[ad_1]
Hello, lovelies, and welcome back to another installment of This Week in Space. Today, as part of our space news tasting menu, we’re happy to bring you a few pieces of unalloyed good news on topics great and small, including the JUICE Jovian ice probe (functional!) and the Earth’s future for the next millennium (asteroid-free!).
This week, we’ll read about new insights on the age of Saturn’s rings, and an “origami-based” heat shield named after King Arthur’s fabled armor. Scientists have located traces of what may be the first Population III star we’ve ever found. Instead of gazing outward into the deep sky, the JWST has been looking at our own solar system and found a strange, icy comet-thing wandering around with the rest of our main belt asteroids. We’ve also got updates from the Artemis project and a new contender for the worst planet ever found.
Private Space Co Has a Plan to Resurrect Spitzer
Last week, we discussed a new mission proposal to save Hubble; this week, it’s the Spitzer Space Telescope’s turn. As my colleague Ryan Whitwam discusses, a private firm named Rhea Space Activity has won a $250,000 grant from the US Space Force SpaceWERX program (oh God, I know) to continue studying whether a robotic service mission could return the observatory to active status.
Unlike Hubble, which emphasizes the visible EM spectrum, the Spitzer Space Telescope specialized in infrared observations. The spacecraft ran out of the helium it required to keep some instruments online in 2009 but operated a limited subset of its cameras until Jan. 30, 2020. NASA put the Spitzer in safe mode on that date and declared the mission over, citing the JWST’s then-approaching deployment and the ever-increasing difficulty of simultaneously managing the SST’s instrument temperatures, orientation, and power reserves.
Credit: Rhea Space Activity
According to Rhea, “This spacecraft would travel to NASA’s Spitzer Space Telescope to service and restore it to operations, and thereby demonstrate the ‘In-space Service Assembly and Manufacturing (ISAM)’ techniques being explored by the Department of the Air Force (DAF) and United States Space Force (USSF).” However, there’s no mention of what restoring the Spitzer Space Telescope would entail. The hypothetical repair craft is also tiny, at an estimated one meter by one meter. It’s unclear what kind of upgrades or additional capabilities the ISAM mission would provide.
Rhea Space Activity has the backing of some big names in the industry, and we love the idea of breathing new life into existing equipment. Still, we’d like to know a bit more about what, specifically, this mission would seek to accomplish.
Percussive Maintenance: JUICE Probe Finally Fully Operational
Earlier this month, the ESA announced that its JUICE orbiter (the Jupiter Icy Moons Explorer) had a stuck antenna. This was a potentially serious problem, given which antenna was stuck. The Radar for Icy Moons Exploration (RIME) relies on the once-frozen boom to scan below ice sheets for liquid water. Europa is most identified with water ice in the public imagination (thank you, Arthur C. Clarke), but Ganymede and Callisto contain large quantities of ice.
The ESA initially diagnosed the problem with the RIME antenna as caused by a small, stuck pin. As discussed several weeks ago, the ESA attempted to shake the pin loose by firing JUICE’s thrusters. When this didn’t work, they tried warming the spacecraft without success. Finally, the team gave up and/or lost its collective temper and very carefully hit the orbiter with a high-tech hammer.
The flight control team fired a “non-explosive actuator (NEA)” to jolt the stuck pin by a few millimeters, allowing the antenna to release fully. This allowed the antenna to deploy successfully. We covered the successful deployment of JUICE earlier this week if you’d like more detail. Congrats to the ESA for restoring its Jupiter-bound spacecraft.
NASA Shuts Down ‘Lunar Flashlight’ Mission After Propulsion Failure, Praises Mission Milestones
NASA announced the premature end of its Lunar Flashlight mission this week after months of effort failed to resolve problems with the diminutive satellite’s propulsion systems. Lunar Flashlight was intended to locate water ice deposits on the Moon and collect information on their size and composition. The spacecraft was a testbed for several new technologies, including a “green” fuel monopropellant (a less toxic alternative to hydrazine), an upgraded radio, and a low-power flight computer.
Credit: NASA
According to NASA, problems in the fuel system unrelated to the new monopropellant caused blockages that prevented the spacecraft from achieving sufficient delta-v to reach lunar orbit. Here’s how JPL’s blog post describes the problem:
The miniaturized propulsion system included an additively manufactured fuel feed system that likely developed the debris – such as metal powder or shavings – and obstructed fuel flow to the thrusters, limiting their performance. Although the team devised a creative method for using just one thruster to maneuver the spacecraft, Lunar Flashlight needed more consistent thrust to reach its planned orbit.
