Ongoing studies of distant galaxy protoclusters using the Multi-Object Infrared Camera and Spectrograph (MOIRCS) instrument on the Subaru Telescope is giving astronomers a closer look at the characteristics of star-forming regions in galaxies in the early universe.
A team of astronomers from the National Astronomical Observatory of Japan (NAOJ) and SOKENDAI (Graduate University of Advanced Studies, Japan) are tracking velocity structures and gaseous metallicities in galaxies in two protoclust [...]
With Jons’ last post, I got to speculating about other ways of getting mass from an asteroid back to Earth. What if the exploring spacecraft carried a tether to the asteroid that was long enough to serve as a beanstalk. Instead of carting the selected boulder(s) all the way home, the beanstalk is used to sling a number of samples to Cislunar space to be caught by some TBD craft.
Instead of the thousand ton boulders slung in the original post, ten or so tons per throw would send a sizable mass to explore and exploit close to home while leaving the spacecraft in the field for a continuing mission. While as in the previous it would be necessary to wait for launch windows to use the tether, the time between arrival and window could be spent exploring the body in question and organizing multiple throws. When the window opens, the ten (or one or thirty) ton samples could be sent Earthward every time the asteroid rotates. A four hour asteroid rotational day would give six launches per Earth day. A window a week long could have forty or so samples heading home at once.
If the asteroid is considered explored by that time to the limits of the available craft, it is time to head to the next target. One way of doing that would be for the spacecraft to climb the tether to well past astrosync orbit to a point calculated to sling it to the next body to be explored. At the right time, the tether is cut loose at the asteroid end to send the vehicle and its’ tether to a new little unexplored world. Once there, the cycle is repeated. It would seem that the craft could explore and exploit indefinitely without running out of propellant.
For a second phase of exploitation, tethers are left attached to the asteroids for use by future visitors. Eventually, spacecraft could visit dozens of rocks during an operational lifetime to prospect for different substances or to test new techniques in a variety of locations.
Certain asteroids would be exceptionally useful in a third phase if they proved exceptionally well suited for transportation hubs. Instead of slinging small robotic prospectors to other rocks, long beanstalks could relay humans and cargo to Mars and other points of interest throughout the inner solar system.
NASA astronauts Terry Virts and Scott Kelly opened the hatches and floated into the new SpaceX Dragon space freighter Saturday morning, beginning five weeks of cargo transfers. The sixth Dragon cargo mission for NASA’s Commercial Resupply Services contract delivered a wide variety of crew supplies and science gear to support dozens of new and ongoing microgravity experiments.
The crew unloaded new Rodent Research gear that will allow scientists to study the effects of microgravity on biolog [...]
The Space Show, hosted by David Livingston at www.TheSpaceShow.com, will have the following guests this week:
1. Monday, April 20, 2015, 2-3:30 PM PDT (21-22:30 GMT)
DR. DONAL RAPP returns to discuss the use of indigenous resources on Mars to reduce the cost of a human mission to Mars and Climate Change from the perspective of those who do not start out with preconceived belief systems, but examine the data (which are fragmentary and noisy) honestly.
Dr. Donald Rapp is author of two ne [...]
Going, going, gone. That was the feeling in Svalbard, Norway last month during a total eclipse of the Sun by the Moon. In the featured image, the eclipse was captured every three minutes and then digitally merged with a foreground frame taken from the same location. Visible in the foreground are numerous gawking eclipse seekers, some deploying pretty sophisticated cameras.
As the Moon and Sun moved together across the sky -- nearly horizontally from this far north -- an increasing fraction o [...]
How could a galaxy become shaped like a ring? The rim of the blue galaxy pictured on the right is an immense ring-like structure 150,000 light years in diameter composed of newly formed, extremely bright, massive stars. That galaxy, AM 0644-741, is known as a ring galaxy and was caused by an immense galaxy collision. When galaxies collide, they pass through each other -- their individual stars rarely come into contact.
The ring-like shape is the result of the gravitational disruption caused [...]
While there has been some slightly more positive discussion about the NASA Asteroid Redirect Mission since my previous blog post and SpaceNews Op-Ed, there have still been a steady stream of criticisms and suggestions of alternatives to the ARM mission being discussed lately. I’ve always been a bit of a knee-jerk defender of the underdog, and I still don’t think ARM is being given a fair shake by many in the space policy community, so I want to take the opportunity to respond to some of these criticisms and alternatives. And by respond, I don’t mean just dismiss–some of the suggestions have real merit, and could lead to ways to improve the existing ARM mission.
We should be looking for asteroids not trying to redirect them — This criticism is that before sending a mission to an asteroid, we should be making more of an effort to find the vast majority of NEOs that we still haven’t identified. I actually agree that a strong effort at identifying more of the NEO population would be money well spent. As I pointed out in a previous post based on a talk by Josh Hopkins about LM’s Plymouth Rock mission concept, more knowledge of the NEO population and orbits gives us more options and can only make missions like ARM and others better over time. I don’t think this should preclude doing ARM as well, but finding ways to invest more effectively in this area would be useful. Some suggestions for how we could do better here range from traditional approaches such as funding a NASA asteroid hunting mission or doing a competition for industry provided asteroid finders, to providing matching funds or a free rides for more commercial missions such as what Sentinel and/or the prospecting spacecraft Planetary Resources and Deep Space Industries are developing, to potentially offering a bounty for detection and verification of new asteroids. It doesn’t have to cost billions, but spending a bit more money in this area is likely to make ARM better, and increase our odds of finding dangerous asteroids with enough time to do something about them.
OSIRIS-REx is already doing this — I’ve heard people criticize ARM because the OSIRIS-REx mission is already going to be returning samples from an asteroid before the ARM mission is flown, and thus we don’t need another mission. I find this argument as silly as Obama dismissing the Moon with his “Buzz has already been there, done that” argument. Just as the Moon is a world the size of Africa, and you can only learn so much from a half-dozen landing missions, how much are we really going to learn about the millions of asteroids in the NEO population from a few hundred grams of materials returned by a handful of sample return missions? How much do we really know about the consistency of material composition even within one single decent-sized asteroid? What are the odds that even two C-type asteroids are going to be identical enough that additional samples wouldn’t be worth it?
We need a large number of samples, not a large sample — I partially agree with this argument–diversity of samples is important, but so is having enough quantity to actually be able to do useful ISRU experimentation. The multi-teaspoon sized samples provided by current missions might provide you with some idea of the chemical composition of at least that part of a given asteroid, but learning how to mine asteroids (and if we can do so in a way that makes economic sense) is going to take larger samples. One possible compromise that could give you the best of both worlds might be a multi-lander/grasper ARM concept. Instead of having one big 4m diameter boulder grasping system, ARM could potentially do 6-7 smaller (~2m) separable grasper/landers, attached to an ESPA-ring like structure, and the spacecraft could also possibly visit more than one asteroid during the mission. As commenters have pointed out previously, there are actually relatively low-delta-V multi-asteroid tours that can be done that go from Earth to several interesting locations along the way before returning to earth. That way you can get sizable samples and variety, maybe 1-2 carbonaceous chondrite boulders, throw in a nickel-iron sample or two, and then one or two samples from another asteroid types. While this may sound a lot more complicated, NASA has already demonstrated multi-asteroid rendezvous with missions like Dawn, and building 6-7 copies of a lander grasper system would actually mean that a lot of the complexity is offset by larger efficiencies of scale–with a Prospector-like Option B grasper mechanism, you’d be making dozens to hundreds of most individual piece parts instead of the one or two that you often see for more traditional science missions. If I get more time, I’d like to flesh this idea out in its own blog post, but I wanted to get it out there publicly in case I can’t find that time.
You shouldn’t pick the boulder just on its pluckability — One concern was that the boulder would be picked entirely from a standpoint of ease of extraction. I agree with this concern wholeheartedly, but NASA has already indicated that they were are planning to include at least a basic sensor suite to help with picking an interesting boulder, not just an easy one.
You should bring the boulder back to Earth Orbit instead of DRO, because that’s just make-work for SLS/Orion — This one also comes up a lot. The fact that ARM is bringing the boulder back to DRO instead of LEO is seen as somehow indicating that this is all just a make-work stunt. But the more you study the problem, the more DRO seems like a reasonable choice. Spiraling in to earth orbit from escape velocity takes >5km/s of delta-V with a low-thrust system, on top of all of the other . This would require either a refueling or two, or a much bigger spacecraft (about 2-3x the size), and would take a really long time. High Thrust-to-Weight SEP stages can take 6 months to 1 yr to spiral out from LEO to escape. But with a 40-80 tonne boulder attached, the T/W ratio for the return spiral would be 5-10x worse, which would mean 3-10 years spiraling through the van Allen Belts. If you use aerocapture/aerobraking instead, with such a large mass, you would need either a large aerobrake, a lot of time, or something like the magnetoshell aerocapture technology we’ve been supporting MSNW on. I’m obviously not opposed to that last option, but this would be a non-trivial additional system development. Plus, even if you could magically snap your fingers and get an asteroid into LEO, there would still be challenges. An asteroid in LEO would be easier to visit but would also be a debris hazard (especially as you try to mine it and accidentally knock dust or rock chunks off or it), would have to deal with a much worse micrometeorite/orbital debris environment than it would in DRO, would be unlikely to have enough T/W to dodge a detected conjunction with other dead space objects in LEO, and would require constant propellant for reboost. It’s not an entirely impossible, but it’s not as much of a slam-dunk as some seem to think.
Grabbing a boulder has nothing to do with planetary defense — This is one of the more ridiculous statements I’ve heard repeated by otherwise very intelligent people. The reality is that unless you’re going to use nukes, the gravity tractor is probably one of your better bets for asteroid deflection. And because the mutual gravitational attraction is proportional to the masses of the two objects multiplied together, there’s a big benefit for being able to increase the mass of the spacecraft using local mass. What better way is there to rapidly increase the mass of your spacecraft via in situ materials than to grab one or more big boulders off the asteroid?
We should do ARM just minus the whole going to an asteroid and bringing a sample back thing — That’s like saying we should go to Mars but without that whole going to Mars thing. I think people are laboring under a false belief that the boulder grasping mechanism is most of the cost of ARM–it probably isn’t. The spacecraft bus and human spaceflight follow-on mission are likely a much bigger chunk, and NASA has already indicated they’d like to do those even if ARM was canceled. Canceling the grasping mechanism is unlikely to save you much at all–maybe the equivalence of a CRS mission or two, or a few months of SLS or Orion development. Spending the vast majority of the cost of the mission but without actually achieving useful exploration or ISRU development would be a waste. Why do people think that play-acting at being astronauts out at DRO without an actual useful mission for them to be performing is somehow more grown-up than doing actual exploration and potential ISRU research?
We should skip the asteroid and go to Phobos instead — This is one of the best alternatives (not surprising considering the source–I have a ton of respect for Wayne Hale), and while I think it’s not the best option, I wouldn’t be heartbroken if ARM was refocused in this way. One of the selling points of ARM was that it is relevant to future Phobos/Deimos missions–the ARM spacecraft can and should be designed so that it can be refueled and “re-clawed” and used for another destination. The marginal cost of a Xenon tank and another copy of the claw is going to be trivial compared to the overall mission development costs, and there are tons of good reasons for an ARM-like mission to go to one or both of those moons. We didn’t explicitly analyze the case of grabbing a boulder from Phobos/Deimos, but a NASA Langley team did, and found that you could get a 1-2m diameter boulder off of them using the existing Option B hardware–notice this is the same size as the multi-lander/grasper concept mentioned above. But by skipping out on the asteroid first, you would lose the ability to test gravity tractor techniques, which could be important, and asteroids are also interesting in their own right. So I’m torn. I’d rather do both.
We shouldn’t do anything that isn’t directly on the quickest path to Mars — I probably won’t convince Zubrinites, but it turns out we have this whole Solar System that doesn’t just consist of Earth and Mars. If manned Mars exploration was something we could do quickly, within NASA’s existing budget, or if there were no other interesting or useful destinations along the way, it might be one thing. But even the committee members who are advocating for this have admitted we don’t have the money to do a manned Mars mission in the next 25 years without significant increases in NASA’s funding. While it has been poorly marketed, Flexible Path wasn’t just about “doing asteroids first” or doing them instead of the Moon or Mars. To me the underlying point was that even if Mars is the long-term goal, we should find ways to do interesting exploration along the way to Mars, even if some of those destinations involve slight detours along the way. When you’re talking about a destination over 25 years out, acting like a 3 month delay is somehow insufferable is flat out ridiculous.
We should just fly an SEP module to Mars and back instead of ARM — While the concept of skipping the asteroid and going straight for a Phobos or Deimos boulder return option actually made some sense–I think the concept of building a big SEP just to fly out to Mars and back is plain ridiculous. We’ve already demonstrated the ability to use SEP systems to do multiple rendezvous with celestial bodies, as mentioned earlier. SEP technology is likely going to shift so much over the next 25 years that the only good reason to spend a lot of money building and flying a demo SEP system now is if we’re using it for something useful like ARM. Building an ARM-class SEP system and just flying it around with no greater purpose seems like a waste to me. And as mentioned previously, you’re not actually saving that much money by ditching the whole grasper thing.
I could go on, and there are other positive suggestions I could provide, like using a COTS model on the SEP module to make something that gets us the experience we want while still being commercially relevant. But I wanted to provide some more thoughts for the ongoing conversation. ARM may not have very good odds of being funded to completion, but it’s not because the arguments against it are actually all that sound.
One of the largest young craters on Mercury, 114 kilometer (71 mile) diameter Hokusai crater's bright rays are known to extend across much of the planet. But this mosaic of oblique views focuses on Hokusai close up, its sunlit central peaks, terraced crater walls, and frozen sea of impact melt on the crater's floor.
The images were captured by the MESSENGER spacecraft. The first to orbit Mercury, since 2011 MESSENGER has conducted scientific explorations, including extensive imaging of the S [...]
In the clouds of Jupiter, scientists have found evidence of a type of atmospheric wave that had long been proposed but had not been identified in images before now.
Researchers consider this kind of wave, called a Kelvin wave, a fundamental part of a planetary atmosphere, so the absence of one on Jupiter has long been a mystery. In Earth’s atmosphere, Kelvin waves are involved in a tropical wind pattern whose influence can reach as far as the polar vortex.
The researchers looked for e [...]
This NASA/ESA Hubble Space Telescope image shows an elliptical galaxy called NGC 2865. It lies just over 100 million light-years away from us in the constellation of Hydra — The Sea Serpent — and was discovered in 1835 by astronomer John Herschel.
Elliptical galaxies are usually filled with old, dying stars. NGC 2865, however, is relatively youthful and dynamic, with a rapidly rotating disk full of young stars and metal-rich gas. For an elliptical galaxy it contains an unusually high numb [...]
The Expedition 43 crew’s delivery arrived Friday aboard the SpaceX Dragon space freighter. Dragon was captured at 6:55 a.m. EDT after a two-day trip and a slow methodical approach. Astronaut Samantha Cristoforetti guided the Canadarm2 and grappled the Dragon as it floated just 10 meters away from the International Space Station.
The crew will open the hatches to Dragon, which is berthed to the Harmony module, Saturday morning and begin 5 weeks of cargo transfer activities. Aside from crew s [...]
The inner Solar System’s biggest known collision was the moon-forming giant impact between a large protoplanet and the proto-Earth. Kilometer-sized fragments from this impact hit main belt asteroids at much higher velocities than typical main belt collisions, heating the surface and leaving behind a permanent record of the impact event.
A team of NASA funded researchers modeled the evolution of giant impact debris and analyzed these ancient impact heat signatures in stony meteorites to con [...]
NASA's Curiosity Mars rover is continuing science observations while on the move this month. On April 16, the mission passed 10 kilometers (6.214 miles) of total driving since its 2012 landing, including about a fifth of a mile (310 meters) so far this month.
The rover is trekking through a series of shallow valleys between the "Pahrump Hills" outcrop, which it investigated for six months, and the next science destination, "Logan Pass," which is still about 200 yards, or meters, ahead toward [...]
Galactic or open star clusters are young. These swarms of stars are born together near the plane of the Milky Way, but their numbers steadily dwindle as cluster members are ejected by galactic tides and gravitational interactions. In fact, this bright open cluster, known as M46, is around 300 million years young. It still contains a few hundred stars within a span of 30 light-years or so.
Located about 5,000 light-years away toward the constellation Puppis, M46 also seems to contain contradi [...]
After spending more than a month in orbit on the dark side of dwarf planet Ceres, NASA's Dawn spacecraft has captured several views of the sunlit north pole of this intriguing world. These images were taken on April 10 from a distance of 21,000 miles (33,000 kilometers), and they represent the highest-resolution views of Ceres to date.
Subsequent images of Ceres will show surface features at increasingly better resolution.
Dawn arrived at Ceres on March 6, marking the first time a space [...]
VLT and Hubble observations show that star formation shuts down in the centres of elliptical galaxies first.
Astronomers have shown for the first time how star formation in “dead” galaxies sputtered out billions of years ago. ESO’s Very Large Telescope and the NASA/ESA Hubble Space Telescope have revealed that three billion years after the Big Bang, these galaxies still made stars on their outskirts, but no longer in their interiors. The quenching of star formation seems to have started [...]
Illuminating the mysterious mechanisms at play at the edge of the event horizon.
The Atacama Large Millimeter/submillimeter Array (ALMA) has revealed an extremely powerful magnetic field, beyond anything previously detected in the core of a galaxy, very close to the event horizon of a supermassive black hole. This new observation helps astronomers to understand the structure and formation of these massive inhabitants of the centres of galaxies, and the twin high-speed jets of plasma they freq [...]
After extraordinary science findings and technological innovations, a NASA spacecraft launched in 2004 to study Mercury will impact the planet’s surface, most likely on April 30, after it runs out of propellant.
NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft will impact the planet at more than 8,750 miles per hour (3.91 kilometers per second) on the side of the planet facing away from Earth. Due to the expected location, engineers will be unabl [...]