Just a couple of weeks ago, astronomers from Caltech announced their third detection of gravitational waves from the Laser Interferometer Gravitational-Wave Observatory or LIGO.
As with the previous two detections, astronomers have determined that the waves were generated when two intermediate-mass black holes slammed into each other, sending out ripples of distorted spacetime.
One black hole had 31.2 times the mass of the Sun, while the other had 19.4 solar masses. The two spiraled inward towards each other, until they merged into a single black hole with 48.7 solar masses. And if you do the math, twice the mass of the Sun was converted into gravitational waves as the black holes merged.
On January 4th, 2017, LIGO detected two black holes merging into one. Courtesy Caltech/MIT/LIGO Laboratory
These gravitational waves traveled outward from the colossal collision at the speed of light, stretching and compressing spacetime like a tsunami wave crossing the ocean until they reached Earth, located about 2.9 billion light-years away.
The waves swept past each of the two LIGO facilities, located in different parts of the United States, stretching the length of carefully calibrated laser measurements. And from this, researchers were able to detect the direction, distance and strength of the original merger.
Seriously, if this isn’t one of the coolest things you’ve ever heard, I’m clearly easily impressed.
Now that the third detection has been made, I think it’s safe to say we’re entering a brand new field of gravitational astronomy. In the coming decades, astronomers will use gravitational waves to peer into regions they could never see before.
Being able to perceive gravitational waves is like getting a whole new sense. It’s like having eyes and then suddenly getting the ability to perceive sound.
This whole new science will take decades to unlock, and we’re just getting started.
As Einstein predicted, any mass moving through space generates ripples in spacetime. When you’re just walking along, you’re actually generating tiny ripples. If you can detect these ripples, you can work backwards to figure out what size of mass made the ripples, what direction it was moving, etc.
Even in places that you couldn’t see in any other way. Let me give you a couple of examples.
Black holes, obviously, are the low hanging fruit. When they’re not actively feeding, they’re completely invisible, only detectable by how they gravitational attract objects or bend light from objects passing behind them.
But seen in gravitational waves, they’re like ships moving across the ocean, leaving ripples of distorted spacetime behind them.
With our current capabilities through LIGO, astronomers can only detect the most massive objects moving at a significant portion of the speed of light. A regular black hole merger doesn’t do the trick – there’s not enough mass. Even a supermassive black hole merger isn’t detectable yet because these mergers seem to happen too slowly.
LIGO has already significantly increased the number of black holes with known masses. The observatory has definitively detected two sets of black hole mergers (bright blue). For each event, LIGO determined the individual masses of the black holes before they merged, as well as the mass of the black hole produced by the merger. The black holes shown with a dotted border represent a LIGO candidate event that was too weak to be conclusively claimed as a detection. Credit: LIGO/Caltech/Sonoma State (Aurore Simonnet)
This is why all the detections so far have been intermediate-mass black holes with dozens of times the mass of our Sun. And we can only detect them at the moment that they’re merging together, when they’re generating the most intense gravitational waves.
If we can boost the sensitivity of our gravitational wave detectors, we should be able to spot mergers of less and more massive black holes.
But merging isn’t the only thing they do. Black holes are born when stars with many more times the mass of our Sun collapse in on themselves and explode as supernovae. Some stars, we’ve now learned just implode as black holes, never generating the supernovae, so this process happens entirely hidden from us.
Is there a singularity at the center of a black hole event horizon, or is there something there, some kind of object smaller than a neutron star, but bigger than an infinitely small point? As black holes merge together, we could see beyond the event horizon with gravitational waves, mapping out the invisible region within to get a sense of what’s going on down there.
This illustration shows the merger of two black holes and the gravitational waves that ripple outward as the black holes spiral toward each other. In reality, the area near the black holes would appear highly warped, and the gravitational waves would be difficult to see directly. Credit: LIGO/T. Pyle
We want to know about even less massive objects like neutron stars, which can also form from a supernova explosion. These neutron stars can orbit one another and merge generating some of the most powerful explosions in the Universe: gamma ray bursts. But do neutron stars have surface features? Different densities? Could we detect a wobble in the gravitational waves in the last moments before a merger?
And not everything needs to merge. Sensitive gravitational wave detectors could sense binary objects with a large imbalance, like a black hole or neutron star orbiting around a main sequence star. We could detect future mergers by their gravitational waves.
Are gravitational waves a momentary distortion of spacetime, or do they leave some kind of permanent dent on the Universe that we could trace back? Will we see echoes of gravity from gravitational waves reflecting and refracting through the fabric of the cosmos?
Perhaps the greatest challenge will be using gravitational waves to see beyond the Cosmic Microwave Background Radiation. This region shows us the Universe 380,000 years after the Big Bang, when everything was cool enough for light to move freely through the Universe.
But there was mass there, before that moment. Moving, merging mass that would have generated gravitational waves. As we explained in a previous article, astronomers are working to find the imprint of these gravitational waves on the Cosmic Microwave Background, like an echo, or a shadow. Perhaps there’s a deeper Cosmic Gravitational Background Radiation out there, one which will let us see right to the beginning of time, just moments after the Big Bang.
And as always, there will be the surprises. The discoveries in this new field that nobody ever saw coming. The “that’s funny” moments that take researchers down into whole new fields of discovery, and new insights into how the Universe works.
The Laser Interferometer Gravitational-Wave Observatory (LIGO) facility in Livingston, Louisiana. The other facility is located in Hanford, Washington. Image: LIGO
The LIGO project was begun back in 1994, and the first iteration operated from 2002 to 2012 without a single gravitational wave detection. It was clear that the facility wasn’t sensitive enough, so researchers went back and made massive improvements.
In 2008, they started improving the facility, and in 2015, Advanced LIGO came online with much more sensitivity. With the increased capabilities, Advanced LIGO made its first discovery in 2016, and now two more discoveries have been added.
LIGO can currently only detect the general hemisphere of the sky where a gravitational wave was emitted. And so, LIGO’s next improvement will be to add another facility in India, called INDIGO. In addition to improving the sensitivity of LIGO, this will give astronomers three observations of each event, to precisely detect the origin of the gravitational waves. Then visual astronomers could do follow up observations, to map the event to anything in other wavelengths.
Current operating facilities in the global network include the twin LIGO detectors—in Hanford, Washington, and Livingston, Louisiana—and GEO600 in Germany. The Virgo detector in Italy and the Kamioka Gravitational Wave Detector (KAGRA) in Japan are undergoing upgrades and are expected to begin operations in 2016 and 2018, respectively. A sixth observatory is being planned in India. Having more gravitational-wave observatories around the globe helps scientists pin down the locations and sources of gravitational waves coming from space. Image made in February 2016. Credit: Caltech/MIT/LIGO Lab
A European experiment known as Virgo has been operating for a few years as well, agreeing to collaborate with the LIGO team if any detections are made. So far, the Virgo experiment hasn’t found anything, but it’s being upgraded with 10 times the sensitivity, which should be fully operational by 2018.
