HiRISE image from NASA's Mars Reconnaissance Orbiter (MRO) showing an impact crater that triggered a slope streak. Credit: NASA/JPL/University of Arizona
In 2006, NASA’s Mars Reconnaissance Orbiter (MRO) established orbit around the Red Planet. Using an advanced suite of scientific instruments – which include cameras, spectrometers, and radar – this spacecraft has been analyzing landforms, geology, minerals and ice on Mars for years and assisting with other missions. While the mission was only meant to last two years, the orbiter has remained in operation for the past twelve.
In that time, the MRO has acted as a relay for other missions to send information back to Earth and provided a wealth of information of its own on the Red Planet. Most recently, it captured an image of an impact crater that caused a landslide, which left a long, dark streak along the crater wall. Such streaks are created when dry dust collapses down the edge of a Martian hill, leaving behind dark swaths.
Close up of the crater captured by the MRO’s HiRISE instrument. Credit: NASA/JPL/University of Arizona
In this respect, these avalanches are not unlike Recurring Slope Lineae (RSL), where seasonal dark streaks appear along slopes during warmer days on Mars. These are believed to be caused by either salt water flows or dry dust grains falling naturally. In this case, however, the dry dust on the slope was destabilized by the meteor’s impact, which exposed darker material beneath.
The impact that created the crater is believed to have happened about ten years ago. And while the crater itself (shown above) is only 5 meters (16.4 feet) across, the streak it resulted in is 1 kilometer (0.62 mi) long! The image also captured the faded scar of an old avalanche, which is visible to the side of the new dark streak.
Wider-angle view of the impact crater captured by the MRO’s HiRISE instrument and the resulting dark streak. Credit: NASA/JPL/University of Arizona
This is just the latest in a long-line of images and data packages sent back by the MRO. By providing daily reports on Mars’ weather and surface conditions, and studying potential landing sites, the MRO also paves the way for future spacecraft and surface missions. In the future, the orbiter will serve as a highly capable relay satellite for missions like NASA’s Mars 2020 rover, which will continue in the hunt for signs of past life on Mars.
At present, the MRO has enough propellant to keep functioning into the 2030s, and given its intrinsic value to the study of Mars, it is likely to remain in operation right up until it exhausts its fuel. Perhaps it will even be working when astronauts arrived on the Red Planet?
This global map of Mars shows a growing dust storm as of June 6, 2018. The map was produced by the Mars Color Imager (MARCI) camera on NASA's Mars Reconnaissance Orbiter spacecraft. The blue dot indicates the approximate location of Opportunity. Image Credit: NASA/JPL-Caltech/MSSS
NASA’s Opportunity mission can rightly be called the rover that just won’t quit. Originally, this robotic rover was only meant to operate on Mars for 90 Martian days (or sols), which works out to a little over 90 Earth days. However, since it made its landing on January 25th, 2004, it has remained in operation for 14 years, 4 months, and 18 days – exceeding its operating plan by a factor of 50!
However, a few weeks ago, NASA received disturbing news that potentially posed a threat to the “little rover that could”. A Martian storm, which has since grown to occupy an area larger than North America – 18 million km² (7 million mi²) – was blowing in over rover’s position in the Perseverance Valley. Luckily, NASA has since made contact with the rover, which is encouraging sign.
NASA’s Mars Reconnaissance Orbiter first detected the storm on Friday, June 1st, and immediately notified the Opportunity team to begin preparing contingency plans. The storm quickly grew over the next few days and resulted in dust clouds that raised the atmosphere’s opacity, which blocked out most of the sunlight from reaching the surface. This is bad news for the rover since it relies on solar panels for power and to recharge its batteries.
Artist’s conception of a Mars Exploration Rover, which included Opportunity and Spirit. Credit: NASA
By Wednesday, June 6th, Opportunity’s power levels had dropped significantly and the rover was required to shift to minimal operations. But beyond merely limiting the rover’s operations, a prolonged dust storm also means that the rover might not be able to keep its energy-intensive survival heaters running – which protect its batteries from the extreme cold of Mars’ atmosphere.
The Martian cold is believed to be what resulted in the loss of the Spirit rover in 2010, Opportunity’s counterpart in the Mars Exploration Rover mission. Much like Opportunity, Spirit‘s mission as only meant to last for 90 days, but the rover managed to remain in operation for 2269 days (2208 sols) from start to finish. It’s also important to note that Opportunity has dealt with long-term storms before and emerged unscathed.
Back in 2007, a much larger storm covered the planet, which led to two weeks of minimal operations and no communications. However, the current storm has intensified as of Sunday morning (June 10th), creating a perpetual state of night over the rover’s location in Perseverance Valley and leading to a level of atmospheric opacity that is much worse than the 2007 storm.
Whereas the previous storm had an opacity level (tau) of about 5.5, this new storm has an estimated tau of 10.8. Luckily, NASA engineers received a transmission from the rover on Sunday, which was a positive indication since it proved that the rover still has enough battery charge to communicate with controllers at NASA’s Jet Propulsion Laboratory. This latest transmission also showed that the rover’s temperature had reached about -29 °C (-20 °F).
This 30-day time-lapse of the Martian atmosphere was capture by Opportunity during the 2007 dust storm. Credit: NASA/JPL-Caltech/Cornell
Full dust storms like this and the one that took place in 2007 are rare, but not surprising. They occur during summer in the southern hemisphere, when sunlight warms dust particles and lifts them higher into the atmosphere, creating more wind. That wind kicks up yet more dust, creating a feedback loop that NASA scientists are still trying to understand. While they can begin suddenly, they tend to last on the order of weeks or even months.
A saving grace about these storms is that they limit the extreme temperature swings, and the dust they kick up can also absorb solar radiation, thus raising ambient temperatures around Opportunity. In the coming weeks, engineers at the JPL will continue to monitor the rover’s power levels and ensure that it maintains the proper balance to keep its batteries in working order.
