There are eight known planets in the solar system (ever since Pluto was booted from the club), but for a while, there has been some evidence that there might be one more. A hypothetical Planet 9 lurking on the outer edge of our solar system. So far this world has eluded discovery, but a new study has pinned down where it should be.Continue reading “If Planet 9 is out There, Here's Where to Look”
Summertime means it’s time to play ball! But what would it be like to play ball on various locations across our Solar System? Planetary scientist Dr. James O’Donoghue has put together a fun animation of how quickly an object falls on to the surfaces of places like the Sun, Earth, Ceres, Jupiter, the Moon, and Pluto.Continue reading “Fantastic Visualization Shows What Would Happen if you Dropped a Ball Across the Solar System”
In physics, there are two main ways to model the universe. The first is the classical way. Classical models such as Newton’s laws of motion and Einstein’s theory of relativity assume that the properties of an object such as its position and motion are absolute. There are practical limits to how accurately we can measure an object’s path through space and time, but that’s on us. Nature knows their motion with infinite precision. Quantum models such as atomic physics assume that objects are governed by interactions. These interactions are probabilistic and indefinite. Even if we constrain an interaction to limited outcomes, we can never know the motion of an object with infinite precision, because nature doesn’t allow it.Continue reading “A new Approach Could Tease out the Connection Between Gravity and Quantum Mechanics”
In all of scientific modeling, the models attempting to replicate planetary and solar system formation are some of the most complicated. They are also notoriously difficult to develop. Normally they center around one of two formative ideas: planets are shaped primarily by gravity or planets are shaped primarily by magnetism. Now a new theoretical model has been developed by a team at the University of Zurich (UZH) that uses math from both methodologies to inform the most complete model yet of planetary formation.Continue reading “Magnetic Fields Help Shape the Formation of New Planets”
It’s not easy living and working in space for extended periods of time. As NASA’s Twins Study illustrated, microgravity takes a toll on human physiology, which is followed by a painful transition back to normal gravity (just ask Scott Kelly!) Aside from muscle and bone degeneration, there’s diminished organ function, effects on cardiovascular health, the central nervous system, and “subtle changes” on the genetic level.
Until now, the biggest unanswered question was what the underlying cause of these physical impacts was. But after reviewing all of the data accumulated from decades of research aboard the International Space Station (ISS) – which included the Twins Study and DNA samples taken from dozens of astronauts – an international team of researchers came to the conclusion that mitochondria might be the driving force for these changes.Continue reading “Health Issues From Spaceflight Might Originate in the Mitochondria”
This week, we welcome Dr. John Kiss from the University of North Carolina, Greensboro (UNCG). Tonight, Dr. Kiss will be discussing the sensory physiology of plants in space research, including the effect of Mars’ levels of gravity on plant development.Continue reading “Weekly Space Hangout: September 30, 2020, Dr. John Kiss Discusses the Growth of Plants in Space”
Gravity was the first force of nature to be realized, and in the centuries since we first cracked the code of that all-pervasive pulling power, scientists have continually come up with clever ways to test our understanding. And it’s no surprise why: the discovery of a new wrinkle in the gravitational force could open up vistas of new physics, and maybe even the nature of reality itself.Continue reading “Gravity is tested down to a scale smaller than the thickness of a human hair”
The Earth looks like a perfect sphere, but down here on the surface we see that there are mountains, rivers, oceans, glaciers, all kinds of features with different densities and shapes. Scientists can map this produce a highly detailed gravity map of our planet. And it turns out, this is very useful for other worlds too.
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At the center of our galaxy, roughly 26,000 light years from Earth, lies the Supermassive Black Hole (SMBH) known as Sagittarius A*. Measuring 44 million km across, this object is roughly 4 million times as massive as our Sun and exerts a tremendous gravitational pull. Since astronomers cannot detect black holes directly, its existence has been determined largely from the effect it has on the small group of stars orbiting it.
In this respect, scientists have found that observing Sagittarius A* is an effective way of testing the physics of gravity. For instance, in the course of observing these stars, a team of German and Czech astronomers noted subtle effects caused by the black hole’s gravity. In so doing, they were able to yet again confirm some of the predictions made by Einstein’s famous Theory of General Relativity.
Their study, titled “Investigating the Relativistic Motion of the Stars Near the Supermassive Black Hole in the Galactic Center“, was recently published in the Astrophysical Journal. As is indicated in the course of it, the team applied new analysis techniques to existing observations that were made by European Southern Observatory’s (ESO) Very Large Telescope (VLT) and other telescopes over the course of the past 20 years.
From this, they measured the orbits of the stars that orbit Sagittarius A* to test predictions made by classical Newtonian physics (i.e. Universal Gravitation), as well as predictions based on general relativity. What they found was that one of the stars (S2) showed deviations in its orbit which were defied the former, but were consistent with the latter.
This star, which has 15 times the mass of our Sun, follows an elliptical orbit around the SMBH, completing a single orbit in about 15.6 years. At its closest, it gets to within 17 light hours of the black hole, which is the equivalent of 120 times the distance between the Sun and the Earth (120 AU). Essentially, the research team noted that S2 had the most elliptical orbit of any star orbiting the Supermassive Black Hole.
They also noted a slight change in its orbit – a few percent in the shape and about one-sixth of a degree in orientation. This could only be explained as being due to the relativistic effects caused by Sagittarius A* intense gravity, which cause a precession in its orbit. What this means is, the elliptical loop of S2’s orbit rotates around the SMBH over time, with its perihelion point aimed in different directions.
Interestingly enough, this is similar to the effect that was observed in Mercury’s orbit – aka. the “perihelion precession of Mercury” – during the late 19th century. This observation challenged classical Newtonian mechanics and led scientists to conclude that Newton’s theory of gravity was incomplete. It is also what prompted Einstein to develop his theory of General Relativity, which offered a satisfactory explanation for the issue.
Should the results of their study be confirmed, this will be the first time that the effects of general relativity have been precisely calculated using the stars that orbit a Supermassive Black Hole. Marzieh Parsa – a PhD student at the University of Cologne, Germany and lead author of the paper – was understandably excited with these results. As she stated in an ESO press statement:
“The Galactic Center really is the best laboratory to study the motion of stars in a relativistic environment. I was amazed how well we could apply the methods we developed with simulated stars to the high-precision data for the innermost high-velocity stars close to the supermassive black hole.“
This study was made possible thanks to the high-accuracy of the VLT’s instruments; in particular, the adaptive optics on the NACO camera and the SINFONI near-infrared spectrometer. These instruments were vital in tracking the star’s close approach and retreat from the black hole, which allowed for the team to precisely determine the shape of its orbit and thusly determine the relativistic effects on the star.
In addition to the more precise information about S2’s orbit, the team’s analysis also provided new and more accurate estimates of Sagittarius A* mass, as well as its distance from Earth. This could open up new avenues of research for this and other Supermassive Black Holes, as well as additional experiments that could help scientists to learn more about the physics of gravity.
The results also provided a preview of the measurements and tests that will be taking place next year. In 2018, the star S2 will be making a very close approach to Sagittarius A*. Scientists from around the world will be using this opportunity to test the GRAVITY instrument, a second-generation instrument that was recently installed on the Very Large Telescope Interferometer (VLTI).
Developed by an international consortium led by the Max Planck Institute for Extraterrestrial Physics, this instrument has been conducting observations of the Galactic Center since 2016. In 2018, it will be used to measure the orbit of S2 with even greater precision, which is expected to be most revealing. At this time, astrophysicists will be seeking to make additional measurements of the SMBH’s general relativistic effects.
Beyond that, they also hope to detect additional deviations in the star’s orbit that could hint at the existence of new physics! With the right tools trained on the right place, and at the right time, scientists just might find that even Einstein’s theories of gravity were not entirely complete. But in the meantime, it looks like the late and great theoretical physicist was right again!
And be sure to check out this video of the recent study, courtesy of the ESO:
With proposed missions to Mars and plans to establish outposts on the Moon in the coming decades, there are several questions about what effects time spent in space or on other planets could have on the human body. Beyond the normal range of questions concerning the effects of radiation and lower-g on our muscles, bones, and organs, there is also the question of how space travel could impact our ability to reproduce.
Earlier this week – on Monday, May 22nd – a team of Japanese researchers announced findings that could shed light on this question. Using a sample of freeze-dried mouse sperm, the team was able to produce a litter of healthy baby mice. As part of a fertility study, the mouse sperm had spent nine months aboard the International Space Station (between 2013 and 2014). The real question now is, can the same be done for human babies?
The study was led by University of Yamanashi‘s Advanced Biotechnology Center. As she and her colleagues explain in their study – which was recently published in the Proceedings of the National Academy of Sciences – assisted reproductive technology will be needed if humanity ever intends to live in space long-term., a student researcher at the
As such, studies that address the effect that living in space could have on human reproduction are needed first. These need to address the impact microgravity (or low-gravity) could have on fertility, human abilities to conceive, and the development of children. And more importantly, they need to deal with one of the greatest hazards of spending time in space – which is the threat posed by solar and cosmic radiation.
To be fair, one need not go far to feel the effects of space radiation. The ISS regularly receives more than 100 times the amount of radiation that Earth’s surface does, which can result in genetic damage if sufficient safeguards are not in place. On other Solar bodies – like Mars and the Moon, which do not have a protective magnetosphere – the situation is similar.
And while the effects of radiation on adults has been studied extensively, the potential damage that could be caused to our offspring has not. How might solar and cosmic radiation affect our ability to reproduce, and how might this radiation affect children when they are still in the womb, and once they are born? Hoping to take the first steps in addressing these questions, Wakayama and her colleagues selected the spermatozoa of mice.
They specifically chose mice since they are a mammalian species that reproduces sexually. As
“So far, only fish or salamanders were examined for reproduction in space. However, mammalian species are very different compared to those species, such as being born from a mother (viviparity). To know whether mammalian reproduction is possible or not, we must use mammalian species for experiments. However, mammalian species such as mice or rats are very sensitive and difficult to take care of by astronauts aboard the ISS, especially for a reproduction study. Therefore, we [have not conducted these studies] until now. We are planning to do more experiments such as the effect of microgravity for embryo development.”
The samples spent nine months aboard the ISS, during which time they were kept at a constant temperature of -95 °C (-139 °F). During launch and recovery, however, they were at room temperature. After retrieval, Wakayama and her team found that the samples had suffered some minor damage,.
“Sperm preserved in space had DNA damage even after only 9 months by space radiation,” said . “However, that damage was not strong and could be repaired when fertilized by oocytes capacity. Therefore, we could obtain normal, healthy offspring. This suggests to me that we must examine the effect when sperm are preserved for longer periods.”
In addition to being reparable, the sperm samples were still able to fertilize mouse embryos (once they were brought back to Earth) and produce mouse offspring, all of which grew to maturity and showed normal fertility levels. They also noted that the fertilization and birth rates were similar to those of control groups, and that only minor genomic differences existed between those and the mouse created using the test sperm.
From all this, they demonstrated that while exposure to space radiation can damage DNA, it need not affect the production of viable offspring (at least within a nine month period). Moreover, the results indicate that human and domestic animals could be produced from space-preserved spermatozoa, which could be mighty useful when it comes to colonizing space and other planets.
As put it, this research builds on fertilization practices already established on Earth, and demonstrated that these same practices could be used in space:
“Our main subject is domestic animal reproduction. In the current situation on the ground, many animals are born from preserves spermatozoa. Especially in Japan, 100% of milk cows were born from preserved sperm due to economic and breeding reasons. Sometimes, sperm that has been stored for more than 10 years was used to produce cows. If humans live in space for many years, then, our results showed that we can eat beefsteak in the space. For that purpose, we did this study. For humans, our finding will probably help infertile couples.”
This research also paves the way for additional tests that would seek to measure the effects of space radiation on ova and the female reproduction system. Not only could these tests tell us a great deal about how time in space could affect female fertility, it could also have serious implications for astronaut safety. As Ulrike Luderer, a professor of medicine at the University of California and one of the co-authors on the paper said in a statement to the AFP:
“These types of exposures can cause early ovarian failure and ovarian cancer, as well as other osteoporosis, cardiovascular disease and neurocognitive diseases like Alzheimer’s. Half the astronauts in the NASA’s new astronaut classes are women. So it is really important to know what chronic health effects there could be for women exposed to long-term deep space radiation.”
However, a lingering issue with these sorts of tests is being able to differentiate between the effects of microgravity and radiation. In the past, research has been conducted that showed how exposure to simulated microgravity can reduce DNA repair capacity and induce DNA damage in humans. Other studies have raised the issue of the interplay between the two, and how further experiments are needed to address the precise impact of each.
In the future, it may be possible to differentiate between the two by placing samples of spermatazoa and ova in a torus that is capable of simulating Earth gravity (1 g). Similarly, shielded modules could be used to isolate the effects of low or even micro-gravity. Beyond that, there will likely be lingering uncertainties until such time as babies are actually born in space, or in a lunar or Martian environment.
And of course, the long-terms impact of reduced gravity and radiation on human evolution remains to be seen. In all likelihood, that won’t become clear for generations to come, and will require multi-generational studies of children born away from Earth to see how they and their progeny differ.