Special Guest:
NAT GEO’s Stephen Petranek is the author of How We’ll Live on Mars (TED Books.) Stephen became a reluctant doomsayer when his earliest TED Talk (10 Ways the World Could End) racked up 1.5 million views. But Petranek is, in fact, an optimist who believes that humanity will escape its predicaments — literally. Within a century, he predicts that humans will have established a city of 80,000 on Mars: and that not only is that plausible, but it’s also inevitable.
Having worked in publishing for four decades — most of it straddling the line with science and technology, Petranek is the former editor-in-chief of Discover magazine, editor of the Washington Post’s magazine, and a renown TED Talk speaker has also given him some unique perspective and insight on the changes that lie ahead and new tools that reflect a potential disruptive shift in how we observe the world around us. Petranek is the editor-in-chief of the Breakthrough Technology Alert, a technology newsletter that ties scientific breakthroughs to investment opportunities.
We use a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!
Announcements:
The WSH recently welcomed back Mathew Anderson, author of “Our Cosmic Story,” to the show to discuss his recent update. He was kind enough to offer our viewers free electronic copies of his complete book as well as his standalone update. Complete information about how to get your copies will be available on the WSH webpage – just visit http://www.wsh-crew.net/cosmicstory for all the details.
If you’d like to join Fraser and Paul Matt Sutter on their Tour to Iceland in February 2018, you can find the information at astrotouring.com.
If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!
We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Universe Today, or the Universe Today YouTube page
Did you know that it’s been almost 45 years since humans walked on the surface of the Moon? Of course you do. Anyone who loves space exploration obsesses about the last Apollo landings, and counts the passing years of sadness.
Sure, SpaceX, Blue Origins and the new NASA Space Launch Systems rocket offer a tantalizing future in space. But 45 years. Ouch, so much lost time.
What would happen if we could go back in time? What amazing and insane plans did NASA have to continue exploring the Solar System? What alternative future could we have now, 45 years later?
In order to answer this question, I’ve teamed up with my space historian friend, Amy Shira Teitel, who runs the Vintage Space blog and YouTube Channel. We’ve decided to look at two groups of missions that never happened.
In her part, Amy talks about the Apollo Applications Program; NASA’s original plans before the human exploration of the Moon was shut down. More Apollo missions, the beginnings of a lunar base, and even a human flyby of Venus.
In my half of the series, I look at Werner Von Braun’s insanely ambitious plans to send a human mission to Mars. Put it together with Amy’s episode and you can imagine a space exploration future with all the ambition of the Kerbal Space Program.
Keep mind here that we’re not going to constrain ourselves with the pesky laws of physics, and the reality of finances. These ideas were cool, and considered by NASA engineers, but they weren’t necessarily the best ideas, or even feasible.
So, 2 parts, tackle them in any order you like. My part begins right now.
Werner Von Braun, of course, was the architect for NASA’s human spaceflight efforts during the space race. It was under Von Braun’s guidance that NASA developed the various flight hardware for the Mercury, Gemini and Apollo missions including the massive Saturn V rocket, which eventually put a human crew of astronauts on the Moon and safely returned them back to Earth.
Wernher von Braun. Credit: NASA/Marshall Space Flight Center
Von Braun was originally a German rocket scientist, pivotal to the Nazi “rocket team”, which developed the ballistic V-2 rockets. These unmanned rockets could carry a 1-tonne payload 800 kilometers away. They were developed in 1942, and by 1944 they were being used in war against Allied targets.
By the end of the war, Von Braun coordinated his surrender to the Allies as well as 500 of his engineers, including their equipment and plans for future rockets. In “Operation Paperclip”, the German scientists were captured and transferred to the White Sands Proving Ground in New Mexico, where they would begin working on the US rocket efforts.
Von Braun and others standing in front a V-2 rocket engine at White Sands. Credit: U.S. Army/ Ordway Collection/Space Rocket Center
Before the work really took off, though, Von Braun had a couple of years of relative downtime, and in 1947 and 1948, he wrote a science fiction novel about the human exploration of Mars.
The novel itself was never published, because it was terrible, but it also contained a detailed appendix containing all the calculations, mission parameters, hardware designs to carry out this mission to Mars.