In the meantime, Opportunity’s science operations remain suspended and the Opportunity team has requested additional communications coverage from NASA’s Deep Space Network – the global system of antennas that communicates with all of the agency’s deep space missions. And if there’s one thing Opportunity has proven, it is that it’s capable of enduring!
Fingers crossed the storm subsides as soon as possible and the little rover that could once again emerges unscathed. At this rate, it could have many more years of life left in it!
This low-angle self-portrait of NASA's Curiosity Mars rover shows the vehicle at the site from which it reached down to drill into a rock target called "Buckskin" on lower Mount Sharp. Credits: NASA/JPL-Caltech/MSSS
Ever since Curiosity landed on Mars in 2012, the rover has made numerous groundbreaking discoveries about the Red Planet. These include confirming how Mars once had flowing water and lakes on its surface, evidence of how it lost its ancient atmosphere, and the discovery of methane and organic molecules. All of these discoveries have bolstered the theory that Mars may have once supported life.
The latest discovery came on Thursday, May 7th, when NASA announced that the Curiosity rover had once again discovered organic molecules. This time, however, the molecules were found in three-billion-year-old sedimentary rocks located near the surface of lower Mount Sharp. This evidence, along with new atmospheric evidence, are another indication that ancient life may have once existed on the Red Planet.
MRO image of Gale Crater illustrating the landing location and trek of the Rover Curiosity since it landed in 2012. Credits: NASA/JPL, illustration, T.Reyes
As Thomas Zurbuchen, the associate administrator for the Science Mission Directorate at NASA Headquarters, explained in a recent NASA press release:
“With these new findings, Mars is telling us to stay the course and keep searching for evidence of life. I’m confident that our ongoing and planned missions will unlock even more breathtaking discoveries on the Red Planet.”
In the first paper, the authors indicate how Curiosity’sSample Analysis at Mars (SAM) suite detected traces of methane in drill samples it took from Martian rocks. Once these rocks were heated, they released an array of organics and volatiles similar to how organic-rich sedimentary rocks do on Earth. On Earth, such deposits are indications of fossilized organic life, which may or may not be the case with the samples examined by Curiosity.
However, this evidence is bolstered by the fact that Curiosity has also found evidence that the Gale Crater was once an ancient lakebed. In addition to water, this lakebed contained all the chemical building blocks and energy sources that are necessary for life. As Jen Eigenbrode of NASA’s Goddard Space Flight Center, and the lead author of the first study, explained:
“Curiosity has not determined the source of the organic molecules. Whether it holds a record of ancient life, was food for life, or has existed in the absence of life, organic matter in materials holds chemical clues to planetary conditions and processes… The Martian surface is exposed to radiation from space. Both radiation and harsh chemicals break down organic matter. Finding ancient organic molecules in the top five centimeters of rock that was deposited when Mars may have been habitable, bodes well for us to learn the story of organic molecules on Mars with future missions that will drill deeper.”
This image illustrates possible ways methane might get into Mars’ atmosphere and also be removed from it. Credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan
In the second paper, the team described how Curiosity’s SAM suite also detected seasonal variations in methane in the Martian atmosphere. These results were obtained over the course of nearly three years on Mars, which works out to almost six Earth years. While the team admits that water-rock chemistry could have generated the methane, they cannot rule out the possibility that it was biological in origin.
In the past, methane and organic molecules have been detected in Mars’ atmosphere and in drill samples, the former of which appeared to spike unpredictably. However, these new results indicate that within the Gale Crater, low levels of methane peak during the warm summer months and drop in the winter months every year. As Chris Webster, a researcher from NASA’s Jet Propulsion Laboratory (JPL) and the lead author of the second paper, explained:
“This is the first time we’ve seen something repeatable in the methane story, so it offers us a handle in understanding it. This is all possible because of Curiosity’s longevity. The long duration has allowed us to see the patterns in this seasonal ‘breathing.'”
To find this organic material, Curiosity drilled into sedimentary rocks (known as mudstone) in four areas in the Gale Crater. These rocks formed over the course of billions of years as sediments were deposited at the bottom of the ancient lake by flowing water. The drill samples were then analyzed by SAM, which used its oven to heat the samples to over 500 °C (900 °F) to release organic molecules from the powdered rock.
Simulated view of Gale Crater Lake on Mars. This illustration depicts a lake of water partially filling Mars’ Gale Crater, receiving runoff from snow melting on the crater’s northern rim. Credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS
These results indicate that some of the drill samples contained sulfur (which could have preserved the organic molecules) as well as thiophenes, benzene, toluene, and small carbon chains – such as propane or butene. They also indicated organic carbon concentrations of about 10 parts per million or more, which is consistent with carbon concentrations observed in Martian meteorites and about 100 times what has been previously detected on Mars’ surface.
While this does not constitute evidence of past life on Mars, these latest findings have increased confidence that future missions will find more organics, both on the surface and slightly beneath the surface. But above all, they have bolstered confidence that Mars may have once had life of its own. As Michael Meyer, the lead scientist for NASA’s Mars Exploration Program, summarized:
“Are there signs of life on Mars? We don’t know, but these results tell us we are on the right track.”
In the coming years, additional missions will also be searching for signs of past life, including NASA’s Mars 2020 rover and the European Space Agency’s ExoMars rover.The Mars 2020 rover will also leave samples behind in a cache that could be retrieved by a future crewed mission for sample-return analysis. So if there was life on Mars (or, fingers crossed, still is) we are sure to find it soon enough!
And be sure to check out this video of this latest discovery by Curiosity, courtesy of NASA’s Jet Propulsion Laboratory:
The first image captured by one of NASA's Mars Cube One (MarCO) CubeSats. The image, which shows both the CubeSat's unfolded high-gain antenna at right and the Earth and its moon in the center, was acquired by MarCO-B on May 9. Credit: NASA/JPL-Caltech
In 1990, the Voyager 1spaceprobe took a picture of Earth when it was about 6.4 billion km (4 billion mi) away. In this image, known as the “pale blue dot“, Earth and the Moon appeared as mere points of light because of the sheer distance involved. Nevertheless, it remains an iconic photo that not only showed our world from space, but also set long-distance record.