A Japanese experiment called the Kamioka Gravitational Wave Detector, or KAGRA, will come online in 2018 as well, and be able to contribute to the observations. It should be capable of detecting binary neutron star mergers out to nearly a billion light-years away.
Just with visual astronomy, there are a set of next generation supergravitational wave telescopes in the works, which should come online in the next few decades.
The Europeans are building the Einstein Telescope, which will have detection arms 10 km long, compared to 4 km for LIGO. That’s like, 6 more km.
There’s the European Space Agency’s space-based Laser Interferometer Space Antenna, or LISA, which could launch in 2030. This will consist of a fleet of 3 spacecraft which will maintain a precise distance of 2.5 million km from each other. Compare that to the Earth-based detection distances, and you can see why the future of observations will come from space.
The Laser Interferometer Space Antenna (LISA) consists of three spacecraft orbiting the sun in a triangular configuration. Credit: NASA
And that last idea, looking right back to the beginning of time could be a possibility with the Big Bang Observer mission, which will have a fleet of 12 spacecraft flying in formation. This is still all in the proposal stage, so no concrete date for if or when they’ll actually fly.
Gravitational wave astronomy is one of the most exciting fields of astronomy. This entirely new sense is pushing out our understanding of the cosmos in entirely new directions, allowing us to see regions we could never even imagine exploring before. I can’t wait to see what happens next.
Artist's impression of the the Interplanetary Spacecraft approaching Mars. Credit: SpaceX
Elon Musk has never been one to keep his long-term plans to himself. Beyond the development of reusable rockets, electric cars, and revolutionizing solar power, he has also been quite vocal about establishing a colony on Mars within his lifetime. The goal here is nothing less than ensuring the survival of the human race by creating a “backup location”, and calls for some serious planning and architecture.
The paper was produced by Scott Hubbard, a consulting professor at Stanford University and the Editor-in-Chief of NewSpace, and includes all the material and slides from Musk’s original presentation. Contained within are Musk’s thoughts on how the colonization of Mars could be accomplished in this century and what issues would need to be addressed.
Elon Musk revealing his Mars Plans at the 67th annual meetings of the IAC. Credit: SpaceX/IAC
These include the costs of sending people and payloads to Mars, the technical details of the rocket and vehicle that would be making the trip, and possible cost breakdowns and timelines. But of course, he also addresses the key philosophical questions – “Why go?” and “Why Mars?”
Addressing this first question is one of the most important aspects of space exploration. Remember John F. Kennedy’s iconic “We Choose to go to the Moon” speech? Far from just being a declaration of intent, this speech was a justification by the Kennedy administration for all the time, energy, and money it was committing to the Apollo program. As such, Kennedy’s speech stressed above all else why the goal was a noble undertaking.
In looking to Mars, Musk struck a similar tone, emphasizing survival and humanity’s need to expand into space. As he stated:
“I think there are really two fundamental paths. History is going to bifurcate along two directions. One path is we stay on Earth forever, and then there will be some eventual extinction event. I do not have an immediate doomsday prophecy, but eventually, history suggests, there will be some doomsday event. The alternative is to become a space-bearing civilization and a multi-planetary species, which I hope you would agree is the right way to go.”
As for what makes Mars the natural choice, that was a bit more of a tough sell. Granted, Mars has a lot of similarities with Earth – hence why it is often called “Earth’s Twin” – which makes it a tantalizing target for scientific research. But it also has some rather stark differences that make long-term stays on the surface seem less than appealing. So why would it be the natural choice?
Artist’s rendition of a passenger aboard the ITS looking down on Mars. Credit: SpaceX
As Musk explains, proximity has a lot to do with it. Sure, Venus is closer to Earth, getting as close as 41 million km (25,476,219 mi), compared to 56 million km (3,4796,787 mi) with Mars. But Venus’ hostile environment is well-documented, and include a super-dense atmosphere, temperatures hot enough to melt lead and sulfuric acid rain! Mercury is too hot and airless, and the Jovian moons are very far.
This leaves us with just two options for the near-future, as far as Musk is concerned. One is the Moon, which is likely to have a permanent settlement on it in the coming years. In fact, between the ESA, NASA, Roscosmos, and the Chines National Space Administration, there is no shortage of plans to build a lunar outpost, which will serve as a successor to the ISS.
But compared to Mars, it is less resource rich, has no atmosphere, and represents a major transition as far as gravity (0.165 g compared to 0.376 g) and length of day (28 days vs. 24.5 hours) are concerned. Herein lies the greatest reason to go to Mars, which is the fact that our options are limited and Mars is the most Earth-like of all the bodies that are currently accessible to us.
What’s more, Musk makes allowances for the fact that colonists could start kick-starting the terraforming process, to make it even more Earth-like over time. As he states (bold added for emphasis):
“In fact, we now believe that early Mars was a lot like Earth. In effect, if we could warm Mars up, we would once again have a thick atmosphere and liquid oceans. Mars is about half as far again from the Sun as Earth is, so it still has decent sunlight. It is a little cold, but we can warm it up. It has a very helpful atmosphere, which, being primarily CO2 with some nitrogen and argon and a few other trace elements, means that we can grow plants on Mars just by compressing the atmosphere.
“It would be quite fun to be on Mars because you would have gravity that is about 37% of that of Earth, so you would be able to lift heavy things and bound around. Furthermore, the day is remarkably close to that of Earth. We just need to change the populations because currently we have seven billion people on Earth and none on Mars.”
Naturally, no mission can be expected to happen without the all-important vehicle. To this end, Musk used the annual IAC meeting to unveil his company’s plans for the Interplanetary Transport System. An updated version of the Mars Colonial Transporter (which Musk began talking about in 2012), the ITS will consist of two main components – a reusable rocket booster and the Interplanetary Spaceship.
The process for getting to Mars with these components involves a few steps. First, the rocket booster and spaceship take off together and the spaceship is delivered into orbit. Next, while the spaceship assumes a parking orbit, the booster returns to Earth to be reloaded with the tanker craft. This vehicle is the same design as the spaceship, but contains propellant tanks instead of cargo areas.
The tanker is then launched into orbit with the booster, where it will rendezvous with the spaceship and refuel it for the journey to Mars. Overall, the propellant tanker will go up anywhere from three to five times to fill the tanks of the spacecraft while it is in orbit. Musk estimates that the turnaround time between the spacecraft launch and the booster retrieval could eventually be as low as 20 minutes.
