This picture was created from images forming part of the Digitized Sky Survey 2. It shows the rich region of sky around the young open star cluster NGC 2547 in the southern constellation of Vela (The Sail). Credit:
ESO/Digitized Sky Survey 2. Acknowledgement: Davide De Martin
Black holes are big influencers for the early universe; these singularities that were close to ancient stars heated up gas and affected star formation across the cosmos. A new study, however, says that heating happened later than previously thought.
“It was previously believed that the heating occurred very early, but we discovered that this standard picture delicately depends on the precise energy with which the X-rays come out,” stated Rennan Barkana, a co-author of the paper who is an astronomer at Tel Aviv University.
“Taking into account up-to-date observations of nearby black-hole binaries changes the expectations for the history of cosmic heating. It results in a new prediction of an early time (when the universe was only 400 million years old) at which the sky was uniformly filled with radio waves emitted by the hydrogen gas.”
These so-called “black-hole binaries” are star pairs where the larger star exploded into a supernova and left behind a black hole. The strong gravity then yanked gas away from the stellar companion, emitting X-rays in the process. The radiation, as it flows across the universe, is cited as the factor behind gas heating in other parts of space.
On Feb. 5, 1974, NASA's Mariner 10 mission took this first close-up photo of Venus during 1st gravity assist flyby. Credit: NASA
Exactly 40 Years ago today on Feb. 5, 1974, Mariner 10, accomplished a history making and groundbreaking feat when the NASA science probe became the first spacecraft ever to test out and execute the technique known as a planetary gravity assisted flyby used to alter its speed and trajectory – in order to reach another celestial body.
Mariner 10 flew by Venus 40 years ago to enable the probe to gain enough speed and alter its flight path to eventually become humanity’s first spacecraft to reach the planet Mercury, closest to our Sun.
Indeed it was the first spacecraft to visit two planets.
During the flyby precisely four decades ago, Mariner 10 snapped its 1st close up view of Venus – see above.
From that moment forward, gravity assisted slingshot maneuvers became an extremely important technique used numerous times by NASA to carry out planetary exploration missions that would not otherwise have been possible.
For example, NASA’s twin Voyager 1 and 2 probes launched barely three years later in 1977 used the gravity speed boost to conduct their own historic flyby expeditions to our Solar Systems outer planets.
Mariner 10’s Mercury.
This is a photomosaic of images collected by Mariner 10 as it flew past Mercury on 29 March 1974. It shows the southern hemisphere. The spacecraft took more than 7,000 images of Mercury, Venus, the Earth, and the moon during its mission. Credit: NASA
Without the flyby’s, the rocket launchers thrust by themselves did not provide sufficient interplanetary speed to reach their follow on targets.
NASA’s Juno Jupiter orbiter just flew back around Earth this past October 9, 2013 to gain the speed it requires to reach the Jovian system.
The Mariner 10 probe used an ultraviolet filter in its imaging system to bring out details in the Venusian clouds which are otherwise featureless to the human eye – as you’ll notice when viewing it through a telescope.
Venus surface is completely obscured by a thick layer of carbon dioxide clouds.
The hellish planet’s surface temperature is 460 degrees Celsius or 900 degrees Fahrenheit.
Diagram of Mariner 10 which flew by Venus and Mercury in 1974 and 1975. This photo identifies various parts of the spacecraft and the science instruments, which were used to study the atmospheric, surface, and physical characteristics of Venus and Mercury. This was the sixth in the series of Mariner spacecraft that explored the inner planets beginning in 1962. Credit: Jet Propulsion Laboratory
Following the completely successful Venus flyby, Mariner 10 eventually went on to conduct a trio of flyby’s of Mercury in 1974 and 1975.
It imaged nearly half of the planets moon-like surface, found surprising evidence of a magnetic field, discovered that a metallic core comprised nearly 80 percent of the planet’s mass, and measured temperatures ranging from 187°C on the dayside to minus 183°C on the nightside.
Mercury was not visited again for over three decades until NASA’s MESSENGER flew by and eventually orbited the planet – and where it remains active today.
Mariner 10 was launched on Nov. 3, 1973 from the Kennedy Space Center atop an Atlas-Centaur rocket.
Mosaic of the Earth from Mariner 10 after launch. Credit: NASAShortly after blastoff if also took photos of the Earth and the Moon.
Ultimately it was the last of NASA’s venerable Mariner planetary missions hailing from the dawn of the Space Age.
Mariner 11 and 12 were descoped due to congressional budget cuts and eventually renamed as Voyager 1 and 2.
The Mariner 10 science team was led by Bruce Murray of the Jet Propulsion Laboratory (JPL), Pasadena, Calif.
Murray eventually became the Director of JPL. After he passed away in 2013, key science features on Martian mountain climbing destinations were named in his honor by the Opportunity and Curiosity Mars rover science teams.
Stay tuned here for Ken’s continuing LADEE, Chang’e-3, Orion, Orbital Sciences, SpaceX, commercial space, Mars rover and more planetary and human spaceflight news.
Mariner 10 trajectory and timeline to Venus and Mercury. Credit: NASADiagram of the Mariner series of spacecraft and launch vehicle. Mariner spacecraft explored Mercury, Venus and Mars. Credit: Jet Propulsion LaboratoryMosaic of Earth from Juno gravity assist Flyby in 2013 –
compare to Mariner 10 Earth mosaic above from 1973 to see advances in space technology
This false color composite shows more than half of Earth’s disk over the coast of Argentina and the South Atlantic Ocean as the Juno probe slingshotted by on Oct. 9, 2013 for a gravity assisted acceleration to Jupiter. The mosaic was assembled from raw images taken by the Junocam imager. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo
Curiosity’s View Past Tall Dune at edge of ‘Dingo Gap’ This photomosaic from Curiosity’s Navigation Camera (Navcam) taken at the edge of the entrance to the Dingo Gap shows a 3 foot (1 meter) tall dune and valley terrain beyond to the west, all dramatically back dropped by eroded rim of Gale Crater. View from the rover’s current position on Sol 528 (Jan. 30, 2014). The rover team may decide soon whether Curiosity will bridge the dune gap as a smoother path to next science destination. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer- kenkremer.com
“Red Rover, Red Rover, I’m looking right over… this sand dune on Mars,” said the Curiosity rover on Twitter, as well as quoting photographer Ansel Adams, “There are always two people in every picture: the photographer and the viewer.”
This new interactive image put together by panoramacist Andrew Bodrov using the latest imagery from Curiosity allows you to nearly join the rover on Mars as it looks down across a sand dune and into the “Dingo Gap” area and the valley beyond.
The rover team is considering driving across and through this meter high sand sand dune to reach their desired science destinations instead of going over terrain with sharp rocks which might poke more holes in the rover’s aluminum wheels.
Thanks to Andrew Bodrov for sharing this new interactive image, which were taken with the rover’s 34-millimeter Mast Camera. The mosaic, which stretches about 30,000 pixels width, includes 101 images taken on Sol 530 (Feb 1, 2014 here on Earth.)
A part of the Small Magellanic Cloud galaxy is dazzling in this new view from NASA's Great Observatories. The Small Magellanic Cloud, or SMC, is a small galaxy about 200,000 light-years way that orbits our own Milky Way spiral galaxy. Credit: NASA.
If you love talking about space — and as a reader of Universe Today, I really hope you do — there’s an awesome podcast for you to add to your playlist. 365 Days of Astronomy puts out an astronomy-themed episode every single day of the year, covering everything from recent discoveries, to folklore, to community events.
If you’ve got a microphone and a desire to contribute, or have at least some coffee money to contribute to charity, they’d really love to hear from you as they enter a sixth (sixth!) year of operation. More details are below the jump.
Full disclosure here: Universe Today is a big supporter of 365 Days of Astronomy, and I’ve been contributing podcasts myself since last year. It is an awesome experience. Pamela Gay (who oversees the project through her astronomy education organization, Cosmoquest) is inspiring to work for as she is a tireless supporter of bringing the joy of space to the general public.
Nancy Atkinson (a fellow contributor and UT senior editor) joked to me today, “It’s kind of like the Mars rovers — the Energizer Bunny of podcasts.” And it’s through your support that we can keep going, and going, and going. Here’s the official press release with information about contributions:
365 Days of Astronomy will continue its service in 2014! This time we will have more days available for new audio. Have something to share? We’re looking for content from 10 minutes long up to an hour! Since 2009, 365 Days of Astronomy has brought a new podcast every day to astronomy lovers around the world to celebrate the International Year of Astronomy. Fortunately, the project has continued until now and we will keep going for another year in 2014. This means we will continue to serve you for a 6th year.
Through these years, 365 Days Of Astronomy has been delivering daily podcasts discussing various topics in the constantly changing realm of astronomy. These include history of astronomy, the latest news, observing tips and topics on how the fundamental knowledge in astronomy has changed our paradigms of the world. We’ve also asked people to talk about the things that inspired them, and to even share their own stories, both of life doing astronomy and science fiction that got them imagining a more scientific future.
365 Days of Astronomy is a community podcast that relies on a network of dedicated podcasters across the globe who are willing to share their knowledge and experiences in astronomy with the world and it will continue that way. In 2013, 365 Days of Astronomy started a new initiative with CosmoQuest. We now offer great new audio every weekend, while on weekdays we serve up interesting podcasts from CosmoQuest and other dedicated partners. We also have several monthly podcasts from dedicated podcasters and have started two new series: Space Stories and Space Scoop. The former is a series of science fiction tales, and the latter is an astronomy news segment for children.
From the universe to the solar system, we’ve had an interesting journey, especially the ostensibly legendary comet ISON which finally ended its days by breaking apart and vaporizing. We hope we won’t end like ISON did! As for 2014, we will have more available days for new podcasts.
A widefield view of Comet ISON, taken from New Mexico Skies at 11h 59m UT using an FSQ 106 ED telescope and STL11K camera on a PME II mount. 1 x 10 min exposures. Credit and copyright: Joseph Brimacombe.
For this upcoming year, the 365 Days of Astronomy podcast is looking for individuals, organizations, schools, companies, and clubs to sign-up for their 5 – 60 minutes of audio for the new daily podcast which will be aired on Tuesday, Thursday, Saturday, and Sunday. As for Monday, Wednesday, and Friday, we will air audio podcasts from CosmoQuest and partners’ Google+ hangouts. We’ll also post the matching video submissions on our YouTube Channel.
We will once again continue our quest in the podcasting arena, but we need your support to be a success. The project is now accepting financial support from individuals as well as organizations to cover our audio engineering and website support costs. The podcast team invites people and organizations to sponsor shows by donating to support one day of the podcast. It costs us about $45 per show. For your donation of $30, a dedication message will be announced in the beginning of the show. For a $15 donation a sponsorship message will be heard at the end of the show. Alternatively, for a $100 donation a sponsor may request a dedication message at the end of a whole week of programs. These donations are essential to cover the price for editing and posting podcasts.
The 365 Days of Astronomy podcast is heard by 5,000 listeners per day and by 2013 we have surpassed 6,8 million downloads. In 2009, the project was awarded a Parsec Award as “The Best Infotainment” podcast and a year later, in 2010-2012, it was nominated for the “Best Fact Behind the Fiction” award.
When stars die, their final gasps can trigger the most powerful blasts of energy in the universe. Their demise can also lead to a bizarre death dance as the voracious corpse of a dead star begins consuming a nearby companion.
Today (Feb. 5) you can watch a live webcast (or watch the replay later) to learn about the recent detection of a dying star igniting the most powerful blast ever seen – something so powerful it radiated energy that was nearly 50 billion times that of visible light. Also learn how scientists have discovered that a familiar sight in the skies is actually our earliest view yet of a star being consumed by the remnant of a nearby exploded star.
The webcast starts at 19:00 UTC (3 pm EDT, Noon PDT). You can watch below. To submit questions ahead of time or during the webcast, send an email to [email protected] or post on Twitter with hashtag #KavliLive. You can find additional information from the Kavli Foundation here.
A fresh impact crater is seen in this image taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter on Nov. 19, 2013. Credit: NASA/JPL/University of Arizona
The great thing about the longevity of the Mars Reconnaissance Orbiter is that we can see changes taking place on the Red Planet, such as this relatively new and rather large impact crater. This image shows a stunning 30-meter-wide crater with a rayed blast zone and far-flung secondary material surrounding. Scientists say the impact and resulting explosion threw debris as far as 15 kilometers in distance.
Before and after pictures of this region show the new impact crater formed between July 2010 and May 2012.
The image has been enhanced in false color and so the fresh crater appears blue because of the lack of reddish dust that covers most of Mars’ surface.
With MRO’s help, scientists have been able to estimate that Mars gets pummeled with about 200 impacts per year, but most are much smaller than this new one.
The usual procedure for finding new craters is that MRO’s Context Camera, or CTX, or cameras on other orbiters identify anomalies or dark spots that appear in new images and then MRO’s High Resolution Imaging Science Experiment (HiRISE) camera is targeted to follow up by imaging those dark spots in greater detail.
Dr. Andrea Ghez has spent much of her career studying the region right around the center of the Milky Way, including its supermassive black hole. In fact, she helped discover it in the first place. Dr. Ghez speaks about this amazing and dynamic region.
“Hi, I’m Dr. Andrea Ghez, and I’m a professor of physics and astronomy at UCLA. I study the center of our galaxy. The original objective was to figure out if there’s a supermassive black hole there, and in doing this, we’ve actually uncovered more questions than answers.”
What are you looking for at the center of the galaxy?
“We are tremendously privileged to be able to study the center of the galaxy, and have this exquisite laboratory to play with, to get insight into the fundamental physics of black holes, and also their astrophysical role in the formation and evolution of galaxies. You can also ask what kinds of phenomena do you expect to see around a black hole, and we have a lot of predictions about our thoughts about how galaxies form and evolve, and our ideas suggest that there’s a feedback between the galaxy and the black hole. But many of these models predict things that we simply don’t see, which again provides yet another playground.”
What’s it like around the supermassive black hole at the center of the galaxy?
“If you could get into a spaceship and get right down to the black hole, it would be a very busy place. Stars would be zooming around, like the sun, but you’d have a very busy day. You wouldn’t survive – I guess that would be another problem! You’d get torn apart. It’s just a very extreme place. The analogy that often gets made with the center of the galaxy is that it’s like the urban downtown, and we live out in the suburbs, so we live in a very calm place whereas the center of the galaxy is a a very extreme place, in almost every way you can describe an environment.”
What are some of the discoveries?
Stars at the Galactic Center. Credit: Astronomy Image Gallery
“The observations at the center of the Milky Way have taught us that one, it’s really normal to have a black hole at the center of the galaxy. I mean, our galaxy is completely ordinary, garden-variety, nothing-special-about-us, so if we have one, presumably every galaxy harbors a supermassive black hole at it’s center. We’ve also learned that the idea that a supermassive black hole should be surrounded by a very dense concentration of very old stars is not true. And that prediction is often used in other galaxies to find their black holes, because we can’t do the kinds of experiments we’ve done at the center of our own – that you look for this concentration of light, but in our galaxy we’re not seeing that, so you have a case where’s there’s absolutely clearly a supermassive black hole, yet you don’t see this collection of old stars. That’s a puzzle.
“Another puzzle that we’ve found that’s illuminating our ideas about other galaxies is that people predicted that you shouldn’t see young stars being formed near a black hole. In fact, in the early 1980’s, when people recognized that there were young stars found in the vicinity of a black hole, that was used to argue that perhaps you couldn’t possibly have a black hole because of these young stars. And yet again, we have a supermassive black hole – we know it, and those young stars are still exist, and we’ve even found stars even closer. And it’s the tidal forces that make it even more difficult to understand why the young stars should be there. The tidal forces pull the gases apart, and for star formation, you need a very fragile balls of gas and dust to collapse, so something’s amiss.”
How might those young stars get formed?
“There are so many ideas about how young stars could form at the center of the galaxy, but the one that has the most support is the idea that, at the time that these stars were being formed, that there was a much denser concentration of gas than there is today, and in that denser concentration you can get the collapse of those little clouds. We think that because as we continue to study the orbits of those stars, and what we’ve seen is that those orbits outside a certain distance start to fall into an ordered plane, like the planets orbiting the sun. We see a substantial fraction of them having a common orbital plane, and that looks very reminiscent to the solar system. The same way the planets formed out of a gas disc in the early days, that’s the same idea that is being invoked for these young stars, on a very different scale.”
While exoplanets make the news on an almost daily basis, one of the biggest announcements occurred in 2012 when astronomers claimed the discovery of an Earth-like planet circling our nearest neighbor, Alpha Centauri B, a mere 4.3 light-years away. That’s almost close enough to touch.
Of course such a discovery has led to a heated debate over the last three years. While most astronomers remain skeptical of this planet’s presence and astronomers continue to study this system, computer simulations from 2008 actually showed the possibility of 11 Earth-like planets in the habitable zone of Alpha Centauri B.
Now, recent research suggests that five of these computer-simulated planets have a high potential for photosynthetic life.
The 2008 study calculated the likely number of planets around Alpha Centauri B by assuming an initial protoplanetary disk populated with 400 – 900 rocks, or protoplanets, roughly the size of the Moon. They then tracked the disk over the course of 200 million years through n-body simulations — models of how objects gravitationally interact with one another over time — in order to determine the total number of planets that would form from the disk.
While the number and type of exoplanets depended heavily on the initial conditions given to the protoplanetary disk, the eight computer simulations predicted the formation of 21 planets, 11 of which resided within the habitable zone of the star.
A second team of astronomers, led by Dr. Antolin Gonzalez of the Universidad Central de Las Villas in Cuba, took these computer simulations one step further by assessing the likelihood these planets are habitable or even contain photosynthetic life.
The team used multiple measures that asses the potential for life. The Earth Similarity index “is a multi-parameter first assessment of Earth-likeness for extrasolar planets,” Dr. Gonzalez told Universe Today. It predicts (on a scale from zero to one with zero meaning no similarity and one being identical to Earth) how Earth-like a planet is based on its surface temperature, escape velocity, mean radius and bulk density.
Planets with an Earth Similar index from 0.8 – 1 are considered capable of hosting life similar to Earth’s. As an example Mars has an Earth Similar index in the range of 0.6 – 0.8. It is thus too low to support life today.
However, the Earth Similarity index alone is not an objective measure of habitability, Gonzalez said. It assumes the Earth is the only planet capable of supporting life. The team also relied on the P model for biological productivity, which takes into account the planet’s surface temperature and the amount of carbon dioxide present.
At this point in time “there is no way to predict, at least approximately, the partial pressure of carbon dioxide with the known data, or the variations from a planet to another,” Gonzalez said. Instead “we assumed a constant partial pressure of carbon dioxide for all planets simplifying the model to a function of temperature.”
Gonzalez’s team found that of the 11 computer-simulated planets in the habitable zone, five planets are prone for photosynthetic life. Their Earth Similarity index values are 0.92, 0.93, 0.87, 0.91 and 0.86. If we take into account their corresponding P model values we find that two of them have better conditions than Earth for life.
According to this highly theoretical paper: if there are planets circling our nearest neighbor, they’re likely to be teeming with life. It’s important to note that while these indexes may prove to be very valuable years down the road (when we have a handful of Earth-like planets to study), we are currently only looking for life as we know it.
The paper has been published in the Cuban journal: Revista Cubana de Fisica and is available for download here. For more information on Alpha Centauri Bb please read a paper available here published in the Astrophysical Journal.
The Soyuz-U rocket sits ready for launch at the baikonur Cosmodrome earlier today. Credit: The Russian Space Agency.
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The first launch of February 2014 worldwide is about to light up the night skies over the Baikonur Cosmodrome in Kazakhstan, with the launch of a Soyuz-U rocket carrying the uncrewed Progress M-22M spacecraft to the ISS. You can watch the launch live here, as well as the “fast-track” docking just 5 hours and 58 minutes later.
Progress will be carrying 2.8 tons of fuel, oxygen, supplies and experiments to the International Space Station. This will be the 54th Progress flight to the International Space Station since the first Progress launch to the station in 2000.
The launch is set to occur at 16:23:33 Universal Time or 11:23:33 AM EST. NASA TV will go live with the launch at 11:00 AM EST/16:00 UT, and TV Tsenki will also broadcast video from the pad just prior, though the broadcast frequently its sans audio.
Progress is also on a four orbit “fast-track” launch headed to the International Space Station. Tune in to NASA TV at 5:00 PM EST/22:00 UT later today, and you’ll be able to catch the docking of the Progress spacecraft to the Pirs module of the ISS as well. Docking is set to occur at 5:25 PM EST/22:25 UT over the North Atlantic Ocean.
Fun fact: Neil Armstrong still holds the record for the fastest journey from liftoff to docking at 5 hours and 33 minutes during Gemini 8 way back in 1966.
Update: ISS Astros indeed report during the live broadcast of the launch of Progress M-22M on NASA TV today of catching sight of the first stage of the Soyuz-U at liftoff… we’ll post any pics if and when they surface.
Progress M-20M undocked from the same Pirs compartment earlier this week on Monday in order to make way for the arrival of Progress M-22M. Progress M-20M is still in orbit, and is slated for a fiery destructive reentry on February 11th over the South Pacific. The long span between undocking and reentry for Progress M-20M allows for experiments on the spacecraft’s attitude control system to be carried out by ground controllers.
…and LIFTOFF of the Soyuz-U rocket from the Baikonur Cosmodrome with Progress M-22M! Credit: NASA TV.
This also marks the start of a busy 2014 season at the International Space Station. On March 1st, SpaceX continues its contract to resupply the station with the launch of a Falcon 9 rocket with its fifth Dragon capsule making its third operational delivery to the station on CRS-3. Then later in March on the 12th, Expedition 38 crewmembers Oleg Kotov, Sergey Ryazansky, and NASA astronaut Michael Hopkins will return to Earth aboard Soyuz TMA-10M. The next crewed launch headed to the International Space Station are Expedition 39 cosmonauts Alexander Skvortsov, Oleg Artemyev, and NASA astronaut Steve Swanson launching from Baikonur on March 26th on Soyuz TMA-12M.
Progress M-22M is ultimately slated to undock from the Pirs module of the International Space Station on April 7th for a destructive reentry over the South Pacific. Three additional SpaceX launches utilizing Dragon capsules and two more launches of Orbital Science’s Cygnus cargo spacecraft will be conducted in 2014, as well as visits by the European Space Agency’s ATV-5 Georges Lemaitre in June and JAXA’s HTV-5 in July.
And another launch from the Baikonur Cosmodrome is coming right up on Valentine’s Day, February 14th, with the liftoff of an International Launch Services Proton rocket carrying the Turksat 4A satellite. The launch will be carried live via the ILS website and is slated for 21:09 UT/4:09 PM EST.
And though these are all standard resupply missions to the International Space Station, spaceflight is anything but routine. Avid trackers of live launches will remember the Progress M-12M spacecraft that was lost shortly after launch back in August 2011. To date, Progress M-12M was the only supply craft that failed to reach the International Space Station. Progress M-12M impacted in the Choisk Region of Russia’s Altai Republic in the Far East. The RD-0110 engine began to experience a flight anomaly just over five minutes after launch, causing the flight computer to execute a termination of thrust. Progress M-12M was the first loss of a Progress spacecraft since the start of the program in 1978. Ironically, Progress M-12M carried among its cargo manifest 10 paintings made by the son of Russian artist Alesandr Shilov said to be for “the psychological support of the crew…” There’s also a small cottage industry in Siberia east of Russian launch sites in salvaging rocket parts and boosters for scrap metal as they plummet from the sky.
Tonight’s passage of Progress M-20M and the International Space Station over the US SE and the Caribbean region. Created by the author using Orbitron.
It’s also possible to spot these spacecraft from your backyard as they arrive and depart from the International Space Station. We caught sight of Progress M-20M just last night, passing very near the waxing crescent Moon. Progress was about magnitude +1 when directly overhead, and was about 9 minutes ahead of the International Space Station. We’ve seen the Dragon, HTV, ATV spacecraft, as well as the U.S. Space Shuttle shortly after undocking from the International Space Station when it was in service. In fact, there’s a series of good passes of the ISS at dusk over the next few evenings for the southeastern United States, including a pass at ~6:58 PM EST tonight. Progress M-20M should be about 20 minutes ahead of the station at this point, assuming, of course, it hasn’t maneuvered in its orbit as a part of ongoing thruster control experiments.
We’ll be checking those final orbital corrections just prior to the pass tonight, as well as tracking the launch and docking of Progress M-22M. Follow us on Twitter (@Astroguyz) for further updates.
Be sure to catch all the action at Baikonur and in low Earth orbit today, both online and overhead!
Itokawa, a peanut-shaped asteroid that has different densities in its small body. Credit: ESO/JAXA
From directly inferring the inside of an asteroid for the first time, astronomers have discovered these space rocks can have strange variations in density. The observations of Itokawa — which you may remember from the Japanese Hayabusa mission that landed on the asteroid in 2005 — not only teach us more about how asteroids came to be, but could help protect Earth against stray space rocks in the future, the researchers said.
“This is the first time we have ever been able to to determine what it is like inside an asteroid,” stated Stephen Lowry, a University of Kent scientist who led the research. “We can see that Itokawa has a highly varied structure; this finding is a significant step forward in our understanding of rocky bodies in the solar system.”
It’s not clear why Itokawa has such different densities at opposite sides of its peanut shape; perhaps it was two asteroids that rubbed up against each other and merged. At just shy of six American football fields long, the space rock has density varying from 1.75 to 2.85 grams per cubic centimetre. This precise measurement came courtesy of the European Southern Observatory’s New Technology Telescope in Chile.
The telescope calculated the speed and speed changes of Itokawa’s spin and combined that information with data on how sunlight can affect the spin rate. Asteroids are generally tiny and irregularly shaped sorts of bodies, which means the effect of heat on the body is not evenly distributed. That small difference makes the asteroid’s spin rate change.
This heat effect (more properly called the Yarkovsky-O’Keefe-Radzievskii-Paddack effect) is slowly making Itokawa’s spin rate go faster, at a rate of 0.045 seconds every Earth year. This change, previously unexpected by scientists, is only possible if the peanut bulges have different densities, the scientists said.
“Finding that asteroids don’t have homogeneous interiors has far-reaching implications, particularly for models of binary asteroid formation,” added Lowry. “It could also help with work on reducing the danger of asteroid collisions with Earth, or with plans for future trips to these rocky bodies.”