As it turns out, NASA set another long-distance record for CubeSats last week (on May. 8th, 2018) when a pair of small satellites called Mars Cube One (MarCO) reached a distance of 1 million km (621,371 mi) from Earth. On the following day, one of the CubeSats (MarCO-B, aka. “Wall-E”) used its fisheye camera to take its own “pale blue dot” photo of the Earth-Moon system.
The two CubeSats were launched on May 5th along with the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) lander, which is currently on its way to Mars to explore the planet’s interior structure. As the first CubeSats to fly to deep pace, the purpose of the MarCO mission is to demonstrate if CubeSats are capable of acting as a relay with long-distance spacecraft.
An artist’s rendering of the twin Mars Cube One (MarCO) spacecraft as they fly through deep space. Credit: NASA/JPL-Caltech
To this end, the probes will be responsible for monitoring InSight as it makes its landing on Mars in late November, 2018. The photo of Earth and the Moon was taken as part of the process used by the engineering team to confirm that the spacecraft’s high-gain antenna unfolded properly. As Andy Klesh, MarCO’s chief engineer at NASA’s Jet Propulsion Laboratory, indicated in a recent NASA press release:
“Consider it our homage to Voyager. CubeSats have never gone this far into space before, so it’s a big milestone. Both our CubeSats are healthy and functioning properly. We’re looking forward to seeing them travel even farther.”
This technology demonstration, and the long-distance record recently set by MarCO satellites, provides a good indication of just how far CubeSats have come in the past few years. Originally, CubeSats were developed to teach university students about satellites, but have since become a major commercial technology. In addition to providing vast amounts of data, they have proven to be a cost-effective alternative to larger, multi-million dollar satellites.
The MarCO CubeSats will be there when the InSight lander accomplishes the most difficult part of its mission, which is entering Mars’ extremely thin atmosphere (which makes landings extremely challenging). As the lander travels to Mars, MarCO-A and B will travel along behind it and (should they make it all the way to Mars) radio back data about InSight as it enters the atmosphere and descends to the planet’s surface.
Artist’s interpretation of the InSight mission on the ground on Mars. Credit: NASA
The job of acting as a data relay will fall to NASA’s Mars Reconnaissance Orbiter (MRO), which has been in orbit of Mars since 2006. However, the MarCOs will also be monitoring InSight to see if future missions will be capable of bringing their own relay to Mars, rather than having to rely on an orbiter that is already there. They may also demonstrate a number of experimental technologies, which includes their radio and propulsion systems.
The main attraction though, are the high-gain antennas which will be providing information on InSights’ progress. At the moment, the team has received early confirmation that the antennas have successfully deployed, but they will continue to test them in the weeks ahead. If all goes according to plan, the MarCOs could demonstrate the ability of CubeSats to act not only as relays, but also their ability to gather information on other planets.
In other words, if the MarCOs are able to make it to Mars and track InSight’s progress, NASA and other agencies may contemplate mounting full-scale missions using CubeSats – sending them to the Moon, Mars, or even beyond. Later this month, the MarCOs will attempt their first trajectory correction maneuvers, which will be the first such maneuver are performed by CubeSats.
In the meantime, be sure to check out this video of the MarCO mission, courtesy of NASA 360:
NASA's Mars Helicopter, a small, autonomous rotorcraft, will travel with the agency's Mars 2020 rover, currently scheduled to launch in July 2020, to demonstrate the viability and potential of heavier-than-air vehicles on the Red Planet. Credits: NASA/JPL-Caltech
For instance, NASA plans to expand on what Curiosity has accomplished by sending the Mars 2020 rover to conduct a sample-return mission. According to a recent announcement issued by NASA, this mission will also include the Mars Helicopter – a small, autonomous rotorcraft that will demonstrate the viability and potential of heavier-than-air vehicles on the Red Planet.
As NASA Administrator Jim Bridenstine declared in a recent NASA press release, this rotocraft is in keeping with NASA’s long-standing traditions of innovation. “NASA has a proud history of firsts,” she said. “The idea of a helicopter flying the skies of another planet is thrilling. The Mars Helicopter holds much promise for our future science, discovery, and exploration missions to Mars.”
This artist’s concept depicts NASA’s Mars 2020 rover exploring Mars. Credit: NASA
U.S. Rep. John Culberson of Texas echoed Bridenstine statement. “It’s fitting that the United States of America is the first nation in history to fly the first heavier-than-air craft on another world,” he said. “This exciting and visionary achievement will inspire young people all over the United States to become scientists and engineers, paving the way for even greater discoveries in the future.”
The Mars Helicopter began as technology development project at NASA’s Jet Propulsion Laboratory (JPL), where it spent the past four years being designed, developed, tested and retested. The result of this is a football-sized rotorcraft that weights just under 1.8 kg (four pounds) and relies on two counter-rotating blades to spin at a rate of almost 3,000 rpm (10 times the rate of a helicopter here on Earth).
As Mimi Aung, the Mars Helicopter project manager at JPL, indicated:
“The altitude record for a helicopter flying here on Earth is about 40,000 feet. The atmosphere of Mars is only one percent that of Earth, so when our helicopter is on the Martian surface, it’s already at the Earth equivalent of 100,000 feet up. To make it fly at that low atmospheric density, we had to scrutinize everything, make it as light as possible while being as strong and as powerful as it can possibly be.”