This process (if Musk gets its way) would expand to include multiple spaceships making the journey to and from Mars every 26 months (when Mars and Earth are closest together):
“You would ultimately have upwards of 1,000 or more spaceships waiting in orbit. Hence, the Mars Colonial fleet would depart en masse. It makes sense to load the spaceships into orbit because you have got 2 years to do so, and then you can make frequent use of the booster and the tanker to get really heavy reuse out of those. With the spaceship, you get less reuse because you have to consider how long it is going to last—maybe 30 years, which might be perhaps 12–15 flights of the spaceship at most.”
In terms of the rocket’s structure, it would consist of an advanced carbon fiber exterior surrounding fuel tanks, which would rely on an autogenous pressurization system. This involves the fuel and oxygen being gasified through heat exchanges in the engine, which would then be used to pressurize the tanks. This is a much simpler system than what is currently being used for the Falcon 9 rocket.
The booster would use 42 Raptor engines arranged in concentric rings to generate thrust. With 21 engines in the outer ring, 14 in the inner ring, and seven in a center cluster, the booster would have an estimated lift-off thrust of 11,793 metric tons (13,000 tons) – 128 MegaNewtons – and a vacuum thrust of 12,714 metric tons (14,015 tons), or 138 MN. This would make it the first spacecraft where the rocket performance bar exceeds the physical size of the rocket.
As for the spacecraft, the designs calls for a pressurized section at the top with an unpressurized section beneath. The pressurized section would hold up to 100 passengers (thought Musk hopes to eventually increase that capacity to 200 people per trip), while all the luggage and cargo necessary for building the Martian colony would be kept in the unpressurized section below.
As for the crew compartments themselves, Musk was sure to illustrate how time in them would not be boring, since the transit time is a long. “Therefore, the crew compartment or the occupant compartment is set up so that you can do zero-gravity games – you can float around,” he said. “There will be movies, lecture halls, cabins, and a restaurant. It will be really fun to go. You are going to have a great time!”
The system architecture of the Interplanetary Transport System. Credit: SpaceX
Below both these sections, the liquid oxygen tank, fuel tank and spacecraft engines are located. The engines, which would be directly attached to the thrust cone at the base, would consists of an outer ring of three sea-level engines – which would generate 361 seconds of specific impulse (Isp) – and an inner cluster of six vacuum engines that would generate 382s Isp.
The exterior of the spacecraft will also be fitted with a heatshield, which will be composed of the same material that SpaceX uses on its Dragon spacecraft. This is known as a phenolic-impregnated carbon ablator (PICA), which SpaceX is on their third version of. In total, Musk estimates that the Interplanetary Spaceship will be able to transport 450 tons of cargo to Mars, depending upon how many times the tanker can refill the craft.
And, depending on the Earth-Mars rendezvous, the transit time could be as little as 80 days one-way (figuring for a speed of 6km/s). But with time, Musk hopes to cut that down to just 30 days, which would make it possible to establish a sizable population on Mars in a relatively short amount of time. As Musk indicated, the magic number here in 1 million, meaning the number of people it would take to establish a self-sustaining colony on Mars.
He admitted that this would be a major challenge, and could as long as a century to complete:
“If you can only go every 2 years and if you have 100 people per ship, that is 10,000 trips. Therefore, at least 100 people per trip is the right order of magnitude, and we may end up expanding the crew section and ultimately taking more like 200 or more people per flight in order to reduce the cost per person. However, 10,000 flights is a lot of flights, so ultimately you would really want in the order of 1,000 ships. It would take a while to build up to 1,000 ships. How long it would take to reach that million-person threshold, from the point at which the first ship goes to Mars would probably be somewhere between 20 and 50 total Mars rendezvous—so it would take 40–100 years to achieve a fully self-sustaining civilization on Mars.”
Cutaway of the Interplanetary Spaceship. Credit: SpaceX
When the ITS is ready to launch, it will do so from Launch Pad 39A at the Kennedy Space Center in Florida, which SpaceX currently uses to conduct Falcon 9 launches from. But of course, the most daunting aspect of any colonization effort is cost. At present, and using current methods, sending upwards of 1 million people to Mars is simply not affordable.
Using Apollo-era methods as a touchstone, Musk indicated that the cost to go to Mars would be around $10 billion per person – which is derived from the fact that the program itself cost between $100 and $200 billion (adjust for inflation) and resulted in 12 astronauts setting foot on the Moon. Naturally, this is far too high for the sake of creating a self-sustaining colony with a population of 1 million.
As a result, Musk claimed that the cost of transporting people to Mars would have to be cut by a whopping 5 million percent! Musk’s desire to lower the costs associated with space launches is well-known, and is the very reason he founded SpaceX and began developing reusable technology. However, costs would need to be lowered to the point where a ticket to Mars would cost about the same as a median house – i.e. $200,000 – before any trips to Mars could happen.
Artist’s impression of the ITS in transit, with its solar arrays deployed. Credit: SpsaceX
As to how this could be done, several strategies are outlined, many of which Musk and space agencies like NASA are already actively pursuing. They include full Reusability, where all stages of a rocket and its cargo module (not just the first stage) would have to be retrievable and reusable. Refueling in Orbit is a second means, which would mean the spacecraft would not have to carry all the fuel they need with them from Earth.
On top of that, there would have to be the option for propellant Production on Mars, where the spaceship will be able to refuel at Mars to make the return trip. This concept has been explored in the past for lunar and Martian missions. And in Mars’ case, the presence of atmospheric and frozen CO², and water in both the soil and the polar ice caps, would mean that methane, oxygen and hydrogen fuel could all be manufactured.
Lastly, there is the question of which propellant would be best. As it stands, there are there basic choices when it comes – kerosene (rocket fuel), hydrogen, and methane. All of these present certain advantages and can be manufactured in-situ on Mars. But based on a cost-benefit breakdown, Musk claims that methane would be the most cost-effective propellant.
As always, Musk also raised the issue of timelines and next steps. This consisted of a rundown of SpaceX’s accomplishments over the past decade and a half, followed by an outline of what he hopes to see his company do in the coming years and decades.
Artist impression of a Mars settlement with cutaway view. Credit: NASA Ames Research Center
These include the development of the first Interplanetary Spaceship in about four years time, which will be followed by suborbital test flights. He even hinted how the spacecraft could have commercial applications, being used for the rapid transportation of cargo around the world. As for the development of the booster, he indicated that this would be a relatively straightforward process since it simply involves scaling up the existing Falcon 9 booster.
Beyond that, he estimated that (assuming all goes well) a ten-year time frame would suffice for putting all the components together so that it would work for bringing people to Mars. Last, but not least, he offered some glimpses of what could be accomplished with ITS beyond Mars. As the name suggests, Musk is hoping to conduct missions to other destination in the Solar System someday.
Given the opportunities for in-situ fuel production (thanks to the abundance of water ice), the moons of both Jupiter and Saturn were mentioned as possible destination. But beyond moons like Europa, Enceladus, and Titan (all of which were mentioned), even destinations in the trans-Neptunian region of the Solar System were indicated as a possibility.
Given that Pluto also has an abundance of water ice on its surface, Musk claimed that a refueling depot could be built here to service missions to the Kuiper Belt and Oort Cloud. “I would not recommend this for interstellar journeys,” he admitted, “but this basic system—provided we have filling stations along the way—means full access to the entire greater solar system.”
Artist’s impression of the ITS conducting a flyby of Jupiter. Credit: SpaceX
The publication of this paper, many months after Musk presented the details of his plan to the annual IAC meeting, has naturally generated both approval and skepticism. While there are those who would question Musk’s timelines and his ability to deliver on the proposals contained within, others see it as a crucial step in the fulfillment of Musk’s long-held desire to see the colonization of Mars happen in this century.
To Scott Hubbard, it serves as a valuable contribution to the history of space exploration, something that future generations will be able to access so they can chart the history of Mars exploration – much in the same way NASA archival materials are used to study the history of the Moon landing. As he remarked:
“In my view, publishing this paper provides not only an opportunity for the spacefaring community to read the SpaceX vision in print with all the charts in context, but also serves as a valuable archival reference for future studies and planning. My goal is to make New Space the forum for publication of novel exploration concepts-particularly those that suggest an entrepreneurial path for humans traveling to deep space.”
Elon Musk is no stranger to thinking big and dreaming big. And while many of his proposals in the past did not come about in the time frame he originally specified, no one can doubt that he’s delivered so far. It will be very exciting to see if he can take the company he founded 15 years ago for the sake of fostering the exploration of Mars, and use it instead to lead a colonization effort!
Update: Musk tweeted his thanks to Hubbard for the publication and has indicated that there are some “major changes to the plan coming soon.”
And be sure to check out this video of Musk’s full speech at the 67th annual meeting of the IAC, courtesy of SpaceX:
Opportunity rover looks south from the top of Perseverance Valley along the rim of Endeavour Crater on Mars in this partial self portrait including the rover deck and solar panels. Perseverance Valley descends from the right and terminates down near the crater floor. This navcam camera photo mosaic was assembled from raw images taken on Sol 4736 (20 May 2017) and colorized. Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer/kenkremer.com
Opportunity rover looks south from the top of Perseverance Valley along the rim of Endeavour Crater on Mars in this partial self portrait including the rover deck and solar panels. Perseverance Valley descends from the right and terminates down near the crater floor. This navcam camera photo mosaic was assembled from raw images taken on Sol 4736 (20 May 2017) and colorized. Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer/kenkremer.com
Now well into her 13th year roving the Red Planet, NASA’s astoundingly resilient Opportunity rover has arrived at the precipice of “Perseverance Valley” – overlooking the upper end of an ancient fluid-carved valley on Mars “possibly water-cut” that flows down into the unimaginably vast eeriness of alien Endeavour crater.
In a remarkable first time feat and treat for having ‘persevered’ so long on the inhospitably frigid Martian terrain, Opportunity has been tasked by her human handlers to drive down a Martian gully carved billions of years ago – by a fluid that might have been water – and conduct unparalleled scientific exploration, that will also extend into the interior of Endeavour Crater for the first time.
No Mars rover has done that before.
“This will be the first time we will acquire ground truth on a gully system that just might be formed by fluvial processes,” Ray Arvidson, Opportunity Deputy Principal Investigator of Washington University in St. Louis, told Universe Today.
“Opportunity has arrived at the head of Perseverance Valley, a possible water-cut valley here at a low spot along the rim of the 22-km diameter Endeavour impact crater,” says Larry Crumpler, a rover science team member from the New Mexico Museum of Natural History & Science.
“The next month or so will be an exciting time, for no rover has ever driven down a potential ancient water-cut valley before,” Crumpler gushes.
“Perseverance Valley” is located along the eroded western rim of gigantic Endeavour crater – as illustrated by our exclusive photo mosaics herein created by the imaging team of Ken Kremer and Marco Di Lorenzo.
The mosaics show the “spillway” as the entry point to the ancient valley.
NASA’s Opportunity rover acquired this Martian panoramic view from a promontory that overlooks Perseverance Valley below – scanning from north to south. It is centered on due East and into the interior of Endeavour crater. Perseverance Valley descends from the right and terminates down near the crater floor in the center of the panorama. The far rim of Endeavour crater is seen in the distance, beyond the dark floor. Rover deck and wheel tracks at right. This navcam camera photo mosaic was assembled from raw images taken on Sol 4730 (14 May 2017) and colorized. Credit: NASA/JPL/Cornell/Ken Kremer/kenkremer.com/Marco Di Lorenzo
“Investigations in the coming weeks will “endeavor” to determine whether this valley was eroded by water or some other dry process like debris flows,” explains Crumpler.
“It certainly looks like a water cut valley. But looks aren’t good enough. We need additional evidence to test that idea.”
The valley slices downward from the crest line through the rim from west to east at a breathtaking slope of about 15 to 17 degrees – and measures about two football fields in length!
Huge Endeavour crater spans some 22 kilometers (14 miles) in diameter on the Red Planet. Perseverance Valley slices eastwards at approximately the 8 o’clock position of the circular shaped crater. It sits just north of a rim segment called “Cape Byron.”
Why go and explore the gully at Perseverance Valley?
“Opportunity will traverse to the head of the gully system [at Perseverance] and head downhill into one or more of the gullies to characterize the morphology and search for evidence of deposits,” Arvidson elaborated.
“Hopefully test among dry mass movements, debris flow, and fluvial processes for gully formation. The importance is that this will be the first time we will acquire ground truth on a gully system that just might be formed by fluvial processes. Will search for cross bedding, gravel beds, fining or coarsening upward sequences, etc., to test among hypotheses.”
Perspective view of Opportunity’s traverse along Endeavour crater rim over the last few weeks towards the Perseverance Valley “spillway” on Mars during Spring 2017. The entry point for the planned drive back into the crater is visible as the low notch just to the left (east) of the current (sol 4718) rover position. Credit: NASA/JPL/Cornell/NMMNH /Larry Crumpler
Exploring the ancient valley is the main science destination of the current two-year extended mission (EM #10) for the teenaged robot, that officially began Oct. 1, 2016. It’s just the latest in a series of extensions going back to the end of Opportunity’s prime mission in April 2004.
What are the immediate tasks ahead that Opportunity must accomplish before descending down the gully to thoroughly and efficiently investigate the research objectives?
In a nutshell, extensive imaging from a local high point promontory to create a long-baseline 3 D stereo image of the valley and a “walk-about” to assess the local geology.
The rover is collecting images from two widely separated points at a dip at the valley spillway to build an “extraordinarily detailed three-dimensional analysis of the terrain” called a digital elevation map.
“Opportunity has been working on a panorama from the overlook for the past couple of sols. The idea is to get a good overview of the valley from a high point before driving down it,” Crumpler explains.
“But before we drive down the valley, we want to get a good sense of the geologic features here on the head of the valley. It could come in handy as we drive down the valley and may help us understand some things, particularly the lithology of any materials we find on the valley floor or at the terminus down near the crater floor.”
“So we will be doing a short “walk-about” here on the outside of the crater rim near the “spillway” into the valley.”
“We will drive down it to further assess its origin and to further explore the structure and stratigraphy of this large impact crater.”
NASA’s Opportunity Mars rover passed near this small, 90-foot-wide and relatively fresh crater in April 2017, during the 45th anniversary of the Apollo 16 mission to the moon. The rover team chose to call it “Orion Crater,” after the Apollo 16 lunar module, Orion, which carried astronauts John Young and Charles Duke to and from the surface of the moon in April 1972 while crewmate Ken Mattingly piloted the Apollo 16 command module, Casper, in orbit around the moon. The rover’s Navigation Camera (Navcam) recorded this view assembled from raw images taken on Sol 4712 (26 April 2017) and colorized. Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer/kenkremer.com
The six wheeled rover landed on Mars on January 24, 2004 PST on the alien Martian plains at Meridiani Planum – as the second half of a stupendous sister act.
Expected to last just 3 months or 90 days, Opportunity has now endured nearly 13 ½ years or an unfathomable 53 times beyond the “warrantied” design lifetime.
Her twin sister Spirit, had successfully touched down 3 weeks earlier on January 3, 2004 inside 100-mile-wide Gusev crater and survived more than six years.
Opportunity has been exploring Endeavour almost six years – since arriving at the humongous crater in 2011. Endeavour crater was formed when it was carved out of the Red Planet by a huge meteor impact billions of years ago.
“Endeavour crater dates from the earliest Martian geologic history, a time when water was abundant and erosion was relatively rapid and somewhat Earth-like,” explains Crumpler.
Exactly what the geologic process was that carved Perseverance Valley into the rim of Endeavour Crater billions of years ago has not yet been determined, but there are a wide range of options researchers are considering.
“Among the possibilities: It might have been flowing water, or might have been a debris flow in which a small amount of water lubricated a turbulent mix of mud and boulders, or might have been an even drier process, such as wind erosion,” say NASA scientists.
“The mission’s main objective with Opportunity at this site is to assess which possibility is best supported by the evidence still in place.”
Extensive imaging with the mast mounted pancam and navcam cameras is currently in progress.
“The long-baseline stereo imaging will be used to generate a digital elevation map that will help the team carefully evaluate possible driving routes down the valley before starting the descent,” said Opportunity Project Manager John Callas of JPL, in a statement.
“Reversing course back uphill when partway down could be difficult, so finding a path with minimum obstacles will be important for driving Opportunity through the whole valley. Researchers intend to use the rover to examine textures and compositions at the top, throughout the length and at the bottom, as part of investigating the valley’s history.”
The team is also dealing with a new wheel issue and evaluating fixes. The left-front wheel is stuck due to an actuator stall.
“The rover experienced a left-front wheel steering actuator stall on Sol 4750 (June 4, 2017) leaving the wheel ‘toed-out’ by 33 degrees,” the team reported in a new update.
Thus the extensive Pancam panorama is humorously being called the “Sprained Ankle Panorama.” Selected high-value targets of the surrounding area will be imaged with the full 13-filter Pancam suite.
After reaching the bottom of Perseverance Valley, Opportunity will explore the craters interior for the first time during the mission.
“Once down at the end of the valley, Opportunity will be directed to explore the crater fill on a drive south at the foot of the crater walls,” states Crumpler.
As of today, June 17, 2017, long lived Opportunity has survived over 4763 Sols (or Martian days) roving the harsh environment of the Red Planet.
Opportunity has taken over 220,800 images and traversed over 27.87 miles (44.86 kilometers) – more than a marathon.
See our updated route map below. It shows the context of the rovers over 13 year long traverse spanning more than the 26 mile distance of a Marathon runners race.
The rover surpassed the 27 mile mark milestone on November 6, 2016 (Sol 4546).
NASA’s Opportunity rover acquired this Martian panoramic view from a promontory that overlooks Perseverance Valley below – scanning from north to south. It is centered on due East and into the interior of Endeavour crater. Perseverance Valley descends from the right and terminates down near the crater floor in the center of the panorama. The far rim of Endeavour crater is seen in the distance, beyond the dark floor. Rover deck and wheel tracks at right. This navcam camera photo mosaic was assembled from raw images taken on Sol 4730 (14 May 2017) and colorized. Credit: NASA/JPL/Cornell/Ken Kremer/kenkremer.com/Marco Di Lorenzo
As of Sol 4759 (June 13, 2017) the power output from solar array energy production is currently 343 watt-hours with an atmospheric opacity (Tau) of 0.842 and a solar array dust factor of 0.529, before heading into another southern hemisphere Martian winter later in 2017. It will count as Opportunity’s 8th winter on Mars.
“The science team is really jazzed at starting to see this area up close and looking for clues to help us distinguish among multiple hypotheses about how the valley formed,” said Opportunity Project Scientist Matt Golombek of NASA’s Jet Propulsion Laboratory, Pasadena, California.
NASA’s Opportunity rover scans around and across to vast Endeavour crater on Dec. 19, 2016, as she climbs steep slopes on the way to reach a water carved gully along the eroded craters western rim. Note rover wheel tracks at center. This navcam camera photo mosaic was assembled from raw images taken on Sol 4587 (19 Dec. 2016) and colorized. Credit: NASA/JPL/Cornell/Ken Kremer/kenkremer.com/Marco Di Lorenzo
Meanwhile Opportunity’s younger sister rover Curiosity traverses and drills into the lower sedimentary layers at the base of Mount Sharp.
And NASA continues building the next two robotic missions due to touch down in 2018 and 2020.
