions, and was also instrumental in the launch and early operations of the MESSENGER mission to Mercury.

However, it was a flagship-level study in 2008 – performed collaboratively between JHUAPL and NASA’s Jet Propulsion laboratory (JPL) – that opened his eyes to the need for missions that took advantage of the process known as In-Situ Resource Utilization (ISRU). As he stated during the seminar:

“That year we actually studied a very large mission to Europa which evolved into the current Europa Clipper mission. And we also studied a flagship mission to the Saturn, to Titan specifically. The Titan-Saturn system mission study was a real eye-opener for me in terms what could be done and why we should be doing a lot of more adventurous and more aggressive exploration of in-situ in certain places.”

The flagship mission to Titan was the subject of Paul’s work since joining Penn Sate’s Applied Research Laboratory in 2009. During his time there, he became a NASA Innovative Advanced Concepts Program (NIAC) Fellow for his co-creation of the Titan Submarine. For this mission, which will explore the methane lakes of Titan, Paul helped to develop underwater power systems that would provide energy for planetary landers that can’t see the Sun.

Having returned to JHUAPL, where he is now the Space Mission Formulation Lead, Paul continues to work on in-situ concepts that could enable missions to locations in the Solar System that present a challenge. In-situ exploration, where local resources are relied upon for various purposes, presents numerous advantages over more traditional concepts, not the least of which is cost-effectiveness.

Consider mission that rely on Multi-Mission Radioisotope Thermoelectric Generators (MMRTG) – where radioactive elements like Plutonium-238 are used to generate electricity. Whereas this type of power system – which was used by the Viking 1 and 2 landers (sent to Mars in 1979) and the more recent Curiosity rover – provides unparalleled energy density, the cost of such missions is prohibitive.

What’s more, in-situ missions could also function in places where conventional solar cells would not work. These include not only locations in the outer Solar System (i.e. Europa, Titan and Enceladus) but also places closer to home. The South Pole-Aitken Basin, for example, is a permanently shadowed location on the Moon that NASA and other space agencies are interesting in exploring (and maybe colonizing) due to the abundance of water ice there.

But there’s also the surface Venus, where sunlight is in short supply because of the planet’s dense atmosphere. As Paul explained in the course of the seminar:

“What can you do with other power systems in places where the Sun just doesn’t shine? Okay, so you want to get to the surface of Venus and last more than a couple of hours. And I think that in the last 10 or 15 years, all the missions that [were proposed] to the surface of Venus pretty much had a two-hour timeline. And those were all proposed, none of those missions were actually flown. And that’s in line with the 2 hours that the Russian landers survived when they got there, to the surface of Venus.”

*Diagram of a Sterling Engine, part of proposed mission to Europe (“Fire on Europa”). Credit: lpi.usra.edu*

The solution to this problem, as Paul sees it, is to employ a Stored-Chemical Energy and Power System (SCEPS), also known as a Sterling engine. This proven technology relies on stored chemical energy to generate electricity, and is typically used in underwater systems. But repurposed for Venus, it could provide a lander mission with a considerable amount of time (compared to previous Venus missions) with which to conduct surface studies.

For the power system Paul and his colleagues are envisioning, the Sterling engine would take solid-metal lithium (or possibly solid iodine), and then liquefy it with a pyrotechnic charge. This resulting liquid would then be fed into another chamber where it would combined with an oxidant. This would produce heat and combustion, which would then be used to boil water, spin turbines, and generate electricity.

Such a system is typically closed and produces no exhaust, which makes it very useful for underwater systems that cannot compromise their buoyancy. On Venus, such a system would allow for electrical production without short-lived batteries, an expensive nuclear fuel cell, and could function in a low solar-energy environment.

An added benefit for such a craft operating on Venus is that the oxidizer would be provided locally, thus removing the need for an heavy component. By simply letting in outside CO2 – which Venus’ atmosphere has in abundance – and combining with the system’s liquified lithium (or iodine), the SCEPS system could provide sustained energy for a period of days.