Artist’s impression of the Mars 2020 with its sky crane landing system deployed. Credit: NASA/JPL
This concept is ideal for navigating through Mars’ thin atmosphere, where the mean surface pressure is about 0.6% that of Earth’s at sea level (0.60 kPa compared to 101.3 kPa). This low-flying helicopter would not only be able to increase the range of a rover, it will be able to explore areas that the rover would find inaccessible. As Thomas Zurbuchen, the Associate Administrator for NASA’s Science Mission Directorate, explained:
“Exploring the Red Planet with NASA’s Mars Helicopter exemplifies a successful marriage of science and technology innovation and is a unique opportunity to advance Mars exploration for the future. After the Wright Brothers proved 117 years ago that powered, sustained, and controlled flight was possible here on Earth, another group of American pioneers may prove the same can be done on another world.”
Other capabilities that make it optimized for Mars exploration include lithium-ion batteries, solar cells to keep them charged, and heating mechanisms that will keep it warm during Martian nights – where average temperatures can get as low as 210 K (-63 °C; -82 °F) around the mid-latitudes. In addition, the helicopter is programmed to fly autonomously, since it cannot be flown in real-time (given the distances involved).
Commands will be issued from controllers on Earth, using the rover as a relay, who will instruct the helicopter to commence flight once it is ready to deploy. This will begin shortly after the rover arrives on the planet (which is expected to happen by February 2021) with the helicopter attached to its belly pan. The rover will then select a location to deploy the helicopter onto the ground.
Artist’s concept of the dragonfly being deployed to Titan and commencing its exploration mission. Credit: APL/Michael Carroll
After it is finished charging its batteries and a series of pre-flight tests are performed, controllers on Earth will relay commands to the Mars Helicopter to commence its first 30-day flight test campaign. This will include up to five flights that will take it to increasingly greater distances from the rover (up to a few hundred meters) for longer periods of time (up to 90 seconds).
On its first flight, the helicopter will make a short vertical climb to 3 meters (10 feet) where it will hover for about 30 seconds. Once these tests are complete, the Mars Helicopter will assist the rover as it conducts geological assessments and determines the habitability of its landing sight. The purpose of this will be to search for signs of ancient life on Mars and assesses the natural resources and hazards for future missions involving human explorers.
The rover will also conduct the first-ever sample-return mission from Mars, obtaining samples of rock and soil, encasing them in sealed tubes, and leaving them on the planet for future retrieval by astronauts. If all goes well, the helicopter will demonstrate that low-flying scouts and aerial vehicles can be a valuable part of any future missions. These will likely include robotic missions to Saturn’s largest moon, Titan, where researchers are hoping to explore the surface and atmosphere using helicopter (such as the Dragonfly concept).
The Mars 2020 mission is expected to reveal some very impressive things about the Red Planet. If the helicopter proves to be a viable part of the mission, we can expect that additional information and images will be provided from locations that a conventional rover cannot go. And in the meantime, be sure to enjoy this animation of the Mars Helicopter in action, courtesy of NASA-JPL:
A new study led by researchers from OU indicates that the outer planets could be why Mars is significantly smaller than Earth. Credit: NASA
For centuries, astronomers and scientists have sought to understand how our Solar System came to be. Since that time, two theories have become commonly-accepted that explain how it formed and evolved over time. These are the Nebular Hypothesis and the Nice Model, respectively. Whereas the former contends that the Sun and planets formed from a large cloud of dust and gas, the latter maintains the giant planets have migrated since their formation.
This is what has led to the Solar System as we know it today. However, an enduring mystery about these theories is how Mars came to be the way it is. Why, for example, is it significantly smaller than Earth and inhospitable to life as we know it when all indications show that it should be comparable in size? According to a new study by an international team of scientists, the migration of the giant planets could have been what made the difference.
For over a decade, astronomers have been operating under the assumption that shortly after the formation of the Solar System, the gas and ice giants of the outer Solar System (Jupiter, Saturn, Uranus and Neptune) began to migrate outward. This is the substance of the Nice Model, which asserts that this migration had a profound effect on the evolution of the Solar System and the formation of the terrestrial planets.
This model – named for the location of the Observatoire de la Côte d’Azur (in Nice, France), where it was initially developed – began as an evolutionary model that helped explain the observed distributions of small objects like comets and asteroids. As Matt Clement, a graduate student in the HL Dodge Department of Physics and Astronomy at the University of Oklahoma and the lead author on the paper, explained to Universe Today via email:
“In the model, the giant planets (Jupiter, Saturn, Uranus and Neptune) originally formed much closer to the Sun. In order to reach their current orbital locations, the entire solar system undergoes a period of orbital instability. During this unstable period, the size and the shape of the giant planet’s orbits change rapidly.”
For the sake of their study, which was recently published in the scientific journal Icarus under the title “Mars Growth Stunted by an Early Giant Planet Instability“, the team expanded on the Nice Model. Through a series of dynamical simulations, they attempted to show how, during the early Solar System, the growth of Mars was halted thanks to the orbital instabilities of the giant planets.
The purpose of their study was also to address a flaw in the Nice Model, which is how the terrestrial planets could have survived a serious shake up of the Solar System. In the original version of the Nice Model, the instability of the giant planets occurred a few hundred million years after the planets formed, which coincided with the Late Heavy Bombardment – when the inner Solar System was bombarded by a disproportionately large number of asteroids.
This period is evidenced by spike in the Moon’s cratering record, which was inferred from an abundance of samples from the Apollo missions with similar geological dates. As Clement explained:
“A problem with this is that it is difficult for the terrestrial planets (Mercury, Venus, Earth and Mars) to survive the violent instability without being ejected out of the solar system or colliding with one another. Now that we have better, high resolution images of lunar craters and more accurate methods for dating the Apollo samples, the evidence for a spike in lunar cratering rates is diminishing. Our study investigated whether moving the instability earlier, while the inner terrestrial planets were still forming, could help them survive the instability, and also explain why Mars is so small relative to the Earth.”