The Mars Project
In 1952, this appendix was published in Germany as “Das Marsproject”, or “The Mars Project”. And an English version was published a few years later. Collier’s Weekly Magazine did an 8-part special on the Mars Project in 1952, captivating the world’s imagination.
Here’s the plan: In the Mars Project, Von Braun envisioned a vast armada of spaceships that would make the journey from Earth to Mars. They would send a total of 10 giant spaceships, each of which would weigh about 4,000 tonnes.
Just for comparison, a fully loaded Saturn V rocket could carry about 140 tonnes of payload into Low Earth Orbit. In other words, they’d need a LOT of rockets. Von Braun estimated that 950 three-stage rockets should be enough to get everything into orbit.
Ships being assembled in orbit. Credit: Collier’s
All the ships would be assembled in orbit, and 70 crewmembers would take to their stations for an epic journey. They’d blast their rockets and carry out a Mars Hohmann transfer, which would take them 8 months to make the journey from Earth to Mars.
The flotilla consisted of 7 orbiters, huge spheres that would travel to Mars, go into orbit and then return back to Earth. It also consisted of 3 glider landers, which would enter the Martian atmosphere and stay on Mars.
Once they reached the Red Planet, they would use powerful telescopes to scan the Martian landscape and search for safe and scientifically interesting landing spots. The first landing would happen at one of the planet’s polar caps, which Von Braun figured was the only guaranteed flat surface for a landing.
A rocket-powered glider descending towards Mars. Credit: Collier’s
At this point, it’s important to note that Von Braun assumed that the Martian atmosphere was about as thick as Earth’s. He figured you could use huge winged gliders to aerobrake into the atmosphere and land safely on the surface.
He was wrong. The atmosphere on Mars is actually only 1% as thick as Earth’s, and these gliders would never work. Newer missions, like SpaceX’s Red Dragon and Interplanetary Transport Ship will use rockets to make a powered landing.
I think if Von Braun knew this, he could have modified his plans to still make the whole thing work.
Landed at the polar cap. Credit: Collier’s
Once the first expedition landed at one of the polar caps, they’d make a 6,400 kilometer journey across the harsh Martian landscape to the first base camp location, and build a landing strip. Then two more gliders would detach from the flotilla and bring the majority of the explorers to the base camp. A skeleton crew would remain in orbit.
Once again, I think it’s important to note that Von Braun didn’t truly understand how awful the surface of Mars really is. The almost non-existent atmosphere and extreme cold would require much more sophisticated gear than he had planned for. But still, you’ve got to admire his ambition.
Preparing the gliders for rocket-powered ascent. Credit: Collier’s
With the Mars explorer team on the ground, their first task was to turn their glider-landers into rockets again. They would stand them up and get them prepped to blast off from the surface of Mars when their mission was over.
The Martian explorers would set up an inflatable habitat, and then spend the next 400 days surveying the area. Geologists would investigate the landscape, studying the composition of the rocks. Botanists would study the hardy Martian plant life, and seeing what kinds of Earth plants would grow.
Zoologists would study the local animals, and help figure out what was dangerous and what was safe to eat. Archeologists would search the region for evidence of ancient Martian civilizations, and study the vast canal network seen from Earth by astronomers. Perhaps they’d even meet the hardy Martians that built those canals, struggling to survive to this day.
Once again, in the 1940s, we thought Mars would be like the Earth, just more of a desert. There’d be plants and animals, and maybe even people adapted to the hardy environment. With our modern knowledge, this sounds quaint today. The most brutal desert on Earth is a paradise compared to the nicest place on Mars. Von Braun did the best he could with the best science of the time.
Finally, at the end of their 400 days on Mars, the astronauts would blast off from the surface of Mars, meet up with the orbiting crew, and the entire flotilla would make the return journey to Earth using the minimum-fuel Mars-Earth transfer trajectory.
The planned trajectories to and from Mars. Credit: Collier’s
Although Von Braun got a lot of things wrong about his Martian mission plan, such as the thickness of the atmosphere and habitability of Mars, he got a lot of things right.
He anticipated a mission plan that required the least amount of fuel, by assembling pieces in orbit, using the Hohmann transfer trajectory, exploring Mars for 400 days to match up Earth and Mars orbits. He developed the concept of using orbiters, detachable landing craft and ascent vehicles, used by the Apollo Moon missions.
The missions never happened, obviously, but Von Braun’s ideas served as the backbone for all future human Mars mission plans.
I’d like to give a massive thanks to the space historian David S.F. Portree. He wrote an amazing book called Humans to Mars, which details 50 years of NASA plans to send humans to the Red Planet, including a fantastic synopsis of the Mars Project.
I asked David about how Von Braun’s ideas influenced human spaceflight, he said it was his…
“… reliance on a conjunction-class long-stay mission lasting 400 days. That was gutsy – in the 1960s, NASA and contractor planners generally stuck with opposition-class short-stay missions. In recent years we’ve seen more emphasis on the conjunction-class mission mode, sometimes with a relatively short period on Mars but lots of time in orbit, other times with almost the whole mission spent on the surface.”
Special Guest:
Eric Fisher is the head of Labfundr, a Canadian crowdsourcing platform for science research and outreach. Eric is an entrepreneur, recovering biochemist, and son of a glaciologist. He completed a PhD in Biochemistry & Molecular Biology at Dalhousie University in Halifax, Nova Scotia, Canada. At Dalhousie, Eric investigated how liver cells create and destroy “bad” cholesterol particles. Eric recently founded Labfundr, Canada’s first crowdfunding platform for science, which aims to boost public engagement and investment in research. He stays on his toes by trying to keep up with his dog Joni, who is smarter and faster than him.
We use a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!
Announcements:
The WSH recently welcomed back Mathew Anderson, author of “Our Cosmic Story,” to the show to discuss his recent update. He was kind enough to offer our viewers free electronic copies of his complete book as well as his standalone update. Complete information about how to get your copies will be available on the WSH webpage – just visit http://www.wsh-crew.net/cosmicstory for all the details.
If you’d like to join Fraser and Paul Matt Sutter on their Tour to Iceland in February 2018, you can find the information at astrotouring.com.
If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!
We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Universe Today, or the Universe Today YouTube page
Asteroid impacts on Mars could have generated supersonic winds that shaped the surface, according to a new study. Credit: geol.umd.edu
The study of another planet’s surface features can provide a window into its deep past. Take Mars for example, a planet whose surface is a mishmash of features that speak volumes. In addition to ancient volcanoes and alluvial fans that are indications of past geological activity and liquid water once flowing on the surface, there are also the many impact craters that dot its surface.
In some cases, these impact craters have strange bright streaks emanating from them, ones which reach much farther than basic ejecta patterns would allow. According to a new research study by a team from Brown University, these features are the result of large impacts that generated massive plumes. These would have interacted with Mars’ atmosphere, they argue, causing supersonic winds that scoured the surface.
These features were noticed years ago by Professor Peter H. Schultz, a professor of geological science with the Department of Earth, Environmental, and Planetary Sciences (DEEPS) at Brown University. When studying images taken at night by the Mars Odyssey orbiter using its THEMIS instrument, he noticed steaks that only appeared when imaged in the infrared wavelength.
Artist’s conception of the Mars Odyssey spacecraft. Credit: NASA/JPL
These streaks were only visible in IR because it was only at this wavelength that contrasts in heat retention on the surface were visible. Essentially, brighter regions at night indicate surfaces that retain more heat during the day and take longer to cool. As Schultz explained in a Brown University press release, this allowed for features to be discerned that would otherwise not be noticed:
“You couldn’t see these things at all in visible wavelength images, but in the nighttime infrared they’re very bright. Brightness in the infrared indicates blocky surfaces, which retain more heat than surfaces covered by powder and debris. That tells us that something came along and scoured those surfaces bare.”
Along with Stephanie N. Quintana, a graduate student from DEEPS, the two began to consider other explanations that went beyond basic ejecta patterns. As they indicate in their study – which recently appeared in the journal Icarus under the title “Impact-generated winds on Mars” – this consisted of combining geological observations, laboratory impact experiments and computer modeling of impact processes.
Ultimately, Schultz and Quintana concluded that crater-forming impacts led to vortex-like storms that reached speeds of up to 800 km/h (500 mph) – in other words, the equivalent of an F8 tornado here on Earth. These storms would have scoured the surface and ultimately led to the observed streak patterns. This conclusion was based in part on work Schultz has done in the past at NASA’s Vertical Gun Range.
An infrared image revealing strange bright streaks extending from Santa Fe crater on Mars. Credit: NASA/JPL-Caltech/Arizona State University.
This high-powered cannon, which can fire projectiles at speeds up to 24,000 km/h (15,000 mph), is used to conduct impact experiments. These experiments have shown that during an impact event, vapor plumes travel outwards from the impact point (just above the surface) at incredible speeds. For the sake of their study, Schultz and Quintana scaled the size of the impacts up, to the point where they corresponded to the impact craters on Mars.
The results indicated that the vapor plume speed would be supersonic, and that its interaction with the Martian atmosphere would generate powerful winds. However, the plume and associated winds would not be responsible for the strange streaks themselves. Since they would be travelling just above the surface, they would not be capable of causing the kind of deep scouring that exists in the streaked areas.
Instead, Schultz and Quintana showed that when the plume struck a raised surface feature – like the ridges of a smaller impact crater – it would create more powerful vortices that would then fall to the surface. It is these, according to their study, that are responsible for the scouring patterns they observed. This conclusion was based on the fact that bright streaks were almost always associated with the downward side of a crater rim.
IR images showing the correlation between the streaks and smaller craters that were in place when the larger crater was formed. Credit: NASA/JPL-Caltech/Arizona State University
As Schultz explained, the study of these streaks could prove useful in helping to establish that rate at which erosion and dust deposition occurs on the Martian surface in certain areas:
“Where these vortices encounter the surface, they sweep away the small particles that sit loose on the surface, exposing the bigger blocky material underneath, and that’s what gives us these streaks. We know these formed at the same time as these large craters, and we can date the age of the craters. So now we have a template for looking at erosion.”
In addition, these streaks could reveal additional information about the state of Mars during the time of impacts. For example, Schultz and Quintana noted that the streaks appear to form around craters that are about 20 km (12.4 mi) in diameter, but not always. Their experiments also revealed that the presence of volatile compounds (such as surface or subsurface water ice) would affect the amount of vapor generated by an impact.
In other words, the presence of streaks around some craters and not others could indicate where and when there was water ice on the Martian surface in the past. It has been known for some time that the disappearance of Mars’ atmosphere over the course of several hundred million years also resulted in the loss of its surface water. By being able to put dates to impact events, we might be able to learn more about Mars’ fateful transformation.
The study of these streaks could also be used to differentiate between the impacts of asteroids and comets on Mars – the latter of which would have had higher concentrations of water ice in them. Once again, detailed studies of Mars’ surface features are allowing scientists to construct a more detailed timeline of its evolution, thus determining how and when it became the cold, dry place we know today!
Artist's impression of the Mars Moons Exploration (MMX) spacecraft. Credit: JAXA
In the coming decades, the world’s largest space agencies hope to mount some exciting missions to the Moon and to Mars. Between NASA, Roscosmos, the European Space Agency (ESA), the Chinese National Space Agency (CNSA) and the Indian Space Research Organization (ISRO), there is simply no shortage of proposals for Lunar bases, crewed missions to Mars, and robotic explorers to both.
However, the Japanese Aerospace Exploration Agency (JAXA) has a different mission in mind when it comes to the coming decades. Instead of exploring the Moon or Mars, they propose exploring the moons of Mars! Known as the Martian Moons Exploration (MMX) mission, the plan is to have a robotic spacecraft fly to Phobos and Deimos to explore their surfaces and return samples to Earth for analysis.
This image taken by the Mars Reconnaissance Orbiter's HiRise camera shows the bright landing platform left behind by NASA's Mars Exploration Rover Opportunity when it landed in 2004. Opportunity landed on the surface of Mars and then bounced and tumbled into the Eagle Crater. The image was taken on April 8, 2017. Image: NASA/JPL-Caltech/Univ. of Arizona
NASA’s eagle-eyed Mars Reconnaissance Orbiter (MRO) has captured orbital images of Opportunity’s Hole-In-One landing site, smack dab in the middle of Eagle Crater on the surface of Mars.
Opportunity arrived at Mars on January 25th, 2005. It’s landing was slowed by parachute, and cushioned by airbags. Once it hit the surface, it bounced its way into “Eagle Crater“, a feature a mere 22 meters across. Not a bad shot!
This is the first color image that the High Resolution Imaging Science Experiment (HiRise) has captured of Opportunity’s landing site. It shows the remarkable landing site inside the crater, where the landing pad was left behind after Opportunity rolled off of it and got going. It also shows the rover’s parachute and backshell.
It’s amazing that, given the relatively smooth surface in Opportunity’s landing area, the rover came to rest inside a small crater. When Opportunity “woke up” at its landing site, its first images were of the inside of Eagle Crater. This was the first look we ever got at the sedimentary rocks on Mars, taken by the rover’s navigation camera.
Opportunity’s navigation camera took this picture, one of the rover’s first, of the inside of Eagle Crater. Exposed Martian rocks are visible. NASA/JPL
After leaving Eagle Crater, Opportunity took a look back and captured a panoramic image. Plainly visible is the rover’s landing pad, the exposed sedimentary rock, and the rover’s tracks in the Martian soil.
This panorama image, called “Lion King” was assembled from 558 images totalling over 75 megabytes. The rock outcrop, the landing pad, and the rover’s tracks are all clearly visible. Image: NASA/JPL/Cornell
MRO arrived at Mars a couple years later, and by that time Opportunity had already left its landing site and made its way south to the much larger Victoria Crater.
When the Mars Reconnaissance Orbiter arrived at Mars, 2 years after Opportunity touched down there, Opportunity had left Eagle Crater and travelled the 6 km to Victoria Crater. By NASA/JPL/University of Arizona – http://photojournal.jpl.nasa.gov/catalog/PIA08813, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4211043
Opportunity is still chugging along, doing valuable work. And so is the MRO and its HiRise instrument. At this point, Opportunity has to be considered one of the most successful scientific undertakings ever.
Special Guest:
This week’s special guest is Brad Peterson. Brad is a returning guest, and since his last appearance, he has been asked by NASA to serve as a community co-chair, with Debra Fischer of Yale, for the Science and Technology Definition Team for the Large Ultraviolet, Optical, and Infrared Surveyor (LUVOIR).
Brad has carried out research on active galactic nuclei for his entire career. He has been developing the technique of reverberation mapping for over 25 years. He is currently on appointment at STScI as Distinguished Visiting Astronomer, after retiring from the faculty of The Ohio State University in 2015 with 35 years of service, the last nine as chair of the Department of Astronomy. He is also a member of the NASA Advisory Council, for which he chairs the Science Committee. He was recently named chair-elect for the Astronomy Section of the AAAS.
We use a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!
Announcements:
On Friday, May 12, the WSH will welcome authors Michael Summers and James Trefil to the show to discuss their new book, Exoplanets: Diamond Worlds, Super Earths, Pulsar Planets and the New Search for Life Beyond Our Solar System. In anticipation of their appearance, the WSH Crew is pleased to offer our viewers a chance to win one of two hard cover copies of Exoplanets. Two winners will be drawn live by @fraser during our show on May 12th. To enter for a chance to win a copy of Exoplanets, send an email to: [email protected] with the Subject: Exoplanets. Be sure to include your name and email address in the body of your message so that we can contact the winners afterward. All entries must be electronically postmarked by 23:59 EST on May 10, 2017, in order to be eligible. No purchase necessary. Two winners will be selected at random from all eligible entries. Good luck!
If you’d like to join Fraser and Paul Matt Sutter on their tour to Iceland in February 2018, you can find the information at astrotouring.com.
If you would like to sign up for the AstronomyCast Solar Eclipse Escape, where you can meet Fraser and Pamela, plus WSH Crew and other fans, visit our site linked above and sign up!
If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!
We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Universe Today, or the Universe Today YouTube page<
Approximately every two years, Earth and Mars are at the closest point to each other in their orbits (i.e. opposition). Credit: NASA
As neighboring planets, Earth and Mars have a few things in common. Both are terrestrial in nature (i.e. rocky), both have tilted axes, and both orbit the Sun within its circumstellar habitable zone. And during the course of their orbital periods (i.e. a year), both planets experience variations in temperature and changes in their seasonal weather patterns.
However, owing to their different orbital periods, a year on Mars is significantly longer than a year on Earth – almost twice as long, in fact. And because their orbits are different, the distance between our two planets varies considerably. Basically, every two years Earth and Mars will go from being “at conjunction” (where they are farther from each other) to being “at opposition” (where they are closer to each other).
Orbital Period:
Earth orbits the Sun at an average distance (semi-major axis) of 149,598,023 km (92,955,902 mi; or 1 AU), ranging from 147,095,000 km (91,401,000 mi) at perihelion to 152,100,000 km (94,500,000 mi) at aphelion. At this distance, and with an orbital velocity of 29.78 km/s (18.5 mi/s) the time it take for the planet to complete a single orbit of the Sun (i.e. orbital period) is equal to about 365.25 days.
A top-down image of the orbits of Earth and Mars. Credit: NASA
Mars, meanwhile, orbits the Sun at an average distance of 227,939,200 km (141,634,850 mi; or 1.523679 AU), ranging from 206,700,000 km (128,437,425 mi) at perihelion to 249,200,000 km (154,845,700 mi) at aphelion. Given this difference in distance, Mars orbits the Sun at a slower speed (24.077 km/s; 14.96 mi/s) and takes about 687 Earth days (or 668.59 Mars sols) to complete a single orbit.
In other words, a Martian year is almost 700 days long, which works out to being 1.88 times as long as a year on Earth. This means that every time Mars completes a single orbit around the Sun, the Earth has gone around almost twice. During the moments when they are on opposite sides of the Sun, this is known as a “conjunction”. When they are on the same side of the Sun, they are at “opposition”.
Mars Opposition:
By definition, a “Mars opposition” occurs when planet Earth passes in between the Sun and planet Mars. The term refers to the fact that Mars and the Sun appear on opposite sides of the sky. Because of their orbits, Mars oppositions happens about every 2 years and 2 months – 779.94 Earth days to be precise. From our perspective here on Earth, Mars appears to be rising in the east just as the Sun sets in the west.
About every two years, the Earth passes Mars as they orbit around the Sun. Credit: NASA
After staying up in the sky for the entire night, Mars then sets in the west just as the Sun begins to rise in the east. During an opposition, Mars becomes one of the brightest objects in the night sky, and is easy to see with the naked eye. Through small telescopes, it will appear as a large and bright object. Through larger telescopes, Mars’ surface features will even become apparent, which would include its polar ice caps.
An opposition can also occur anywhere along Mars’ orbit. However, opposition does not necessary mean that the two planets are at their closest overall. In truth, it just means that they are are at their closest point to each other within their current orbital period. If Earth and Mars’ orbits were perfectly circular, they would be closest to each other whenever they were at opposition.
Instead, their orbits are elliptical, and Mars’ orbit is more elliptical than Earth’s – which means the difference between their respective perihelion and aphelion is greater. Gravitational tugging from other planets constantly changes the shape of our orbits too – with Jupiter pulling on Mars and Venus and Mercury affecting Earth.
Color composite of Mars from seven of its previous oppositions, taken with the Hubble Space Telescope. Credit: NASA/ESA/HST
Lastly, Earth and Mars do not orbit the Sun on the exact same plane – i.e. their orbits are slightly tilted relative to each other. Because of this, Mars and Earth become closest to each other only over the long-term. For instance, every 15 or 17 years, an opposition will occur within a few weeks of Mars’ perihelion. When it happens while the Mars is closest to the sun (called “perihelic opposition”), Mars and Earth get particularly close.
And yet, the closest approaches between the two planets only take place over the course of centuries, and some are always closer than others. To make matters even more confusing, over the past few centuries, Mars’ orbit has been getting more and more elongated, carrying the planet even nearer to the Sun at perihelion and even farther away at aphelion. So future perihelic oppositions will bring Earth and Mars even closer.
On August 28th, 2003, astronomers estimated that Earth and Mars were just 55,758,118 km (34,646,488 mi; 0.37272 AU) apart. This was the closest the two planets had come to each other in almost 60,000 years. This record will stand until August 28th, 2287, at which point the planets will be an estimated 55,688,405 km (34,603,170.6 mi; 0.372254 AU) from each other.
Future Oppositions:
Want to organize your schedule for the next time Mars will be close to Earth? Here are some upcoming dates, covering the next few decades. Plan accordingly!
July 27th, 2018
October 13th, 2020
December 8th, 2022
January 16th, 2025
February 19th, 2027
Mar 25th, 2029
May 4th, 2031
June 27th, 2033
September 15th, 2035
November 19th, 2037
January 2nd, 2040
February 6th, 2042
March 11th, 2044
April 17th, 2046
June 3rd, 2048
August 14th, 2050
And in case your interested, Mars will be making close approaches on two occasions this century. The first will take place on August 14th, 2050, when Mars and Earth will be 55.957 million km (34.77 million mi; or 0.374051 AU) apart; and on September 1st, 2082, when they will be 55,883,780 km (34,724,571 mi; 0.373564 AU) apart.
There’s a reason missions to Mars depart from Earth every two years. Seeking to take advantage of shorter travel times, rovers, orbiters and landers are launched to coincide with Mars being at opposition. And when it comes time to send crewed mission to Mars (or even settlers) the same timing will apply!
A new study led by researchers from OU indicates that the outer planets could be why Mars is significantly smaller than Earth. Credit: NASA
Trojan asteroids are a fascinating thing. Whereas the most widely known are those that orbit Jupiter (around its L4 and L5 Lagrange Points), Venus, Earth, Mars, Uranus and Neptune have populations of these asteroids as well. Naturally, these rocky objects are a focal point for a lot of scientific research, since they can tell us much about the formation and early history of the Solar System.
And now, thanks to an international team of astronomers, it has been determined that the Trojan asteroids that orbit Mars are likely the remains of a mini-planet that was destroyed by a collision billions of years ago. Their findings are detailed in a paper that will be published in The Monthly Notices of the Royal Astronomical Society later this month.
For the sake of their study, the team – which was led by Galin Borisov and Apostolos Christou of the Armagh Observatory and Planetarium in Northern Ireland, examined the composition of Marian Trojans. This consisted of using spectral data obtained by the XSHOOTER spectrograph on the Very Large Telescope (VLT) and photometric data from the National Astronomical Observatory‘s two-meter telescope, and the William Herschel Telescope.
Diagram of Jupiter and the inner Solar System, showing the Jupiter and Martian Trojans (light green) and the Main Belt (teal). Credit: Wikipedia Commons/AndrewBuck
Specifically, they examined two members of the Eureka family – a group of Martian Trojans located at the planet’s L5 point. It is here that eight of Mars’ nine known Trojans exist in stable orbits (the other being at L4), and which are named after the first Martian Trojan ever discovered – 5261 Eureka. Like all Trojans, the Eurekas are thought to have orbited Mars ever since the formation of the Solar System.
In fact, astronomers have suspected for some time that the Martian Trojans could be the survivors of an early generation of planetesimals from which the inner Solar System formed. As Dr. Christou told Universe Today via email:
“[The Trojan family] is unique in the Solar System, in more ways than one. Unlike every other family that exists in the Main Asteroid Belt between Mars and Jupiter, it is made up of olivine-rich asteroids. Also, the asteroids are < 2km across, much smaller than we can see at other families, basically because they are much closer to the Earth than other asteroids. Finally, it is the closest family we know to the Sun, and this has implications on how it formed in that the tiny but continuous action of sunlight may have played a role.”
After combining spectrographic and photometric data on these asteroids, the team found that they were rich in the mineral olivine – a magnesium iron silicate that is a primary component of the Earth’s mantle and (it is believed) other terrestrial planets. This was unusual find as far as asteroids go, but it was even more interesting when compared to 5261 Eureka itself – which also has an olivine-rich composition.