*The Advanced Lithium Ion Venus Explorer (ALIVE), derived from the COMPASS final report (2016). Credit: Oleson, Steven R., and Michael Paul.*

With the help of NASA’s Innovative Advanced Concepts (NIAC) and funding from the Hot Operating Temperature Technology (HOTTech) program – which is overseen by NASA’s Planetary Science Division – Paul and his colleagues were able to test their concept, and found that it was capable of producing sustained heat that was both controllable and tunable.

Further help came from the Glenn Research Center’s COMPASS lab, were engineers from multiple disciplines performs integrated vehicle systems analyses. From all of this, a mission concept known as the Advanced Lithium Venus Explorer (ALIVE) was developed. With the help of Steven Oleson – the head of GRC’s COMPASS lab – Paul and his team envision a mission where a lander would reach the surface of Venus and study it for 5 to 10 days.

All told, that’s an operational window of between 120 and 240 hours – in other words, 60 to 120 times as long as previous missions. However, how much such a mission would cost remains to be seen. According to Paul, that question became the basis of an ongoing debate between himself and Oleson, who disagreed as to whether it would be part of the Discovery Program or the New Frontiers Program.

As Paul explained, missions belonging to the former were recently capped at the $450 to $500 million level while the latter are capped at $850 million. “I believe that if you did this right, you could get it into a Discovery mission,” he said. “Here at APL, I’ve seen really complicated ideas fit inside a Discovery cost cap. And I believe that the way we crafted this mission, you could do this for a Discovery mission. And it would be really exciting to get that done.”

*Artist’s impression of the surface of Venus. Credit: ESA/AOES*

From a purely technological standpoint, this not a new idea. But in terms of space exploration, it has never been done before. Granted, there are still many tests which would need to be conducted before any a mission to Venus can be planned. In particular, there are the byproducts created by combusting lithium and CO2 under Venus-like conditions, which already produced some unexpected results during tests.

In addition, there is the problem of nitrogen gas (N2) – also present in Venus’ atmosphere – building up in the system, which would need to be vented in order to prevent a blowout. But the advantages of such a system are evident, and Paul and his colleagues are eager to take additional steps to develop it. This summer, they will be doing another test of a lithium SCEPS under the watchful eye of NAIC.

By this time next year, they hope to have completed their analysis and their design for the system, and begin building one which they hope to test in a controlled temperature environment. This will be the first step in what Paul hopes will be a three-year period of testing and development.

“The first year we’re basically going to do a lot of number crunching to make sure we got it right,” he said. “The second year we’re going to built it, and test it at higher temperatures than room temperature – but not the high temperatures of Venus! And in the third year, we’re going to do the high temperature test.”

Ultimately, the concept could be made to function in any number of high and low temperature conditions, allowing for cost-effective long-duration missions in all kinds of extreme environments. These would include Titan, Europa and Enceladus, but also Venus, the Moon, and perhaps the permanently-shadowed regions on Mercury’s poles as well.

Space exploration is always a challenge. Whenever ideas come along that make it possible to peak into more environments, and on a budget to boot, it is time to start researching and developing them!

To learn more about the results of the SCEPS tests, and for more information on the proposed systems, check out the slideshow and audio recording of this week’s FISO seminar. You can also check out the presentation titled “A Combustion-Driven Power Plant For Venus Surface Exploration“, which Paul and Oleson made during the 48th Lunar and Planetary Conference (which ran from March 20th-24th, 2017).

Further Reading: FISO

April 4, 2017April 28, 2017 by Matt Williams

Venus 2.0 Discovered In Our Own Back Yard

Artist's impression of Kepler-1649b, the "Venus-like" world orbiting an M-class star 219 light-years from Earth. Credit: Danielle Futselaar

It has been an exciting time for exoplanet research of late! Back in February, the world was astounded when astronomers from the European Southern Observatory (ESO) announced the discovery of seven planets in the TRAPPIST-1 system, all of which were comparable in size to Earth, and three of which were found to orbit within the star’s habitable zone.