Clement was joined by Nathan A. Kaib, a OU astrophysics professor, as well as Sean N. Raymond of the University of Bordeaux and Kevin J. Walsh from the Southwest Research Institute. Together, they used the computing resources of the OU Supercomputing Center for Education and Research (OSCER) and the Blue Waters supercomputing project to perform 800 dynamical simulations of the Nice model to determine how it would impact Mars.
These simulations incorporated recent geological evidence from Mars and Earth that indicate that Mars’ formation period was about 1/10th that of Earth’s. This has led to the theory that Mars was left behind as a “stranded planetary embryo” during the formation of the Sun’s inner planets. As Prof. Kaib explained to Universe Today via email, this study was therefore intended to test how Mars emerged from planetary formation as a planetary embryo:
“We simulated the “giant impact phase” of terrestrial planet formation (the final stage of the formation process). At the beginning of this phase, the inner Solar System (0.5-4 AU) consists of a disk of about 100 moon-to-mars-sized planetary embryos embedded in a sea of much smaller, more numerous rocky planetesimals. Over the course of 100-200 million years the bodies making up this system collide and merge into a handful (typically 2-5) rocky planetary mass bodies. Normally, these types of simple initial conditions build planets on Mars-like orbits that are about 10x more massive than Mars. However, when the terrestrial planet formation process is interrupted by the Nice model instability, many of the planet building blocks near the Mars region are lost or tossed into the Sun. This limits the growth of Mars-like planets and produces a closer match to our actual inner solar system.”
Size comparison between Earth and Mars. Credit: NASA
What they found was that this revised timeline explained the disparity between Mars and Earth. In short, Mars and Earth vary considerably in size, mass and density because the giant planets became unstable very early in the Solar System’s history. In the end, this is what allowed Earth to become the only life-bearing terrestrial planet in the Solar System, and for Mars to become the cold, desiccated and thinly-atmosphered place that it is today.
As Prof. Kaib explained, this is not the only model for explaining the disparity between Earth and Mars, but the evidence all fits:
“Without this instability, Mars likely would have had a mass closer to Earth’s and would be a very different, perhaps more Earth-like, planet compared to what it is today,” he said. “I should also say that this is not the only mechanism capable of explaining the low mass of Mars. However, we already know that the Nice model does an excellent job of reproducing many features of the outer Solar System, and if it occurs at the right time in the Solar System’s history it also ends up explaining our inner Solar System.”
This study could also have drastic implications when it comes to the study of extra-solar systems. At present, our models for how planets form and evolve are based on what we have been able to learn from our own Solar System. Hence, by learning more about how gas giants and terrestrial planets grew and assumed their current orbits, scientists will be able to create more comprehensive models of how life-bearing planets could merge around other stars.
It certainly would help narrow the search for “Earth-like” planets and (dare we dream?) planets that support life.
A couple watches the Moon rise from the icy shore of Lake Superior in Duluth earlier this month on March 1. Credit: Bob King
I apologize for the end-of-the-world title, but everything in it is true. And the world will still be here after it’s all done. On Friday (March 31) at 7:36 a.m. Central Time, the Moon will be full for the second time this month, which makes it a Blue Moon according to popular usage. Enjoy it. What with January’s Blue Moon and now this, we’ve chewed through all our Blue Moons till Halloween 2020.
I look forward to every full moon. Watching a moonrise, we get to see all manner of amazing atmospheric distortions play across the squat, orange disk. Once the sky’s dark, its outpouring of light makes walking at night a pleasure.
When a full moon occurs in spring, it hurries south down the ecliptic, the imaginary circle in the sky defining Earth’s orbit around the Sun. For northern hemisphere skywatchers, this southward sprint delays its rising by more an hour each night, forcing a quick departure from the evening sky. And that means blessed darkness for hunting down favorite galaxies and star clusters.
Tiangong 1 and a reentry simulation
As the Moon rolls along, the hapless Chinese space station Tiangong 1 hurtles toward Earth. Drag caused by friction with the upper atmosphere continues to shrink the spacecraft’s orbit, bringing it closer and closer to inevitable breakup and incineration. Since the Chinese National Space Administration (CNSA) lost touch with Tiangong 1 in March 2016, mission control can no longer power thrusters to de-orbit it at chosen time over a safe location like the ocean. The 9.3-ton (8,500 kg) station will burn up somewhere anywhere over a vast swath of the planet between latitudes 43°N and 43°S. Included within this zone are the southern half of Europe, the southern two-thirds of the U.S., India, Australia and much of Africa and South America.
Not until the day of or even hours before will have a clear idea of when and where the station will meet its fate. According to the latest update from the Aerospace Corp., which monitors falling spacecraft, reentry is expected on Easter Sunday (April 1) at 10:30 UT / 5:30 a.m. Central Time plus or minus 16 hours. This morning (March 29), the space station is circling Earth at about 118 miles (190 km) altitude. The lowest a satelllite can still make a complete orbit of the planet is about 62 miles (100 km). Below that, break-up begins.
A high definition TV camera on an aircraft took this photo of the cargo ship ATV-1 reentering the atmosphere in September 2008. Tiangong 1 is about the same size and will likely shatter and burn in similar fashion. Credit: ESA/NASA
For up-to-the-minute updates on when to expect Tiangong 1’s orbit to decay and the machine to plunge to Earth, check out Joseph Remis’ Twitter page. Most of the space station is expected to burn up on reentry, but larger chunks might survive all the way to the ground. Since much more of the Earth’s surface is water these remnants will likely end up in the drink … but you never know. If Tiangong-1 does come down over a populated area, observers on the ground will witness a spectacular, manmade fireball day or night.
Mars (right) and Saturn pair up in Sagittarius this morning, March 29 at dawn seen from Duluth, Minn. The two planets were 2.2° apart. Details: 35mm lens, f/2.8, 13 second exposure at ISO 800. Credit: Bob King
On the quieter side but nearly as eye-catching, Mars will overtake Saturn in the coming week, passing just 1° south of the ringed planet in a thrilling dawn conjunction on April 2. If the weather forecast doesn’t look promising that morning, the two planets will remain within 2° of each other now through April 6th, providing plenty of opportunities for a look.
