Matt Williams is a space journalist and science communicator for Universe Today and Interesting Engineering. He's also a science fiction author, podcaster (Stories from Space), and Taekwon-Do instructor who lives on Vancouver Island with his wife and family.
Mars from orbit. Valles Marineris and Volcanic region
Given it’s similarities to Earth, Mars is often referred to as “Earth’s Twin”. Like Earth, Mars is a terrestrial planet, which means it is composed largely of silicate rock and minerals that are differentiated into a core, mantle and crust. It is also located within the Sun’s “Goldilocks Zone” (aka. habitable zone), has polar ice caps, and once had flowing water on its surface. But beyond these, Mars and Earth are very different worlds.
In addition to their stark contrasts in temperature, surface conditions, and exposure to harmful radiation, Mars also takes a significantly longer time to complete a single orbit of the Sun. In fact, a year on Mars is almost twice as long as a year here on Earth – lasting 686.971 days, which works out to about 1.88 Earth years. And in the course of that orbit, the planet undergoes some rather interesting changes.
A view of Ceres in natural colour, pictured by the Dawn spacecraft in May 2015. Credit: NASA/ JPL/Planetary Society/Justin Cowart
We continue our “Definitive Guide to Terraforming” series with a look at another body in our Solar System – the dwarf planet Ceres. Like many moons in the outer Solar System, Ceres is a world of ice and rock, and is the largest body in the Asteroid Belt. Humans beings could one day call it home, but could its surface also be made “Earth-like”?
In the Solar System’s Main Asteroid Belt, there are literally millions of celestial bodies to be found. And while the majority of these range in size from tiny rocks to planetesimals, there are also a handful of bodies that contain a significant percentage of the mass of the entire Asteroid Belt. Of these, the dwarf planet Ceres is the largest, constituting of about a third of the mass of the belt and being the sixth-largest body in the inner Solar System by mass and volume.
In addition to its size, Ceres is the only body in the Asteroid Belt that has achieved hydrostatic equilibrium – a state where an object becomes rounded by the force of its own gravity. On top of all that, it is believed that this dwarf planet has an interior ocean, one which contains about one-tenth of all the water found in the Earth’s oceans. For this reason, the idea of colonizing Ceres someday has some appeal, as well as terraforming.
Artist's concept of the prototype starshade, a giant structure designed to block the glare of stars so that future space telescopes can take pictures of planets. Credit: NASA/JPL
For countless generations, people have looked up at the stars and wondered if life exists somewhere out there, perhaps on planets much like ours. But it has only been in recent decades that we have been able to confirm the existence of extrasolar planets (aka. exoplanets) in other star systems. In fact, between 1988 and April 20th of 2016, astronomers have been able to account for the existence of 2108 planets in 1350 different star systems, including 511 multiple planetary systems.
Most of these discoveries have taken place within just the past three years, thanks to improvements in our detection methods, and the deployment of the Kepler space observatory in 2009. Looking ahead, astronomers hope to improve on these methods even further with the introduction of the Starshade, a giant space structure designed to block the glare of stars, thus making it easier to find planets – and perhaps another Earth!
Images of Mercury's northern polar region, provided by MESSENGER. Credit: NASA/JPL
Welcome back to another installment in the “Definitive Guide to Terraforming” series! We complete our tour of the Solar System with the planet Mercury. Someday, humans could make a home on this hostile planet, leading to the first Hermians!
The planet Mercury is an intensely hot place. As the nearest planet to our Sun, surface temperatures can get up to a scorching 700 K (427° C). Ah, but there’s a flip-side to that coin. Due to it having no atmosphere to speak of, Mercury only experiences intensely hot conditions on the side that is directly facing the Sun. On the nighttime side, temperatures drop to well below freezing, as low as 100 K (-173° C).
Due to its low orbital period and slow rate of rotation, the nighttime side remains in the dark for an extended period of time. What’s more, in the northern polar region, which is permanently shaded, conditions are cold enough that water is able to exist there in ice form. Because of this, and a few reasons besides, there are many who believe that humanity could colonize and even terraform parts of Mercury someday.
William Blake's Newton (1795), depicted as a divine geometer. Credit: William Blake Archive/Wikipedia
Four fundamental forces govern all interactions within the Universe. They are weak nuclear forces, strong nuclear forces, electromagnetism, and gravity. Of these, gravity is perhaps the most mysterious. While it has been understood for some time how this law of physics operates on the macro-scale – governing our Solar System, galaxies, and superclusters – how it interacts with the three other fundamental forces remains a mystery.
Naturally, human beings have had a basic understanding of this force since time immemorial. And when it comes to our modern understanding of gravity, credit is owed to one man who deciphered its properties and how it governs all things great and small – Sir Isaac Newton. Thanks to this 17th century English physicist and mathematician, our understanding of the Universe and the laws that govern it would forever be changed.
While we are all familiar with the iconic image of a man sitting beneath an apple tree and having one fall on his head, Newton’s theories on gravity also represented a culmination of years worth of research, which in turn was based on centuries of accumulated knowledge. He would present these theories in his magnum opus, Philosophiae Naturalis Principia Mathematica (“Mathematical Principles of Natural Philosophy”), which was first published in 1687.
In this volume, Newton laid out what would come to be known as his Three Laws of Motion, which were derived from Johannes Kepler’s Laws of Planetary Motion and his own mathematical description of gravity. These laws would lay the foundation of classical mechanics, and would remain unchallenged for centuries – until the 20th century and the emergence of Einstein’s Theory of Relativity.
Newton’s own copy of his Principia, with hand-written corrections for the second edition. Credit: Trinity Cambridge/Andrew Dunn
Physics by 17th Century:
The 17th century was a very auspicious time for the sciences, with major breakthroughs occurring in the fields of mathematics, physics, astronomy, biology and chemistry. Some of the greatest developments in the period include the development of the heliocentric model of the Solar System by Nicolaus Copernicus, the pioneering work with telescopes and observational astronomy by Galileo Galilei, and the development of modern optics.
It was also during this period that Johannes Kepler developed his Laws of Planetary Motion. Formulated between 1609 and 1619, these laws described the motion of the then-known planets (Mercury, Venus, Earth, Mars, Jupiter, and Saturn) around the Sun. They stated that:
Planets move around the Sun in ellipses, with the Sun at one focus
The line connecting the Sun to a planet sweeps equal areas in equal times.
The square of the orbital period of a planet is proportional to the cube (3rd power) of the mean distance from the Sun in (or in other words–of the”semi-major axis” of the ellipse, half the sum of smallest and greatest distance from the Sun).
These laws resolved the remaining mathematical issues raised by Copernicus’ heliocentric model, thus removing all doubt that it was the correct model of the Universe. Working from these, Sir Isaac Newton began considering gravitation and its effect on the orbits of planets.
A comparison of the geocentric and heliocentric models of the universe. Credit: history.ucsb.edu
Newton’s Three Laws:
In 1678, Newton suffered a complete nervous breakdown due to overwork and a feud with fellow astronomer Robert Hooke. For the next few years, he withdrew from correspondence with other scientists, except where they initiated it, and renewed his interest in mechanics and astronomy. In the winter of 1680-81, the appearance of a comet, about which he corresponded with John Flamsteed (England’s Astronomer Royal) also renewed his interest in astronomy.
After reviewing Kepler’s Laws of Motion, Newton developed a mathematical proof that the elliptical form of planetary orbits would result from a centripetal force inversely proportional to the square of the radius vector. Newton communicated these results to Edmond Halley (discoverer of “Haley’s Comet”) and to the Royal Society in his De motu corporum in gyrum.
This tract, published in 1684, contained the seed of what Newton would expand to form his magnum opus, the Philosophiae Naturalis Principia Mathematica. This treatise, which was published in July of 1687, contained Newton’s three laws of motion, which stated that:
When viewed in an inertial reference frame, an object either remains at rest or continues to move at a constant velocity, unless acted upon by an external force.
The vector sum of the external forces (F) on an object is equal to the mass (m) of that object multiplied by the acceleration vector (a) of the object. In mathematical form, this is expressed as: F=ma
When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
Together, these laws described the relationship between any object, the forces acting upon it and the resulting motion, laying the foundation for classical mechanics. The laws also allowed Newton to calculate the mass of each planet, the flattening of the Earth at the poles, and the bulge at the equator, and how the gravitational pull of the Sun and Moon create the Earth’s tides.
In the same work, Newton presented a calculus-like method of geometrical analysis using ‘first and last ratios’, worked out the speed of sound in air (based on Boyle’s Law), accounted for the procession of the equinoxes (which he showed were a result of the Moon’s gravitational attraction to the Earth), initiated the gravitational study of the irregularities in the motion of the moon, provided a theory for the determination of the orbits of comets, and much more.
Newton and the “Apple Incident”:
The story of Newton coming up with his theory of universal gravitation as a result of an apple falling on his head has become a staple of popular culture. And while it has often been argued that the story is apocryphal and Newton did not devise his theory at any one moment, Newton himself told the story many times and claimed that the incident had inspired him.
In addition, the writing’s of William Stukeley – an English clergyman, antiquarian and fellow member of the Royal Society – have confirmed the story. But rather than the comical representation of the apple striking Newton on the head, Stukeley described in his Memoirs of Sir Isaac Newton’s Life (1752) a conversation in which Newton described pondering the nature of gravity while watching an apple fall.
“…we went into the garden, & drank thea under the shade of some appletrees; only he, & my self. amidst other discourse, he told me, he was just in the same situation, as when formerly, the notion of gravitation came into his mind. “why should that apple always descend perpendicularly to the ground,” thought he to himself; occasion’d by the fall of an apple…”
John Conduitt, Newton’s assistant at the Royal Mint (who eventually married his niece), also described hearing the story in his own account of Newton’s life. According to Conduitt, the incident took place in 1666 when Newton was traveling to meet his mother in Lincolnshire. While meandering in the garden, he contemplated how gravity’s influence extended far beyond Earth, responsible for the falling of apple as well as the Moon’s orbit.
Similarly, Voltaire wrote n his Essay on Epic Poetry (1727) that Newton had first thought of the system of gravitation while walking in his garden and watching an apple fall from a tree. This is consistent with Newton’s notes from the 1660s, which show that he was grappling with the idea of how terrestrial gravity extends, in an inverse-square proportion, to the Moon.
Sapling of the reputed original tree that inspired Sir Isaac Newton to consider gravitation. Credit: Wikipedia Commons/Loodog
However, it would take him two more decades to fully develop his theories to the point that he was able to offer mathematical proofs, as demonstrated in the Principia. Once that was complete, he deduced that the same force that makes an object fall to the ground was responsible for other orbital motions. Hence, he named it “universal gravitation”.
Various trees are claimed to be “the” apple tree which Newton describes. The King’s School, Grantham, claims their school purchased the original tree, uprooted it, and transported it to the headmaster’s garden some years later. However, the National Trust, which holds the Woolsthorpe Manor (where Newton grew up) in trust, claims that the tree still resides in their garden. A descendant of the original tree can be seen growing outside the main gate of Trinity College, Cambridge, below the room Newton lived in when he studied there.
Newton’s work would have a profound effect on the sciences, with its principles remaining canon for the following 200 years. It also informed the concept of universal gravitation, which became the mainstay of modern astronomy, and would not be revised until the 20th century – with the discovery of quantum mechanics and Einstein’s theory of General Relativity.
The moons of Saturn, from left to right: Mimas, Enceladus, Tethys, Dione, Rhea; Titan in the background; Iapetus (top) and irregularly shaped Hyperion (bottom). Some small moons are also shown. All to scale. Credit: NASA/JPL/Space Science Institute
Continuing with our “Definitive Guide to Terraforming“, Universe Today is happy to present our guide to terraforming Saturn’s Moons. Beyond the inner Solar System and the Jovian Moons, Saturn has numerous satellites that could be transformed. But should they be?
Around the distant gas giant Saturn lies a system of rings and moons that is unrivaled in terms of beauty. Within this system, there is also enough resources that if humanity were to harness them – i.e. if the issues of transport and infrastructure could be addressed – we would be living in an age a post-scarcity. But on top of that, many of these moons might even be suited to terraforming, where they would be transformed to accommodate human settlers.
As with the case for terraforming Jupiter’s moons, or the terrestrial planets of Mars and Venus, doing so presents many advantages and challenges. At the same time, it presents many moral and ethical dilemmas. And between all of that, terraforming Saturn’s moons would require a massive commitment in time, energy and resources, not to mention reliance on some advanced technologies (some of which haven’t been invented yet).
Artistic concepts of the Falcon Heavy rocket (left) and the Dragon capsule deployed on the surface of Mars (right). Credit: SpaceX
Fans of Elon Musk and commercial space exploration are buzzing over the news! Back in 2002, when Musk first established the private aerospace company SpaceX, he did so with the intent of creating the technologies needed to reduce the cost of space transportation and enable crewed missions to Mars. And for the past few years, industry and the general public alike have been waiting on him to say when missions to Mars might truly begin.
Earlier this morning, Elon Musk did just that, when he tweeted from his company account that SpaceX plans to send a Dragon capsule to Mars by 2018. Despite talking about his eventual plans to mount crewed missions to Mars in the coming decades, and to even build a colony there, this is the first time that a specific date has been attached to any plans.
What was also indicated in the announcement was that the missions would be built around the “Red Dragon” mission architecture. As a modified, unmanned version of the Dragon capsule, this craft was conceived back in 2013 and 2015 as part of the NASA Discovery Program – specifically for Mission 13, a series of concepts which are scheduled to launch sometime in 2022.
Concept art showing a Dragon capsule landing on Mars. Credit: SpaceX
Though the idea was never submitted to NASA, SpaceX has kept them on hand as part of a proposed low-cost Mars lander mission that would deploy a sample-return rover to the Martian surface. The mission will be deployed using a Falcon Heavy rocket, based on the mission profile and the illustrations that accompanied the announcement.
This mission would not only demonstrate SpaceX’s ability to procure samples from the Martian environment and bring them back to Earth – something that only federal space agencies like NASA have been able to do so far – but also test techniques and equipment that human crews will be using to enter the Martian atmosphere.
And if all goes well, we can expect that Musk will push forward with his plans for both crewed missions, and the development of all the necessary architecture to being work on his Mars Colonial Transporter, which he hopes to use to begin ferrying people to Mars to build his planned colony.
Stay tuned for more in-depth analysis of this announcement from our resident expert, Ken Kremer!
Atlantis lifts off on the last launch of the shuttle program, STS-135, on July 8, 2011. Credit: NASA/Bill Ingalls
At least, that was what the results of a recent study conducted by the University of Colorado’s Anschutz Medical Campus suggest. After examining a group of test mice that spent two weeks in space aboard STS-135 – the final mission of NASA’s space shuttle program – they concluded that spending prolonged periods of time in space could in fact result liver damage.
For some time now, scientists have understood that exposure to zero-gravity or micro-gravity environments comes with its share of health effects. But so far, the research has been largely confined to other areas of the human body. Understanding the effects it has on internal organs and other aspects of one’s health are of extreme importance as NASA begins preparations for a crewed mission to Mars.
Surface features of the four members at different levels of zoom in each row
Continuing with our “Definitive Guide to Terraforming“, Universe Today is happy to present to our guide to terraforming Jupiter’s Moons. Much like terraforming the inner Solar System, it might be feasible someday. But should we?
Fans of Arthur C. Clarke may recall how in his novel, 2010: Odyssey Two (or the movie adaptation called 2010: The Year We Make Contact), an alien species turned Jupiter into a new star. In so doing, Jupiter’s moon Europa was permanently terraformed, as its icy surface melted, an atmosphere formed, and all the life living in the moon’s oceans began to emerge and thrive on the surface.
As we explained in a previous video (“Could Jupiter Become a Star“) turning Jupiter into a star is not exactly doable (not yet, anyway). However, there are several proposals on how we could go about transforming some of Jupiter’s moons in order to make them habitable by human beings. In short, it is possible that humans could terraform one of more of the Jovians to make it suitable for full-scale human settlement someday.
A team of astronomers from South Africa have noticed a series of supermassive black holes in distant galaxies that are all spinning in the same direction. Credit: NASA/JPL-Caltech
In 1974, astronomers detected a massive source of radio wave emissions coming from the center of our galaxy. Within a few decades time, it was concluded that the radio wave source corresponded to a particularly large, spinning black hole. Known as Sagittarius A, this particular black hole is so large that only the designation “supermassive” would do. Since its discovery, astronomers have come to conclude that supermassive black holes (SMBHs) lie at the center of almost all of the known massive galaxies.
But thanks to a recent radio imaging by a team of researchers from the University of Cape Town and University of the Western Cape, in South Africa, it has been further determined that in a region of the distant universe, the SMBHs are all spinning out radio jets in the same direction. This finding, which shows an alignment of the jets of galaxies over a large volume of space, is the first of its kind, and could tell us much about the early Universe.