And now, a team of international astronomers has announced the discovery of an extra-solar body that is similar to another terrestrial planet in our own Solar System. It’s known as Kepler-1649b, a planet that appears to be similar in size and density to Earth and is located in a star system just 219 light-years away. But in terms of its atmosphere, this planet appears to be decidedly more “Venus-like” (i.e. insanely hot!)

The team’s study, titled “Kepler-1649b: An Exo-Venus in the Solar Neighborhood“, was recently published in The Astronomical Journal. Led by Isabel Angelo – of the SETI Institute, NASA Ames Research Center, and UC Berkley – the team included researchers also from SETI and Ames, as well as the NASA Exoplanet Science Institute (NExScl), the Exoplanet Research Institute (iREx), the Center for Astrophysics Research, and other research institutions.

*Diagram comparing the Solar System to Kepler 69 and its system of exoplanets. Credit: NASA Ames/JPL-Caltech*

Needless to say, this discovery is a significant one, and the implications of it go beyond exoplanet research. For some time, astronomers have wondered how – given their similar sizes, densities, and the fact that they both orbit within the Sun’s habitable zone – that Earth could develop conditions favorable to life while Venus would become so hostile. As such, having a “Venus-like” planet that is close enough to study presents some exciting opportunities.

In the past, the Kepler mission has located several extra-solar planets that were similar in some ways to Venus. For instance, a few years ago, astronomers detected a Super-Earth – Kepler-69b, which appeared to measure 2.24 times the diameter of Earth – that was in a Venus-like orbit around its host the star. And then there was GJ 1132b, a Venus-like exoplanet candidate that is about 1.5 times the mass of Earth, and located just 39 light-years away.

In addition, dozens of smaller planet candidates have been discovered that astronomers think could have atmospheres similar to that of Venus. But in the case of Kepler-1649b, the team behind the discovery were able to determine that the planet had a sub-Earth radius (similar in size to Venus) and receives a similar amount of light (aka. incident flux) from its star as Venus does from Earth.

However, they also noted that the planet also differs from Venus in a few key ways – not the least of which are its orbital period and the type of star it orbits. As Dr. Angelo told Universe Today via email:

“The planet is similar to Venus in terms of it’s size and the amount of light it receives from it’s host star. This means it could potentially have surface temperatures similar to Venus as well. It differs from Venus because it orbits a star that is much smaller, cooler, and redder than our sun. It completes its orbit in just 9 days, which places it close to its host star and subjects it to potential factors that Venus does not experience, including exposure to magnetic radiation and tidal locking. Also, since it orbits a cooler star, it receives more lower-energy radiation from its host star than Earth receives from the Sun.”

*Artist’s impression of a Venus-like exoplanet orbiting close to its host star. Credit: CfA/Dana Berry*

In other words, while the planet appears to receive a comparable amount of light/heat from its host star, it is also subject to far more low-energy radiation. And as a potentially tidally-locked planet, the surface’s exposure to this radiation would be entirely disproportionate. And last, its proximity to its star means it would be subject to greater tidal forces than Venus – all of which has drastic implications for the planet’s geological activity and seasonal variations.

Despite these differences, Kepler-1649b remains the most Venus-like planet discovered to date. Looking to the future, it is hoped that next-generations instruments – like the Transiting Exoplanet Survey Satellite (TESS), the James Webb Telescope and the Gaia spacecraft – will allow for more detailed studies. From these, astronomers hope to more accurately determine the size and distance of the planet, as well as the temperature of its host star.

This information will, in turn, help us learn a great deal more about what goes into making a planet “habitable”. As Angelo explained:

“Understanding how hotter planets develop thick, Venus-like atmospheres that make them inhabitable will be important in constraining our definition of a ‘habitable zone’. This may become possible in the future when we develop instruments sensitive enough to determine chemical compositions of planet atmospheres (around dim stars) using a method called ‘transit spectroscopy’, which looks at the light from the host star that has passed through the planet’s atmosphere during transit.”

The development of such instruments will be especially useful given joust how many exoplanets are being detected around neighboring red dwarf stars. Given that they account for roughly 85% of stars in the Milky Way, knowing whether or not they can have habitable planets will certainly be of interest!

Further Reading: The Astronomical Journal