Attempts to shift Lunar Flashlight into a secondary orbit that would have allowed it to achieve some of its mission objectives were unsuccessful.
Space is hard. Congratulations to the teams working on Lunar Flashlight on their successful tests. My colleague Ryan Whitwam has more on the mission cancellation.
Origami in Space: UK, ESA Debut Foldable ‘Space Forge’ Heat Shield
You can deal with the heat of re-entry from space in a few ways. The standard aerospace workhorse is an ablative heat shield, thick enough to allow for some of it to be vaporized by heat or scoured away by atmospheric friction. But what if it didn’t have to be that way? What if, instead of absorbing all that energy, a spacecraft could simply radiate it away? That’s the idea behind Pridwen, an ambitious new heat shield named after the shield of the legendary King Arthur. Its “high-temperature alloy fabric” unfurls, slowing like a parachute and radiating away energy like a truly gigantic version of a CPU heat sink’s slender fins.
Credit: Space Forge via ESA
Pridwen’s designer, UK-based Space Forge, says that since the new design folds out like origami, its size isn’t constrained by the diameter of the rocket body that takes it to space. Instead, the Pridwen design can unfold to a much larger diameter—so much larger that it may be able to slow down a satellite enough to survive landing without a parachute.
Space Forge, working with the European Space Agency (ESA), has already put the new design through “multiple drop tests from as high as 17 km,” but the next step is to test the thing out live. The ESA said, “The first Pridwen heat shield is planned for flight aboard the company’s inaugural ForgeStar-1A mission later this year.”
No Disaster-oids For At Least a Millennium: Study
A comprehensive examination of potentially problematic space rocks has concluded that Earth is probably safe from a devastating asteroid impact for at least the next thousand years.
The newly completed catalog examined the positions and orbits of known near-Earth objects (NEOs) a kilometer (3300 feet, or 0.6 mi) wide or more. NASA experts estimate that they’ve found at least 95% of the rocks of that size that will pass within 30 million miles of the Earth in the next thousand years. (For reference, the Moon is about 238,000 miles away—less than one percent of that 30 million figure—and the rock that smote the dinosaurs measured some 10 km long.) But now, we can all rest just a bit easier, according to Davide Farnocchia, lead author of a study that appeared this week on arXiv, documenting the new catalog.
Farnocchia and colleagues arrived at their prediction using a new model of asteroid orbital dynamics, which pays close attention to the places in those asteroids’ orbits that shift them closer to Earth.
“For a significant fraction of these over-3,300-feet (1 km) objects, we were able to see that, even over long time scales, their orbital ellipse or path was sufficiently far from that of the Earth,” Farnocchia said. “Therefore, even if the position along the orbit becomes necessarily uncertain over time, we know that the asteroid cannot reach the Earth.”
The work has been accepted for publication in The Astronomical Journal.
Saturn’s Rings Are Probably Much Younger Than Saturn Itself
For decades, astronomers have assumed that Saturn’s rings were stable structures that formed at the same time as the rest of the planet. That idea was seriously challenged in 2019 when a new analysis of Cassini data showed the rings were probably less than a hundred million years old. A different team of scientists has examined the ring age question from a different angle. This new work agrees with the earlier team’s assessment that Saturn’s rings are much younger than Saturn itself, although this team proposes an age between 100 million and 400 million years.
Saturn’s rings, as seen from the Cassini probe
Credit: NASA
The new team used information from Cassini’s Cosmic Dust Analyzer to assess the age of Saturn’s rings. From 2004 – 2013, this instrument gathered information on the dust particles in orbit around Saturn and its various moons. Over that period, the spacecraft detected just 163 dust grains that originated outside the Saturnian system. The high water ice volume in the rings (an estimated 98% of their mass) indicates dust hasn’t had much time to settle on the ring system.
If this new hypothesis continues to bear up under testing, it’s likely to force a reevaluation of how Saturn’s rings formed in the first place. Existing models that assumed Saturn’s rings formed at the same time as the planet were in solid agreement with the conditions we see today. Those models may be wrong, which raises several intriguing questions: If Saturn’s ring system didn’t coalesce gradually at the same time the gas giant did, where did the rings come from? Could they be the product of a catastrophic collision? Were one or more moons destroyed in the process? Did the same process that formed the rings in the past 100-400M years influence current conditions on Titan, the only Moon in the solar system to possess a significant atmosphere?
This ongoing work is an excellent example of how we can continue to learn from data long after the spacecraft responsible for gathering it has shut down. Six years after Cassini’s final plunge, we’re still gleaning new insights from the information it beamed back.
Dispatches From the Artemis Project
This morning, NASA announced that it had awarded a contract to Blue Origin to build a lunar lander for the Artemis V flight, currently (loosely) scheduled for 2029. Blue Origin will collaborate with Boeing and Lockheed Martin on the lander. Two other companies on the roster are Astrobotic, out of Pittsburgh, which makes robotic landers, and Honeybee Robotics, which Blue Origin bought in January last year.
SLS (Space Launch System) Chief Engineer John Blevins met NASA’s Stennis Space Center team at the agency’s Marshall Space Center in the back half of last week, for a hot-fire test of the SLS’ spangly new RS-25 engines, in support of engine production for future SLS flights and Artemis missions. During the test, the engine fired for more than 10 minutes (630 seconds), which the Marshall Space Center’s newsletter, The Marshall Star, pointed out is significantly longer than the 500 seconds the engines will have to fire to get the SLS rocket to orbit. According to the Star, it was the seventh hot-fire test in a planned 12-test series of the newly redesigned RS-25 engines that will be used, beginning with Artemis V.
When the SLS finally made its inaugural flight last autumn, it did so as the largest, most powerful rocket ever built by human hands. It also did so years late and billions of dollars over budget. Watching Artemis 1 take flight was a moment of profoundly mixed emotions: On one hand, it hit space enthusiasts square in the feels because Artemis 1 represented America’s collective will to return to the Moon. On the other, the prevailing sentiment among folks who report on NASA and Congress was basically, “This was an incredible, awe-inspiring new height of human achievement. Let’s never do this again.”
Artemis was nosebleed-inducingly expensive. Now, surprising no one, the program is running out of cash. Artemis II was supposed to launch in 2028, but it’ll be a miracle if it goes up on schedule. So how on Earth will we go from there to Artemis V in a year? There’s an Iron Triangle in engineering: you can have a thing done well, fast, or cheap—pick two.
Considering the cost, it’s hard to argue for the Artemis program’s Congressional mandate. There is a point at which taxpayer money is simply better spent elsewhere, leaving the commercialization of low-earth orbit (LEO) and the Moon to private space companies. But where is that point? When a SpaceX launch costs just a few percent of an SLS launch, how many SLS launches can we justify? This is not to say we should abandon space exploration! Suppose domestic space companies can do the launches and landings for so much less overhead. Might there not be a better arrangement, possibly wherein NASA focuses on planetary exploration and simply contracts for launch services? This week, Wayne Hale, chair of NASA’s Advisory Committee for Human Spaceflight, brought up the question at a committee meeting.
“Ultimately, what kind of space program we have depends on what the American people want from their elected representatives,” Hale said. “We as space aficionados here would like to have much more, but the use of taxpayers’ money comes with priority setting, among all the different things the government has to do.”
It never rains, but it pours, eh?
Betelgeuse Brightens Again, But (Probably) Won’t Go Supernova Anytime Soon
Betelgeuse, a bright red star in the constellation Orion, made headlines a few years ago when it dimmed dramatically over a short period of time. This started a discussion of whether the star’s supernova was imminent, only for that chatter to recede once the star brightened, and it became clear that dust, not an incipient explosion, had reduced our view of the star. However, the star has brightened dramatically in a relatively short period, raising the question of whether Betelgeuse is closer to exploding than we thought.
Credit: ESO/Davide De Martin
Sadly, probably not—but that doesn’t mean we can’t learn a lot from watching Betelgeuse as it goes through this pattern of dimming and brightening. As a star ages, it stops burning hydrogen and begins fusing other elements deep within the core, including helium, carbon, oxygen, and silicon. Betelgeuse is thought to be pretty early in the helium fusion process, which means it still has many elements to work through (in human timescales). It takes the star less time to fuse each element in the sequence. A star that has fused everything below iron on the periodic table can no longer produce enough energy from fusion to counteract its own gravity. Once that occurs, the star collapses into a supernova. (Supernovae can also occur if runaway nuclear fusion occurs within a white dwarf, but Betelgeuse is a red supergiant, arguably about as far from a white dwarf as a star can be).
While Betelgeuse is not thought to be near to a supernova collapse in human timescales, we haven’t been able to observe many nearby supernovae with modern scientific tools. Again, “nearby” is relative, but at 650 light-years away, Betelgeuse is close enough to make a very pretty bang and still distant enough to pose no threat to life on Earth. The dramatic dimming events of 2019-2020, and this significant increase in brightness over just the past few months, suggest that the star may be entering an increased period of activity. Even if this new phase doesn’t result in a cataclysmic explosion, it could still teach us a lot about how stars die.
European Astronomers May Have Finally Found Traces of Ancient, Mysterious ‘Supermassive’ Stars
Researchers may have detected traces of so-called supermassive stars in galaxy GN-z11*, which formed 13.4 billion years ago, roughly 400 million years after the Big Bang. If confirmed, the discovery provides further evidence for a mysterious class of stellar objects known as Population III stars. Population III stars are the first generation of stars believed to have formed after the Big Bang. Scientists don’t know the exact characteristics of Population III stars because we’ve never observed one. But we know these first-generation stellar furnaces would have contained very little “metal” (in astronomy, every element heavier than helium is a metal). In addition to being metal-poor, some Population III stars may have been absolutely enormous, even compared with the largest stars known today. Such giant stars would have a lifespan of just millions of years, explaining why none remain.
The research team proposes that these supermassive Population III stars may have once existed in globular clusters, which are truly ancient spherical conglomerations of stars bound together by gravity. One poorly understood feature of globular clusters is the varied distribution of metals across nearby stellar populations. The supernovae of these short-lived stars might explain how various metals, including nitrogen, were heterogeneously seeded through areas where stellar formation was either possible or underway.
The JWST’s ability to observe GN-z11 in such detail enabled observations that support this hypothesis. “It has been established that [GN-z11] contains very high proportions of nitrogen and a very high density of stars,” says Daniel Schaerer, associate professor in the Department of Astronomy at the UNIGE Faculty of Science, and co-author of the study. This suggests that several globular clusters are forming in the galaxy, and that when they emitted the light we’re seeing now, they still harbored an active supermassive star.
“The strong presence of nitrogen can only be explained by the combustion of hydrogen at extremely high temperatures, which only the core of supermassive stars can reach, as shown by the models of Laura Ramirez-Galeano, a Master’s student in our team,” explains co-author Corinne Charbonnel.
* Z11 denotes the redshift, z = 11. We’ve found other galaxies with redshift values of up to 13, suggesting they formed just a few hundred million years after the Big Bang.
Newly Discovered Exoplanet Could Be a Dead Ringer for ‘Crematoria’
Scientists reported an exoplanet this week that may be unlike any other. It’s like every “extreme hazard planet” from No Man’s Sky rolled together into one slightly-less-than-Earth-sized ball of unpleasantry we’re currently calling LP 791-18 d. It’s the “middle child” between two other exoplanets in the same star system. Both are larger than Earth, although one is estimated to be more than double the mass of our blue marble. However, the team that found this lovely little slice of real estate is pretty sure it’s not compatible with life as we understand it.
LP 791-18 d is probably tidally locked to its star, which means that one side of the planet is always facing sunward, and the other side always faces away. But the constant gravitational tug-of-war means that the planet’s surface is probably wracked with constant volcanic eruptions.
“On the dayside, it is too hot for liquid water, so it is likely very dry and hot—likely a desert. On the night side, there is possibly a large icy glacier,” study co-author Björn Benneke told Reuters.
“The most interesting region is near the terminator region where the day and nightside meet,” Benneke said. “Here, water from the nightside glacier can melt and possibly form liquid surface water. In addition, there is likely volcanism all around the planet, even under the ice on the nightside and possibly under the water near the terminator.”
JWST Discovers Water—and a New Puzzle—Around Rare ‘Main Belt’ Comet
The James Webb Space Telescope is unique among space telescopes for its outstanding resolution. Webb can look far out into space, far back into the deepest reaches of time. But sometimes, astronomers turn the telescope’s powerful eye upon targets within our own solar system, the better to resolve mysteries close to home.
Credit: NASA/ESA/Webb
What surprised the team was the total absence of any detectable CO2. Typically, they said, carbon dioxide makes up about 10% of the volatile material in a comet—that is, the material that can be easily vaporized or sublimated away by the sun’s heat. But Comet Read seems to have no CO2 at all.
How could this happen? “Being in the asteroid belt for a long time could do it – carbon dioxide vaporizes more easily than water ice and could percolate out over billions of years,” said Michael Kelley of the University of Maryland, lead author of a study on Comet Read describing the findings. Alternatively, he said, Comet Read may have formed in a relatively warm nook of the Solar System, where no carbon dioxide was available because of that same volatility.
Skywatchers Corner
It’s official: the rock that punched through an unsuspecting New Jersey family’s roof last week is confirmed to be a meteorite. (Thankfully, no one was home at the time.)
Tonight is the new Moon. Starting Monday, the Moon will appear in a “close grouping” with Venus and Mars after sunset in the Western sky. We’re at a bit of a lull with meteor showers, although the eta Aquariids that dropped the above space rock on Jersey are still going, if on their way out. So, if you’ve got clear skies tonight, why not take some time and see if you can see the Milky Way?
[ad_2]
Source link