The first X-ray view of Martian soil by Curiosity rover at the “Rocknest” (October 17, 2012), showing traces of feldspar, pyroxenes, and olivine. Credit: NASA/JPL-Caltech/Ames
Given that the Eureka asteroids also have similar orbits, the team concluded that every member of this family is likely to have a common composition – and hence, a common origin. These findings could have drastic implications for both the origin of Martian Trojans, and the origin of the inner Solar System. As Dr. Christou explained:
“The presence of asteroids with exposed olivine on their surfaces constrains the sequence of events that led to Mars’ formation. Olivine forms within objects that grew large enough to differentiate into a crust, mantle and core. Therefore, these objects must have formed before Mars did and were available to participate in Mars’ formation. To expose the olivine, it is necessary to break these objects up through collisions. Our ongoing work indicates that this is unlikely to have happened after the Solar System settled down in its current configuration, therefore there must have been period of intense collisional evolution during the planet formation process.”
In other words, if Mars formed from several types of material that was mixed together, these asteroids would be samples of the original source – i.e. planetesimals. By examining these asteroids further, scientists will be able to learn more about the process through which Mars came to be and (as Christou says) help us “unscramble the Martian omelette.”
This research is also likely to reveal much about the formation of Earth and the other terrestrial planets of the Solar System. Similar efforts will be made with NASA’s upcoming Lucy mission, which is scheduled to launch in October of 2021. Between 2027 and 2033, this probe will study Jupiter’s Trojan population, obtaining information on six of the asteroid’s geology, surface features, compositions, masses and densities to learn more about their origins.
Special Guest:
This week’s special guests are Timothy Spuck, Kathryn Meredith, Dr. James Hammerman and Andreas Stefik of the Innovators Developing Accessible Tools for Astronomy (IDATA) Project Team. The IDATA project aims to design and develop Afterglow Access, a new software tool that will expand accessibility beyond touch, making the universe more accessible to those with visual impairments.
Yerkes Outreach website
Tim Spuck (email: [email protected]) (Associated Universities Inc. STEM Education Development Officer and IDATA PI) currently serves as PI on three NSF supported programs including, Innovators Developing Accessible Tools for Astronomy, the Chile-US Astronomy Education Outreach Summit, and the Astronomy in Chile Educator Ambassadors Program. Tim also remains active within the amateur astronomy community, has directed numerous outreach efforts, and led several small-scale observatory design and construction projects. He earned his Masters degree in Science Education from Clarion University or PA, and is completing his Ed.D. in Curriculum & Instruction at West Virginia University.
Kate Meredith (Yerkes Observatory – University of Chicago, Director of Education Outreach, and IDATA Project Educator) has engaged in curriculum development and project management for the Zooniverse, the Sloan Digital Sky Survey, the Lawrence Hall of Science, the Adler Planetarium Space and Science Museum, and Skynet Junior Scholars (University of Chicago Yerkes Observatory). Kate is passionate about programs that bring authentic research science to learners of all ages, languages, and abilities. As Education Lead on the IDATA project, Kate looks forward to being part of the team that takes accessibility to the next level by creating vision-neutral data acquisition and analysis tools as well as the instructional materials needed to teach new users how to use and apply those tools.
Dr. James K. L. Hammerman (TERC, Co-Director of SEEC and Senior Researcher and Evaluator, IDATA Co-PI) currently leads external evaluations for several projects, including an immersive computer environment for conducting experiments to explore causality and ecology, a state-wide initiative to engage rural youth in computing through programming an online game, and an effort to improve pedagogy among university STEM faculty. Jim has designed, implemented, and researched mathematics and science education curricula and professional development programs, as well as technology tools that support inquiry-oriented learning. Jim is especially interested in adult developmental differences in professional development, data and statistics learning, online and software tools that support exploration, and supporting deeper learning and more reflective practice in professional communities.
Andreas Stefik (University of Nevada – Las Vegas, Assistant Professor of Computer Science and IDATA Co-PI) – For the last decade, Dr. Stefik has been creating technologies that make it easier for people, including those with disabilities, to write computer software. With grants from the National Science Foundation, he helped establish the first national educational infrastructure for blind or visually impaired students to learn computer science. He is the inventor of Quorum, the first evidence-oriented programming language. As part of his work, he is a PI on the NSF-funded AccessCS10K grant that is helping CS 10K projects prepare K-12 teachers to be more inclusive in their computing courses with students with disabilities. Most recently, Dr. Stefik was honored with the 2016 White House Champions of Change award in computer science education.
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