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.
A new study from UNLV indicates that the health risks for astronauts exploring Mars could be twice as bad as previously thought. Credit: NASA/Pat Rawlings, SAIC
Astronauts hoping to take part in a crewed mission to Mars might want to pack some additional rad tablets! Long before NASA announced their proposal for a “Journey to Mars“, which envisions putting boots on the Red Planet by the 2030s, mission planners have been aware that one of the greatest risks for such a mission has to do with the threat posed by cosmic and solar radiation.
But according to a new study from the University of Nevada, Las Vegas, this threat is even worse than previously thought. Using a predictive model, this study indicates that astronauts that are the surface of Mars for extended periods of time could experience cell damage from cosmic rays, and that this damage will extend to other healthy cells – effectively doubling the risk of cancer!
At one time, Mars had a magnetic field similar to Earth, which prevented its atmosphere from being stripped away. Credit: NASA
Galactic cosmic rays (GCRs) are one of the greatest hazards posed by space exploration. These particles, which originate from beyond our Solar System, are basically atomic nuclei that have been stripped of their surrounding electrons, thanks to their high-speed journey through space. In the cases of iron and titanium atoms, these have been known to cause heavy damage to cells because of their very high rates of ionization.
Here on Earth, we are protected from these rays and other sources of radiation thanks to our protective magnetosphere. But with missions that would take astronauts well beyond Earth, they become a much greater threat. And given the long-term nature of a mission to Mars, mitigation procedures and shielding are being investigated quite thoroughly. As Cucinotta explained in a UNLV press statement:
“Exploring Mars will require missions of 900 days or longer and includes more than one year in deep space where exposures to all energies of galactic cosmic ray heavy ions are unavoidable. Current levels of radiation shielding would, at best, modestly decrease the exposure risks.”
Previous studies have indicated that the effects of prolonged exposure to cosmic rays include cancer, central nervous system effects, cataracts, circulatory diseases and acute radiation syndromes. However, until now, the damage these rays cause was thought to be confined to those cells that they actually traverse – which was based on models that deal with the targeted effects of radiation.
Artist’s impression of astronauts exploring the surface of Mars. Credit: NASA/JSC/Pat Rawlings, SAIC
For the sake of their study, Dr. Cucinotta and Dr. Eliedonna Cacao (a Chemical Engineer at UNLV) consulted the mouse Harderian gland tumor experiment. This is the only extensive data-set to date that deals with the non-targeted effects (NTEs) of radiation for a variety of particles. Using this model, they tracked the effects of chronic exposure to GCRs, and determined that the risks would be twice as high as those predicted by targeted effects models.
“Galactic cosmic ray exposure can devastate a cell’s nucleus and cause mutations that can result in cancers,” Cucinotta explained. “We learned the damaged cells send signals to the surrounding, unaffected cells and likely modify the tissues’ microenvironments. Those signals seem to inspire the healthy cells to mutate, thereby causing additional tumors or cancers.”
Naturally, any indication that there could be an elevated risk calls for additional research. As Cucinotta and Cacao indicated in their study, “The scarcity of data with animal models for tissues that dominate human radiation cancer risk, including lung, colon, breast, liver, and stomach, suggest that studies of NTEs in other tissues are urgently needed prior to long-term space missions outside the protection of the Earth’s geomagnetic sphere.”
These studies will of course need to happen before any long-term space missions are mounted beyond Earth’s magnetosphere. In addition, the findings also raise undeniable ethical issues, such as whether or not these risks could (or should) be waived by space agencies and astronauts. If in fact we cannot mitigate or protect against the hazards associated with long-term missions, is it even right to ask or allow astronauts to take part in them?
In the meantime, NASA may want to have another look at the mission components for the Journey to Mars, and maybe contemplate adding an additional layer or two of lead shielding. Better to be prepared for the worst, right?
Scientists may now know why the Boomerang Nebula, the coldest object in the known Universe. Credit: NASA/ESA/The Hubble Heritage Team (STScI/AURA)
The Boomerang Nebula, a proto-planetary nebula that was created by a dying red giant star (located about 5000 light years from Earth), has been a compelling mystery for astronomers since 1995. It was at this time, thanks to a team using the now-decommissioned 15-meter Swedish-ESO Submillimetre Telescope (SESTI) in Chile, that this nebula came to be known as the coldest object in the known Universe.
And now, over 20 years later, we may know why. According to a team of astronomers who used the Atacama Large Millimeter/submillimeter Array (ALMA) – located in the Atacama desert in northern Chile – the answer may involve a small companion star plunging into the red giant. This process could have ejected most of the larger star’s matter, creating an ultra-cold outflow of gas and dust in the process.
Composite image of the Boomerang Nebula, with ALMA observations (orange) showing the e hourglass-shaped outflow on top of an image from the Hubble Space Telescope (blue). Credit: ALMA (ESO/NAOJ/NRAO); NASA/ESA Hubble; NRAO/AUI/NSF
Originally discovered in 1980 by a team of astronomers using the Anglo-Australian telescope at the Siding Spring Observatory, the mystery of this nebula became apparent when astronomers noted that it appeared to be absorbing the light of the Cosmic Microwave Background (CMB). This background radiation, which is the energy leftover from the Big Bang, provides the natural background temperature of space – 2.725 K (–270.4 °C; -454.7 °F).
For the Boomerang Nebula to absorb that radiation, it had to be even colder than the CMB. Subsequent observations revealed that this was in fact the case, as the nebula has a temperature of less than half a degree K (-272.5 °C; -458.5 °F). The reason for this, according to the recent study, has to do with the gas cloud that extends from the central star to a distance of 21,000 AU (21 thousands times the distance between Earth and the Sun).
The gas cloud – which is the result of a jet that is being fired by the central star – is expanding at a rate that is about 10 times faster than what a single star could produce on its own. After conducting measurements with ALMA that revealed regions of the outflow that were never before seen (out to a distance of about 120,000 AUs), the team concluded that this is what is driving temperatures to levels lower than that of background radiation
They further argue that this was the result of the central star having collided with a binary companion in the past, and were even able to deduce what the primary was like before this took place. The primary, they claim, was a Red Giant Branch (RGB) or early-RGB star – i.e. a star in the final phase of its life cycle – whose expansion caused its binary companion to be pulled in by its gravity.
ALMA image of the Boomerang Nebula, showing its massive outflowCredit: ALMA (ESO/NAOJ/NRAO), R. Sahai
The companion star would have eventually merged with its core, which caused the outflow of gas to begin. As Raghvendra Sahai explained in a NRAO press release:
“These new data show us that most of the stellar envelope from the massive red giant star has been blasted out into space at speeds far beyond the capabilities of a single, red giant star. The only way to eject so much mass and at such extreme speeds is from the gravitational energy of two interacting stars, which would explain the puzzling properties of the ultra-cold outflow.”
These findings were made possible thanks to the ALMA’s ability to provide precise measurements on the extent, age, mass and kinetic energy of the nebula. Also, in addition to measuring the rate of outflow, they gathered that it has been taking place for around 1050 to 1925 years. The findings also indicate that the Boomerang Nebula’s days as the coldest object in the known Universe may be numbered.
Looking forward, the red giant star in the center is expected to continue the process of becoming a planetary nebula – where stars shed their outer layers to form an expanding shell of gas. In this respect, it is expected to shrink and get hotter, which will warm up the nebula around it and make it brighter.
As Lars-Åke Nyman, an astronomer at the Joint ALMA Observatory in Santiago, Chile, and co-author on the paper, said:
“We see this remarkable object at a very special, very short-lived period of its life. It’s possible these super cosmic freezers are quite common in the universe, but they can only maintain such extreme temperatures for a relatively short time.”
These findings could also provide new insights into another cosmological mystery, which is how giant stars and their companions behave. When the larger star in these systems exists its main-sequence phase, it may consume its smaller companion and similarly become a “cosmic freezer”. Herein lies the value of objects like the Boomerang Nebula, which challenges conventional ideas about the interactions of binary systems.
It also demonstrates the value of next-generations instruments like ALMA. Given their superior optical capabilities and ability to obtain more high-resolution information, they can show us some never-before-seen things about our Universe, which can only challenge our preconceived notions of what is possible out there.
A new study has offered a new take on the Fermi Paradox - alien civilizations are not visible to us because they are sleeping. Credit and Copyright: Kevin M. Gill
When you consider that age of the Universe – 13.8 billion years by our most recent counts – and that which is “observable” to us measures about 93 billion light-years in diameter, you begin to wonder why we haven’t found signs of extra-terrestrial intelligence (ETI) beyond our Solar System. To paraphrase Enrico Fermi, the 20th-century physicists who advanced the famous Fermi Paradox – “where the heck are all the aliens?”
Naturally, Fermi’s Paradox has attracted a lot of theoretical explanations over the years – which include ETI being very rare, humanity being early to the Universe, and the aliens being extinct! But a new study by a team of scientists from the Future of Humanity Institute (FHI) offers a different take on this age-old paradox. According to their study, the key to answering this question is to consider the possibility that the aliens are engaged in “aestivation”.
Beyond the Solar System’s Main Asteroid Belt lies the realm of the giants. It is here, staring with Jupiter and extending to Neptune, that the largest planets in the Solar System are located. Appropriately named “gas giants” because of their composition, these planets dwarf the rocky (terrestrial) planets of the inner Solar System many times over.
Just take a look at Saturn, the gas giant that takes its name from the Roman god of agriculture, and the second largest planet in the Solar System (behind Jupiter). In addition to its beautiful ring system and its large system of moons, this planet is renowned for its incredible size. Just how big is this planet? Well that depends on what your frame of reference is.
Diameter:
First let’s consider how large Saturn is from one end to the other – i.e. it’s diameter. The equatorial diameter of Saturn is 120,536 km ± 8 km (74,898 ± 5 mi) – or the equivalent of almost 9.5 Earths. However, as with all planets, their is a difference between the equatorial vs. the polar diameter. This difference is due to the flattening the planet experiences at the poles, which is caused by the planet’s rapid rotation.
Like all the giant planets, Saturn is many times the size of Earth and the other rocky planets. Credit: NASA/JPL-Caltech/Space Science Institute.
The poles are about 5,904 km closer to the center of Saturn than points on the equator. As a result, Saturn’s polar radius is about 108,728 ± 20 km (67,560 ± 12 mi) – or the equivalent of 8.5 Earths. That’s a pretty big difference, and you can actually see that Saturn looks a little squashed in pictures. Just for comparison, the equatorial diameter of Saturn is 9.4 times bigger than Earth, and it’s about 84% the diameter of Jupiter.
Volume and Surface Area:
In terms of volume and surface area, the numbers get even more impressive! For starters, the surface area of Saturn is 42.7 billion km² (16.5 billion sq miles), which works out to about 83.7 times the surface area of Earth. That’s smaller than Jupiter though, being only 68.7% of Jupiter’s surface area. Still, that is pretty astounding when put into perspective.
On the other hand, Saturn has a volume of 827.13 trillion km³ (198.44 trillion cubic miles), which effectively means you could fit Earth inside of it 763 times over and still have room enough for about twenty Moons! Again, Jupiter has it beat since Saturn has only 57.8% the volume of Jupiter. It’s big, but Jupiter is just that much bigger.
Mass and Density:
What about mass? Of course Saturn is much, much, MUCH more massive than Earth. In fact, it’s mass has been estimated to be a whopping 568,360,000 trillion trillion kg (1,253,000,000 trillion trillion lbs) – which works out to 95 times the mass of Earth. Granted, that only works out to about 30% the mass of Jupiter, but that’s still a staggering amount of matter.
Diagram of Saturn’s interior. Credit: Kelvinsong/Wikipedia Commons
Looking at the numbers, you may notice that this seems like a bit of a discrepancy. If you could actually fit 763 Earth-sized planets inside Saturn with room to spare, how is it that it is only 95 times Earth’s mass? The answer to that has to do with density. Since Saturn is a gas giant, its matter is distributed less densely than a rocky planet’s.
Whereas Earth has a density of 5.514 g/cm³ (or 0.1992 lb per cubic inch), Saturn’s density is only 0.687 g/cm3 (0.0248 lb/cu in). Like all gas giants, Saturn’s is made up largely of gases that exist under varying degrees of pressure. Whereas the density increases considerably the deeper one goes into Saturn’s interior, the overall density is less than that of water – 1 g/cm³ (0.0361273 lb/cu in).
Yes, Saturn is quite the behemoth. And yet, ongoing investigations into extra-solar planets are revealing that even it and its big brother Jupiter can be beaten in the size department. In fact, thanks to the Kepler mission and other exoplanet surveys, astronomers have found a plethora of “Super-Jupiters” in the cosmos, which refers to planets that are up to 80 times the mass of Jupiter.
I guess the takeaway from this is that there’s always a bigger planet out there. So watch your step and remember not to throw your weight (or mass or volume) around!
The NICER payload, shown here on the outside of the International Space Station. Credit: NASA
When a large star undergoes gravitational collapse near the end of its lifespan, a neutron star is often the result. This is what remains after the outer layers of the star have been blown off in a massive explosion (i.e. a supernova) and the core has compressed to extreme density. Afterwards, the star’s rotation rate increases considerably, and where they emit beams of electromagnetic radiation, they become “pulsars”.
And now, 50 years after they were first discovered by British astrophysicist Jocelyn Bell, the first mission devoted to the study of these objects is about to be mounted. It is known as the Neutron Star Interior Composition Explorer (NICER), a two-part experiment that will be deployed to the International Space Station this summer. If all goes well, this platform will shed light on one of the greatest astronomical mysteries, and test out new technologies.
Astronomers have been studying neutron stars for almost a century, which have yielded some very precise measurements of their masses and radii. However, what actually transpires in the interior of a neutron star remains an enduring mystery. While numerous models have been advanced that describe the physics governing their interiors, it is still unclear how matter would behave under these types of conditions.
Not surprising, since neutron stars typically hold about 1.4 times the mass of our Sun (or 460,000 times the mass of the Earth) within a volume of space that is the size of a city. This kind of situation, where a considerable amount of matter is packed into a very small volume – resulting in crushing gravity and an incredible matter density – is not seen anywhere else in the Universe.
As Keith Gendreau, a scientist at NASA’s Goddard Space Flight Center, explained in a recent NASA press statement:
“The nature of matter under these conditions is a decades-old unsolved problem. Theory has advanced a host of models to describe the physics governing the interiors of neutron stars. With NICER, we can finally test these theories with precise observations.”
NICE was developed by NASA’s Goddard Space Flight Center with the assistance of the Massachusetts Institute of Technology (MIT), the Naval Research Laboratory, and universities across the U.S. and Canada. It consists of a refrigerator-sized apparatus that contains 56 X-ray telescopes and silicon detectors. Though it was originally intended to be deployed late in 2016, a launch window did not become available until this year.
Once installed as an external payload aboard the ISS, it will gather data on neutron stars (mainly pulsars) over an 18-month period by observing neutron stars in the X-ray band. Even though these stars emit radiation across the spectrum, X-ray observations are believed to be the most promising when it comes to revealing things about their structure and various high-energy phenomena associated with them.
SEXTANT will demonstrate a GPS-like absolute position determination capability by observing millisecond pulsars. Credit: NASA
These include starquakes, thermonuclear explosions, and the most powerful magnetic fields known in the Universe. To do this, NICER will collect X-rays generated from these stars’ magnetic fields and magnetic poles. This is key, since it is at the poles that the strength of a neutron star’s magnetic fields causes particles to be trapped and rain down on the surface, which produces X-rays.
In pulsars, it is these intense magnetic fields which cause energetic particles to become focused beams of radiation. These beams are what give pulsars their name, as they appear like flashes thanks to the star’s rotation (giving them their “lighthouse”-like appearance). As physicists have observed, these pulsations are predictable, and can therefore be used the same way atomic-clocks and Global Positioning System are here on Earth.
While the primary goal of NICER is science, it also offers the possibility of testing new forms of technology. For instance, the instrument will be used to conduct the first-ever demonstration of autonomous X-ray pulsar-based navigation. As part of the Station Explorer for X-ray Timing and Navigation Technology (SEXTANT), the team will use NICER’s telescopes to detect the X-ray beams generated by pulsars to estimate the arrival times of their pulses.
The team will then use specifically-designed algorithms to create an on-board navigation solution. In the future, interstellar spaceships could theoretically rely on this to calculate their location autonomously. This wold allow them to find their way in space without having to rely on NASA’s Deep Space Network (DSN), which is considered to be the most sensitive telecommunications system in the world.
Beyond navigation, the NICER project also hopes to conduct the first-ever test of the viability of X-ray based-communications (XCOM). By using X-rays to send and receive data (in the same way we currently use radio waves), spacecraft could transmit data at the rate of gigabits per second over interplanetary distances. Such a capacity could revolutionize the way we communicate with crewed missions, rover and orbiters.
Central to both demonstrations is the Modulated X-ray Source (MXS), which the NICER team developed to calibrate the payload’s detectors and test the navigation algorithms. Generating X-rays with rapidly varying intensity (by switching on and off many times per second), this device will simulate a neutron star’s pulsations. As Gendreau explained:
“This is a very interesting experiment that we’re doing on the space station. We’ve had a lot of great support from the science and space technology folks at NASA Headquarters. They have helped us advance the technologies that make NICER possible as well as those that NICER will demonstrate. The mission is blazing trails on several different levels.”
It is hoped that the MXS will be ready to ship to the station sometime next year; at which time, navigation and communication demonstrations could begin. And it is expected that before July 25th, which will mark the 50th anniversary of Bell’s discovery, the team will have collected enough data to present findings at scientific conferences scheduled for later this year.
If successful, NICER could revolutionize our understanding of how neutron stars (and how matter behaves in a super-dense state) behaves. This knowledge could also help us to understand other cosmological mysteries such as black holes. On top of that, X-ray communications and navigation could revolutionize space exploration and travel as we know it. In addition to providing greater returns from robotic missions located closer to home, it could also enable more lucrative missions to locations in the outer Solar System and even beyond.
Stratolaunch Systems just conducted their first rollout of the Roc aircraft to begin fueling tests. Credit: Stratolaunch Systems
In 2011, Microsoft co-founder Paul G. Allen and Scaled Composites founder Burt Rutan announced the launch of their private space venture. Known as Stratolaunch Systems, this Seattle-based company was founded with the intention of developing air-launch-to-orbit systems. Similar to Virgin Galactic’s SpaceShipTwo, this concept involves a large air carrier flying rockets to launch altitude as cost-effective means of delivering small payloads to orbit.
On Thursday, May 31st, the company unveiled their launch vehicle, the Scaled Composites Model 351 (aka. the “Roc”). Consisting of two 747 hulls mated together, this aircraft is the the largest in the world – spanning 117 meters (385 ft) from one wingtip to the other and weighing 226,796 kg (500,000 lbs). This plane will make its first test flight in a few days time, and the company hopes to make its first commercial launch by 2019.
The rollout of the Roc – which took place at the company’s hangar facility at the Mojave Air and Space Port in California – was a media circus. In addition to being the first time that the public got to see the aircraft since construction began, the occasion marked the beginning of several tests which will take place over the coming days – including fueling tests, engine runs, taxi tests, and its first test flight.
Aerial view of the Roc aircraft, showing its massive 117 m (385 ft) wingspan. Credit: Stratolaunch Systems
“We’re excited to announce that Stratolaunch aircraft has reached a major milestone in its journey toward providing convenient, reliable, and routine access to low Earth orbit. Today, we’re moving the Stratolaunch aircraft out of the hangar – for the first time ever – to conduct aircraft fueling tests. This marks the completion of the initial aircraft construction phase and the beginning of the aircraft ground and flight testing phase.”
Measuring about 72.5 meters (238 ft) from nose to tail, the aircraft also stands 15.24 meters (50 ft) tall, measured from the ground to the top of the vertical tail. It has a maximum takeoff weight of 589,670 kg (1.3 million lbs), meaning that it is capable of airlifting payloads of up to 249,476 kg (550,000 lbs). These kinds of payloads mean that it will be capable of flying rockets and heavy space planes to launch altitude.
Last fall, the company announced their plan to conduct a launch using a single Orbital ATK Pegasus XL vehicle, a three-stage rocket used to deploy small satellites to Low-Earth Orbit (LEO). This agreement was part of a multi-year collaboration between the two companies, which would see the former combining their aircraft with the latter’s extensive air-launch experience.
Artist’s impression of the Roc aircraft, with a full loadout of three Pegasus rockets. Credit: Stratolaunch Systems
First unveiled in 1990, the Pegasus XL quickly established itself as a cost-effective means for launching small payloads to LEO. These typically would consist of small satellites weighing up to 443 kg (977 lbs) from beneath a NASA B-52 aircraft. Since then, the Pegasus has carried out 43 space launch missions and successfully placed a total of 94 satellites into orbit for various reasons – ranging from scientific research and communications to defense.
In time, the company plans to explore a wide range of launch vehicles that can provide flexibility in terms of missions and payloads. But in the meantime, they will be conducting ground and flight line testing from the Mojave Air and Space Port to ensure that Roc is capable of doing all it was designed for. If all goes well, they plan to make their first commercial launch by 2019.
“This marks a historic step in our work to achieve Paul G. Allen’s vision of normalizing access to low Earth orbit,” said Floyd. “It is proud day for us at Stratolaunch, for our partners at Scaled Composites, and for our founder Paul Allen. We have a lot of exciting activity ahead as we enter the testing process, and we look forward to sharing our progress during the coming months.”
One of the hallmarks of the commercial aerospace (aka. NewSpace) industry has been the development of cost-saving measures. Whereas companies like SpaceX and Blue Origin has looked to reusable rocket technology, other companies have sought to reduce costs with Single-Stage-to-Orbit (SSTO) rockets and plug-in payloads. Air-launch-to-orbit systems are just another way in which space is becoming more accessible.
And be sure to check out this video of the Roc’s unveiling:
One of the Daya Bay detectors.
Roy Kaltschmidt, Lawrence Berkeley National Laboratory
It is no easy thing to search for signs of intelligent life beyond our Solar System. In addition to the incredible distances involved and the fact that we really only have indirect methods at our disposal, there is also the small problem of not knowing exactly what to look for. If intelligent life does exist beyond our Solar System, would they even communicate as we do, using radio transmitters and similar forms of technology?
Such has been the preoccupation of groups like the Search for Extra Terrestrial Intelligence (SETI) Institute and, more recently, organizations like Messaging Extraterrestrial Intelligence (METI) International. A non-profit dedicated to communicating with extra-terrestrial intelligence (ETI), the organization recently suggested that looking for neutrinos and other exotic particles could help us find signals as well.
First, some clarification should be made as to what SETI and METI are all about it and what sets them apart. The term METI was coined by Russian scientist Alexander Zaitsev, who sought to draw a distinction between SETI and METI. As he explained in a 2006 paper on the subject:
“The science known as SETI deals with searching for messages from aliens. METI science deals with the creation of messages to aliens. Thus, SETI and METI proponents have quite different perspectives. SETI scientists are in a position to address only the local question “does Active SETI make sense?” In other words, would it be reasonable, for SETI success, to transmit with the object of attracting ETI’s attention? In contrast to Active SETI, METI pursues not a local and lucrative impulse, but a more global and unselfish one – to overcome the Great Silence in the Universe, bringing to our extraterrestrial neighbors the long-expected annunciation ‘You are not alone!'”
One of the 42 dishes in the Allen Telescope Array that searches for signals from space. Credit: Seth Shostak/SETI Institute.
In short, METI looks for ways in which we might be able to contact aliens instead of waiting to hear from them. However, this does not mean that organizations like METI International are without ideas on how me might better listen to our (potential) alien neighbors. After all, communication goes beyond mere messages, and also requires that a medium exist with which to convey the message.
Such is the recommendation put forth by Dr. Morris Jones, a space analyst and writer who serves on the METI advisory council. In a recent article published on METI International’s website, he addressed the two main challenges when it comes to looking for ETI. On the one hand, you have the need for multiple methodologies to increase the odds of finding something. But as he indicates, there’s also the problem of knowing what to look for:
“We are not really sure of how extraterrestrials would communicate with us. Would they use radio waves, lasers, or something more exotic? Perhaps the universe is awash in extraterrestrial signals that we cannot even receive. SETI and METI practitioners spend a lot of time wondering how a message would be encoded in terms of language and content. It’s also important to consider the medium of transmission.”
In the past, says Jones, SETI searches were based on radio astronomy because that was the only practical means of doing so. Since then, efforts have expanded to include optical telescopes and the search for laser signals. This is due to the fact that in the past few decades, human beings have developed the technology to use laser for the sake of communications.
An artist’s illustration of a light-sail powered by a radio beam (red) generated on the surface of a planet. Could the part of the beam that misses the sail be our mysterious Fast Radio Bursts? Image Credit: M. Weiss/CfA
In a 2016 SETI paper, Dr. Philip Lubin of the University of California, Santa Barbara, explained how the development of directed-energy propulsion could help us search for evidence of aliens. As one of the scientific minds behind Breakthrough Starshot – a laser-driven lightsail that would be fast enough to make the trip to Alpha Centauri in just 20 years – he believes it’s a safe bet that ETI could be using similar technology to travel or communicate.
In addition, Dr. Avi Loeb from the Harvard-Smithsonian Center for Astrophysics (also one of the minds behind Starshot) has also suggested that fast-radio bursts (FRBs) could be evidence of alien activity. FRBs have been a subject of fascination to scientists since they were first detected in 2007 (the “Lorimer Burst“), and could also be a sign of alien communications or a means of propulsion.
Another means involves searching for artefacts – i.e. looking for evidence of physical infrastructure in other star systems. Case in point, since 2015, astronomers have been seeking to determine what is responsible for the periodic dimming of KIC 8462852 (aka. Tabby’s Star). Whereas most studies have sought to explain this in terms of natural causes, others have suggested it could be evidence of an alien megastructure.
To this array of search methods, Dr. Jones offers a few other possibilities. One way is to look for neutrinos, a type of subatomic particle that is produced by the decay of radioactive elements and interacts with matter very weakly. This allows them to pass through solid matter and also makes them very difficult to detect. Neutrinos are produced in large quantities by our Sun and astronomical sources, but they can also be produced artificially by nuclear reactors.
Ever since it was first announced in 2015, there has been speculation as to what could account for the dimming of KIC 8462852. Credit: SentientDevelopments.com
These, claims Jones, could be used for the sake of communications. The only problem is that looking for them would require some specialized equipment. Currently, all means of detecting neutrinos involve expensive facilities that have to be built either underground or in extremely isolated locations to ensure that they are not subject to any kind of electromagnetic interference.
Another possibility is searching for evidence of communications that rely on gravitational waves. Predicted by Einstein’s Theory of General Relativity, the first detection of these mysterious waves was first made in February 2016. And in the coming years and decades, it is expected that gravitational wave observatories will be established so the presence of these “ripples” in spacetime can be visualized.
However, compared to neutrinos, Jones admits that this seems like a long shot. “It’s hard to conceive with our current grasp of physics,” he writes. “They are extremely difficult to generate at a detectable level. You would need abilities similar to those of superheroes, and be able to smash neutron stars and black holes together at will. There are probably easier ways to get a message across the stars.”
Breakthrough Listen will monitor the 1 million closest stars to Earth over a ten year period. Credit: Breakthrough Initiatives
Beyond these, there is the even more exotic possibility of “Zeta Rays”, which Dr. Jones is not prepared to rule out. Basically, “Zeta Rays” is a term used by physicists to describe physics that go beyond the Standard Model. As scientists are currently looking for evidence of new particles with the Large Hadron Collider and other particle accelerators, it stands to reason that anything they discover will be the added to the SETI and METI search manifest.
But could such physics entail new forms of communication? Hard to say, but definitely worth considering. After all, the physics that power our current technology certainly existed before we did. Or as Jones put it:,
“Is it possible to transmit with something better than we already have? Until we know a lot more physics, we just won’t know. Humanity in the twenty-first century could be like an isolated tribe in the Amazon jungle a century ago, unaware that the air around them was filled with radio signals. SETI uses the science and technology provided to us by other disciplines. Thus, we must wait until physics itself makes some more major breakthroughs. Only then can we consider such exotic methods of searching. We think a lot about the message. But we should also think about the medium.”
Other projects that are dedicated to METI include Breakthrough Listen, a ten-year initiative launched by Breakthrough Initiatives to conduct the largest survey to date for extraterrestrial communications – encompassing the 1,000,000 closest stars and 100 closest galaxies. Back in April of 2017, the scientists behind this project shared their analysis of the first year of Listen data. No definitive results have been announced yet, but they are just getting started!
Ever since Drake proposed his famous equation, human beings have eagerly sought to find evidence of extra-terrestrial intelligence. Unfortunately, all of our efforts have been haunted by Fermi’s equally-famous paradox! But of course, as space exploration goes, we’ve really only begun to scratch the surface of our Universe. And the only way we can ever expect to find evidence of intelligent life out there is to keep looking.
And with greater knowledge and increasingly sophisticated methods at our disposal, we can be sure that if intelligent life is out there somewhere, we will find it eventually. One can always hope, right? And be sure to check out this video of Dr. Jones 2014 presentation at the SETI Institute, titled “A Journalistic Perspective on SETI-Related Message Composition“:
The surface of Venus has been a mystery to scientists ever since the Space Age began. Thanks to its dense atmosphere, its surface is inaccessible to direct observations. In terms of exploration, the only missions to penetrate the atmosphere or reach the surface were only able to transmit data back for a matter of hours. And what we have managed to learn over the years has served to deepen its mysteries as well.
For instance, for years, scientists have been aware of the fact that Venus experiences volcanic activity similar to Earth (as evidenced by lighting storms in its atmosphere), but very few volcanoes have been detected on its surface. But thanks to a new study from the School of Earth and Environmental Sciences (SEES) at the University of St. Andrews, we may be ready to put that particular mystery to bed.
The study was conducted by Dr. Sami Mikhail, a lecturer with the SEES, with the assistance of researchers from the University of Strasbourg. In examining Venus’ geological past, Mikhail and his colleagues sought to understand how it is that the most Earth-like planet in our Solar System could be considerably less geologically-active than Earth. According to their findings, the answer lies in the nature of Venus’ crust, which has a much higher plasticity.
Image of the “pancake volcanoes” located in the Eistla region, taken by the Magellan space probe. Credit: NASA/JPL
This is due to the intense heat on Venus’ surface, which averages at 737 K (462 °C; 864 °F) with very little variation between day and night or over the course of a year. Given that this heat is enough to melt lead, it has the effect of keeping Venus’ silicate crust in a softened and semi-viscous state. This prevents lava magmas from being able to move through cracks in the planets’ crust and form volcanoes (as they do on Earth).
In fact, since the crust is not particularly solid, cracks are unable to form in the crust at all, which causes magma to get stuck in the soft, malleable crust. This is also what prevents Venus from experiencing tectonic activity similar to what Earth experiences, where plates drift across the surface and collide, occasionally forcing magma up through vents. This cycle, it should be noted, is crucial to Earth’s carbon cycle and plays a vital role in Earth’s climate.
Not only do these findings explain one of the larger mysteries about Venus’ geological past, but they also are an important step towards differentiating between Earth and it’s “sister planet”. The implications of this goes far beyond the Solar System. As Dr. Mikhail said in a St. Andrews University press release:
“If we can understand how and why two, almost identical, planets became so very different, then we as geologists, can inform astronomers how humanity could find other habitable Earth-like planets, and avoid uninhabitable Earth-like planets that turn out to be more Venus-like which is a barren, hot, and hellish wasteland.”
Volcanoes and lava flows on Venus. Credit: NASA/JPL
In terms of size, composition, structure, chemistry, and its position within the Solar System (i.e. within the Sun’s habitable zone), Venus is the most-Earth like planet discovered to date. And yet, the fact that it is slightly closer to our Sun has resulted in it having a vastly different atmosphere and geological history. And these differences are what make it the hellish, uninhabitable place that is today.
Beyond our Solar System, astronomers have discovered thousands of exoplanets orbiting various types of stars. In some cases, where the planets exist close to their sun and are in possession of an atmosphere, the planets have been designated as being “Venus-like“. This naturally sets them apart from the planets that are of particular interest to exoplanet hunters – i.e. the “Earth-like” ones.
Knowing how and why these two very similar planets can differ so dramatically in terms of their geological and environmental conditions is therefore key to being able to tell the difference between planets that are conducive to life and hostile to life. That can only come in handy when we begin to study multiple-planet systems (such as the seven-planet system of TRAPPIST-1) more closely.
Artistic design of the super-Earth GJ 625 b and its star, GJ625 (Gliese 625). Credit: Gabriel Pérez/SMM (IAC)
M-type stars, also known as “red dwarfs”, have become a popular target for exoplanet hunters of late. This is understandable given the sheer number of terrestrial (i.e. rocky) planets that have been discovered orbiting around red dwarf stars in recent years. These discoveries include the closest exoplanet to our Solar System (Proxima b) and the seven planets discovered around TRAPPIST-1, three of which orbit within the star’s habitable zone.
The latest find comes from a team of international astronomers who discovered a planet around GJ 625, a red dwarf star located just 21 light years away from Earth. This terrestrial planet is roughly 2.82 times the mass of Earth (aka. a “super-Earth”) and orbits within the star’s habitable zone. Once again, news of this discovery is prompting questions about whether or not this world could indeed be habitable (and also inhabited).
Diagram showing GJ 625’s habitable zone in comparison’s to the Sun’s. Credit: IAC
The study which details their findings was recently accepted for publication by the journal Astronomy & Astrophysics, and appears online under the title “A super-Earth on the Inner Edge of the Habitable Zone of the Nearby M-dwarf GJ 625“. According to the study, the team used radial-velocity measurements of GJ 625 in order to determine the presence of a planet that has between two and three times the mass of Earth.
Using this instrument, the team collected high-resolution spectroscopic data of the GJ 625 system over the course of three years. Specifically, they measured small variations in the stars radial velocity, which are attributed to the gravitational pull of a planet. From a total of 151 spectra obtained, they were able to determine that the planet (GJ 625 b) was likely terrestrial and had a minimum mass of 2.82 ± 0.51 Earth masses.
Moreover, they obtained distance estimates that placed it roughly 0.078 AU from its star, and an orbital period estimate of 14.628 ± 0.013 days. At this distance, the planet’s orbit places it just within GJ 625’s habitable zone. Of course, this does not mean conclusively that the planet has conditions conducive to life on its surface, but it is an encouraging indication.
Tjhe Observatorio del Roque de los Muchachos, located on the island of La Palma. Credit: IAC
As Alejandro Suárez Mascareño explained in an IAC press release:
“As GJ 625 is a relatively cool star the planet is situated at the edge of its habitability zone, in which liquid water can exist on its surface. In fact, depending on the cloud cover of its atmosphere and on its rotation, it could potentially be habitable”.
This is not the first time that the HADES project detected an exoplanet around a red dwarf star. In fact, back in 2016, a team of international researchers used this project to discover 2 super-Earths orbiting GJ 3998, a red dwarf located about 58 ± 2.28 light years from Earth. Beyond HADES, this discovery is yet another in a long line of rocky exoplanets that have been discovered in the habitable zone of a nearby red dwarf star.
Such findings are very encouraging since red dwarfs are the most common type of star in the known Universe- accounting for an estimated 70% of stars in our galaxy alone. Combined with the fact that they can exist for up to 10 trillion years, red dwarf systems are considered a prime candidate in the search for habitable exoplanets.
But as with all other planets discovered around red dwarf stars, there are unresolved questions about how the star’s variability and stability could affect the planet. For starters, red dwarf stars are known to vary in brightness and periodically release gigantic flares. In addition, any planet close enough to be within the star’s habitable zone would likely be tidally-locked with it, meaning that one side would be exposed to a considerable amount of radiation.
Artist’s impression of of the exoplanets orbiting a red dwarf star. Credit: ESO/M. Kornmesser/N. Risinger (skysurvey.org).
As such, additional observations will need to be made of this exoplanet candidate using the time-tested transit method. According to Jonay Hernández – a professor from the University of La Laguna, a researcher with the IAC and one of the co-authors on the study – future studies using this method will not only be able to confirm the planet’s existence and characterize it, but also determine if there are any other planets in the system.
“In the future, new observing campaigns of photometric observations will be essential to try to detect the transit of this planet across its star, given its proximity to the Sun,” he said. “There is a possibility that there are more rocky planets around GJ 625 in orbits which are nearer to, or further away from the star, and within the habitability zone, which we will keep on combing”.
According to Rafael Rebolo – one of the study’s co-authors from the Univeristy of La Laguna, a research with the IAC, and a member of the CSIS – future surveys using the transit method will also allow astronomers to determine with a fair degree of certainty whether or not GJ 625 b has the all-important ingredient for habitability – i.e. an atmosphere:
“The detection of a transit will allow us to determine its radius and its density, and will allow us to characterize its atmosphere by the transmitted light observe using high resolution high stability spectrographs on the GTC or on telescopes of the next generation in the northern hemisphere, such as the Thirty Meter Telescope (TMT)”.
Artist’s impression of a system of exoplanets orbiting a low mass, red dwarf star. Credit: NASA/JPL
But what is perhaps most exciting about this latest find is how it adds to the population of extra-solar planets within our cosmic neighborhood. Given their proximity, each of these planets represent a major opportunity for research. And as Dr. Mascareño told Universe Today via email:
“While we have already found more than 3600 extra-solar planets, the exoplanet population in our near neighborhood is still somewhat unknown. At 21 ly from the Sun, GJ 625 is one of the 100 nearest stars, and right now GJ 625 b is one of the 30 nearest exoplanets detected and the 6th nearest potentially habitable exoplanet.”
Once again, ongoing surveys of nearby star systems is providing plenty of potential targets in the search for life beyond our Solar System. And with both ground-based and space-based next-generation telescopes joining the search, we can expect to find many, many more candidates in the coming years. In the meantime, be sure to check out this animation of GJ 625 b and its parent star:
The first wild back-and-forth line records the moment (October 13, 2014 at 21:18:48.404 UTC) that the left NAC radiator was struck by a meteoroid. Credit: NASA/GSFC/Arizona State University
On October 13th, 2014, the Lunar Reconnaissance Orbiter (LRO) experienced something rare and unexpected. While monitoring the surface of the Moon, the LRO’s main instrument – the Lunar Reconnaissance Orbiter Camera (LROC) – produced an image that was rather unusual. Whereas most of the images it has produced were detailed and exact, this one was subject to all kinds of distortion.
From the way this image was disturbed, the LRO science team theorized that the camera must have experienced a sudden and violent movement. In short, they concluded that it had been struck by a tiny meteoroid, which proved to a significant find in itself. Luckily, the LRO and its camera appear to have survived the impact unharmed and will continue to survey the surface of the Moon for years to come.
The LROC is a system of three cameras that are mounted aboard the LRO spacecraft. This include two Narrow Angle Cameras (NACs) – which capture high-resolution black and white images – and a third Wide Angle Camera (WAC), which captures moderate resolution images that provide information about the properties and color of the lunar surface.
The NAC on a bench in the clean room at Malin Space Science Systems. Credit: Courtesy of Malin Space Science Systems/ASU SESE
The NACs works by building an image one line at a time, with thousands of lines being used to compile a full image. In between the capture process, the spacecraft moves the camera relative to the surface. On October 13th, 2014, at precisely 21:18:48 UTC, the camera added a line that was visibly distorted. This sent the LRO team on a mission to investigate what could have caused it.
Led by Mark Robinson – a professor and the principal investigator of the LROC at Arizona State University’s School of Earth and Space Exploration – the LROC researchers concluded that the left Narrow Angle Camera must have experienced a brief and violent movement. As there were no spacecraft events – like a solar panel movement or antenna tracking – that might have caused this, the only possibility appeared to be a collision.
As Robinson explained in a recent post on the LROC’s website:
“There were no spacecraft events (such as slews, solar panel movements, antenna tracking, etc.) that might have caused spacecraft jitter during this period, and even if there had been, the resulting jitter should have affected both cameras identically… Clearly there was a brief violent movement of the left NAC. The only logical explanation is that the NAC was hit by a meteoroid! How big was the meteoroid, and where did it hit?”
To test this, the team used a detailed computer model that was developed specifically for the LROC to ensure that the NAC would not fail during the launch of the spacecraft, when severe vibrations would occur. With this model, the LROC team ran simulations to see if they could reproduce the distortions that would have caused the image. Not only did they conclude it was the result of a collision, but they were also able to determine the size of the meteoroid that hit it.
LROC Narrow Angle Camera (NAC). Credit: ASU/LROC SESE
The results indicated that the impacting meteoroid would have measured about 0.8 mm in diameter and had a density of a regular chondrite meteorite (2.7 g/cm³). What’s more, they were able to estimate that it was traveling at a velocity of about 7 km/s (4.3 miles per second) when it collided with the NAC. This was rather surprising, given the odds of collisions and how much time the LRO spends gathering data.
Typically, the LROC only captures images during daylight hours, and for about 10% of the day. So for it to have been hit while it was also capturing images is statistically unlikely – only about 5% by Robinson’s own estimate. Luckily, the impact has not caused any technical problems for the LROC, which is also something of a minor miracle. As Robinson explained:
“For comparison, the muzzle velocity of a bullet fired from a rifle is typically 0.5 to 1.0 kilometers per second. The meteoroid was traveling much faster than a speeding bullet. In this case, LROC did not dodge a speeding bullet, but rather survived a speeding bullet! LROC was struck and survived to keep exploring the Moon, thanks to Malin Space Science Systems’ robust camera design.”
It was only after the team deduced that no damage had been caused that prompted the announcement. According to John Keller, the LRO project scientist from NASA’s Goddard Space Flight Center, the real story here was how the imagery that was being acquired at the time was used to deduce how and when the LRO had been struck by a meteoroid.
Artist’s rendering of Lunar Reconnaissance Orbiter (LRO) in orbit. Credit: ASU/LROC
“Since the impact presented no technical problems for the health and safety of the instrument,” he said, “the team is only now announcing this event as a fascinating example of how engineering data can be used, in ways not previously anticipated, to understand what is happening to the spacecraft over 236,000 miles (380,000 kilometers) from the Earth.”
In addition, the impact of a meteoroid on the LRO demonstrates just how precious the information that missions like the LRO provides truly is. Beyond mapping the lunar surface, the orbiter was also able to let its science team know exactly and when its images were comprised, all because of the high-quality data it collects.
Since it launched in June of 2008, the LRO has collected an immense amount of data on the lunar surface. The mission has been extended several times, from its original duration of two years to the just under nine. Its ongoing performance is also a testament to the durability of the craft and its components.
Be sure to enjoy this video of the images obtained by the LRO, courtesy of the LROC team:
