Artist's impression (not to scale) of the Rosetta orbiter deploying the Philae lander to comet 67P/Churyumov–Gerasimenko. Credit: ESA–C. Carreau/ATG medialab.
It’s being called “the most important alarm clock in the Solar System” — this Monday, January 20, at 10:00 GMT (which is 5:00 a.m. for U.S. East Coasters like me) the wake-up call will ring on ESA’s Rosetta spacecraft, bringing it out of hibernation after over two and a half years in preparation of its upcoming and highly-anticipated rendezvous with a comet.
The wake-up will incite the warming of Rosetta’s star trackers, which allow it to determine its orientation in space. Six hours later its thrusters will fire to stop its slow rotation and ensure that its solar arrays are receiving the right amount of sunlight. Using its thawed-out star trackers Rosetta will aim its transmitter towards Earth and, from 500 million miles (807 million km) away, will send a thumbs-up signal that everything is OK and it’s time to get back to work.
From that distance the transmission will take 45 minutes to reach us. Rosetta’s first signal is expected between 17:30 – 18:30 GMT (12:30 – 1:30 p.m. ET). Once we’re assured all is well, Rosetta has a very exciting year ahead!
After nearly a decade of soaring through the inner solar system, flying past Mars and Earth several times and even briefly visiting a couple of asteroids (2867 Steins on September 5, 2008 and 21 Lutetia on July 10, 2010) Rosetta is finally entering the home stretch of its mission to orbit the 4-km-wide comet 67P/Churyumov-Gerasimenko.
Once Rosetta enters orbit around the comet — the first time a spacecraft has ever done so — it will map its surface and, three months later in November, deploy the 220-lb (100-kg) Philae lander that will intimately investigate the surface of the nucleus using a suite of advanced science instruments. (Watch a video here of how all this will happen… using Legos!)
With Philae firmly attached to the comet, Rosetta will follow it around the Sun as it makes its closest pass in August 2015 and then heads back out towards the orbit of Jupiter. Rosetta will provide the most detailed observations ever of a comet’s composition and dramatic evolution as it encounters the heat and energy of our home star.
Of course, before all this can happen Rosetta first has to… WAKE UP! It entered hibernation in July 2011 and has remained silent in a slow spin ever since, with only its computer and some heaters kept running. Waking up from a 31-month nap can’t be easy, so ESA is inviting people around the world to help Wake Up Rosetta (and possibly even win a trip to Germany for the landing in November) by sharing their short movies of how best to awaken a sleeping spacecraft and sharing them to the contest page on Facebook or to Twitter, Vine, or Instagram with the #WakeUpRosetta hashtag.
See more about the contest below:
Video submissions to the Wake Up Rosetta video contest will be accepted until 17:30 GMT on Monday so if you haven’t already, get your cameras out and your imaginations going… this spacecraft isn’t going to wake itself! (Well, actually it kinda is but you can still show off your creativity!)
Want to find out where Rosetta is right now? Check out this cool interactive map from Daniel Scuka, Senior Editor of Spacecraft Operations at ESOC.
Rosetta launched on March 2, 2004 by an Ariane-5 G+ from Europe’s spaceport in Kourou, French Guiana. Read more on the mission page and the Rosetta blog here.
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UPDATEJan. 20: Rosetta has awoken! This afternoon at 18:18 UTC, after 48 minutes of increasingly tense anticipation, a signal from the spacecraft was received by both NASA’s Deep Space Network in Goldstone, CA and the ground station in Canberra, Australia. Rosetta is up and running and so far seems to be in good condition — Go Rosetta and Philae! Read the full story here.
Little by little we’re getting sharper, clearer pictures from the Chinese Chang’e 3 moon mission. Yesterday the lander beamed back a series of new photos taken with its panoramic camera. Stitched together, they give us a more detailed and colorful look of the rover’s surroundings in northern Mare Imbrium. I’ve ordered the images starting with a nice crisp view of the Yutu rover; from there we turn by degree to the right across the five frames. The final mosaic unfortunately doesn’t have the resolution yet of the other images. Perhaps one will be published soon.
The lander’s solar panels stand out in the foreground with a smattering of small craters nearby. Credit: Chinanews.comRight of the rover we see more panels and a radio communications dish. Credit: Chinanews.comA larger crater surrounded by what appears to be excavated impact ejecta is visible near the horizon at upper right. Credit: Chinanews.comYutu’s tracks and another crater with ejecta stand out in this final image. Credit: Chinanews.com
Complete, if small, panorama stitched from the single images. Credit: Chinanews.com
One thing that stands out to my eye when looking at the photos is the brown color of the lunar surface soil or regolith. Color images of the moon’s surface by the Apollo astronauts along with their verbal descriptions indicate a uniform gray color punctuated in rare spots by patches of more colorful soils.
Apollo 15 astronauts salutes next to the American flag in 1971. The moon’s regolith or soil appears a variety of shades of gray. Credit: NASA
The famous orange soil scooped up by Apollo 17 astronaut Eugene Cernan comes to mind. Because Apollo visited six different moonscapes – all essentially gray – it makes me wonder if the color balance in the Chinese images might be off. Or did Chang’e 3 just happen to land on browner soils?
The orange soil found by Apollo 17 astronauts really stands out against a uniform gray moonscape. Credit: NASA
An artist's concept of Kepler-69c, a super-Earth in the habitable zone of a sun-like star.
Three decades ago we were unaware that exoplanets circled other stars. We had just started talking about dark matter but remained blissfully ignorant of dark energy. The Hubble Space Telescope was still on the drawing board and our understanding of the life cycle of stars, the evolution of galaxies, and the history of the Universe was shaky.
But over the past three decades we have discovered thousands of exoplanets around other stars. We have mapped the life cycle of stars from their formation in beautiful stellar nurseries to their sometimes explosive deaths. We have seen deep into the history of the Universe allowing us to paint a picture of galaxies growing from mere shreds to the incredible spiral structures we see today. We now believe dark matter dominates the underlying framework of the Universe, while dark energy drives its accelerating expansion.
The amount of growth over the past three decades has been dramatic. To better access what the next three decades will bring, NASA has laid out a roadmap — a long-term vision for future missions — necessary to advance our understanding of the Universe.
In March 2013, the NASA Advisory Council/Science Committee assembled a group of astronomers who would determine the goals and aims of NASA for the next 30 years. The final product is this so-called roadmap officially titled “Enduring Quests Daring Visions — NASA Astrophysics in the Next Three Decades.”
The roadmap first notes three defining questions NASA should continue to pursue:
— Are we alone?
— How did we get here?
— How does the Universe work?
“Seeking answers to these age-old questions are enduring quests of humankind,” the roadmap states. “The coming decades will see giant strides forward in finding earthlike habitable worlds, in understanding the history of star and galaxy formation and evolution, and in teasing out the fundamental physics of the cosmos.”
In order to better address these questions, the roadmap defines three broad categories of time: the Near-Term Era, defined by missions that are currently flying or planned for this coming decade, the Formative Era, defined by missions that are designed and built in the 2020s, and the Visionary Era, defined by advanced missions for the 2030s and beyond.
A schematic of the next 30 years subdivided into three decades across the entire electromagnetic spectrum. Image Credit: NASA 2014
Are we alone?
The Near-Term Era’s goal is to develop a comprehensive understanding of the demographics of planetary systems. The Kepler mission has already supplied a plethora of information on hot planets orbiting close to their parent stars. The WFIRST-AFTA mission — a wide-field infrared survey planned to launch in 2024 — will compliment this by supplying information on cold and free-floating planets.
The Formative Era’s goal is to characterize the surfaces and atmospheres of nearby stars. This will allow us to move beyond characterizing planets as Earth-like in mass and radius to truly being Earth-like in planetary and atmospheric composition. A proposed mission that allows a large star-planet contrast will directly measure oxygen, water vapor, and other molecules in the atmospheres of Earth-like exoplanets.
The Visionary Era’s goal is to produce the first resolved images of Earth-like planets around other stars. The roadmap team hopes to identify continents and oceans on distant worlds using optical telescopes orbiting hundreds of kilometers apart.
How did we get here?
The Near-Term Era will use the James Webb Space Telescope to supply unprecedented views of protostars and star clusters. It will resolve nearby stellar nurseries and take a closer look at the earliest galaxies.
The Formative Era will trace the origins of planets, stars and galaxies across a spectrum of wavelengths. An infrared surveyor will resolve protoplanetary disks while an X-ray surveyor will observe supernova remnants and trace how these incredible explosions affected the evolution of galaxies. Gravitational wave detectors will untangle the complicated dance between galaxies and the supermassive black holes at their centers.
The Visionary Era will peer nearly 14 billion years into the past when ultraviolet photons from the first generation of stars and black holes flooded spaced with enough energy to free electrons. The James Webb Space Telescope will provide an extraordinary means to better view this threshold.
How does the Universe work?
The Universe is full of extremes. Conditions created in the first nanoseconds of cosmic time and near the event horizons of black holes cannot be recreated in the lab. But the Near-Term and Formative Era’s goals will be to measure the cosmos with such precision that scientists can probe the underlying physics of cosmic inflation and determine the exact mechanisms driving today’s accelerating expansion.
The Visionary Era may use gravitational wave detectors to detect space-time ripples produced during the early stages of the Universe or map the shadow cast by a black hole’s event horizon.
The past 30 years have shown a dramatic growth in knowledge with unimaginable turns. Even with such a detailed framework laid out for the next 30 years, it’s likely that many missions are currently beyond the edge of the present imagination. The most exciting results will be drawn from the questions we haven’t even thought to ask yet.
And as with any of the recent “roadmaps” that the various divisions throughout NASA have presented, the biggest question will be if the funding will be available to make these missions a reality.
The roadmap team consists of Chryssa Kouveliotou (NASA/MSFC), Eric Agol (University of Washington), Natalie Batalha (NASA/Ames), Jacob Bean (University of Chicago), Misty Bentz (Georgia State University), Neil Cornish (Montana State University), Alan Dressler (The Observatories of the Carnegie Institution for Science), Scott Gaudi (Ohio State University), Olivier Guyon (University of Arizona/Subaru Telescope), Dieter Hartmann (Clemson University), Enectali Figueroa-Feliciano (MIT), Jason Kalirai (STScI/Johns Hopkins University), Michael Niemack (Cornell University), Feryal Ozel (University of Arizona), Christopher Reynolds (University of Maryland), Aki Roberge (NASA/GSFC), Kartik Sheth (National Radio Astronomy Observatory/University of Virginia), Amber Straughn (NASA/GSFC), David Weinberg (Ohio State University), Jonas Zmuidzinas (Caltech/JPL), Brad Peterson (Ohio State University) and Joan Centrella (NASA Headquarters).
Screenshot from Steve Squyres presentation celebrating 10 years of the Mars Exploration Rovers. A rock suddenly appeared where there was none 12 sols earlier.
During last night’s celebration at the Jet Propulsion Laboratory of ten years of the Mars Exploration Rovers, mission principal investigator Steve Squyres shared several stories about the exploration and discoveries made by the rovers Spirit and Opportunity since they landed on Mars in 2004. An intriguing recent mystery is a strange rock that suddenly appeared in photos from the Opportunity rover in a spot where photos taken just 12 sols earlier showed no rock.
“One of the things I like to say is that Mars keeps throwing new things at us,” Squyres deadpanned.
A colorized version of the rock called Pinnacle Island. Credit: NASA/JPL, color by Stuart Atkinson.
Squyres described the rock as “white around the outside, in the middle there’s low spot that is dark red. It looks like a jelly donut,” he said. “And it appeared. It just plain appeared and we haven’t driven over that spot.”
They’ve named it “Pinnacle Island,” and the team is contemplating a few ideas of why the rock mysteriously showed up.
“One theory is that we somehow flicked it with a wheel,” Squyres said. “We had driven a meter or two away from here and somehow maybe one of the wheels managed spit it out of the ground. That’s the more likely theory.”
The other?
“The other theory is that there might be a smoking hole in the ground nearby and this may be crater ejecta. But that one is less likely,” Squyres said.
Another idea suggested by others is that it may have tumbled down from a nearby rock outcrop.
Image from Sol 3528 of the area showing no rock. Click to see original on the rover’s raw image website. Credit: NASA/JPL.Image of same area on Sol 3540 where the ‘jelly donut’ rock appears. Click to see original. Credit: NASA/JPL.
But as intriguing as the sudden appearance of the rock is what the team is finding out about it.
“We are as we speak situated with the rover, with its instruments, making measurements on this rock. We’ve taken pictures of both the donut part and the jelly part,” Squyres said. “The jelly part is like nothing we’ve seen before on Mars. It’s very high in sulfur and magnesium and it has twice as much manganese as anything we’ve seen before. I don’t know what any of this means. We’re completely confused, everybody on the team is arguing and fighting. We’re having a wonderful time!”
But that’s the beauty of this mission, Squyres said.
“I used to have this comforting notion that at some point, we could sit back and say ‘we did it, we’re finished, we’ve learned everything we could about this location.’ But Mars is not like that. It keeps throwing new things at us.”
“And what I’ve come to realize,” Squyres concluded, ” – and it was true when we lost Spirit and it will be true when we lose Opportunity — there will always be something tantalizing just beyond our reach that we just won’t get to. That’s just the nature of exploration, and I feel so very fortunate to have been part of this mission.”
You can watch the entire replay of the celebration below, and read a great look back at the past 10 years from Stuart Atkinson’s Road to Endeavour blog.
The Red Rectangle Nebula. Credit and copyright: Adam Block/Mount Lemmon SkyCenter/University of Arizona
Due to gravity, most objects in space are spherical — whether it’s round planets and stars or swirling spiral galaxies. That’s why this object, the Red Rectangle Nebula, or HD 44179, is so intriguing.
“The overall shape of the nebula is a puzzle for astronomers to figure out,” said astronomer Adam Block from the Mount Lemmon SkyCenter at the University of Arizona, via email. “The leading theory suggests that bipolar, cone-shaped, and periodic outflows, when viewed in profile as we do, may give the shape we see. The intense red color still remains a bit of a mystery.”
From most “smaller” ground based telescopes, this object really does look like a rectangle, but images from space, such as from the Hubble Space Telescope, reveal that rather than being rectangular, is shaped like an X with additional complex structures of spaced lines of glowing gas, a little like the rungs of a ladder. This stunning new image from Adam also captures these features.
He said he wanted to know what it really looked like from a ground-based telescope using full color (broad band) filters.
“I didn’t know, but now I do,” Adam said. “It is a tiny tiny thing; but it was wonderful to see it develop from the raw data to this rendered result. The central star is very bright and nearly overwhelms the interesting parts of the nebula. In addition to its size, the central star is a big challenge to tame.”
See a larger version and find out more of the observing details here.
The International Space Station as seen from the crew of STS-119. Credit: NASA
We now take it for granted that astronauts on the International Space Station can tweet and post things on Facebook and G+ live from space, but it wasn’t always so. Before January of 2010, any emails, news, or Twitter messages were sent to and from the ISS in uplink and downlink packages, so for example, Twitter messages from the astronauts were downlinked to mission control in Houston, and someone there posted them on the astronauts’ Twitter accounts. But now they have “live” internet. However, as you can imagine, there are no fiberoptic cables hooking up to the ISS, so the internet speeds aren’t blazing fast. Find out how fast in this latest video update from NASA’s Space to Ground, a weekly update on what’s happening aboard the ISS.
The International Space Station as seen from the crew of STS-119. Credit: NASA
The International Space Station could potentially function far beyond its new extension to 2024. Perhaps out to 2050. The ISS as seen from the crew of STS-119. Credit: NASA
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WALLOPS ISLAND, VA – Just days ago, the Obama Administration approved NASA’s request to extend the lifetime of the International Space Station (ISS) to at least 2024. Ultimately this will serve as a stepping stone to exciting deep space voyages in future decades.
“I think this is a tremendous announcement for us here in the space station world,” said Bill Gerstenmaier, associate administrator for NASA’s Human Exploration and Operations Mission Directorate, at a press briefing on Jan. 8.
But there’s really “no reason to stop it there”, said Frank Culbertson, VP at Orbital Sciences and former NASA astronaut and shuttle commander, to Universe Today when I asked him for his response to NASA’s station extension announcement.
“In my opinion, if it were up to me, we would fly it [the station] to 2050!” Culbertson added with a smile. “Of course, Congress would have to agree to that.”
Gerstenmaier emphasized that the extension will allow both the research and business communities to plan for the longer term and future utilization, be innovative and realize a much greater return on their investments in scientific research and capital outlays.
“The station is really our stepping stone,” Robert Lightfoot, NASA Associate Administrator, told me at Wallops following Antares launch.
The Alpha Magnetic Spectrometer (AMS) – which is searching for elusive dark matter – was one of the key science experiments that Gerstenmaier cited as benefitting greatly from the ISS extension to 2024. The AMS is the largest research instrument on the ISS.
ISS Astronauts grapple Orbital Sciences Cygnus spacecraft with robotic arm and guide it to docking port on Jan. 12, 2014. Credit: NASA TV
The extension will enable NASA, the academic community and commercial industry to plan much farther in the future and consider ideas not even possible if the station was de-orbited in 2020 according to the existing timetable.
Both the Antares rocket and Cygnus cargo freighter are private space vehicles developed and built by Orbital Sciences with seed money from NASA in a public-private partnership to keep the station stocked with essential supplies and research experiments and to foster commercial spaceflight.
So I asked Culbertson and Lightfoot to elaborate on the benefits of the ISS extension to NASA, scientific researchers and commercial company’s like Orbital Sciences.
“First I think it’s fantastic that the Administration has committed to extending the station, said Culbertson. “They have to work with the ISS partners and there is a lot to be done yet. It’s a move in the right direction.”
“There is really no reason to stop operations on the space station until it is completely no longer usable. And I think it will be usable for a very long time because it is very built and very well maintained.”
“If it were up to me, we would fly it to 2050!”
“NASA and the engineers understand the station very well. I think they are operating it superbly.”
Birds take flight as Antares lifts off for Space Station from Virginia Blastoff of Antares commercial rocket built by Orbital Sciences on Jan. 9, 2014 from Launch Pad 0A at NASA Wallops Flight Facility, VA on a mission for NASA bound for the International Space Station and loaded with science experiments. Credit: Ken Kremer – kenkremer
“The best thing about the station is it’s now a research center. And it is really starting to ramp up. It’s not there yet. But it is now finished [the assembly] as a station and a laboratory.”
“The research capability is just starting to move in the right direction.”
The Cygnus Orbital 1 cargo vehicle launched on Jan. 9 was loaded with approximately 2,780 pounds/1,261 kilograms of cargo for the ISS crew for NASA including vital science experiments, computer supplies, spacewalk tools, food, water, clothing and experimental hardware.
The research investigations alone accounted for over 1/3 of the total cargo mass. It included a batch of 23 student designed experiments representing over 8700 students sponsored by the National Center for Earth and Space Science Education (NCESSE).
“So extending it [ISS] gives not only commercial companies but also researchers the idea that ‘Yes I can do long term research on the station because it will be there for another 10 years. And I can get some significant data.”
“I think that’s really important for them [the researchers] to understand, that it will be backed for that long time and that they won’t be cut off short in the middle of preparing an experiment or flying it.”
Robert Lightfoot; NASA Associate Administrator, and Frank Culbertson; executive vice president and general manager of Orbital’s advanced spaceflight programs group and former Space Shuttle commander, at NASA Wallops Flight Facility, VA discuss extension of the International Space Station lifetime following Jan. 9 Antares/Cygnus blastoff bound for the station loaded with science experiments. Credit: Ken Kremer – kenkremer.com
“So I think that first of all it demonstrates the commitment of the government to continue with NASA. But also it presents a number of opportunities for a number of people.”
What does the ISS extension mean for Orbital?
The purpose for NASA and Orbital Sciences in building Antares and Cygnus was to restore America’s ability to launch cargo to the ISS – following the shutdown of NASA’s space shuttles – by using commercial companies and their business know how to thereby significantly reduce the cost of launching cargo to low Earth orbit.
“As far as what it [the ISS extension] means for Orbital and other commercial companies – Yes, it does allow us to plan long term for what we might be able to do in providing a service for NASA in the future,” Culbertson replied.
“It also gives us the chance to be innovative and maybe invest in some improvements in how we can do this [cargo service] – to make it more cost effective, more efficient, turnaround time quicker, go more often, go a lot more often!”
“So it allows us the chance to think long term and make sure we can get a return on our investment.”
What does the ISS extension mean for NASA?
“The station is really our stepping stone,” Robert Lightfoot, NASA Associate Administrator, told Universe Today. “If you use that analogy of stepping stones and the next stone. We need to use this stone to know what the next stone looks like. So we can get ready. Whether that’s research or whether that things about the human body. You don’t want to jump off that platform before you are ready.”
“We are learning every day how to live and operate in space. Fortunately on the ISS we are close to home. So if something comes up we can get [the astronauts] home.”
The ISS extension is also the pathway to future exciting journey’s beyond Earth and into deep space, Culbertson and Lightfoot told Universe Today.
“It actually also presents a business opportunity that can be expanded not just to the station but to other uses in spaceflight, such as exploration to Asteroids, Mars and wherever we are going,” said Culbertson.
And we hope it will extend to other civilian uses in space also. Maybe other stations in space will follow this one and we’ll be able to participate in that.”
Lightfoot described the benefits for astronaut crews.
“The further out we go, the more we need to know about how to operate in space, what kind of protection we need, what kind of research we need for the astronauts,” said Lightfoot.
“Orbital is putting systems up there that allow us to test more and more. Get more time. Because when we get further away, we can’t get home as quick. So those are the kinds of things we can do.
“So with this extension I can make those investments as an Agency. And not just us, but also our academic research partners, our industry partners, and the launch market too is part of this.”
He emphasized the benefits for students, like those who flew experiments on Cygnus, and how that would inspire the next generation of explorers!
“You saw the excitement we had today with the students at the viewing area. For example with those little cubesats, 4 inches by 4 inches, that they worked on, and got launched today!”
“That’s pretty cool! And that’s exactly what we need to be doing!
Student Space Flight teams at NASA Wallops
These are among the students benefiting from ISS extension
Science experiments from these students representing six schools across America were selected to fly aboard the Cygnus spacecraft which launched to the ISS from NASA Wallops, VA, on Jan . 9, 2014, as part of the Student Spaceflight Experiments Program (SSEP). Credit: Ken Kremer – kenkremer.com
“So eventually they can take our jobs. And as long as they know that station will be there for awhile, the extension gives them the chance to get the training and learning and do the research we need to take people further out in space.”
“The station is the stepping stone.”
“And it really is important to have this station extension,” Lightfoot explained to me.
The Jan. 9 launch of the Orbital-1 mission is the first of eight operational Antares/Cygnus flights to the space station scheduled through 2016 by Orbital Sciences under its $1.9 Billion Commercial Resupply Services (CRS) contract with NASA to deliver 20,000 kg of cargo to orbit.
Orbital Sciences and SpaceX – NASA’s other cargo provider – will compete for follow on ISS cargo delivery contracts.
The next Antares/Cygnus flight is slated for about May 1 from NASA Wallops.
In an upcoming story, I’ll describe Orbital Sciences’ plans to upgrade both Antares and Cygnus to meet the challenges of the ISS today and tomorrow.
Stay tuned here for Ken’s continuing Orbital Sciences, SpaceX, commercial space, Chang’e-3, LADEE, Mars and more news.
This Cygnus launched atop Antares on Jan. 9 and docked on Jan. 12 Cygnus pressurized cargo module – side view – during exclusive visit by Ken Kremer/Universe Today to observe prelaunch processing by Orbital Sciences at NASA Wallops, VA. ISS astronauts will open this hatch to unload 2780 pounds of cargo. Docking mechanism hooks and latches to ISS at left. Credit: Ken Kremer – kenkremer.comFrank Culbertson; executive vice president and general manager of Orbital’s advanced spaceflight programs group and former Space Shuttle commander, and Ken Kremer; Universe Today, at NASA Wallops Flight Facility, VA, discuss extension of the International Space Station lifetime following Jan. 9 Antares/Cygnus blastoff. Credit: Ken Kremer – kenkremer.com
Distribution of Kuiper belt objects (green), along with various other outer Solar System bodies, based on data from the Minor Planet Center. [Credit: Minor Planet Center; Murray and Dermott]
The Kuiper belt — the region beyond the orbit of Neptune inhabited by a number of small bodies of rock and ice — hides many clues about the early days of the Solar System. According to the standard picture of Solar System formation, many planetesimals were born in the chaotic region where the giant planets now reside. Some were thrown out beyond the orbit of Neptune, while others stayed put in the form of Trojan asteroids (which orbit in the same trajectory as Jupiter and other planets). This is called the Nice model.
However, not all Kuiper belt objects (KBOs) play nicely with the Nice model.
(I should point out that the model is named named for the city in France and therefore pronounced “neese”.) A new study of large scale surveys of KBOs revealed that those with nearly circular orbits lying roughly in the same plane as the orbits of the major planets don’t fit the Nice model, while those with irregular orbits do. It’s a puzzling anomaly, one with no immediate resolution, but it hints that we need to refine our Solar System formation models.
This new study is described in a recently released paper by Wesley Fraser, Mike Brown, Alessandro Morbidelli, Alex Parker, and Konstantin Baygin (to be published in the Astrophysical Journal, available online). These researchers combined data from seven different surveys of KBOs to determine roughly how many of each size of object are in the Solar System, which in turn is a good gauge of the environment in which they formed.
The difference between this and previous studies is the use of absolute magnitudes — a measure of how bright an object really is — as opposed to their apparent magnitudes, which are simply how bright an object appears. The two types of magnitude are related by the distance an object is from Earth, so the observational challenge comes down to accurate distance measurements. Absolute magnitude is also related to the size of an KBO and its albedo (how much light it reflects), both important physical quantities for understanding formation and composition.
Finding the absolute magnitudes for KBOs is more challenging than apparent magnitudes for obvious reasons: these are small objects, often not resolved as anything other than points of light in a telescope. That means requires measuring the distance to each KBO as accurately as possible. As the authors of the study point out, even small errors in distance measurements can have a large effect on the estimated absolute magnitude.
The bodies in the Kuiper Belt. Credit: Don Dixon
In terms of orbits, KBOs fall into two categories: “hot” and “cold”, confusing terms having nothing to do with temperature. The “cold” KBOs are those with nearly circular orbits (low eccentricity, in mathematical terms) and low inclinations, meaning their trajectories lie nearly in the ecliptic plane, where the eight canonical planets also orbit. In other words, these objects have nearly planet-like orbits. The “hot” KBOs have elongated orbits and higher inclinations, behavior more akin to comets.
The authors of the new study found that the hot KBOs have the same distribution of sizes as the Trojan asteroids, meaning there are the same relative number of small, medium, and large KBOs and similarly sized Trojans. That hints at a probable common origin in the early days of the Solar System. This is in line with the Nice model, which predicts that, as they migrated into their current orbits, the giant planets kicked many planetesimals out beyond Neptune.
However, the cold KBOs don’t match that pattern at all: there are fewer large KBOs relative to smaller objects. To make matters more strange, both hot and cold seem to follow the same pattern for the smaller bodies, only deviating at larger masses, which is at odds with expectations if the cold KBOs formed where they orbit today.
To put it another way, the Nice model as it stands could explain the hot KBOs and Trojans, but not the cold. That doesn’t mean all is lost, of course. The Nice model seems to do very well except for a few nagging problems, so it’s unlikely that it’s completely wrong. As we’ve learned from studying exoplanet systems, planet formation models are a work in progress — and astronomers are an ingenious lot.
You probably know we only see one side of the Moon from the Earth. But for the majority of human history, we had no idea what the far side looked like.
Billions of years ago, our Moon was formed when a Mars-sized object smashed into the Earth, spinning out a ring of debris. This debris collected into the Moon we know today. It started out rotating from our perspective, but the Earth’s gravity slowed it down until its rotation became locked with the Earth’s, keeping one half forever hidden from our view.
It wasn’t until the space age that humans finally got a chance to see what’s on the other side. The first spacecraft to image the far side of the Moon was the Soviet Luna 3 probe in 1959, which returned 18 usable images to scientists. And then in 1965, the Soviet Zond 3 transmitted another 25 pictures of higher quality that gave much more detail of the surface. The first humans to actually see the far side with their own eyes, were the crew of Apollo 8, who did a flyover in 1968.
We now have high resolution cameras imaging every square meter, even the far side. And here’s the amazing surprise….
You would think that the far side of the Moon would look like the near side, but check out the two hemispheres…They’re totally different.
The near side of the has huge regions of ancient lava flows, called maria. While the far side is almost entirely covered in crater impacts. Planetary geologists aren’t sure, but it’s possible that the Earth used to have two Moons.
Billions of years ago, the second, smaller moon crashed into the far side of the Moon, covering up the darker maria regions.
And just to clarify things with Pink Floyd’s reference to the “Dark Side of the Moon”… Except for the occasional lunar eclipse, half of the Moon is always in darkness and half is always illuminated. But that illuminated half changes as the Moon orbits around us.
High resolution photo map of the moon’s far side imaged by NASA’s Lunar Reconnaissance Orbiter. Credit: NASA
Just like half of the Earth is always in darkness, and half of every other large object in the Solar System. There’s no permanent “dark side” of the Moon. The side facing towards the Sun is lit up, and the side facing away is in shadows.
There are, however, some spots on the Moon which are in eternal darkness. There are craters at the north and south poles deep enough that the light from the Sun never illuminates their floors. In these places, It’s possible that there are reserves of ice that future space colonies could use for their supplies of water, air, and even rocket fuel.
Pink Floyd was right if you’re talking radio waves instead of visible light. The far side of the Moon is naturally shielded from the Earth’s radio transmissions, so it makes an ideal spot to locate a sensitive radio observatory.
I’ll see you in the permanently shadowed craters of the Moon.