You can easily tell them apart by color: Mars is distinctly red-orange and Saturn looks creamy white. Both are bright at around magnitude 0 though Mars is now a hair brighter by two-tenths of a magnitude. Will you be able to see the difference?
Mars passes close to Saturn on Monday, April 2. Look low in the southeastern sky shortly before and at dawn. Try getting a picture of the lovely couple by setting up your camera on a tripod and doing a series of time exposures from 5-30 seconds at f/3.5 and ISO 800. No fancy telephoto equipment is needed: a 35-55mm lens is perfect. Created with Stellarium
In most telescopes at low magnification both planets will comfortably fit in the same field of view. Saturn’s rings are tilted nearly wide open and quite beautiful. Mars appears gibbous and though still rather small, it’s brightening rapidly and drawing closer in time for its closest approach to Earth since 2003. Wishing you clear skies!
This mosaic taken by NASA's Mars Curiosity rover looks uphill at Mount Sharp, which Curiosity has been climbing since 2014. Highlighted in white is an area with clay-bearing rocks that scientists are eager to explore; it could shed additional light on the role of water in creating Mount Sharp. Credit: NASA/JPL-Caltech/MSSS
Since it landed on Mars in 2012, the Curiosity rover has made some rather startling scientific discoveries. These include the discovery of methane and organic molecules, evidence of how it lost its ancient atmosphere, and confirming that Mars once had flowing water and lakes on its surface. In addition, the rover has passed a number of impressive milestones along the way.
In fact, back in January of 2018, the rover had spent a total of 2,000 Earth days on Mars. And as of March 22nd, 2018, NASA’s Mars Curiosity rover had reached its two-thousandth Martian day (Sol) on the Red Planet! To mark the occasion, NASA released a mosaic photo that previews what the rover will be investigating next (hint: it could shed further light on whether or not Mars was habitable in the past).
The image (shown at top and below) was assembled from dozens of images taken by Curiosity‘s Mast Camera (Mastcam) on Sol 1931 (back in January). To the right, looming in the background, is Mount Sharp, the central peak in the Gale Crater (where Curiosity landed back in 2012). Since September of 2014, the rover has been climbing this feature and collecting drill samples to get a better understanding of Mars’ geological history.
Image of the mosaic taken by NASA’s Mars Curiosity rover in January of 2018 (Sol 1931). Click to enlarge. Credit: NASA/JPL-Caltech/MSSS
In the center of the image is the rover’s next destination and scientific target. This area, which scientists have been studying from orbit, is rich in clay minerals, which indicates that water once existed there. In the past, the Curiosity rover found evidence of clay minerals on the floor of the Gale Crater. This confirmed that the crater was a lake bed between 3.3 and 3.8 billion years ago.
Mount Sharp, meanwhile, is believed to have formed from sedimentary material that was deposited over a period of about 2 billion years. By examining patches of clay minerals that extend up the mountain’s side, scientists hope to gain insight into the history of Mars since then. These include how long water may have persisted on its surface and how the planet made the transition to the cold and desiccated place it is today.
The Curiosity science team is eager to analyze rock samples pulled from the clay-bearing rocks seen in the center of the image, and not just because of the results they could provide. Recently, the science team developed a new drilling technique to compensate for the failure of a faulty motor (which allows the drill to extend and retract). When the rover begins to drill again, it will be the first time since December 2016.
All told, the rover has spent a total of about 2055 Earth days (5 years and 230 days), which means Curiosity now ranks third behind the Opportunity (5170 days; 5031 sols) and the Spirit rovers (2269 days; 2208 sols) in terms of total time spent on Mars. Since it arrived on Mars in 2012, Curiosity has also traveled a total distance of 18.7 km (11.6 mi) and studied more than 180 meters (600 feet) vertical feet of rock.
But above all, Curiosity‘s greatest achievement has been the discovery that Mars once had all the necessary conditions and chemical ingredients to support microbial life. Based on their findings, Curiosity‘s international science team has concluded that habitable conditions must have lasted for at least millions of years before Mars’ atmosphere was stripped away.
Finding the evidence of this, and how the transition occurred, will not only advance our understanding of the history of Mars, but of the Solar System itself. It also might provide clues as to how Mars could be made into a warmer, wetter environment again someday!
Image of the Tharsis region of Mars taken by Mars Express featuring several prominent shield volcanoes includes the massive Olympus Mons (at left). Credit: ESA
Thanks to the many missions that have been studying Mars in recent years, scientists are aware that roughly 4 billion years ago, the planet was a much different place. In addition to having a denser atmosphere, Mars was also a warmer and wetter place, with liquid water covering much of the planet’s surface. Unfortunately, as Mars lost its atmosphere over the course of hundreds of millions of years, these oceans gradually disappeared.
When and where these oceans formed has been the subject of much scientific inquiry and debate. According to a new study by a team of researchers from UC Berkeley, the existence of these oceans was linked to the rise of the Tharis volcanic system. They further theorize that these oceans formed several hundred millions years earlier than expected and were not as deep as previously thought.
The early ocean known as Arabia (left, blue) would have looked like this when it formed 4 billion years ago on Mars, while the Deuteronilus ocean (right), about 3.6 billion years old, had a smaller shoreline. Credit: Robert Citron/UC Berkeley
As Michael Manga explained in a recent Berkeley News press release:
“The assumption was that Tharsis formed quickly and early, rather than gradually, and that the oceans came later. We’re saying that the oceans predate and accompany the lava outpourings that made Tharsis.”
The debate over the size and extent of Mars’ past oceans is due to some inconsistencies that have been observed. Essentially, when Mars lost its atmosphere, its surface water would have frozen to become underground permafrost or escaped into space. Those scientists who don’t believe Mars once had oceans point to the fact that the estimates of how much water could have been hidden away or lost is not consistent with estimates on the oceans’ sizes.