13 Year Traverse Map for NASA’s Opportunity rover from 2004 to 2017. This map shows the entire 44 kilometer (27 mi) path the rover has driven on the Red Planet during over 13 years and more than a marathon runners distance for over 4763 Sols, or Martian days, since landing inside Eagle Crater on Jan 24, 2004 – to current location at the western rim of Endeavour Crater at the head of Perseverance Valley. After studying Spirit Mound and ascending back uphill the rover has reached her next destination in May 2017- the Martian water carved gully at Perseverance Valley near Orion crater. Rover surpassed Marathon distance on Sol 3968 after reaching 11th Martian anniversary on Sol 3911. Opportunity discovered clay minerals at Esperance – indicative of a habitable zone – and searched for more at Marathon Valley. Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer/kenkremer.com
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
Learn more about the Opportunity rover and upcoming SpaceX launch of BulgariaSat 1, recent SpaceX Dragon CRS-11 resupply launch to ISS, NASA missions and more at Ken’s upcoming outreach events at Kennedy Space Center Quality Inn, Titusville, FL:
June 17-19: “Opportunity Mars rover, SpaceX BulgariaSat 1 launch, SpaceX CRS-11 and CRS-10 resupply launches to the ISS, Inmarsat 5 and NRO Spysat, EchoStar 23, SLS, Orion, Commercial crew capsules from Boeing and SpaceX , Heroes and Legends at KSCVC, ULA Atlas/John Glenn Cygnus launch to ISS, SBIRS GEO 3 launch, GOES-R weather satellite launch, OSIRIS-Rex, Juno at Jupiter, InSight Mars lander, SpaceX and Orbital ATK cargo missions to the ISS, ULA Delta 4 Heavy spy satellite, Curiosity explores Mars, Pluto and more,” Kennedy Space Center Quality Inn, Titusville, FL, evenings
This graphic shows the route that NASA’s Mars Exploration Rover Opportunity drove in its final approach to “Perseverance Valley” on the western rim of Endeavour Crater during spring 2017. Credits: NASA/JPL-Caltech/Univ. of Arizona/NMMNH13 Years on Mars! On Christmas Day 2016, NASA’s Opportunity rover scans around vast Endeavour crater as she ascends steep rocky slopes on the way to reach a water carved gully along the eroded craters western rim. This navcam camera photo mosaic was assembled from raw images taken on Sol 4593 (25 Dec. 2016) and colorized. Credit: NASA/JPL/Cornell/Ken Kremer/kenkremer.com/Marco Di Lorenzo
Alphecca is the brightest star in a C-shaped pattern of stars: the constellation Corona Borealis. It’s near the bright star Arcturus on the sky’s dome. Credit: EarthSky
Welcome to another edition of Constellation Friday! Today, in honor of the late and great Tammy Plotner, we take a look at the “Northern Crown” – the Corona Borealis constellation. Enjoy!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of all the then-known 48 constellations. This treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come, effectively becoming astrological and astronomical canon until the early Modern Age.
One of these constellations was Corona Borealis, otherwise known as the “Northern Crown”. This small, faint constellation is the counterpart to Corona Australis – aka. the “Southern Crown”. It is bordered by the constellations of Hercules, Boötes and Serpens Caput, and has gone on to become one of the 88 modern constellations recognized by the International Astronomical Union.
Name and Meaning:
In mythology, Corona Borealis was supposed to represent the crown worn by Ariadne – a present from Dionysus. In Celtic lore, it was known as Caer Arianrhod, or the “Castle of the Silver Circle”, home to the Lady Arianrhod. Oddly enough, it was also known to the Native Americans as well, who referred to it as the “Camp Circle” – a heavenly rendition of their celestial ancestors.
Hercules and Corona Borealis, as depicted in Urania’s Mirror (c.?1825). Credit: Library of Congress
History of Observation:
Corona Borealis was one of the original 48 constellations mentioned in the Almagest by Ptolemy. To the medieval Arab astronomers, the constellation was known as al-Fakkah, which means “separated” or “broken up”– a reference to the resemblance of the constellation’s stars to a loose string of jewels (sometimes portrayed as a broken dish). The name was later Latinized as Alphecca, which was later given to Alpha Coronae Borealis. In 1920, it was adopted by the International Astronomical Union (IAU) as one of the 88 modern constellations.
Notable Objects:
Corona Borealis has no bright stars, 6 main stars and 24 stellar members with Bayer/Flamsteed designations. It’s brightest star – Alpha Coronae Borealis (Alphecca) – is an eclipsing binary located about 75 light years away. The primary components is a white main sequence star that is believed to have a large disc around it (as evidenced by the amount of infrared radiation it emits), and may even have a planetary or proto-planetary system.
The second brightest star, Beta Coronae Borealis (Nusakan), is a spectroscopic binary that is located 114 light years away. It is an Alpha-2 Canum Venaticorum (ACV) type star, a class of variable (named after a star in the constellation Canes Venatici) that are main sequence stars that are chemically peculiar and have strong magnetic fields. Its traditional name, Nusakan, comes from the Arabic an-nasaqan which means “the (two) series.”
Corona Borealis Galaxy Cluster – Abell 2065. Credit: NASA (Wikisky)
Corona Borealis contains few Deep Sky Objects that would be visible to amateur astronomers. The most notable is the Corona Borealis Galaxy Cluster (aka. Abell 2065), a densely-populated cluster located between 1 and 1.5 billion years from Earth. It lies about one degree southwest of Beta Coronae Borealis, in the southwest corner of the constellation. The cluster contains more than 400 galaxies in an area spanning about one degree in the sky.
Corona Borealis also has five stars that have confirmed exoplanets orbiting them, most of which were detected using the radial velocity method. These include the the orange giant Epsilon Coronae Borealis, which has a Super-Jupiter (6.7 Jupiter masses) that orbits it at a distance of 1.3 AU and with a period of 418 days.
There’s also Kappa Coronae Borealis, an orange subgiant that is orbited by both a debris disk and a gas giant. This planet is 2.5 times as massive as Jupiter and orbits the star with a period of 3.4 years. Omicron Coronae Borealis is a clump giant (a type of red giant) with one confirmed exoplanet – a gas giant with 0.83 Jupiter masses that orbits its star every 187 days.
HD 145457 is an orange giant that has one confirmed planet of 2.9 Jupiter masses that takes 176 days to complete an orbit. XO-1 is a yellow main-sequence star located approximately 560 light-years away with a hot Jupiter (roughly the same size as Jupiter) exoplanet. This planet was discovered using the transit method and completes an orbit around its star every three days.
Artist’s concept of “hot Jupiter” orbiting a distant star. Credit: NASA/JPL-Caltech
Finding Corona Borealis:
Corona Borealis is visible at latitudes between +90° and -50° and is best seen at culmination during the month of July. Using binoculars, let’s start with Alpha Coronae Borealis. It’s name is Gemma, or on some star charts – Alphecca. At 75 light years away, we have a nice binary star system whose companion star produces a very faint eclipse every 17.3599 days. Even though Gemma is quite some distance in relative sky terms from Ursa Major, you might be surprised to know that it’s actually part of the Ursa Major moving star group!
Shift your attention to Beta Coronae Borealis. It’s traditional name Nusakan. Again, it looks like one star, but it’s actually two. Nusakan is a double star that’s about 114 light-years and the primary is a variable star that changes every so slightly about every 41 days. The two components are separated by about 0.25 arc seconds – way too close for amateur telescopes – but that’s not all. In 1944 F.J. Neubauer found a small variation in the radial velocity of Nusakan which may lead to a third orbiting body about 10 times the size of Jupiter.
Now have a look at Gamma. Again, we have a binary star that’s just too darn close to split with anything but a large telescope. Struve 1967 is a close binary with an orbit of 91 years. The position angle is 265º and separation about 0.2″. Instead, try focusing your attention on Zeta 1 and Zeta 2. Known as Struve 1965, this pair is a pretty blue white and they are well spaced at 7.03″ and about one stellar magnitude in difference. Nu1 and Nu2 are also very pretty in binoculars. Here we have an optic double star. Although they aren’t physically related, this widely seperated pair of orange giant stars is a pleasing sight in binoculars!
The location of the Corona Borealis Constellation. Credit: IAU/Sky&Telescope magazine
Out of all the singular stars here, you definitely have to take a look at R Coronae Borelis – known as R Cor Bor. Discovered nearly 200 years ago by English amateur, Edward Pigot, R Coronae Borealis is the prototype star of the R Coronae Borealis (RCB) type variables. They are very unusual type of variable star – one where the variability is caused by the formation of a cloud of carbon dust in the line of sight. Near the stellar photosphere, a cloud is formed – dimming the star’s visual brightness by several magnitudes.
Then the cloud dissipates as it moves away from the star. All RCB types are hydrogen-poor, carbon- and helium-rich, and high-luminosity. They are simultaneously eruptive and pulsating. They could fade anywhere from 1 to 9 magnitudes in a month… Or in a hundred days. It’s normally magnitude 6… But it could be magnitude 14. No wonder it has the nickname “Fade-Out star,” or “Reverse Nova”!
Unfortunately, Corona Borealis contains no bright deep sky objects, but it does have one claim to fame – the highly concentrated galaxy cluster, Abell 2065. For observers with larger telescope, many members of this fascinating 1-1.5 billion light years distant group are visible. This rich cluster of galaxies is located slightly more than a degree southwest of Beta Cor Bor and covers about a full degree of sky! Not for the faint of heart… Some of these galaxies list at magnitude 18….
Special Guest:
Dr. Natalie Batalha is an astrophysicist at NASA Ames Research Center and project scientist for NASA’s Kepler Mission. Dr. Batalha leads the effort to understand planet populations in the galaxy based on Kepler’s discoveries, and in 2015 she joined the leadership team of NASA’s Nexus for Exoplanet System Science Coalition (NExSS,) a multidisciplinary team dedicated to searching for evidence of life beyond the Solar System as well as understanding the diversity of exoplanetary worlds and which of these worlds are most likely to harbor life.
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Artist's impression of a brown dwarf orbiting a white dwarf star. Credit: ESO
Death is simply a part of life, and this is no less the case where stars and other astronomical objects are concerned. Sure, the timelines are much, much greater where these are concerned, but the basic rule is the same. Much like all living organism, stars eventually reach old age and become white dwarfs. And some are not even fortunate enough to be born, instead becoming a class of failed stars known as brown dwarfs.
Despite being familiar with these objects, astronomers were certainly not expecting to find examples of both in a single star system! And yet, according to a new study, that is precisely what an international team of astronomers discovered when looked at WD 1202-024. Using data from the Kepler space telescope, they spotted a binary system consisting of a failed star (a brown dwarf) and the remnant of a star (a white dwarf).
Stardust in the Perseus Molecular Cloud, a star-forming region in the Perseus constellation. Credit & Copyright: Lorand Fenyes
For us Earthlings, life under a single Sun is just the way it is. But with the development of modern astronomy, we’ve become aware of the fact that the Universe is filled with binary and even triple star systems. Hence, if life does exist on planets beyond our Solar System, much of it could be accustomed to growing up under two or even three suns. For centuries, astronomers have wondered why this difference exists and how star systems came to be.
Whereas some astronomers argue that individual stars formed and acquired companions over time, others have suggested that systems began with multiple stars and lost their companions over time. According to a new study by a team from UC Berkeley and the Harvard-Smithsonian Center for Astrophysics (CfA), it appears that the Solar System (and other Sun-like stars) may have started out as binary system billions of years ago.
This study, titled “Embedded Binaries and Their Dense Cores“, was recently accepted for publication in the Monthly Notices of the Royal Astronomical Society. In it, Sarah I. Sadavoy – a radio astronomer from the Max Planck Institute for Astronomy and the CfA – and Steven W. Stahler (a theoretical physicist from UC Berkeley) explain how a radio surveys of a star nursery led them to conclude that most Sun-like stars began as binaries.
The dark molecular cloud, Barnard 68, is a stellar nursery that can only be studied using radio astronomy. Credit: FORS Team, 8.2-meter VLT Antu, ESO
For several decades, astronomers have known that stars are born inside “stellar nurseries”, which are the dense cores that exist within immense clouds of dust and cold, molecular hydrogen. These clouds look like holes in the star field when viewed through an optical telescope, thanks to all the dust grains that obscure light coming from the stars forming within them and from background stars.
Radio surveys are the only way to probe these star-forming regions, since the dust grains emit radio transmissions and also do not block them. For years, Stahler has been attempting to get radio astronomers to examine molecular clouds in the hope of gathering information on the formation of young stars inside them. To this end, he approached Sarah Sadavoy – a member of the VANDAM team – and proposed a collaboration.
The two began their work together by conducting new observations of both single and binary stars within the dense core regions of the Perseus cloud. As Sadavoy explained in a Berkeley News press release, the duo were looking for clues as to whether young stars formed as individuals or in pairs:
“The idea that many stars form with a companion has been suggested before, but the question is: how many? Based on our simple model, we say that nearly all stars form with a companion. The Perseus cloud is generally considered a typical low-mass star-forming region, but our model needs to be checked in other clouds.”
Infrared image from the Hubble Space Telescope, showing a bright, fan-shaped object (lower right quadrant) thought to be a binary star that emits light pulses as the two stars interact. Credit: NASA/ESA/ J. Muzerolle (STScI)
Their observations of the Perseus cloud revealed a series of Class 0 and Class I stars – those that are <500,000 old and 500,000 to 1 million years old, respectively – that were surrounded by egg-shaped cocoons. These observations were then combined with the results from VANDAM and other surveys of star forming regions – including the Gould Belt Survey and data gathered by SCUBA-2 instrument on the James Clerk Maxwell Telescope in Hawaii.
From this, they created a census of stars within the Perseus cloud, which included 55 young stars in 24 multiple-star systems (all but five of them binary) and 45 single-star systems. What they observed was that all of the widely separated binary systems – separated by more than 500 AU – were very young systems containing two Class 0 stars that tended to be aligned with the long axis of their egg-shaped dense cores.
Meanwhile, the slightly older Class I binary stars were closer together (separated by about 200 AU) and did not have the same tendency as far as their alignment was concerned. From this, the study’s authors began mathematically modelling multiple scenarios to explain this distribution, and concluded that all stars with masses comparable to our Sun start off as wide Class 0 binaries. They further concluded that 60% of these split up over time while the rest shrink to form tight binaries.
“As the egg contracts, the densest part of the egg will be toward the middle, and that forms two concentrations of density along the middle axis,” said Stahler. “These centers of higher density at some point collapse in on themselves because of their self-gravity to form Class 0 stars. “Within our picture, single low-mass, sunlike stars are not primordial. They are the result of the breakup of binaries. ”
The two brightest stars of the Centaurus constellation, the binary star system of Alpha Centauri. Credit: Wikipedia Commons/Skatebiker
Findings of this nature have never before been seen or tested. They also imply that each dense core within a stellar nursery (i.e. the egg-shaped cocoons, which typically comprise a few solar masses) converts twice as much material into stars as was previously thought. As Stahler remarked:
“The key here is that no one looked before in a systematic way at the relation of real young stars to the clouds that spawn them. Our work is a step forward in understanding both how binaries form and also the role that binaries play in early stellar evolution. We now believe that most stars, which are quite similar to our own sun, form as binaries. I think we have the strongest evidence to date for such an assertion.”
This new data could also be the start of a new trend, where astronomers rely on radio telescopes to examine dense star-forming regions with the hopes of witnessing more in the way of stellar formations. With the recent upgrades to the VLA and the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, and the ongoing data provided by the SCUBA-2 survey in Hawaii, these studies may be coming sooner other than later.
Another interesting implication of the study has to do with something known as the “Nemesis hypothesis”. In the past, astronomers have conjectured that a companion star named “Nemesis” existed within our Solar System. This star was so-named because the theory held that it was responsible for kicking the asteroid which caused the extinction of the dinosaurs into Earth’s orbit. Alas, all attempts to find Nemesis ended in failure.
Artist’s impression of the binary star system of Sirius, a white dwarf star in orbit around Sirius (a white supergiant). Credit: NASA, ESA and G. Bacon (STScI)
As Steven Stahler indicated, these findings could be interpreted as a new take on the Nemesis theory:
“We are saying, yes, there probably was a Nemesis, a long time ago. We ran a series of statistical models to see if we could account for the relative populations of young single stars and binaries of all separations in the Perseus molecular cloud, and the only model that could reproduce the data was one in which all stars form initially as wide binaries. These systems then either shrink or break apart within a million years.”
So while their results do not point towards a star being around for the extinction of the dinosaurs, it is possible (and even highly plausible) that billions of years ago, the Solar planets orbited around two stars. One can only imagine what implications this could have for the early history of the Solar System and how it might have affected planetary formation. But that will be the subject of future studies, no doubt!
Welcome, come in to the 513th Carnival of Space! The Carnival is a community of space science and astronomy writers and bloggers, who submit their best work each week for your benefit. I’m Susie Murph, part of the team at Universe Today and CosmoQuest. So now, on to this week’s stories! Continue reading “Carnival of Space #513”
Using a wormhole to travel through time? Credit: NASA.
“Tell me what time is it?” asked the stranger on the street.
A simple enough question that can be answered with a simple enough glance at the watch on your wrist. And so goes the appreciation of time for the average person. But is time simply a notation of events in our life? Or is it a truly robust dimensional attribute? For one answer read Paul Nahin’s book “Time Machine Tales” and you will soon discover that it is the latter. And that time may be much, much more.
If time is a dimension, then Nahin’s book has us believe that we can move along this dimension as easily as we move along a Euclidean spatial dimension. This means that time travel should be possible. Yet, as someone said, “If people can travel in time then why aren’t we seeing time travelers popping up all over?”
And in a sense, this conundrum shapes this book. From very many perspectives, Nahin explores and conjectures. From the viewpoint of ancient Greeks or Catholic scholars long since gone, the book gives rise to, what is time? does the past stop at the Big Bang? and is our future predefined?
This book presents philosophers’ quotes and their views from yesteryear and from today. Now philosophy is fascinating unto itself but throw in large quantiles of technical lore and this book’s perspective on time expands to a much larger knowledge base. That is, the book brings up exotics like Dirac radios, block universes, the bilking paradox, chronons and things smaller than the Planck length.
Intrigued by this? It gets better as the book takes the reader through the derivation of the Lorentz transformation and on to the backward and forward tilt of light cones. If this doesn’t get your interest up, then also consider that Nahin has liberally strewn quotes and references from science fiction throughout. This leaves the reader pondering if the fiction stories are forerunners to reality or merely offshoots of very active imaginations.
And a lasting question revolves around whether scientific discovery is attained through hard work, through thoughtful imagination or through provisions by a time traveler. That’s just one of the choices that you, as the reader, get to make. Just give yourself the time to decide.
Given the fascinating, current discussions on dimensionality, it’s not difficult to pique a science reader’s interest on time travel. And this book grabs and holds such a reader. However, abrupt swings like from the musings of H.G. Wells to the showcasing of the concerns of John Wheeler make for bumpy reading on occasion. Further, the introduction implies that teachers could use the book; implying that this book is a textbook. Yet where are the courses on time travel? Nevertheless, from the view of simply enjoying science, this book makes for enjoyable reading, homework assignments and all.
Will people travel in time? Will they only travel forward in time? Can they only travel between here and other universes? When will this take place? There are so many questions about time. If nothing else, use the time you have wisely.
The Drake Equation, a mathematical formula for the probability of finding life or advanced civilizations in the universe. Credit: University of Rochester
Is there life out there in the Universe? That is a question that has plagued humanity long before we knew just how vast the Universe was – i.e. before the advent of modern astronomy. Within the 20th century – thanks to the development of modern telescopes, radio astronomy, and space observatories – multiple efforts have been made in the hopes of finding extraterrestrial intelligence (ETI).
