The science return from OSIRIS-REx has been surprisingly swift as the spacecraft returns data on near-Earth asteroid 101955 Bennu. We're aided here by the timing, as early results are being discussed at the ongoing conference of the American Geophysical Union (AGU) in Washington, DC. The imagery we've received of Bennu's surface has scientists buzzing. Thus Humberto Campins (University of Central Florida) a member of the OSIRIS-REx Science Team, who notes the comparison between what we see now and the Arecibo radar imagery in the late 1990s: "The images are spectacular and spot on, what we expected thanks to predictions made with the instrumentation at the Arecibo Observatory in the late 90s and early 2000s. We will spend a year and a half mapping Bennu and have to wait until mid 2020 [when] we collect the sample, but it is pretty amazing to actually see it now. Christmas came early." The Arecibo work began shortly after the asteroid's discovery in 1999, when both the Puerto Rico...

You wouldn't think the Yarkovsky effect would have any real significance on a half-kilometer wide pile of rubble like the asteroid 101955 Bennu. With a currently estimated mass somewhere between 60 and 80 billion kilograms, Bennu seems unlikely to receive much of a nudge from differences in heat on the object's surface. But the people who specialize in these things say otherwise. Sunlight warms one side of the asteroid while the other experiences the cold of space. Rotation keeps the dark side radiating heat, accounting for a tiny thrust. We call it the Yarkovsky effect after Ivan Osipovich Yarkovsky, a Polish engineer who came up with it in 1901, though if we want to give credit across the board, we might refer to the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. Here we honor, in addition to Yarkovsky, an American scientist, a Russian astronomer and a NASA aerospace engineer, all of whom played a role in our understanding of the phenomenon as it relates to asteroids. Image:...

December 3 goes down as the day when OSIRIS-REx arrived at the asteroid called Bennu. The spacecraft, whose acronym untangles as Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, has been performing braking maneuvers to slow for the approach since October. This has been a long and delicate operation, with arrival marked by a maneuver on Monday to set up the first flyover of the object's north pole. Even so, spacecraft and asteroid are flying together while not yet in an orbital relationship. That won't happen until December 31, when the mission's navigation team will use the preliminary survey they're building now to initiate the orbit. Bear in mind that we are dealing with an object less than 500 meters across (about 1,600 feet), so one of Bennu's distinctions will be that it is to become the smallest object ever orbited by a spacecraft. Now the learning period intensifies. "During our approach toward Bennu, we have taken observations at much...

A crater roughly the size of the area inside Washington DC's beltway has been found beneath the Greenland ice. On this, some thoughts, but first, a reminiscence. If you've ever driven the Capital Beltway at rush hour, you'll have some sense of the crater's size. My own experiences of it have been few, but the most memorable was the afternoon I spent at NASA Goddard Space Flight Center, where Greg Benford was speaking. We had agreed that after his talk, Greg and I would head out for dinner at a local restaurant, the exact venue to be determined later. It was about 5:00 PM when we were in the GSFC parking lot ready to go, now joined by Gloria Lubkin, editor emerita at Physics Today. With the help of Greg's nephew Dominic, we had chosen a French restaurant about 10 miles away. The problem: Greg and Gloria were in one car, I was in another, and it was rush hour. An out-of-towner who rarely got to DC, I was not remotely prepared for the beltway under these conditions. I had no smartphone...

Following a week when we learned of the end of both Kepler and Dawn, let's turn to a mission that is just coming into its own. The earliest images of target asteroid 101955 Bennu from OSIRIS-REx have been tightened by computer algorithm to heighten their resolution. The mission plan here is to examine the small object (approximately 500 meters in mean diameter) and return samples to Earth in 2023. More than a few people have reacted to the similarity in shape between this asteroid, a carbonaceous (C-type) Earth-crossing object in the Apollo group of near-Earth asteroids, and 162173 Ryugu, now under active exploration by the Japanese Hayabusa2 mission. Here we're looking at Bennu through the OSIRIS-REx PolyCam, one of three cameras aboard the spacecraft, from a distance of 330 kilometers. The image is a combination of eight images taken by PolyCam that have been combined to cancel out the asteroid's rotation and produce a high-resolution result. Of the comparison to Ryugu, Julia de...

With two rovers and a lander already deployed on the asteroid 162173 Ryugu, the Japan Aerospace Exploration Agency (JAXA) must be basking in the glow of an unusually successful venture. Now we turn to a key part of the Hayabusa2 mission, the retrieval of a surface sample. Two touchdown rehearsals have gone well, providing detailed views of the asteroid's surface. The plan is to return samples to Earth in December of 2020, but let's continue to take one thing at a time. Sample retrieval can be dicey, as we saw with the first Hayabusa. Once known as MUSES-C, the original Hayabusa reached asteroid Itokawa in September of 2005 (I can't believe it was that long ago -- as the cliché would have it, it seems like yesterday). A series of enroute problems included a solar flare that damaged the craft's solar cells and the failure of attitude-adjusting reaction wheels, while the launch of a probe called MINERVA also failed. Nonetheless, surface particles from Itokawa were successfully...

With a robotic presence at Ryugu, JAXA's Hayabusa2 mission is showing what can be done as we subject near-Earth asteroids to scrutiny. We'll doubtless learn a lot about asteroid composition, all of which can factor into, among other things, the question of how we would approach changing the trajectory of any object that looked like it might come too close to Earth. The case for studying near-Earth asteroids likewise extends to learning more about the evolution of the Solar System. NASA's first near-Earth asteroid visit will take place on December 3, when the OSIRIS-REx mission arrives at asteroid Bennu, with a suite of instruments including the OCAMS camera suite (PolyCam, MapCam, and SamCam), the OTES thermal spectrometer, the OVIRS visible and infrared spectrometer, the OLA laser altimeter, and the REXIS x-ray spectrometer. Like Hayabusa2, this mission is designed to collect a surface sample and return it to Earth. And while Hayabusa2 has commanded the asteroid headlines in recent...

To me, the image below is emblematic of space exploration. We look out at vistas that have never before been seen by human eye, contextualized by the banks of equipment that connect us to our probes on distant worlds. The fact that we can then sling these images globally through the Internet, opening them up to anyone with a computer at hand, gives them additional weight. Through such technologies we may eventually recover what we used to take for granted in the days of the Moon race, a sense of global participation and engagement. We're looking at the MASCOT Control Centre at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) in Cologne, where the MASCOT lander was followed through its separation from the Japanese Hayabusa2 probe on October 3, its landing on asteroid Ryugu, and the end of the mission, some 17 hours later. Image: In the foreground is MASCOT project manager Tra-Mi Ho from the DLR Institute of Space Systems in Bremen at the MASCOT Control...

That small spacecraft can become game-changers, our topic last Friday, is nowhere more evident than in the success of Rover 1A and 1B, diminutive robot explorers that separated from the Hayabusa2 spacecraft at 0406 UTC on September 21 and landed soon after. Their target, the asteroid Ryugu, will be the site of detailed investigation not only by these two rovers, but also by two other landers, the German-built Mobile Asteroid Surface Scout (MASCOT) and Rover 2, the first of which is to begin operations early in October. Congratulations to JAXA, Japan's space agency, for these early successes delivered by its Hayabusa2 mission. Surface operations will be interesting indeed. Both rovers were released at an altitude of 55 meters above the surface, their successful deployment marking an advance over the original Hayabusa mission, which was unable to land its rover on the asteroid Itokawa in 2005. Assuming all goes well, the mission should gather three different samples of surface material...

How extraordinary that we can sometimes tell so much from so little. Extraordinary too how careful we must be to make sure we're not reading too much into small sample sizes. All of which brings me to the Japanese Hayabusa probe, a spacecraft that survived continual mischance on its journey to asteroid 25143 Itokawa, but was somehow able to return tiny grains of surface material to Earth. And using those materials, scientists are now revealing a violent past that tells us something not only about how the asteroid formed but what happened to it long after. The work of Kentaro Terada (Osaka University) and colleagues, the investigation follows a complicated path back to the earliest era of our system. But let’s start with the sample collection, which almost didn’t happen: Already damaged from a major solar flare not long after liftoff on May 9, 2003, Hayabusa (the word means ‘falcon’ in Japanese) would also lose two of its three stabilizing reaction wheels. And when the command to...

The OSIRIS-REx spacecraft carries three cameras as it makes its way to the asteroid called Bennu, a suite that is collectively known as the OSIRIS-REx Camera Suite (OCAMS). So now we're into the realm of OSIRIS-REx acronyms, and these should become familiar in coming months just as New Horizons' instruments like LORRI (Long Range Reconnaissance Imager) and PEPSSI (Pluto Energetic Particle Spectrometer Science Investigation) did enroute to Pluto. The camera called PolyCam is responsible for the image below, an animation showing the target acquired on August 17, at a distance of 2.25 million kilometers. PolyCam will serve as a reconnaissance camera as the spacecraft nears Bennu, but its other role is that illustrated here, as a long-range acquisition camera whose first visual of the target has been in the works for nine weeks. That's the length of the planning process, testing, reviews and code upload. "Right now, Bennu just looks like a star, a point source," said Carl Hergenrother,...

We learned late last week that the near-Earth asteroid 2017 YE5, discovered just last December, is what is described as an 'equal mass' binary. This would make it the fourth near-Earth asteroid binary ever detected in which the two objects are nearly identical in size, both about 900 meters. The binary's closest approach to Earth was on June 21, 2017, when it came to within 6 million kilometers, some 16 times the distance between the Earth and the Moon. It won't be that close again for at least another 170 years. Image: Artist's concept of what binary asteroid 2017 YE5 might look like. The two objects show striking differences in radar reflectivity, which could indicate that they have different surface properties. Credit: NASA/JPL-Caltech. What you have above is an artist's impression of how 2017 YE5 appears, but have a look at the radar imagery below. This comes from NASA's Goldstone Solar System Radar (GSSR, observations conducted on June 23, 2018), and shows the presence of two...

The asteroid game is heating up. The Japanese probe Hayabusa 2 has arrived at asteroid 162173 Ryugu, the plan being to reach the surface with landers later this year and bring back samples in 2020. We also have ORISIS-REx, launched in 2014, on course to 101955 Bennu in December, with a sample return planned for 2023. Assuming both missions are successful, scientists will have the opportunity to compare the composition of the two. Both are C-type (carbonaceous) asteroids, darker than previously explored asteroid Itokawa. The current Hayabusa is similar to the probe that first returned an Itokawa sample to Earth in 2010. JAXA confirmed the arrival of Hayabusa 2 at 9:35 (Japan time) on the 27th: "The National Research and Development Corporation Japan Aerospace Exploration Agency (JAXA) announces that we have confirmed the arrival at asteroid Ryugu (Ryugu) of the asteroid explorer 'Hayabusa 2'", adding that the distance between the spacecraft and the asteroid is about 20 kilometers....

The Wide-field Infrared Survey Explorer (WISE) has been featured often in these pages, usually in terms of brown dwarfs and the possibility of uncovering a small star or brown dwarf closer than Proxima Centauri. But while we still have no evidence of such, we do have abundant data on brown dwarfs, as well as a useful compendium of objects that come close to the Earth. For WISE, launched in 2009 and placed into hibernation in 2011 upon completion of its primary mission, was reactivated in 2013 as NEOWISE. The goal is now the observation of asteroids and comets both near and far by way of characterizing their size and composition. Amy Mainzer (JPL), NEOWISE principal investigator, points to the mission's success: "NEOWISE continues to expand our catalog and knowledge of these elusive and important objects. In total, NEOWISE has now characterized sizes and reflectivities of over 1,300 near-Earth objects since the spacecraft was launched, offering an invaluable resource for understanding...

Given the vast distances of interstellar space, you wouldn’t think there would be much chance of stars colliding. But it’s conceivable that so-called ‘blue straggler’ stars are the remnants of just such an event. A large blue straggler contains far more hydrogen than smaller stars around it, and burns at higher temperatures, with a correspondingly shorter life. When you find a blue straggler inside an ancient globular cluster, it’s natural to ask: How did this star emerge? Packing stars as tightly as globular clusters must produce the occasional collision, and in fact astrophysicist Michael Shara (then at the American Museum of Natural History) has estimated there may be as many as several hundred collisions per hour somewhere in the universe. We would never be aware of most of these, but we could expect a collision every 10,000 years or so within one of the Milky Way’s globular clusters. In fact, the globular cluster NGC 6397 shows evidence for what may have been a three-star...

With the holidays behind us (alas), I want to be sure to cover the Arecibo observations of asteroid 3200 Phaethon, not only for their intrinsic interest but as a nod to the restoration of operations at the Puerto Rico observatory. We are fortunate indeed that the structural damage Arecibo suffered on September 20 because of hurricane Maria was relatively minor. Radio astronomy work was back in progress within days of the storm, though it took until early December before commercial power was restored and radar work could resume. If you're interested in radar astronomy, have a look at Alessondra Springmann's How Radar Really Works: The Steps Involved Before Getting an Image, which is available via The Planetary Society. Springmann offers a detailed overview of radar operations with a splash of humor: Arecibo Observatory is known for its 305-meter (1000-foot) diameter telescope and its appearances in Goldeneye and Contact. Aside from battling Bond villains and driving red diesel Jeeps...

Volatiles for propulsion and life support only scratch the surface of what we might extract once viable mining communities begin tapping the asteroids. Metals like platinum remind us how readily available some resources will be in space as opposed to trying to dig them out from the depths of our planet. Centauri Dreams regular Alex Tolley continues to explore these matters in today's essay, which looks at how companies will turn a profit and what kinds of targets most justify early efforts. Key to our hopes for asteroid mining is reducing the costs of getting payloads into space. That's a driver for an infrastructure whose demands may well produce the propulsion solutions we'll need as we push outside the Solar System. by Alex Tolley "There's gold in them thar hills" - M. F. Stephenson Introduction In 1848, James Marshall discovered gold at Sutter's Mill, on the American River, in foothills of the Sierra Nevada mountains of California.  The California gold rush ensued.   Science...

I used to think the Kuiper Belt object Quaoar was hard to pronounce ("Kwawar"), and even muffed it despite having plenty of time to practice before the recent Tennessee Valley Interstellar Workshop. Pontus Brandt (JHU/APL) had mentioned Quaoar in his talk in Huntsville as a target that lined up in useful ways with a proposed interstellar precursor mission he was presenting, one designed to examine dust distribution from within the system by looking back at our heliosphere at distances up to 1000 AU, seeing it as we see other stars’ dust environments. So I summarized Brandt’s ideas in my wrap-up talk and couldn’t get Quaoar pronounced properly without multiple tries. But even Quaoar pales into the realm of everyday lingo when compared to 1I/'Oumuamua. Please tell me how to do this. The word is a Hawaiian term for ‘scout,’ and the Ulukau: Hawaiian Electronic Library’s online dictionary tells me it’s pronounced this way: ?'u-mu'-a-mu'-?. I could work with that and maybe get it right in...

NASA's OSIRIS-REx spacecraft, now on a two year outbound journey to the near-Earth asteroid Bennu, is a good deal closer to home than you might think. At play is a gravity assist maneuver that will take the craft past the Earth on September 22nd, propelling OSIRIS-REx into the orbital plane of its target. As of August 25th, the spacecraft was 16.6 million kilometers from the Earth. Twenty-four days and a wake-up! You know I'm getting close when the one-way light time is under a minute.https://t.co/rACre4nDe4 pic.twitter.com/uvKBaNoqYM— NASA's OSIRIS-REx (@OSIRISREx) August 28, 2017 The OSIRIS-REx team is reporting that a course adjustment burn was performed on August 23rd, a successful correction that marked the first time the spacecraft's attitude control system (ACS) had been used in what is being called a 'turn-burn-turn' sequence. It's a precision maneuver requiring the momentum wheels on OSIRIS-REx to turn the spacecraft so its thrusters are lined up for the burn....

Some people tell me that the dangers posed by an asteroid or comet impact on Earth are over-publicized. Surely whatever object hits us would land some place harmless, causing nothing but a flurry of news stories. Others remind me that Chelyabinsk was seriously rattled by the explosion of a small asteroid in 2013, an event that could have created appalling damage with a slight deviation in trajectory. My own view is that guessing at the odds doesn't do much for us. I favor a strong research effort into asteroid deflection and risk mitigation strategies. Normally planetary protection wouldn't be high on the agenda on Centauri Dreams because I focus on deep space issues and our exploration possibilities far from Earth. But asteroid deflection merits our attention because I'm convinced it is one of the drivers for space research. Protecting the planet means learning not only how to deflect potentially risky objects but also how to detect them long before they pose a problem. The two work...