What’s more, the ice that is now concentrated in the polar caps is not enough to create an ocean. This means that either less water was present on Mars than previous estimates indicate, or that some other process was responsible for water loss. To resolve this, Citron and his colleagues created a new model of Mars where the oceans formed before or at the same time as Mars’ largest volcanic feature – Tharsis Montes, roughly 3.7 billion years ago.
A colorized image of the surface of Mars taken by the Mars Reconnaissance Orbiter. The line of three volcanoes is the Tharsis Montes, with Olympus Mons to the northwest. Valles Marineris is to the east. Image: NASA/JPL-Caltech/ Arizona State University
Since Tharsis was smaller at the time, it did not cause the same level of crustal deformation that it did later. This would have been especially true of the plains that cover most the northern hemisphere and are believed to have been an ancient seabed. Given that this region was not subject to the same geological change that would have come later, it would have been shallower and held about half the water.
“The assumption was that Tharsis formed quickly and early, rather than gradually, and that the oceans came later,” said Manga. “We’re saying that the oceans predate and accompany the lava outpourings that made Tharsis.”
In addition, the team also theorized that the volcanic activity that created Tharsis may have been responsible for the formation of Mars’ early oceans. Basically, the volcanoes would have spewed gases and volcanic ash into the atmosphere that would have led to a greenhouse effect. This would have warmed the surface to the point that liquid water could form, and also created underground channels that allowed water to reach the northern plains.
Their model also counters other previous assumptions about Mars, which are that its proposed shorelines are very irregular. Essentially, what is assumed to have been “water front” property on ancient Mars varies in height by as much as a kilometer; whereas on Earth, shorelines are level. This too can be explained by the growth of the Tharsis volcanic region, roughly 3.7 billion years ago.
A map of Mars today shows where scientists have identified possible ancient shoreline that may have been etched by intermittent oceans billions of years ago. Credit: Robert Citron/UC Berkeley.
Using current geological data of Mars, the team was able to trace how the irregularities we see today could have formed over time. This would have began when Mars first ocean (Arabia) started forming 4 billion years ago and was around to witness the first 20% of Tharsis Montes growth. As the volcanoes grew, the land became depressed and the shoreline shifted over time.
Similarly, the irregular shorelines of a subsequent ocean (Deuteronilus) can be explained by this model by indicating that it formed during the last 17% of Tharsis’ growth – roughly 3.6 billion years ago. The Isidis feature, which appears to be an ancient lakebed slightly removed from the Utopia shoreline, could also be explained this way. As the ground deformed, Isidis ceased being part of the northern ocean and became a connected lakebed.
“These shorelines could have been emplaced by a large body of liquid water that existed before and during the emplacement of Tharsis, instead of afterwards,” said Citron. This is certainly consistent with the observable effect that Tharsis Mons has had on the topography of Mars. It’s bulk not only creates a bulge on the opposite side of the planet (the Elysium volcanic complex), but a massive canyon system in between (Valles Marineris).
This new theory not only explains why previous estimates about the volume of water in the northern plains were inaccurate, it can also account for the valley networks (cut by flowing water) that appeared around the same time. And in the coming years, this theory can be tested by the robotic missions NASA and other space agencies are sending to Mars.
This artist’s concept from August 2015 depicts NASA’s InSight Mars lander fully deployed for studying the deep interior of Mars. Credit: NASA/JPL-Caltech
Consider NASA’s Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission, which is scheduled for launch in May, 2018. Once it reaches Mars, this lander will use a suite of advanced instruments – which includes a seismometer, temperature probe and radio science instrument – to measure Mars interior and learn more about its geological activity and history.
Among other things, NASA anticipates that InSight might detect the remains of Mars’ ancient ocean frozen in the interior, and possibly even liquid water. Alongside the Mars 2020 rover, the ExoMars 2020, and eventual crewed missions, these efforts are expected to provide a more complete picture of Mars past, which will include when major geological events took place and how this could have affected the planet’s ocean and shorelines.
The more we learn about what happened on Mars over the past 4 billion years, the more we learn about the forces that shaped our Solar System. These studies also go a long way towards helping scientists determine how and where life-bearing conditions can form. This (we hope) will help us locate life it in another star system someday!
Artist's impression of the the Interplanetary Spacecraft approaching Mars. Credit: SpaceX
Elon Musk has a reputation for pushing the envelop and making bold declarations. In 2002, he founded SpaceX with the intention of making spaceflight affordable through entirely reusable rockets. In April of 2014, his company achieved success with the first successful recovery of a Falcon 9 first stage. And in February of this year, his company successfully launched its Falcon Heavy and managed to recover two of the three boosters.
But above and beyond Musk’s commitment to reusability, there is also his longer-term plans to use his proposed Big Falcon Rocket (BFR) to explore and colonize Mars. The topic of when this rocket will be ready to conduct launches was the subject of a recent interview between Musk and famed director Jonathon Nolan, which took place at the 2018 South by Southwest Conference (SXSW) in Austin, Texas.
During the interview, Musk reiterated his earlier statements that test flights would begin in 2019 and an orbital launch of the full BFR and Big Falcon Spaceship (BFS) would take place by 2020. And while this might seem like a very optimistic prediction (something Musk is famous for), this timeline does not seem entirely implausible given his company’s work on the necessary components and their success with reusability.
As Musk emphasized during the course of the interview:
“People have told me that my timelines have historically been optimistic. So I am trying to re-calibrate to some degree here. But I can tell what I know currently is the case is that we are building the first ship, the first Mars or interplanetary ship, right now, and I think we’ll probably be able to do short flights, short sort of up-and-down flights probably in the first half of next year.”
To break it down, the BFR – formerly known as the Interplanetary Transport System – consists of a massive first stage booster and an equally massive second stage/spaceship (the BFS). Once the spacecraft is launched, the second stage would detach and use its thrusters to assume a parking orbit around Earth. The first stage would then guide itself back to its launchpad, take on a propellant tanker, and return to orbit.
The propellant tanker would then attach to the BFS and refuel it and return to Earth with the first stage. The BFS would then fire its thrusters again and make the journey to Mars with its payload and crew. While much of the technology and concepts have been tested and developed through the Falcon 9 and Falcon Heavy, the BFR is distinct from anything else SpaceX has built in a number of ways.
For one, it will be much larger (hence the nickname, Big F—— Rocket), have significantly more thrust, and be able carry a much larger payload. The BFR’s specifications were the subject of a presentation Musk made at the 68th International Astronautical Congress on September 28th, 2017, in Adelaide, Australia. Titled “Making Life Interplanetary“, his presentation outlined his vision for colonizing Mars and presented an overview of the ship that would make it happen.
According to Musk, the BFR will measure 106 meters (348 ft) in height and 9 meters (30 ft) in diameter. It will carry 110 tons (~99,700 kg) of propellant and will have an ascent mass of 150 tons (~136,000 kg) and a return mass of 50 tons (~45,300 kg). All told, it will be able to deliver a payload of 150,000 kg (330,000 lb) to Low-Earth Orbit (LEO) – almost two and a half times the payload of the Falcon Heavy (63,800 kg; 140,660 lb)
“This a very big booster and ship,” said Musk. “The liftoff thrust of this would be about twice that of a Saturn V (the rockets that sent the Apollo astronauts to the Moon). So it’s capable of doing 150 metric tons to orbit and be fully reusable. So the expendable payload is about double that number.”
In addition, the BFR uses a new type of propellant and tanker system in order to refuel the spacecraft once its in orbit. This goes beyond what SpaceX is used to, but the company’s history of retrieving rockets and reusing them means the technical challenges this poses are not entirely new. By far, the greatest challenges will be those of cost and safety, since this will be only the third reusable second stage spacecraft in history.
The other two consist of the NASA Space Shuttles, which were officially retired in 2011, and the Soviet/Russian version of the Space Shuttle known as the Buran spacecraft. While the Buran only flew once (an uncrewed flight that took place in 1988), it remains the only Russian reusable spacecraft to have even been built or flown.
Where costs are concerned, the Space Shuttle Program provides a pretty good glimpse into what Musk and his company will be facing in the years ahead. According to estimates compiled in 2010 (shortly before the Space Shuttle was retired), the program cost a total of about $ 210 billion USD. Much of these costs were due to maintenance between launches and the costs of propellant, which will need to be kept low for the BFR to be economically viable.
Addressing the question of costs, Musk once again stressed how reusability will be key:
“What’s amazing about this ship, assuming we can make full and rapid reusability work, is that we can reduce the marginal cost per flight dramatically, by orders of magnitude compared to where it is today. This question of reusability is so fundamental to rocketry, it is the fundamental breakthrough that’s needed.”
As an example, Musk compared the cost of renting a 747 with full cargo (about $500,000) and flying from California to Australia to buying a single engine turboprop plane, – which would run about $1.5 million and cannot even reach Australia. In short, the BFR relies on the principle that it costs less for an entirely reusable large spaceship to make a long trip that it does to launch a single rocket on a short trip that would never return.
“A BFR flight will actually cost less than our Falcon 1 flight did,” he said. “That was about a 5 or 6 million dollar marginal cost per flight. We’re confident the BFR will be less than that. That’s profound, and that is what will enable the integration of a permanent base on the Moon and a city on Mars. And that’s the equivalent of like the Union Pacific Railroad, or having ships that can quickly cross the oceans.”
Artist concept of NASA’s Space Launch System (SLS) on the left, and the Orion Multi-Purpose Crew Vehicle (right). Credit: NASA
Beyond manufacturing and refurbishing costs, the BFR will also need to have an impeccable safety record if SpaceX is to have a hope of making money from it. In this respect, SpaceX hopes to follow a development process similar to what they did with the Falcon 9. Before conducting full launch tests to see if the first stage of the rocket could safely make it to orbit and then be retrieved, the company conducted short hop tests using their “Grasshopper” rocket.
According to the timeline Musk offered at the 2018 SXSW, the company will be using the spaceship that is currently being built to conduct suborbital tests as soon as 2019. Orbital launches, which may include both the booster and the spaceship, are expected to occur by 2020. At present, Musk’s earlier statements that the first flight of the BFR would take place by 2022 and the first crewed flight by 2024 still appear to be on.
For comparison, the Space Launch System (SLS) – which is NASA’s proposed means of getting to Mars – is scheduled to conduct its first launch in 2019 as well. Known as Exploration Mission 1 (EM-1), this launch will involve sending an uncrewed Orion capsule on a trip around the Moon. EM-2, in which a crewed Orion capsule will delver the first module of the Lunar Orbital Platform-Gateway (LOP-G, formerly the Deep Space Gateway) to lunar orbit, will take place in 2022.
The ensuing missions will consist of more modules being delivered to lunar orbit to complete construction of the LOP-G, as well as the Deep Space Transport (DST). The first interplanetary trip to Mars, Exploration Mission 11 (EM-11), won’t to take place until 2033. So if Musk’s timelines are to be believed, SpaceX will be beating NASA to Mars, both in terms of uncrewed and crewed missions.
As for who will be enabling a permanent stay on both the Moon and Mars, that remains to be seen. And as Musk emphasized, he hopes that by showing that creating an interplanetary spaceship is possible, agencies and organizations all over the planet will mobilize to do the same. For all we know, the creation of the BFR could enable the creation of an entire fleet of Interplanetary Transport Systems.
The South by Southwest Conference began on Friday, March 9th and will continue until Sunday, March 18th. And be sure to check out the video of the interview below:
