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.
The technique of gravitational lensing relies on the presence of a large cluster of matter between the observer and the object to magnify light coming from that object. Credit: NASA
Dark Matter has been something of a mystery ever since it was first proposed. In addition to trying to find some direct evidence of its existence, scientists have also spent the past few decades developing theoretical models to explain how it works. In recent years, the popular conception has been that Dark Matter is “cold”, and distributed in clumps throughout the Universe, an observation supported by the Planck mission data.
However, a new study produced by an international team of researchers paints a different picture. Using data from the Kilo Degree Survey (KiDS), these researchers studied how the light coming from millions of distant galaxies was affected by the gravitational influence of matter on the largest of scales. What they found was that Dark Matter appears to more smoothly distributed throughout space than previously thought.
Earth, seen from space, above the Pacific Ocean. Credit: NASA
Since the election of Donald Trump, NASA has had its share of concerns about the future. Given the President-elect’s position and past statements on climate science, there has been speculation that his presidency will curtail funding to some of their research efforts, particularly those that are maintained by the Earth Science Directorate.
Things took another turn on Monday (Dec. 5th) as Trump met with former Vice President and environmental activist Al Gore to discuss his administration’s policy. This meeting was the latest in a series of gestures that suggest that the President-elect might be softening his stances on the environment. However, there is little reason to suspect that this meeting could mean any changes in policy.
The meeting was apparently arranged by the President-elect’s daughter, Ivanka Trump, to coincide with the former VP’s attendance of a conference in New York on Monday. Said conference was the 24 hour live broadcast titled “24 Hours of Reality”, an event being put on by the Climate Reality Project – a non-profit organization founded by Gore to educate the public on climate change and policy.
Much of NASA’s research into Climate Change takes place through the Earth Sciences Directorate. Credit: NASA
The meeting lasted 90 minutes, after which Gore spoke to reporters about the discussion he and the President-elect had. As he was quoted as saying by The Washington Post:
“I had a lengthy and very productive session with the president-elect. It was a sincere search for areas of common ground. I had a meeting beforehand with Ivanka Trump. The bulk of the time was with the president-elect, Donald Trump. I found it an extremely interesting conversation, and to be continued, and I’m just going to leave it at that.”
While this meeting has led to speculation that Trump’s administration might be softening its stance on environmental issues, many are unconvinced. Based on past statements – which include how Climate Change is a “hoax invented by the Chinese” – to his more recent picks for his cabinet, there are those who continue to express concern for the future of NASA programs that are centered on Earth sciences and the environment.
For instance, after weeks of remaining mute on the subject of NASA’s future, the Trump campaign announced that it had appointed Bob Walker – a former Pennsylvania Congressman and the chair of the House Science Committee from 1995 to 1997. A fierce conservative, Walker was recently quoted as saying that NASA should cease its climate research and focus solely on space exploration.
Artist’s impression of the carbon dioxide that will be present in Earth’s atmosphere if half of global-warming emissions are not absorbed. Credit: NASA/JPL/GSFC
“My guess is that it would be difficult to stop all ongoing Nasa programs but future programs should definitely be placed with other agencies,” he said in an interview with the Guardian in late November. “I believe that climate research is necessary but it has been heavily politicized, which has undermined a lot of the work that researchers have been doing. Mr Trump’s decisions will be based upon solid science, not politicized science.”
From statements such as these, plus things said during the campaign that emphasized NASA’s important role in space exploration, the general consensus has been that a Trump administration will likely slash funding to NASA’s Earth Science Directorate while leaving long-term exploration programs unaffected. According to David Titley, who recently wrote an op-ed piece for The Conversation, this would be a terrible mistake.
As he noted in his piece, NASA’s Earth science and Earth observation efforts are vital, and the shared missions they have with organizations like the NOAA have numerous benefits. As he explained:
“There’s a reason why space is called ‘the ultimate high ground’ and our country spends billions of dollars each year on space-based assets to support our national intelligence community. In addition to national security, NASA missions contribute vital information to many other users, including emergency managers and the Federal Emergency Management Agency (FEMA), farmers, fishermen and the aviation industry.”
An artist’s conception of an asteroid passing near the Earth. NASA is getting better at spotting them and giving us advance warning of their approach. Image credit: ESA.
In the past, NASA’s Earth Science Directorate has contributed vital information on how rising temperatures could affect water tables and farmlands (such as the ongoing drought in California), and how changes in oceanic systems would affect fisheries. On top of that, FEMA has been working with NASA in recent years in order to develop a disaster-readiness program to address the fallout from a possible asteroid impact.
This has included three tabletop exercises where the two agencies worked through asteroid impact scenarios and simulated how information would be exchanged between NASA scientists an FEMA emergency managers. As Melissa Weihenstroer – a Presidential Management Fellow in FEMA’s Office of External Affairs and who works with NASA’s Planetary Defense Coordination Office – recently wrote about this inter-agency cooperation:
“Since FEMA doesn’t have direct experience with asteroids or their impacts, we’ve turned to some people who do: our partners at the National Aeronautics and Space Administration (NASA). While FEMA will be the agency in charge of the U.S. government efforts in preparing for and responding to any anticipated asteroid-related event here on Earth, NASA is responsible for finding, tracking, and characterizing potentially hazardous asteroids and comets while they are still in space.
Whenever a transition occurs between one presidential administration and the next, there is always some level of concern about the impact it will have on federal organization. However, when an administration is unclear about its policies, and has made statements to the effect that federal agencies should cease conducting certain types of research, NASA can be forgiven for getting a little nervous.
In the coming years, it will be interesting to see how the budget environment changes for Earth science research. One can only hope that a Trump administration will not see fit to make sweeping cuts without first considering the potential consequences.
The Geoid 2011 model, based on data from LAGEOS, GRACE, GOCE and surface data. Credit: GFZ
Gravity is a pretty awesome fundamental force. If it wasn’t for the Earth’s comfortable 1 g, which causes objects to fall towards the Earth at a speed of 9.8 m/s², we’d all float off into space. And without it, all us terrestrial species would slowly wither and die as our muscles degenerated, our bones became brittle and weak, and our organs ceased to function properly.
So one can say without exaggerations that gravity is not only a fact of life here on Earth, but a prerequisite for it. However, since human beings seem intent on getting off this rock – escaping the “surly bonds of Earth”, as it were – understanding Earth’s gravity and what it takes to escape it is necessary. So just how strong is Earth’s gravity?
Definition:
To break it down, gravity is a natural phenomena in which all things that possess mass are brought towards one another – i.e. asteroids, planets, stars, galaxies, super clusters, etc. The more mass an object has, the more gravity it will exert on objects around it. The gravitational force of an object is also dependent on distance – i.e. the amount it exerts on an object decreases with increased distance.
Artist’s impression of the effect Earth’s gravity has on spacetime. Credit: NASA
Gravity is also one of the four fundamental forces which govern all interactions in nature (along with weak nuclear force, strong nuclear force, and electromagnetism). Of these forces, gravity is the weakest, being approximately 1038 times weaker than the strong nuclear force, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak nuclear force.
As a consequence, gravity has a negligible influence on matter at the smallest of scales (i.e. subatomic particles). However, at the macroscopic level – that of planets, stars, galaxies, etc. – gravity is the dominant force affecting the interactions of matter. It causes the formation, shape and trajectory of astronomical bodies, and governs astronomical behavior. It also played a major role in the evolution of the early Universe.
It was responsible for matter clumping together to form clouds of gas that underwent gravitational collapse, forming the first stars – which were then drawn together to form the first galaxies. And within individual star systems, it caused dust and gas to coalesce to form the planets. It also governs the orbits of the planets around stars, of moons around planets, the rotation of stars around their galaxy’s center, and the merging of galaxies.
Universal Gravitation and Relativity:
Since energy and mass are equivalent, all forms of energy, including light, also cause gravitation and are under the influence of it. This is consistent with Einstein’s General Theory of Relativity, which remains the best means of describing gravity’s behavior. According to this theory, gravity is not a force, but a consequence of the curvature of spacetime caused by the uneven distribution of mass/energy.
Artist’s impression of the frame-dragging effect in which space and time are dragged around a massive body. Credit: einstein.stanford.edu
The most extreme example of this curvature of spacetime is a black hole, from which nothing can escape. Black holes are usually the product of a supermassive star that has gone supernova, leaving behind a white dwarf remnant that has so much mass, it’s escape velocity is greater than the speed of light. An increase in gravity also results in gravitational time dilation, where the passage of time occurs more slowly.
For most applications though, gravity is best explained by Newton’s Law of Universal Gravitation, which states that gravity exists as an attraction between two bodies. The strength of this attraction can calculated mathematically, where the attractive force is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
Earth’s Gravity:
On Earth, gravity gives weight to physical objects and causes the ocean tides. The force of Earth’s gravity is the result of the planets mass and density – 5.97237 × 1024 kg (1.31668×1025 lbs) and 5.514 g/cm3, respectively. This results in Earth having a gravitational strength of 9.8 m/s² close to the surface (also known as 1 g), which naturally decreases the farther away one is from the surface.
In addition, the force of gravity on Earth actually changes depending on where you’re standing on it. The first reason is because the Earth is rotating. This means that the gravity of Earth at the equator is 9.789 m/s2, while the force of gravity at the poles is 9.832 m/s2. In other words, you weigh more at the poles than you do at the equator because of this centripetal force, but only slightly more.
The International Space Station (ISS), seen here from an undocked crew mission with Earth as a backdrop. Credit: NASA
Finally, the force of gravity can change depending on what’s under the Earth beneath you. Higher concentrations of mass, like high-density rocks or minerals can change the force of gravity that you feel. But of course, this amount is too slight to be noticeable. NASA missions have mapped the Earth’s gravity field with incredible accuracy, showing variations in its strength, depending on location.
Gravity also decreases with altitude, since you’re further away from the Earth’s center. The decrease in force from climbing to the top of a mountain is pretty minimal (0.28% less gravity at the top of Mount Everest), but if you’re high enough to reach the International Space Station (ISS), you would experience 90% of the force of gravity you’d feel on the surface.
However, since the station is in a state of free fall (and also in the vacuum of space) objects and astronauts aboard the ISS are capable of floating around. Basically, since everything aboard the station is falling at the same rate towards the Earth, those aboard the ISS have the feeling of being weightless – even though they still weight about 90% of what they would on Earth’s surface.
Earth’s gravity is also responsible for our planet having an “escape velocity” of 11.186 km/s (or 6.951 mi/s). Essentially, this means that a rocket needs to achieve this speed before it can hope to break free of Earth’s gravity and reach space. And with most rocket launches, the majority of their thrust is dedicated to this task alone.
Because of the difference between Earth’s gravity and the gravitational force on other bodies – like the Moon (1.62 m/s²; 0.1654 g) and Mars (3.711 m/s²; 0.376 g) – scientists are uncertain what the effects would be to astronauts who went on long-term missions to these bodies.
While studies have shown that long-duration missions in microgravity (i.e. on the ISS) have a detrimental effect on astronaut health (including loss of bone density, muscle degeneration, damage to organs and to eyesight) no studies have been conducted regarding the effects of lower-gravity environments. But given the multiple proposals made to return to the Moon, and NASA’s proposed “Journey to Mars“, that information should be forthcoming!
As terrestrial beings, we humans are both blessed and cursed by the force of Earth’s gravity. On the one hand, it makes getting into space rather difficult and expensive. On the other, it ensures our health, since our species is the product of billions of years of species evolution that took place in a 1 g environment.
If we ever hope to become a truly space-faring and interplanetary species, we better figure out how we’re going to deal with microgravity and lower-gravity. Otherwise, none of us are likely to get off-world for very long!
Using data provided by the Very Large Telescope in Chile, the ESO has been able to discern the "fingerprints" of the early Universe. Credit: ESO
Back in November, a team of researchers from the Swinburne University of Technology and the University of Cambridge published some very interesting findings about a galaxy located about 8 billion light years away. Using the La Silla Observatory’s Very Large Telescope (VLT), they examined the light coming from the supermassive black hole (SMBH) at its center.
In so doing, they were able to determine that the electromagnetic energy coming from this distant galaxy was the same as what we observe here in the Milky Way. This showed that a fundamental force of the Universe (electromagnetism) is constant over time. And on Monday, Dec. 4th, the ESO followed-up on this historic find by releasing the color spectrum readings of this distant galaxy – known as HE 0940-1050.
To recap, most large galaxies in the Universe have SMBHs at their center. These huge black holes are known for consuming the matter that orbits all around them, expelling tremendous amounts of radio, microwave, infrared, optical, ultra-violet (UV), X-ray and gamma ray energy in the process. Because of this, they are some of the brightest objects in the known Universe, and are visible even from billions of light years away.
Artist’s interpretation of ULAS J1120+0641, a very distant quasar. Credit: ESO/M. Kornmesser
But because of their distance, the energy which they emit has to pass through the intergalactic medium, where it comes into contact with incredible amount of matter. While most of this consists of hydrogen and helium, there are trace amounts of other elements as well. These absorb much of the light that travels between distant galaxies and us, and the absorption lines this creates can tell us of lot about the kinds of elements that are out there.
At the same time, studying the absorption lines produced by light passing through space can tell us how much light was removed from the original quasar spectrum. Using the Ultraviolet and Visual Echelle Spectrograph (UVES) instrument aboard the VLT, the Swinburne and Cambridge team were able to do just that, thus sneaking a peak at the “fingerprints of the early Universe“.
What they found was that the energy coming from HE 0940-1050 was very similar to that observed in the Milky Way galaxy. Basically, they obtained proof that electromagnetic energy is consistent over time, something which was previously a mystery to scientists. As they state in their study, which was published in the Monthly Notices of the Royal Astronomical Society:
“The Standard Model of particle physics is incomplete because it cannot explain the values of fundamental constants, or predict their dependence on parameters such as time and space. Therefore, without a theory that is able to properly explain these numbers, their constancy can only be probed by measuring them in different places, times and conditions. Furthermore, many theories which attempt to unify gravity with the other three forces of nature invoke fundamental constants that are varying.“
A laser beam launched from the Very Large Telescope (VLT) at the ESO’s La Silla Observatory in Chile. Credit: ESO
Since it is 8 billion light years away, and its strong intervening metal-absorption-line system, probing the electromagnetic spectrum being put out by HE 0940-1050 central quasar – not to mention the ability to correct for all the light that was absorbed by the intervening intergalactic medium – provided a unique opportunity to precisely measure how this fundamental force can vary over a very long period of time.
On top of that, the spectral information they obtained happened to be of the highest quality ever observed from a quasar. As they further indicated in their study:
“The largest systematic error in all (but one) previous similar measurements, including the large samples, was long-range distortions in the wavelength calibration. These would add a ?2 ppm systematic error to our measurement and up to ?10 ppm to other measurements using Mg and Fe transitions.”
However, the team corrected for this by comparing the UVES spectra to well-calibrated spectra obtained from the High Accuracy Radial velocity Planet Searcher (HARPS) – which is also located at the at the La Silla Observatory. By combining these readings, they were left with a residual systematic uncertainty of just 0.59 ppm, the lowest margin of error from any spectrographic survey to date.
High Accuracy Radial velocity Planet Searcher at the ESO La Silla 3.6m telescope. Credit: ESO
This is exciting news, and for more reasons that one. On the one hand, precise measurements of distant galaxies allow us to test some of the most tricky aspects of our current cosmological models. On the other, determining that electromagnetism behaves in a consistent way over time is a major find, largely because it is responsible for such much of what goes on in our daily lives.
But perhaps most importantly of all, understanding how a fundamental force like electromagnetism behaves across time and space is intrinsic to finding out how it – as well as weak and strong nuclear force – unifies with gravity. This too has been a preoccupation of scientists, who are still at a loss when it comes to explaining how the laws governing particles interactions (i.e. quantum theory) unify with explanations of how gravity works (i.e general relativity).
By finding measurements of how these forces operate that are not varying could help in creating a working Grand Unifying Theory (GUT). One step closer to truly understanding how the Universe works!
Welcome back to our planetary weather series! Today, we look at Earth’s overheated “sister planet”, Venus!
Venus is often called Earth’s “Sister Planet” because of all the things they have in common. They are comparable in size, have similar compositions, and both orbit within the Sun’s habitable zone. But beyond that, there are some notable differences that makes Venus a molten hellhole, and about the last place anyone would want to visit!
Much of this has to do with Venus’ atmosphere, which is incredibly dense and entirely hostile to life as we know it. And because of its natural density and composition, the average surface temperature of Venus is hot enough to melt lead. All of this adds up to some pretty interesting weather patterns, which are also incredibly hostile!
Venus Atmosphere:
Although carbon dioxide is invisible, the clouds on Venus are made up of opaque clouds of sulfuric acid, so we can’t see down to the surface using conventional methods. Everything we know about the surface of Venus has been gathered by spacecraft equipped with radar imaging instruments, which can peer through the dense clouds and reveal the surface below.
From the many flybys and atmospheric probes sent into its thick clouds, scientists have learned that Venus’ atmosphere is incredibly dense. In fact, the mass of Venus atmosphere is 93 times that of Earth’s, and the air pressure at the surface is estimated to be as high as 92 bar – i.e. 92 times that of Earth’s at sea level. If it were possible for a human being to stand on the surface of Venus, they would be crushed by the atmosphere.
The composition of the atmosphere is extremely toxic, consisting primarily of carbon dioxide (96.5%) with small amounts of nitrogen (3.5%) and traces of other gases – most notably sulfur dioxide. Combined with its density, the composition generates the strongest greenhouse effect of any planet in the Solar System.
It is also the hottest planet in the Solar System, experiencing mean surface temperatures of 735 K (462 °C; 863.6 °F). Above the dense CO² layer, thick clouds consisting mainly of sulfur dioxide and sulfuric acid droplets scatter about 90% of the sunlight back into space.
The planet is also isothermal, which means that there is little variation in Venus’ surface temperature between day and night, or the equator and the poles. The planet’s minute axial tilt – less than 3° compared to Earth’s 23.5° – and its very slow rotational period (the planet takes around 243 days to complete a single rotation) also minimizes seasonal temperature variation.
Artist’s impression of the surface of Venus. Credit: ESA/AOES
The only appreciable variation in temperature occurs with altitude. The highest point on Venus, Maxwell Montes, is therefore the coolest point on the planet, with a temperature of about 655 K (380 °C; 716 °F) and an atmospheric pressure of about 4.5 MPa (45 bar).
Meteorological Phenomena:
The weather on Venus is one of the aspects of the planet under constant study from Earth-based telescopes and space missions to Venus. And from what we’ve seen, the weather on Venus is very extreme. The entire atmosphere of the planet circulates around quickly, with winds reaching speeds of up to 85 m/s (300 km/h; 186.4 mph) at the cloud tops, which circle the planet every four to five Earth days.
At this speed, these winds move up to 60 times the speed of the planet’s rotation, whereas Earth’s fastest winds are only 10-20% of the planet’s rotational speed. Spacecraft equipped with ultraviolet imaging instruments are able to observe the cloud motion around Venus, and see how it moves at different layers of the atmosphere. The winds blow in a retrograde direction, and are the fastest near the poles.
Closer to the equator, the wind speeds die down to almost nothing. Because of the thick atmosphere, the winds move much slower as you get close to the surface of Venus, reaching speeds of about 5 km/h. Because it’s so thick, though, the atmosphere is more like water currents than blowing wind at the surface, so it is still capable of blowing dust around and moving small rocks across the surface of Venus.
Over the past six years wind speeds in Venus’ atmosphere have been steadily rising (ESA
Several flybys past the planet have also indicated that its dense clouds are capable of producing lightning, much like the clouds on Earth. Their intermittent appearance indicates a pattern associated with weather activity, and the lightning rate is at least half of that on Earth. Since Venus does not experience rainfall (except in the form of sulfuric acid), it has been theorized that the lightning is being caused by a volcanic eruption.
What is the weather like on Venus? Terrible, would be the short answer. The long answer is that it is extremely hot, the air pressure is extremely high, there are very strong winds, sulfuric acid rain (at higher altitudes) and lightning storms driven by volcanic eruptions. It is little wonder then why the only practical option for colonizing Venus involves creating floating cities above the cloud layer.
In the 18th century, observations made of all the known planets (Mercury, Venus, Earth, Mars, Jupiter and Saturn) led astronomers to discern a pattern in their orbits. Eventually, this led to the Titius–Bode law, which predicted the amount of space between the planets. In accordance with this law, there appeared to be a discernible gap between the orbits of Mars and Jupiter, and investigation into it led to a major discovery.
Eventually, astronomers realized that this region was pervaded by countless smaller bodies which they named “asteroids”. This in turn led to the term “Asteroid Belt”, which has since entered into common usage. Like all the planets in our Solar System, it orbits our Sun, and has played an important role in the evolution and history of our Solar System.
Structure and Composition:
The Asteroid Belt consists of several large bodies, along with millions of smaller size. The larger bodies, such as Ceres, Vesta, Pallas, and Hygiea, account for half of the belt’s total mass, with almost one-third accounted for by Ceres alone. Beyond that, over 200 asteroids that are larger than 100 km in diameter, and 0.7–1.7 million asteroids with a diameter of 1 km or more.
Ceres compared to asteroids visited to date, including Vesta, Dawn’s mapping target in 2011. Credit: NASA/ESA/Paul Schenck
It total, the Asteroid Belt’s mass is estimated to be 2.8×1021 to 3.2×1021 kilograms – which is equivalent to about 4% of the Moon’s mass. While most asteroids are composed of rock, a small portion of them contain metls such as iron and nickel. The remaining asteroids are made up of a mix of these, along with carbon-rich materials. Some of the more distant asteroids tend to contain more ices and volatiles, which includes water ice.
Despite the impressive number of objects contained within the belt, the Main Belt’s asteroids are also spread over a very large volume of space. As a result, the average distance between objects is roughly 965,600 km (600,000 miles), meaning that the Main Belt consists largely of empty space. In fact, due to the low density of materials within the Belt, the odds of a probe running into an asteroid are now estimated at less than one in a billion.
The main (or core) population of the asteroid belt is sometimes divided into three zones, which are based on what is known as “Kirkwood gaps”. Named after Daniel Kirkwood, who announced in 1866 the discovery of gaps in the distance of asteroids, these gaps are similar to what is seen with Saturn’s and other gas giants’ systems of rings.
Origin:
Originally, the Asteroid Belt was thought to be the remnants of a much larger planet that occupied the region between the orbits of Mars and Jupiter. This theory was originally suggested by Heinrich Olbders to William Herschel as a possible explanation for the existence of Ceres and Pallas. However, this hypothesis has since been shown to have several flaws.
For one, the amount of energy required to destroy a planet would have been staggering, and no scenario has been suggested that could account for such events. Second, there is the fact that the mass of the Asteroid Belt is only 4% that of the Moon (and 22% that of Pluto). The odds of a cataclysmic collision with such a tiny body are very unlikely. Lastly, the significant chemical differences between the asteroids do no point towards a common origin.
Today, the scientific consensus is that, rather than fragmenting from an original planet, the asteroids are remnants from the early Solar System that never formed a planet at all. During the first few million years of the Solar System’s history, gravitational accretion caused clumps of matter to form out of an accretion disc. These clumps gradually came together, eventually undergoing hydrostatic equilibrium (become spherical) and forming planets.
However, within the region of the Asteroid Belt, planestesimals were too strongly perturbed by Jupiter’s gravity to form a planet. As such, these objects would continue to orbit the Sun as they had before, with only one object (Ceres) having accumulated enough mass to undergo hydrostatic equilibrium. On occasion, they would collide to produce smaller fragments and dust.
The asteroids also melted to some degree during this time, allowing elements within them to be partially or completely differentiated by mass. However, this period would have been necessarily brief due to their relatively small size. It likely ended about 4.5 billion years ago, a few tens of millions of years after the Solar System’s formation.
Though they are dated to the early history of the Solar System, the asteroids (as they are today) are not samples of its primordial self. They have undergone considerable evolution since their formation, including internal heating, surface melting from impacts, space weathering from radiation, and bombardment by micrometeorites. Hence, the Asteroid Belt today is believed to contain only a small fraction of the mass of the primordial belt.
Computer simulations suggest that the original asteroid belt may have contained mass equivalent to the Earth. Primarily because of gravitational perturbations, most of the material was ejected from the belt a million years after its formation, leaving behind less than 0.1% of the original mass. Since then, the size distribution of the asteroid belt is believed to have remained relatively stable.
When the asteroid belt was first formed, the temperatures at a distance of 2.7 AU from the Sun formed a “snow line” below the freezing point of water. Essentially, planetesimals formed beyond this radius were able to accumulate ice, some of which may have provided a water source of Earth’s oceans (even more so than comets).
Distance from the Sun:
Located between Mars and Jupiter, the belt ranges in distance between 2.2 and 3.2 astronomical units (AU) from the Sun – 329 million to 478.7 million km (204.43 million to 297.45 million mi). It is also an estimated to be 1 AU thick (149.6 million km, or 93 million mi), meaning that it occupies the same amount of distance as what lies between the Earth to the Sun.
The asteroids of the inner Solar System and Jupiter: The donut-shaped asteroid belt is located between the orbits of Jupiter and Mars. Credit: Wikipedia Commons
The distance of an asteroid from the Sun (its semi-major axis) depends upon its distribution into one of three different zones based on the Belt’s “Kirkwood Gaps”. Zone I lies between the 4:1 resonance and 3:1 resonance Kirkwood gaps, which are roughly 2.06 and 2.5 AUs (3 to 3.74 billion km; 1.86 to 2.3 billion mi) from the Sun, respectively.
Zone II continues from the end of Zone I out to the 5:2 resonance gap, which is 2.82 AU (4.22 billion km; 2.6 mi) from the Sun. Zone III, the outermost section of the Belt, extends from the outer edge of Zone II to the 2:1 resonance gap, located some 3.28 AU (4.9 billion km; 3 billion mi) from the Sun.
While many spacecraft have been to the Asteroid Belt, most were passing through on their way to the outer Solar System. Only in recent years, with the Dawn mission, that the Asteroid Belt has been a focal point of scientific research. In the coming decades, we may find ourselves sending spaceships there to mine asteroids, harvest minerals and ices for use here on Earth.
CERN visualization showing two electrons (green), one to two muons (red lines) resulting from a collision between two Z bosons. Credit: CERN
During the 19th and 20th centuries, physicists began to probe deep into the nature of matter and energy. In so doing, they quickly realized that the rules which govern them become increasingly blurry the deeper one goes. Whereas the predominant theory used to be that all matter was made up of indivisible atoms, scientists began to realize that atoms are themselves composed of even smaller particles.
From these investigations, the Standard Model of Particle Physics was born. According to this model, all matter in the Universe is composed of two kinds of particles: hadrons – from which Large Hadron Collider (LHC) gets its name – and leptons. Where hadrons are composed of other elementary particles (quarks, anti-quarks, etc), leptons are elementary particles that exist on their own.
Definition:
The word lepton comes from the Greek leptos, which means “small”, “fine”, or “thin”. The first recorded use of the word was by physicist Leon Rosenfeld in his book Nuclear Forces (1948). In the book, he attributed the use of the word to a suggestion made by Danish chemist and physicist Prof. Christian Moller.
The Standard Model of Particle Physics, showing all known elementary particles. Credit: Wikipedia Commons/MissMJ/PBS NOVA/Fermilab/Particle Data GroupThe term was chosen to refer to particles of small mass, since the only known leptons in Rosenfeld’s time were muons. These elementary particles are over 200 times more massive than electrons, but have only about one-ninth the the mass of a proton. Along with quarks, leptons are the basic building blocks of matter, and are therefore seen as “elementary particles”.
Types of Leptons:
According to the Standard Model, there are six different types of leptons. These include the Electron, the Muon, and Tau particles, as well as their associated neutrinos (i.e. electron neutrino, muon neutrino, and tau neutrino). Leptons have negative charge and a distinct mass, whereas their neutrinos have a neutral charge.
Electrons are the lightest, with a mass of 0.000511 gigaelectronvolts (GeV), while Muons have a mass of 0.1066 Gev and Tau particles (the heaviest) have a mass of 1.777 Gev. The different varieties of the elementary particles are commonly called “flavors”. While each of the three lepton flavors are different and distinct (in terms of their interactions with other particles), they are not immutable.
A neutrino can change its flavor, a process which is known as “neutrino flavor oscillation”. This can take a number of forms, which include solar neutrino, atmospheric neutrino, nuclear reactor, or beam oscillations. In all observed cases, the oscillations were confirmed by what appeared to be a deficit in the number of neutrinos being created.
Muons, a type of lepton, shown being produced by the Large Hadron Collider. Credit: CERN
One observed cause has to do with “muon decay” (see below), a process where muons change their flavor to become electron neutrinos or tau neutrinos – depending on the circumstances. In addition, all three leptons and their neutrinos have an associated antiparticle (antilepton).
For each, the antileptons have an identical mass, but all of the other properties are reversed. These pairings consist of the electron/positron, muon/antimuon, tau/antitau, electron neutrino/electron antineutrino, muon neutrino/muan antinuetrino, and tau neutrino/tau antineutrino.
The present Standard Model assumes that there are no more than three types (aka. “generations”) of leptons with their associated neutrinos in existence. This accords with experimental evidence that attempts to model the process of nucleosynthesis after the Big Bang, where the existence of more than three leptons would have affected the abundance of helium in the early Universe.
Properties:
All leptons possess a negative charge. They also possess an intrinsic rotation in the form of their spin, which means that electrons with an electric charge – i.e. “charged leptons” – will generate magnetic fields. They are able to interact with other matter only though weak electromagnetic forces. Ultimately, their charge determines the strength of these interactions, as well as the strength of their electric field and how they react to external electrical or magnetic fields.
None are capable of interacting with matter via strong forces, however. In the Standard Model, each lepton starts out with no intrinsic mass. Charged leptons obtain an effective mass through interactions with the Higgs field, while neutrinos either remain massless or have only very small masses.
History of Study:
The first lepton to be identified was the electron, which was discovered by British physicist J.J. Thomson and his colleagues in 1897 using a series of cathode ray tube experiments. The next discoveries came during the 1930s, which would lead to the creation of a new classification for weakly-interacting particles that were similar to electrons.
The first discovery was made by Austrian-Swiss physicist Wolfgang Pauli in 1930, who proposed the existence of the electron neutrino in order to resolve the ways in which beta decay contradicted the Conservation of Energy law, and Newton’s Laws of Motion (specifically the Conservation of Momentum and Conservation of Angular Momentum).
The positron and muon were discovered by Carl D. Anders in 1932 and 1936, respectively. Due to the mass of the muon, it was initially mistook for a meson. But due to its behavior (which resembled that of an electron) and the fact that it did not undergo strong interaction, the muon was reclassified. Along with the electron and the electron neutrino, it became part of a new group of particles known as “leptons”.
In 1962, a team of American physicists – consisting of Leon M. Lederman, Melvin Schwartz, and Jack Steinberger – were able to detect of interactions by the muon neutrino, thus showing that more than one type of neutrino existed. At the same time, theoretical physicists postulated the existence of many other flavors of neutrinos, which would eventually be confirmed experimentally.
The tau particle followed in the 1970s, thanks to experiments conducted by Nobel-Prize winning physicist Martin Lewis Perl and his colleagues at the SLAC National Accelerator Laboratory. Evidence of its associated neutrino followed thanks to the study of tau decay, which showed missing energy and momentum analogous to the missing energy and momentum caused by the beta decay of electrons.
In 2000, the tau neutrino was directly observed thanks to the Direct Observation of the NU Tau (DONUT) experiment at Fermilab. This would be the last particle of the Standard Model to be observed until 2012, when CERN announced that it had detected a particle that was likely the long-sought-after Higgs Boson.
Today, there are some particle physicists who believe that there are leptons still waiting to be found. These “fourth generation” particles, if they are indeed real, would exist beyond the Standard Model of particle physics, and would likely interact with matter in even more exotic ways.
For more information, SLAC’s Virtual Visitor Center has a good introduction to Leptons and be sure to check out the Particle Data Group (PDG) Review of Particle Physics.
Portrait of Giovanni Domenico Cassini, with the Paris Observatory in the background. Credit: Wikipedia Commons
During the Scientific Revolution, which took place between the 15th and 18th centuries, numerous inventions and discoveries were made that forever changed the way humanity viewed the Universe. And while this explosion in learning owed its existence to countless individuals, a few stand out as being especially worthy of praise and remembrance.
One such individual is Gionvanni Domenico Cassini, also known by his French name Jean-Dominique Cassini. An Italian astronomer, engineer, and astrologer, Cassini made many valuable contributions to modern science. However, it was his discovery of the gaps in Saturn’s rings and four of its largest moons for which he is most remembered, and the reason why the Cassini spacecraft bears his name.
Early Life and Education:
Giovanni Domenico Cassini was born on June 8th, 1625, in the small town of Perinaldo (near Nice, France) to Jacopo Cassini and Julia Crovesi. Educating by Jesuit scientists, he showed an aptitude for mathematics and astronomy from an early age. In 1648, he accepted a position at the observatory at Panzano, near Bologna, where he was employed by a rich amateur astronomer named Marquis Cornelio Malvasia.
During his time at the Panzano Observatory, Cassini was able to complete his education and went on to become the principal chair of astronomy at the University of Bologna by 1650. While there, he made several scientific contributions that would have a lasting mark.
La Meridiana, the meridian line calculated by Cassini while living in Bologna. Credit: Wikipedia Commons/Ilario/Cassinam
This included the calculation of an important meridian line, which runs along the left aisle of the San Petronio Basilica in Bologna. At 66.8 meters (219 ft) in length, it is one of the largest astronomical instruments in the worl and allowed for measurements that were (at the time) uniquely precise. This meridian also helped to settle the debate about whether or not the Universe was geocentric or heliocentric.
During his time in Italy, Cassini determined the obliquity of the Earth’s ecliptic – aka. it’s axial tilt, which he calculated to be 23° and 29′ at the time. He also studied the effects of refraction and the Solar parallax, worked on planetary theory, and observed the comets of 1664 and 1668.
In recognition of his engineering skills, Pope Clement IX employed Cassini with regard to fortifications, river management and flooding along the Po River in northern Italy. In 1663, Cassini was named superintendent of fortifications and oversaw the fortifying of Urbino. And in 1665, he was named the inspector for the town of Perugia in central Italy.
Paris Observatory:
In 1669, Cassini received an invitation by Louis XIV of France to move to Paris and help establish the Paris Observatory. Upon his arrival, he joined the newly-founded Academie Royale des Sciences (Royal Academy of Sciences), and became the first director of the Paris Observatory, which opened in 1671. He would remain the director of the observatory until his death in 1712.
An engraving of the Paris Observatory during Cassini’s time. Credit: Public Domain
In 1673, Cassini obtained his French citizenship and in the following year, he married Geneviève de Laistre, the daughter of the lieutenant general of the Comte de Clermont. During his time in France, Cassini spent the majority of his time dedicated to astronomical studies. Using a series of very long air telescopes, he made several discoveries and collaborated with Christiaan Huygens in many projects.
In the 1670s, Cassini began using the triangulation method to create a topographic map of France. It would not be completed until after his death (1789 or 1793), when it was published under the name Carte de Cassini. In addition to being the first topographical map of France, it was the first map to accurately measure longitude and latitude, and showed that the nation was smaller than previously thought.
In 1672, Cassini and his colleague Jean Richer made simultaneous observations of Mars (Cassini from Paris and Richer from French Guiana) and determined its distance to Earth through parallax. This enabled him to refine the dimensions of the Solar System and determine the value of the Astronomical Unit (AU) to within 7% accuracy. He and English astronomer Robert Hooke share credit for the discovery of the Great Red Spot on Jupiter (ca. 1665).
In 1683, Cassini presented an explanation for “zodiacal light” – the faint glow that extends away from the Sun in the ecliptic plane of the sky – which he correctly assumed to be caused by a cloud of small particles surrounding the Sun. He also viewed eight more comets before his death, which appeared in the night sky in 1672, 1677, 1698, 1699, 1702 (two), 1706 and 1707.
Illustration of Jupiter and the Galilean satellites. Credit: NASA
In ca. 1690, Cassini was the first to observe differential rotation within Jupiter’s atmosphere. He created improved tables for the positions of Jupiter’s Galilean moons, and discovered the periodic delays between the occultations of Jupiter’s moons and the times calculated. This would be used by Ole Roemer, his colleague at the Paris Observatory, to calculate the velocity of light in 1675.
In 1683, Cassini began the measurement of the arc of the meridian (longitude line) through Paris. From the results, he concluded that Earth is somewhat elongated. While in fact, the Earth is flattened at the poles, the revelation that Earth is not a perfect sphere was groundbreaking.
Cassini also observed and published his observations about the surface markings on Mars, which had been previously observed by Huygens but not published. He also determined the rotation periods of Mars and Jupiter, and his observations of the Moon led to the Cassini Laws, which provide a compact description of the motion of the Moon. These laws state that:
The Moon takes the same amount of time to rotate uniformly about its own axis asit takes to revolve around the Earth. As a consequence, the same face is always pointed towards Earth.
The Moon’s equator is tilted at a constant angle (about 1°32′ of arc) to the plane of the Earth’s orbit around the Sun (i.e. the ecliptic)
The point where the lunar orbit passes from south to north on the ecliptic (aka. the ascending node of the lunar orbit) always coincides with the point where the lunar equator passes from north to south on the ecliptic (the descending node of the lunar equator).
A collage of Saturn (bottom left) and some of its moons: Titan, Enceladus, Dione, Rhea and Helene. Credit: NASA/JPL/Space Science Institute
Thanks to his leadership, Giovanni Cassini was the first of four successive Paris Observatory directors that bore his name. This would include his son, Jaques Cassini (Cassini II, 1677-1756); his grandson César François Cassini (Cassini III, 1714-84); and his great grandson, Jean Dominique Cassini (Cassini IV, 1748-1845).
Observations of Saturn:
During his time in France, Cassini also made his famous discoveries of many of Saturn’s moons – Iapetus in 1671, Rhea in 167, and Tethys and Dione in 1684. Cassini named these moons Sidera Lodoicea (the stars of Louis), and correctly explained the anomalous variations in brightness to the presence of dark material on one hemisphere (now called Cassini Regio in his honor).
In 1675, Cassini discovered that Saturn’s rings are separated into two parts by a gap, which is now called the “Cassini Division” in his honor. He also theorized that the rings were composed of countless small particles, which was proven to be correct.
Death and Legacy:
After dedicating his life to astronomy and the Paris Observatory, Cassini went blind in 1711 and then died on September 14th, 1712, in Paris. And although he resisted many new theories and ideas that were proposed during his lifetime, his discoveries and contributions place him among the most important astronomers of the 17th and 18th centuries.
A comparison of the geocentric and heliocentric models of the universe. Credit: history.ucsb.edu
As a traditionalist, Cassini initially held the Earth to be the center of the Solar System. In time, he would come to accept the Solar Theory of Nicolaus Copernicus within limits, to the point that he accepted the model proposed by Tycho Brahe. However, he rejected the theory of Johannes Kepler that planets travel in ellipses and proposed hat their paths were certain curved ovals (i.e. Cassinians, or Ovals of Cassini)
Cassini also rejected Newton’s Theory of Gravity, after measurements he conducted which (wrongly) suggested that the Earth was elongated at its poles. After forty years of controversy, Newton’s theory was adopted after the measurements of the French Geodesic Mission (1736-1744) and the Lapponian Expedition in 1737, which showed that the Earth is actually flattened at the poles.
For his lifetime of work, Cassini has been honored in many ways by the astronomical community. Because of his observations of the Moon and Mars, features on their respective surfaces were named after him. Both the Moon and Mars have their own Cassini Crater, and Cassini Regio on Saturn’s moon Iapetus also bears his name.
Then there is Asteroid (24101) Cassini, which was discovered by C.W. Juels at in 1999 using the Fountain Hills Observatory telescope. Most recently, there was the joint NASA-ESA Cassini-Huygens missions which recently finished its mission to study Saturn and its moons. This robotic orbiter and lander mission was named in honor of the two astronomers who were chiefly responsible for discovering Saturn system of moons.
Artist’s impression of the Cassini space probe, part of the Cassini-Huygens mission to explore Saturn and its moons. Credit: NASA/JPL
In the end, Cassini’s passion for astronomy and his contributions to the sciences have ensured him a lasting place in the annals of history. In any discussion of the Scientific Revolution and of the influential thinkers who made it happen, his name appears alongside such luminaries as Copernicus, Galileo, and Newton.
Soviet Cosmonaut Valentina Tereshkova photographed inside the Vostok-6 spacecraft on June 16, 1963. Credit: Roscosmos
When it comes to the “Space Race” of the 1960s, several names come to mind. Names like Chuck Yeager, Yuri Gagarin, Alan Shepard, and Neil Armstrong, but to name a few. These men were all pioneers, braving incredible odds and hazards in order to put a man into orbit, on the Moon, and bring humanity into the Space Age. But about the first women in space?
Were the challenges they faced any less real? Or were they even more difficult considering the fact that space travel – like many professions at the time – was still thought to be a “man’s game”? Well, the first woman to break this glass ceiling was Valentina Tereshkova, a Soviet Cosmonaut who has the distinction of being the first woman ever to go into space as part of the Vostok 6 mission.
Early Life:
Tereshkova was born in the village of Maslennikovo in central Russia (about 280 km north-east of Moscow) after her parents migrated from Belarus. Her father was a tractor driver and her mother worked in a textile plant. Her father became a tank officer and died during the Winter War (1939-1940) when the Soviet Union invaded Finland over a territorial dispute.
Russian BT-5 tank destroyed during the Winter War (1939-1940). Credit: Wikipedia Commons/SA-kuva/Finnish Army Pictures
Between 1945 to 1953, Tereshkova went to school but dropped out when she was sixteen, and completed her education through correspondence. Following in her mother’s footsteps, she began working at a textile factory, where she remained until becoming part of the Soviet cosmonaut program.
She became interested in parachuting from a young age and trained in skydiving at the local Aeroclub. In 1959, at the age of 22, she made her first jump. It was her expertise in skydiving that led to her being selected as a cosmonaut candidate a few years later. In 1961, she became the secretary of the local Komsomol (Young Communist League) and later joined the Communist Party of the Soviet Union.
Vostok Program:
Much like Yuri Gagarin, Tereshkova took part in the Vostok program, which was the Soviet Unions’ first attempt at putting crewed missions into space. After the historic flight of Gagarin in 1961, Sergey Korolyov – the chief Soviet rocket engineer – proposed sending a female cosmonaut into space as well.
At the time, the Soviets believed that sending women into space would achieve a propaganda victory against the U.S., which maintained a policy of only using military and test pilots as astronauts. Though this policy did not specifically discriminate on the basis of gender, the lack of women combat and test pilots effectively excluded them from participating.
Valentina Tereshkova, pilot-cosmonaut, first female cosmonaut, Hero of the USSR. Pictured as a Major of the Soviet Air Forces. Credit: RIA Novosti/Alexander Mokletsov
In April 1962, five women were chosen for the program out of hundreds of potential candidates. These included Tatyana Kuznetsova, Irina Solovyova, Zhanna Yorkina, Valentina Ponomaryova, and Valentina Tereshkova. In order to qualify, the women needed to be parachutists under 30 years of age, under 170 cm (5’7″) in height, and under 70 kg (154 lbs.) in weight.
Along with four colleagues, Tereshkova spent several months in training. This included weightless flights, isolation tests, centrifuge tests, rocket theory, spacecraft engineering, parachute jumps, and pilot training in jet aircraft. Their examinations concluded in November 1962, after which Tereshkova and Ponomaryova were considered the leading candidates.
A joint mission profile was developed that would see two women launched into space on separate Vostok missions in March or April of 1963. Tereshkova, then 25, was chosen to be the first woman to go into space, for multiple reasons. First, there was the fact that she conformed to the height and weight specifications to fit inside the relatively cramped Vostok module.
Second, she was a qualified parachutist, which given the nature of the Vostok space craft (the re-entry craft was incapable of landing) was absolutely essential. The third, and perhaps most important reason, was her strong “proletariat” and patriotic background, which was evident from her family’s work and the death of her father (Vladimir Tereshkova) during the Second World War.
The Vostok 6 capsule at the Science Museum, London. Credit: Wikipedia Commons/Andrew Grey
Originally, the plan was for Tereshkova to launch first in the Vostok 5 ship while Ponomaryova would follow her into orbit in Vostok 6. However, this flight plan was altered in March 1963, with a male cosmonaut flying Vostok 5 while Tereshkova would fly aboard Vostok 6 in June 1963. After watching the successful launch of Vostok 5 on 14 June, Tereshkova (now 26) began final preparations for her own flight.
Launch:
Tereshkova’s Vostok 6 flight took place on the morning of June 16th, 1963. After performing communications and life support checks, she was sealed inside the capsule and the mission’s two-hour countdown began. The launch took place at 09:29:52 UTC with the rocket lifting off faultlessly from the Baikonur launchpad.
During the flight – which lasted for two days and 22 hours – Tereshkova orbited the Earth forty-eight times. Her flight took place only two days after Vostok 5 was launched, piloted by Valery Bykovsky, and orbited the Earth simultaneously with his craft. In the course of her flight, ground crews collected data on her body’s reaction to spaceflight.
Aside from some nausea (which she later claimed was due to poor food!) she maintained herself for the full three days. Like other cosmonauts on Vostok missions, she kept a flight log and took photographs of the horizon – which were later used to identify aerosol layers within the atmosphere – and manually oriented the spacecraft.
First woman in space Soviet cosmonaut Valentina Tereshkova is seen during a training session aboard a Vostok spacecraft simulator on January 17, 1964. Credit: AFP Photo / RIA Novosti
On the first day of her mission, she reported an error in the control program, which made the spaceship ascend from orbit instead of descending. The team on Earth provided Tereshkova with new data to enter into the descent program which corrected the problem. After completing 48 orbits, her craft began descending towards Earth.
Once the craft re-entered the atmosphere, Tereshkova ejected from the capsule and parachuted back to earth. She landed hard after a high wind blew her off course, which was fortunate since she was descending towards a lake at the time. However, the landing caused her to seriously bruise her face, and heavy makeup was needed for the public appearances that followed.
Vostok 6 would be the last of the Vostok missions, despite there being plans for further flights involving women cosmonauts. None of the other four in Tereshkova’s early group got a chance to fly, and, in October of 1969, the pioneering female cosmonaut group was dissolved. It would be 19 years before another woman would fly as part of the Soviet space program – Svetlana Savitskaya, who flew as part of the Soyuz T-7 mission.
After Vostok 6:
After returning home, certain elements within the Soviet Air Force attempted to discredit Tereshkova. There were those who said that she was drunk when she reported to the launch pad and was insubordinate while in orbit. These charges appeared to be related to the sickness she experienced while in space, and the fact that she issued corrections to the ground control team – which was apparently seen as a slight.
Nikita Khrushchev, Valentina Tereshkova, Pavel Popovich and Yury Gagarin at Lenin Mausoleum on June 22nd, 1963. Credit: Wikipedia Commons/RIA Novosti Archive
She was also accused of drunken and disorderly conduct when confronting a militia Captain in Gorkiy. However, General Nikolai Kamanin – the head of cosmonaut training in the Soviet space program at the time – defended Tereshkova’s character and dismissed her detractors instead. Tereshkova’s reputation remained unblemished and she went on to become a cosmonaut engineer and spent the rest of her life in key political positions.
In November of 1963, Tereshkova married Andrian Nikolayev, another Soviet cosmonaut, at a wedding that took place at the Moscow Wedding Palace. Khrushchev himself presided, with top government and space program leaders in attendance. In June of 1964, she gave birth to their daughter Elena Andrianovna Nikolaeva-Tereshkova, who became the first person in history to have both a mother and father who had traveled into space.
She and Nikolayev divorced in 1982, and Nikolayev died in 2004. She went on to remarry an orthopaedist named Yuliy G. Sharposhnikov, who died in 1999. After her historic flight, Tereshkova enrolled at the Zhukovsky Air Force Academy and graduated with distinction as a cosmonaut engineer. In 1977, she earned her doctorate in engineering.
Her fame as a cosmonaut also led to several key political positions. Between 1966 and 1974, she was a member of the Supreme Soviet of the Soviet Union. She was also a member of the Presidium of the Supreme Soviet from 1974 to 1989, and a Central Committee Member from 1969 to 1991. Her accomplishments also led to her becoming a representative of the Soviet Union abroad.
The wedding ceremony of pilot-cosmonauts Valentina Tereshkova and Andriyan Nikolayev, Nov. 3rd, 1963. Credit: RIA Novosti Archive/Alexander Mokletsov
After the collapse of the Soviet Union, Tereshkova lost her political office but remained an important public figure. To this day, she is revered as a hero and a major contributor to the Russian space program. In 2011, she was elected to the State Duma (the lower house of the Russian legislature) where she continues to serve.
In 2008, Tereshkova was invited to Prime Minister Vladimir Putin’s residence in Novo-Ogaryovo for the celebration of her 70th birthday. In that same year, she became a torchbearer of the 2008 Summer Olympics torch relay in Saint Petersburg, Russia. She has also expressed interest in traveling to Mars, even if it were a one-way trip.
Legacy and Honors:
For her accomplishments, Tereshkova has received many honors and awards. She has been decorated with the Hero of the Soviet Union medal (the USSR’s highest award) as well as the Order of Lenin, the Order of the October Revolution, and many other medals.
Foreign governments have also awarded her with the Karl Marx Order, the Hero of Socialist Labor of Czechoslovakia, the Hero of Labor of Vietnam, the Hero of Mongolia, the UN Gold Medal of Peace, and the Simba International Women’s Movement Award. She has honorary citizenship in multiple cities from Bulgaria, Slovakia, Belarus and Mongolia in the east, to Switzerland, France, and the UK in the west.
Commemorative Hungarian stamp featuring Soviet cosmonauts Valentina Tereshkova and Andrian G. Nikolayev (her husband). Credit: Wikipedia Commons/Darjac
Due to her pioneering role in space exploration, a number of astronomical objects and features are named in her honor. For example, the Tereshkova crater on the far side of the Moon was named after her. The minor planet 1671 Chaika (which translates to “Seagull” in Russian) is named in honor of her Vostok 6 mission call sign.
Numerous monuments and statues have been erected in her honor and the Monument to the Conquerors of Space in Moscow features her image. Streets all across the former Soviet Union and Eastern Bloc nations were renamed in her honor, as was the school in Yaroslavl where she studied as a child. The Yaroslavl Planetarium, built in 2011, was created in her honor, and the Museum of V.V. Tereshkova – Cosmos exists near her native village of Maslennikovo.
The Space Age was a time of truly amazing accomplishments. Not only did astronauts like Tereshkova break the surly bonds of Earth, but they also demonstrated that space exploration knows no gender restrictions. And though it would be decades before people like Svetlana Savitskaya and Sally Ride would into space, Tereshkova will forever be remembered as the woman who blazed the trail for all female astronauts.
Astronauts Kate Rubins (left) and Jeff Williams (right) looking out of the ISS' cupola at a SpaceX Dragon supply spacecraft. Until recently, the effects of long-duration missions on eyesight was something of a mystery. Credit: NASA
The ability to take part in long-term space missions is a rare privilege, usually enjoyed by only a handful of men and women within every generation. But that privilege comes with a pretty high price. In addition to all the hard work, training, and sacrifice that is needed to go into space, there are also the health effects of spending prolonged periods in a microgravity environment.
Until recently, the most well-document of these effects were muscle degeneration and loss of bone density. But thanks to a new study released by the Radiological Society of America, it is now understood how microgravity can impair eyesight. This is certainly good news for ISS crews, not to mention the astronauts who will be taking part in long-range missions to Mars and beyond in the near future.
For years, NASA and other space agencies have been seeking to understand how time in space can adversely affect eyesight. Nearly two-thirds of astronauts who have taken part in long-duration missions aboard the International Space Station (ISS) have been diagnosed with Visual Impairment Intracranial Pressure (VIIP) syndrome. Symptoms include blurred vision, flattening at the back of eyeballs, and inflammation of the head of the optic nerves.
Expedition 46 Commander Scott Kelly of NASA resting after returning to Earth in March, 2016. At the time, Kelly established the record for longest time spent in space. Credits: NASA/Bill Ingalls
Previously, scientists believed that the primary source of VIIP was a shift of vascular fluid toward the upper body that takes place when astronauts spend time in the microgravity of space. But thanks to the new study, which was led by Dr. Noam Alperin and his team of researchers from the University of Miami, the cause of the syndrome has been properly diagnosed.
Dr. Alperin is a professor of radiology and biomedical engineering at the Miller School of Medicine at the University of Miami and the lead author of the study. According to the study he and his colleagues produced – which was presented on Monday, Nov. 28th, at the annual meeting of the Radiological Society of North America in Chicago – the culprit is cerebrospinal fluid (CSF).
This clear fluid is chiefly responsible for cushioning the brain and spinal cord, circulating nutrients and removing waste materials. At the same time, the CSF system is designed to accommodate significant changes in hydrostatic pressures, like when a person goes from lying down or sitting to a standing position. However, this system evolved within Earth’s own gravity environment, and exposing it to microgravity presents unique challenges.
As Dr. Alperin explained in a RSNA press statement, which coincided with the annual meeting:
“People initially didn’t know what to make of it, and by 2010 there was growing concern as it became apparent that some of the astronauts had severe structural changes that were not fully reversible upon return to Earth. On earth, the CSF system is built to accommodate these pressure changes, but in space the system is confused by the lack of the posture-related pressure changes.”
Astronaut Jeff Williams, who recently broke Kelly’s record for most time spent in space by a NASA astronaut. Credit: NASA
To arrive at this conclusion, Dr. Alperin and his colleague performed a series of before and after MRI scans on seven astronauts who took part in long-duration missions aboard the ISS. The results were compared against nine astronauts who took part in short-duration missions aboard the now-retired Space Shuttle. With the help of some special imaging algorithms, they looked for correlations between changes in CSF volumes and VIIP.
The results of their study Their study, titled “Role of Cerebrospinal Fluid in Spaceflight-Induced Visual Impairment and Ocular Changes“, showed that astronauts who participated in long-duration missions experienced a comparably higher flattening of their eyeballs and protrusions in their optic nerves. These astronauts also had significantly higher post-flight increases in CSF around their optic nerves and in the cavities of the brain where CSF is produced.
This study is both timely and significant, given the growing important of long-duration space missions. At present, it is expected that operations aboard the ISS will last for another decade. One of the most important activities there will be the study of the long-term effects of microgravity on human physiology, which will be intrinsic to preparing astronauts for missions to Mars and other long-range destinations.
Magnetic-resonance (MR) image of an astronauts eye before and after a long-duration space flight. Credit: RSNA
In short, identifying the origin of the space-induced ocular changes will help NASA and other space agencies to develop the proper countermeasures to protect the crew from potentially harmful changes to their eyesight. It will also come in handy for private space ventures that are hoping to send human beings on one-way trips to locations where the gravity is lower than on Earth (i.e. the Moon and Mars).
“The research provides, for the first time, quantitative evidence obtained from short- and long-duration astronauts pointing to the primary and direct role of the CSF in the globe deformations seen in astronauts with visual impairment syndrome,” said Alperin. If the ocular structural deformations are not identified early, astronauts could suffer irreversible damage. As the eye globe becomes more flattened, the astronauts become hyperopic, or far-sighted.”
As the old saying goes, “an ounce of prevention is worth a pound of cure”. In addition to having regiments that will help maintain their musculature and bone density, astronauts taking part in long-term missions in the future will also likely need to undergo treatments to ensure their eyesight doesn’t suffer.
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