The orbital space around Earth must urgently be protected by environmental rules and regulations akin to those that safeguard the planet’s land, seas and air, leading scientists say.
An international team of researchers warn that a dramatic rise in the number of satellites is polluting the night sky for astronomers and stargazers, while increasing the risk of objects colliding in space and potentially even striking people or aircraft when they fall back to Earth.
Much of the concern is driven by the surge in mega-constellations, which involve placing tens of thousands of satellites in low Earth orbit to deliver broadband internet and other services.
While companies such as SpaceX and OneWeb are leading the way, others are interested, including Rwanda, which recently filed an application to launch 327,000 satellites in a single project.
Writing in Nature Astronomy, scientists from the UK, US, Canada and the Netherlands warn the number of satellites in low Earth orbit could exceed 100,000 by 2030, disrupting the work of astronomers and reshaping our view of the heavens as the number of satellites seen as “fake stars” starts to rival the number of real stars seen with the naked eye.
“We really need to get our act together. We need to see where have we got regulations that we’re not applying properly, and where do we need new regulations?” said the lead author, Andy Lawrence, a regius professor of astronomy at the University of Edinburgh.
“This is about recognising that the problems we see in orbit are the same as those we see when we worry about the land, the oceans and the atmosphere. We need to knock heads together and say how can we solve this problem.”
Among the proposals are regulations based on a satellite’s space traffic footprint and limits on the carrying capacity of different orbits.
In late 2018, about 2,000 active satellites circled Earth. That number has nearly doubled in the past two years with SpaceX launches alone. All have gone into the most congested low Earth orbit, which reaches from 100-2,000km above Earth. In 2019, the European Space Agency moved its orbiting Aeolus observatory to avoid colliding with a SpaceX satellite, the first time it had swerved around an active satellite. Last year, the Chinese moved their space station twice because of similar concerns.
The scientists argue that while there is robust regulation to ensure satellites are launched safely and transmit signals only within certain frequency bands, there is almost nothing to govern the impact of satellites on the night sky, astronomy, Earth’s atmosphere or the orbital environment.
The researchers describe how light reflecting off satellites can ruin astronomical observations by leaving streaks across images, while their broadcasts can drown out the faint, natural radio signals that astronomers study to understand some of the most exotic objects in the cosmos. But the visible presence of so many satellites also undermines the ability to enjoy the night sky, they argue, an act the International Astronomical Union asserts should be a fundamental right.
There are other concerns too. The risk of falling satellite debris causing damage to property or harm to life today is relatively low. But the danger will notch upwards as more satellites re-enter Earth’s atmosphere at the end of their lives, with potentially lethal consequences.
“The first aircraft strike or ground casualty is only a matter of time,” the researchers warn. Yet another issue is rocket launch emissions which include carbon dioxide, nitric oxide and soot.
“The problem of increasing debris and congestion in Earth orbit poses a real challenge for the governance of human space activity,” said Chris Newman, a professor of space law and policy at the University of Northumbria.
“The breadth of new actors and increased geopolitical tensions mean that a binding international treaty is a long way off. In any event, the law can only take us so far. Countries and companies that are active in space need to demonstrate responsible leadership.”
A dance of death is taking place at the heart of a galaxy in the distant Universe.
Some 10 billion light-years away, two supermassive black holes are locked in an orbit so tight that they will collide with each other and form one much larger black hole in the relatively short time of just 10,000 years.
That equates to an orbital distance of just 0.03 light-years, around 50 times the average distance between the Sun and Pluto. Yet, so fast are they moving that it takes just two Earth years for the two objects to complete a binary orbit, compared to Pluto’s 248 years.
There are multiple reasons why supermassive black hole binaries are of interest to astronomers.
Supermassive black holes are found at the centers of most galaxies, the nuclei around which everything else whirls. When two are found together, it indicates that two galaxies have come together.
We know this process occurs, so finding a supermassive black hole binary can tell us what it looks like in the final stages.
Supermassive black hole binaries can also tell us something about how these colossal objects – millions to billions of times the mass of the Sun – can get so incredibly massive.
Binary black hole mergers are one way this growth can occur. Finding binary supermassive black holes will help us understand if it’s a common pathway for this growth, and that could lead to more accurate modeling.
The object in question is a quasar, named PKS 2131-021. These are galaxies in which the galactic nucleus is active; that is, the supermassive black hole is accreting matter at a furious rate, blazing with the heat generated by friction and gravity in the material roiling around the nucleus.
Some quasars blast jets of plasma almost at light-speed from the polar regions of the black hole, funneled along and accelerated by magnetic field lines around the object’s exterior. PKS 2131 is a quasar blasting out a jet right in the direction of Earth, making it what we call a blazar.
A team of astronomers studying brightness variations in quasars noticed something odd about the PKS 2131 blazar beam in radio frequencies, finding the same signature in data collected back in 2008. It seemed to oscillate on regular timescales, its brightness fluctuating with an almost perfect sine wave pattern never before seen in a quasar.
“PKS 2131 was varying not just periodically, but sinusoidally,” astronomer Tony Readhead of Caltech said. “That means that there is a pattern we can trace continuously over time.”
The trail seemed to end when only two more peaks were found in archival data, one in 2005, and another in 1981. But then, in 2021, the project piqued the interest of astronomer Sandra O’Neill of Caltech. She and a team of researchers revisited data archives to see how far back in time they could trace this strange pattern.
They hit paydirt. In data from the Haystack Observatory made between 1975 and 1983, more of the pattern emerged, consistent with the timing of the rest of the observations.
“When we realized that the peaks and troughs of the light curve detected from recent times matched the peaks and troughs observed between 1975 and 1983, we knew something very special was going on,” O’Neill said.
According to the team’s analysis, the regular ‘ticking’ of the signal is generated by the orbital motion of the two black holes. As they go around each other on two-year timescales, the radio light dims and brightens, due to the orbital motion of the jet, which causes a Doppler shift that boosts the light when the black hole is moving towards us.
The archival data shows that this sine wave can be observed consistently for eight years from 1976, after which it disappeared for 20 years. This was probably due to a change or disruption in the supply of material feeding into the supermassive black hole. After 20 years, the pattern re-emerged, and has continued ever since, about 17 years now, the researchers said.
Another similar system, OJ 287, suggests that the interpretation is valid. This blazar has two close supermassive black holes orbiting each other every 12 years, at a separation of a third of a light-year. It shows fluctuations in radio brightness, too, albeit more irregularly and without the sinusoidal waveform.
Although we won’t be around to see the eventual merger of the supermassive black holes in PKS 2131, they could show us how to look for similar systems. In turn, these could bring us closer to understanding how these colossal collisions take place.
The research has been published in The Astrophysical Journal Letters.
A large, rocky asteroid is going to fly by Earth next week.
At 1 kilometer (3,280 feet) long, it’s roughly two and a half times the height of the Empire State Building, and it’s been classed a “Potentially Hazardous Asteroid” due to its size and its regular close visits to our planet.
But don’t worry, this month’s visit is going to have a very safe clearance, with the asteroid zipping by at a distance of 1.93 million kilometers (~1.2 million miles) away from Earth – that’s roughly 5.15 times more distant than the Moon.
The calculations of its trajectory only come with a 133-kilometer (~83-mile) margin of error, so there’s no risk we’ll be colliding with this asteroid any time soon.
In fact, if you’re a stargazer, you’re in for a treat as it visits our skies. The closest approach will take place on January 18 at 21:51 UTC (4.51pm EST).
Known as asteroid (7482) 1994 PC1, the space rock was first discovered in 1994 by astronomer Robert McNaught at the Siding Spring Observatory in Australia.
Tracing its path back, scientists were able to find images of it all the way back to September 1974, which is why we can be so confident in its orbital path.
In fact, asteroid (7482) 1994 PC1 has an orbital arc of just 47 years, which is the length of time between observations in our night sky.
The last close approach was 89 years ago on 17 January 1933, at the slightly closer (but still very safe) distance of 1.1 million kilometers (~699,000 miles). It’s next expected to be within a similar distance of Earth on 18 January 2105.
This close visit will allow astronomers to study more about the stony, S-type asteroid, which belongs to the Apollo asteroid group.
These are the most common group of asteroids we know of, and they all have a similar orbital length to Earth – asteroid (7482) 1994 PC1 orbits the Sun every 1 year and 7 months in Earth time, at a distance of between 0.9 and 1.8 times that of Earth.
Position of asteroid (7482) 1994 PC1 January 1. (Tomruen/Wikimedia, CC BY 4.0)
The flyby also gives amateur astronomers and stargazers a chance to see the massive rock hurtle past.
The asteroid will be traveling at the mind-boggling speed of around 19.56 kilometers per second (43,754 miles per hour) relative to Earth, which means it’ll appear similar to a star, but will travel across the night sky across the evening.
At a magnitude of 10, the asteroid will be too dim to be seen with the naked eye or binoculars. But if you’ve got at least a 6-inch backyard telescope, you should be able to get a glimpse of it as it whizzes past, according to Eddie Irizarry over at EarthSky.org.
EarthSky also has a full guide on how to view and best photograph the asteroid, which is worth checking out if you’ve got a backyard setup.
With a lot of the world watching Don’t Look Up over the holidays, it’s easy to feel stressed about an asteroid passing this close to Earth. But if the film taught us anything, it was to trust the scientists and their orbital calculations.
An asteroid of this size is only predicted to hit Earth once every 600,000 year or so. Fortunately, NASA is in the process of testing its DART (Double Asteroid Redirection Test) mission, which will aim to deflect a small asteroid moonlet off its course by crashing into it.
If it works, it may help us to deflect future asteroid threats. In the meantime, let’s enjoy the view and look up as asteroid (7482) 1994 PC1 whizzes past. There’s nothing better to remind us of our precarious place in the galaxy.
Hanging around in earth orbit is like walking into the middle of a Wild West gunfight — bullets are flying around everywhere, and even though none are purposefully aimed at you, one might have your name on it. Many of these bullets are artificial satellites that are actively controlled and monitored, but we also find dead satellites, remnants of satellites, discarded rocket stages, tools lost during spacewalks, and even flecks of paint and rust, much of it zipping around at multiple kilometers per second without any guidance.
While removing this space debris directly would be ideal, the reality is that any spacecraft and any spacesuit that has to spend time in orbit needs to be capable of sustaining at least some hits by space debris impacting it.
Orbital Mechanics
That it’s easy to create new debris should come as no surprise to anyone. What may take a bit more imagination is just how long it can take for this debris to make its way towards earth’s atmosphere, where it will uneventfully burn up. Everything in orbit is falling toward the earth, but its tangential velocity keeps it from hitting — like a marble spinning around the hole in a funnel. Drag from the planet’s atmosphere is the friction that eventually slows the object down, and where it orbits in the planet’s atmosphere determines how long this descent will take.
Orbital decay rate infographic. (Credit: ULA)
As cited by NASA’s Orbital Debris Program Office at ARES in their FAQ, there are over 23,000 debris objects larger than 10 cm in orbit, in addition to more than half a million objects between 1 cm and 10 cm, and millions of objects between 1 mm and 10 mm. The principal sources of orbital debris are satellite explosions and collisions. This includes China’s 2007 anti-satellite (ASAT) test, as well as India’s 2019 and Russia’s 2021 ASAT tests, which happened in addition to the USSR & US 57 (total) ASAT tests.
Satellites sometimes explode, such as the 2004 and 2015 US DSMP satellite explosions. Other times satellites collide with each other, like Iridium-33 with Cosmos-2251, get hit by debris or micrometeorites, and so on. As in low earth orbit (LEO) debris tends to travel at speeds upwards of 7 km/s.
Depending on the mass of the debris object, the effect of it impacting with a satellite or other object in its path, likely adding another ~7 km/s into the opposite direction, could be the transfer of gigajoules worth of kinetic energy, equivalent to tons of TNT. Even a fleck of paint traveling at these speeds have been shown to cause significant damage, especially to fragile structures such as solar panels. As mentioned, this makes it essential that such structures can accept some level of impact damage.
Always the Small Ones
The Whipple Shield used on NASA’s Stardust probe. (Credit: NASA)
Although obviously carrying more energy, the nice thing about the larger debris pieces is that they are relatively easy to track using ground-based equipment. A satellite or space station can use onboard thrusters if it gets too close to the orbit of one of those big pieces of debris.
This then mostly leaves the smaller debris, especially the small flakes and grains that are too small to track, but with enough mass to cause significant damage. For decades, the go-to protection for spacecraft is the Whipple shield. Much like the similar multi-shock shield, it is a type of spaced armor, which is a type of armor first made popular with iron warships of the mid-19th century.
Instead of simply making armor thicker, multiple layers are used, with empty space or some kind of padding in between them. This saves on weight, while allowing for an incoming projectile to harmlessly dissipate its energy. This same principle can be seen with e.g. the windows on the ISS, which consists out of multiple layers. In the case of the ISS’ Cupola, there are four layers:
Outer debris pane.
Two 25 mm pressure panes.
Inner scratch pane.
The outer pane is supposed to dissipate most of the energy of a strike, with the layer behind it catching the debris cloud, which should be traveling at slow enough speeds that they should do no significant harm. Each window can be replaced in-orbit after fitting an external cover, should they suffer so much damage that replacement is warranted.
Damage observed to ISS solar array 3A, panel 58 (cell side on left, Kapton backside on right). Note by-pass diode is disconnected due to MMOD impact. (Credit: Hyde et al., 2019)
For the remaining sections of the ISS, ballistic panels are placed some distance from the primary hull, which are designed to capture and dissipate the energy from micrometeorites and small orbital debris. Meteoroid and orbital debris damage on the ISS has been studied for decades now, with a 2019 paper by Hyde et al. describing recent findings.
An interesting finding is that of damage to the ISS’ Solar Array Wings. In one case an micrometeorite impacted one of the panels and created a 7 mm diameter hole. This destroyed a bypass diode in the panel and caused a current buildup that ultimately resulted in a nearly 40 cm long burn-through along the edges of three cells.
Obviously, protecting solar panels in this environment is anything but easy, as by definition adding protective panels in front of them rather defeats the entire purpose of having solar panels. The ISS has over 250,000 cells, with the expectation that some of them will inevitably be lost over time. In June 2021, astronauts at the ISS installed new solar panels to replace the oldest.
While replacing solar panels like this is a viable option to deal with accumulated damage on a space station, it is less practical for satellites, which should thus have sufficient excess electrical capacity to deal with the loss over time.
Offense as Best Defense
Because the debris in some orbits will hang around for decades or longer, we may eventually reach a point where active removal of this debris becomes a necessity. This is where orbital mechanics and the incredible amount of space in, well, space make things very tricky. Even though the risk of orbital debris is high, because satellites and debris are both moving around quite quickly, the density is very low. That’s why astronauts on the ISS don’t see bits of debris zipping by all the time.
This sparseness makes active debris removal a chore, and explains why recent high-profile missions such as RemoveDEBRIS, ClearSpace-1, and others focus on large debris that travels in previously known orbits. They often require satellites to move within a certain distance from the target, and perform delicate operations. As previously established, the largest threat comes from the debris that cannot be easily tracked, which would thus seem to largely defeat these clean-up methods.
Here perhaps the best method is to not actively hunt these objects down, but to passively catch them using an expansive system, much like how a spider uses a web to catch unsuspecting prey. This is what Russian startup StartRocket with their Foam Debris Catcher has in mind. The use of foam to capture orbital debris is not new, with an ESA report from 2011 also covering the use of foam in depth.
No Littering
Even with mitigation solutions in place, and with orbital debris removal methods being investigated and possibly being deployed over the coming decades, the best thing we can do right now is to prevent making more of a mess. These days, space traffic management is handled primarily by the United Nations Office for Outer Space Affairs (UNOOSA), with national policies following international agreements on preventing orbital debris and other considerations.
The increasing focus on re-usability of spacecraft is a fortunate development. The grandest goal of the US Space Shuttle program — that it would serve as a platform for servicing satellites — never came to fruition beyond servicing Hubble. However, we may hope to soon see an end to the routine discarding of simply leaving entire rocket stages floating around, reducing at least one source of space pollution.
As our living ark swings around the Sun, its current loop is fairly circular. But Earth’s orbit isn’t as stable as you may think.
Every 405,000 years, our planet’s orbit stretches out and becomes 5 percent elliptical, before returning to a more even path.
We’ve long understood this cycle, known as orbital eccentricity, drives changes in the global climate, but exactly how this impacts life on Earth was unknown.
Now, new evidence suggests that Earth’s fluctuating orbit could actually impact biological evolution.
A team of scientists led by paleoceanographer Luc Beaufort, from the French National Centre for Scientific Research (CNRS) have found clues that orbital eccentricity is driving evolutionary bursts of new species, at least in plankton of the photosynthesizing variety (phytoplankton).
Coccolithophores are microscopic sunlight-eating algae that create plates of limestone around their soft, single-cellular bodies. These limestone shells, called coccoliths, are extremely prevalent in our fossil records – first appearing around 215 million years ago during the Upper Triassic.
Did you ever wonder how the White Cliffs of Dover were formed?
They’re made of #microfossils! Single-celled coccolithophores produce calcium carbonate #coccoliths that fossilize and form chalk!
Watch this clip of coccolith formation courtesy of Alison R. Taylor!#paleontology pic.twitter.com/5N95rQxB20
— The FOSSIL Project (@projectFOSSIL) December 13, 2018
These oceanic drifters are so abundant they contribute massively to Earth’s nutrient cycles, so forces that alter their presence can have a huge impact on our planet’s systems.
Beaufort and colleagues measured a staggering 9 million coccoliths across 2.8 million years of evolution in the Indian and Pacific oceans, with the help of AI automated microscopy. Using well-dated ocean sedimentary samples they were able to obtain an incredibly detailed resolution of around 2,000 years.
The researchers were able to use size ranges of the coccoliths to estimate species numbers, as previous genetic studies have confirmed different species in the Noelaerhabdaceae family of coccolithophores can be told apart through their cell sizes.
They discovered the average length of a coccolith followed a regular cycle in line with the 405,000 year orbital eccentricity cycle. The largest average coccolith size appeared a slight time lag after the highest eccentricity. This was irrespective of if Earth was experiencing a glacial or interglacial state.
“In the modern ocean, the highest phytoplankton diversity is found in the tropical band, a pattern probably related to high temperatures and stable conditions, whereas seasonal species turnover is highest at mid-latitudes because of a strong seasonal temperature contrast,” Beaufort and colleagues explained in their paper.
They found this same pattern was reflected across the large time scales they examined. As Earth’s orbit becomes more elliptical the seasons around its equator become more pronounced. These more varied conditions spurred coccolithophores to diversify into more species.
“A greater diversity of ecological niches when seasonality is high leads to a larger number of species because Noelaerhabdaceae adaptation is characterized by the adjustment of coccolith size and degree of calcification to thrive in the new environments.”
Size variation of coccoliths across different time periods: Miocene (left), Pleistocene (right). (Weimin Si)
The most recent evolutionary phase the team detected started around 550,000 years ago – a radiation event in which new Gephyrocapsa species emerged. Beaufort and colleagues confirmed this interpretation using genetic data on the species alive today.
By using data from both oceans they were also able to distinguish between local and global events.
What’s more, by calculating mass accumulation rates in the sediment samples the researchers untangled the potential impact morphologically different species had on Earth’s carbon cycle, which they can modulate through both photosynthesis and the production of their limestone (CaCO3) shells.
“Lighter species (for example, E. huxleyi and G. caribbeanica) contribute the most to coccolith carbonate export,” the team wrote, explaining that when mid-size opportunistic species dominate there is less carbon being stored away through shells from the dead animals sinking into the depths.
In light of these findings and other supporting research, Beaufort and team suggest the lag seen between orbital eccentricity and changes in climate could hint that “coccolithophores may drive – rather than just respond to – carbon cycle changes.”
In other words, these minuscule little organisms, along with other phytoplankton, may help change Earth’s climate in response to these orbital events. But further work is required to confirm this.
An illustration showing what the TRAPPIST-1 system might look like from a vantage point near planet TRAPPIST-1f (right). Credit: NASA/JPL-Caltech
Seven Earth-sized planets orbit the star TRAPPIST-1 in near-perfect harmony, and U.S. and European researchers have used that harmony to determine how much physical abuse the planets could have withstood in their infancy.
“After rocky planets form, things bash into them,” said astrophysicist Sean Raymond of the University of Bordeaux in France. “It’s called bombardment, or late accretion, and we care about it, in part, because these impacts can be an important source of water and volatile elements that foster life.”
In a study available online today in Nature Astronomy, Raymond and colleagues from Rice University’s NASA-funded CLEVER Planets project and seven other institutions used a computer model of the bombardment phase of planetary formation in TRAPPIST-1 to explore the impacts its planets could have withstood without getting knocked out of harmony.
Deciphering the impact history of planets is difficult in our solar system and might seem like a hopeless task in systems light-years away, Raymond said.
“On Earth, we can measure certain types of elements and compare them with meteorites,” Raymond said. “That’s what we do to try to figure out how much stuff bashed into the Earth after it was mostly formed.”
But those tools don’t exist for studying bombardment on exoplanets.
“We’ll never get rocks from them,” he said. “We’re never going to see craters on them. So what can we do? This is where the special orbital configuration of TRAPPIST-1 comes in. It’s a kind of a lever we can pull on to put limits on this.”
TRAPPIST-1, about 40 light-years away, is far smaller and cooler than our sun. Its planets are named alphabetically from b to h in order of their distance from the star. The time needed to complete one orbit around the star—equivalent to one year on Earth—is 1.5 days on planet b and 19 days on planet h. Remarkably, their orbital periods form near-perfect ratios, a resonant arrangement reminiscent of harmonious musical notes. For example, for every eight “years” on planet b, five pass on planet c, three on planet d, two on planet e and so on.
“We can’t say exactly how much stuff bashed into any of these planets, but because of this special resonant configuration, we can put an upper limit on it,” Raymond said. “We can say, ‘It can’t have been more than this.’ And it turns out that that upper limit is actually fairly small.
“We figured out that after these planets formed, they weren’t bombarded by more than a very small amount of stuff,” he said. “That’s kind of cool. It’s interesting information when we’re thinking about other aspects of the planets in the system.”
Planets grow within protoplanetary disks of gas and dust around newly formed stars. These disks only last a few million years, and Raymond said previous research has shown that resonant chains of planets like TRAPPIST-1’s form when young planets migrate closer to their star before the disk disappears. Computer models have shown disks can shepherd planets into resonance. Raymond said it’s believed that resonant chains like TRAPPIST-1’s must be set before their disks disappear.
The upshot is TRAPPIST-1’s planets formed fast, in about one-tenth the time it took Earth to form, said Rice study co-author Andre Izidoro, an astrophysicist and CLEVER Planets postdoctoral fellow.
CLEVER Planets, led by study co-author Rajdeep Dasgupta, the Maurice Ewing Professor of Earth Systems Science at Rice, is exploring the ways planets might acquire the necessary elements to support life. In previous studies, Dasgupta and colleagues at CLEVER Planets have shown a significant portion of Earth’s volatile elements came from the impact that formed the moon.
“If a planet forms early and it is too small, like the mass of the moon or Mars, it cannot accrete a lot of gas from the disk,” Dasgupta said. “Such a planet also has much less opportunity to gain life-essential volatile elements through late bombardments.”
Izidoro said that would have been the case for Earth, which gained most of its mass relatively late, including about 1% from impacts after the moon-forming collision.
“We know Earth had at least one giant impact after the gas (in the protoplanetary disk) was gone,” he said. “That was the moon-forming event.
“For the TRAPPIST-1 system, we have these Earth-mass planets that formed early,” he said. “So one potential difference, compared to the Earth’s formation, is that they could have, from the beginning, some hydrogen atmosphere and have never experienced a late giant impact. And this might change a lot of the evolution in terms of the interior of the planet, outgassing, volatile loss and other things that have implications for habitability.”
Raymond said this week’s study has implications not only for the study of other resonant planetary systems, but for far more common exoplanet systems that were believed to have begun as resonant systems.
“Super-Earths and sub-Neptunes are very abundant around other stars, and the predominant idea is that they migrated inward during that gas-disk phase and then possibly had a late phase of collisions,” Raymond said. “But during that early phase, where they were migrating inward, we think that they pretty much—universally maybe—had a phase where they were resonant chain structures like TRAPPIST-1. They just didn’t survive. They ended up going unstable later on.”
Izidoro said one of the study’s major contributions could come years from now, after NASA’s James Webb Space Telescope, the European Southern Observatory’s Extremely Large Telescope and other instruments allow astronomers to directly observe exoplanet atmospheres.
“We have some constraints today on the composition of these planets, like how much water they can have,” Izidoro said of planets that form in a resonant, migration phase. “But we have very big error bars.”
In the future, observations will better constrain the interior composition of exoplanets, and knowing the late bombardment history of resonant planets could be extremely useful.
“For instance, if one of these planets has a lot of water, let’s say 20% mass fraction, the water must have been incorporated into the planets early, during the gaseous phase,” he said. “So you will have to understand what kind of process could bring this water to this planet.”
Additional study co-authors include Emeline Bolmont and Martin Turbet of the University of Geneva, Caroline Dorn of the University of Zurich, Franck Selsis of the University of Bordeaux, Eric Agol of the University of Washington, Patrick Barth of the University of St. Andrews, Ludmila Carone of the Max Planck Institute for Astronomy in Heidelberg, Germany, Michael Gillon of the University of Liège and Simon Grimm of the University of Bern.
The orbital flatness of planetary systems
More information:
Sean Raymond, An upper limit on late accretion and water delivery in the TRAPPIST-1 exoplanet system, Nature Astronomy (2021). DOI: 10.1038/s41550-021-01518-6. www.nature.com/articles/s41550-021-01518-6
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NASA’s SpaceX Crew-3 arrives at International Space Station
SpaceX founder and CEO Elon Musk says his aerospace firm is aiming for its Starship rocket to launch its first orbital flight in January.
SN8 rocket: SpaceX Chief Engineer Elon Musk speaks in front of Crew Dragon cleanroom at SpaceX Headquarters in Hawthorne, California on October 10, 2019. (Photo by Yichuan Cao/NurPhoto via Getty Images) Background Photo: SpaceX (Photo by Yichuan Cao/NurPhoto via Getty Images) – Background Photo: SpaceX)
“We’re close to our initial orbital launch,” Musk said in an address to the Space Studies Board and Board on Physics and Astronomy at the National Academies on Wednesday. “We’ve done several sub-orbital flights and have been able to land the vehicle successfully,” he continued, reiterating, “the first orbital flight, we’re hoping to do in January.”
Elon Musk, founder of SpaceX and chief executive officer of Tesla Inc., arrives at the Axel Springer Award ceremony in Berlin, Germany, on Tuesday, Dec. 1, 2020.. Photographer: Liesa Johannssen-Koppitz/Bloomberg via Getty Images (Liesa Johannssen-Koppitz/Bloomberg via Getty Images / Getty Images)
TESLA CEO ELON MUSK CRITICIZES DEMOCRATS’ PROPOSAL TO TAX BILLIONAIRES
Musk noted that “there is a lot of risk associated with this first launch, so I would not say that it is likely to be successful, but I think we’ll make a lot of progress.”
He explained that SpaceX aims to have the launch pad and launch tower completed later this month, and will conduct a series of tests in December to prepare for the launch.
Elon Musk. (AP Photo/Matt Rourke) (AP Photo/Matt Rourke / AP Newsroom)
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Musk, who is also the CEO of Tesla and the richest man in the world thanks to his holdings in the electric car behemoth, said SpaceX has built a factory to produce Starships, saying, “ultimately, I think in order for life to become multi-planetary, we’ll need maybe 1,000 ships or something like that.”
Earlier this week, the International Space Station (ISS) was forced to maneuver out of the way of a potential collision with space junk. With a crew of astronauts and cosmonauts on board, this required an urgent change of orbit on November 11.
Over the station’s 23-year orbital lifetime, there have been about 30 close encounters with orbital debris requiring evasive action. Three of these near-misses occurred in 2020.
In May this year there was a hit: a tiny piece of space junk punched a 5mm hole in the ISS’s Canadian-built robot arm.
This week’s incident involved a piece of debris from the defunct Fengyun-1C weather satellite, destroyed in 2007 by a Chinese anti-satellite missile test. The satellite exploded into more than 3,500 pieces of debris, most of which are still orbiting. Many have now fallen into the ISS’s orbital region.
To avoid the collision, a Russian Progress supply spacecraft docked to the station fired its rockets for just over six minutes. This changed the ISS’s speed by 0.7 meters per second and raised its orbit, already more than 400 km (250 miles) high, by about 1.2 km (0.7 miles).
Orbit is getting crowded
Space debris has become a major concern for all satellites orbiting the Earth, not just the football-field-sized ISS. As well as notable satellites such as the smaller Chinese Tiangong space station and the Hubble Space Telescope, there are thousands of others.
As the largest inhabited space station, the ISS is the most vulnerable target. It orbits at 7.66 kilometers (4.75 miles) a second, fast enough to travel from Perth to Brisbane in under eight minutes.
A collision at that speed with even a small piece of debris could produce serious damage. What counts is the relative speed of the satellite and the junk, so some collisions could be slower while others could be faster and do even more damage.
As low Earth orbit becomes increasingly crowded, there is more and more to run into. There are already almost 5,000 satellites currently operating, with many more on the way.
SpaceX alone will soon have more than 2,000 Starlink internet satellites in orbit, on its way to an initial goal of 12,000 and perhaps eventually 40,000.
A rising tide of junk
If it was only the satellites themselves in orbit, it might not be so bad. But according to the European Space Agency’s Space Debris Office, there are estimated to be about 36,500 orbiting artificial objects larger than 10 cm (4 inches) across, such as defunct satellites and rocket stages. There are also around a million between 1 cm and 10 cm, and 330 million measuring 1 mm to 1 cm.
Most of these items are in low Earth orbit. Because of the high speeds involved, even a speck of paint can pit an ISS window and a marble-sized object could penetrate a pressurized module.
The ISS modules are somewhat protected by multi-layer shielding to lessen the probability of a puncture and depressurization. But there remains a risk that such an event could occur before the ISS reaches the end of its lifetime around the end of the decade.
Watching the skies
Of course, no one has the technology to track every piece of debris, and we also don’t possess the ability to eliminate all that junk. Nevertheless, possible methods for removing larger pieces from orbit are being investigated.
Meanwhile, nearly 30,000 pieces larger than 10 cm are being tracked by organizations around the world such as the US Space Surveillance Network.
Here in Australia, space debris tracking is an area of increasing activity. Multiple organizations are involved, including the Australian Space Agency, Electro Optic Systems, the ANU Institute for Space, the Space Surveillance Radar System, the Industrial Sciences Group, and the Australian Institute for Machine Learning with funding from the SmartSat CRC.
In addition, the German Aerospace Center (DLR) has a SMARTnet facility at the University of Southern Queensland’s Mt Kent Observatory dedicated to monitoring geostationary orbit at a height of around 36,000km – the home of many communication satellites, including those used by Australia.
One way or another, we will eventually have to clean up our space neighborhood if we want to continue to benefit from the nearest regions of the ‘final frontier’.
Mark Rigby, Adjunct Research Fellow, University of Southern Queensland and Brad Carter, Professor (Physics), University of Southern Queensland.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
A Falcon 9 rocket climbs above a fog layer at Cape Canaveral Space Force Station with 53 Starlink internet satellites. Credit: SpaceX
SpaceX shot 53 Starlink internet satellites into orbit on top of a Falcon 9 rocket Saturday from foggy Cape Canaveral, commencing a new phase of deploying the global broadband network with the first launch into a new “shell” some 335 miles above Earth.
The mission was the 31st Falcon 9 launch in two-and-a-half years dedicated to carrying satellites for the Starlink internet network, bringing the total number of Starlink spacecraft launched to 1,844.
Veiled in fog, the Falcon 9 lifted off from pad 40 at Cape Canaveral at 7:19:30 a.m. EST (1219:30 GMT) Saturday. Nine Merlin main engines throttled up to produce 1.7 million pounds of thrust, powering the launcher off the pad and quickly through the ground-hugging fog layer.
The two-stage, kerosene-fueled rocket rolled to line up with a flight path northeast from Florida’s Space Coast. The Falcon 9 arced downrange over the Atlantic Ocean, exceeding the speed of sound in about a minute.
The first stage shut down and separated about two-and-a-half minutes into the flight. While the booster stage descended back to Earth for landing, the Falcon 9’s second stage engine fired to propel the 53 Starlink spacecraft into orbit.
SpaceX showed views of the booster — designated B1058 in SpaceX’s fleet — falling back through the atmosphere. A landing burn using the rocket’s center engine slowed the vehicle down for an on-target touchdown on SpaceX’s drone ship “Just Read the Instructions” positioned east of Charleston, South Carolina.
The landing concluded the ninth trip to space and back for the booster, which debuted in May 2020 with the launch of astronauts Doug Hurley and Bob Behnken on SpaceX’s first crew mission. The historic launch ended a nine-year drought of orbital crew launches from U.S. soil.
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SpaceX’s Falcon 9 rocket heads downrange Saturday. Credit: Stephen Clark/Spaceflight Now
The rocket’s upper stage burned its engine for six minutes to inject the Starlink satellites into orbit, shutting down just as the Falcon 9 booster landed in the Atlantic Ocean.
After coasting nearly seven minutes, the upper stage fired thrusters to go into a spin, setting up for release of the 53 Starlink satellites at about T+plus 15 minutes, 31 seconds.
A live camera view from the Falcon 9’s second stage showed retention rods jettisoning to release the flat-panel satellites as the rocket soared 141 miles (227 kilometers) over the North Atlantic Ocean.
The satellites were programmed to deploy solar panels to begin charging their batteries, then activate krypton ion engines to raise their orbits to an altitude of 335 miles (540 kilometers) to enter the Starlink fleet.
The mission Saturday, known as Starlink 4-1, was scheduled to take off Friday, but SpaceX kept the rocket on the ground an extra day due to storms near Cape Canaveral.
The launch capped a busy week for SpaceX.
The company’s Crew Dragon Endeavour capsule undocked from the International Space Station Monday to bring home a crew of four astronauts after nearly seven months in orbit. The spacecraft splashed down in the Gulf of Mexico Monday night to end SpaceX’s second operational crew mission to the space station.
Two days later, SpaceX launched a Falcon 9 rocket from pad 39A at NASA’s Kennedy Space Center Wednesday night with three NASA astronauts and one European Space Agency flight engineer. The four-person crew arrived at the space station Thursday to replace the astronauts that departed the complex earlier in the week.
SpaceX’s Falcon 9 booster — tail number B1058 — on the drone ship “Just Read the Instructions.” Credit: SpaceX
The launch Saturday was the first to target a new orbital “shell” in SpaceX’s Starlink network at an inclination angle of 53.2 degrees to the equator.
Most of the Starlink satellites launched so far have deployed into a 341-mile-high (550-kilometer), 53-degree inclination orbit, the first of five orbital shells SpaceX plans to complete full deployment of the Starlink network. SpaceX finished launching satellites in that shell with a series of Starlink flights from Cape Canaveral from May 2019 through May of this year.
Since May, SpaceX has rushed to complete development of new inter-satellite laser terminals to put on all future Starlink satellites. The laser crosslinks, which have been tested on a handful of Starlink satellites on prior launches, will reduce the reliance of SpaceX’s internet network on ground stations.
The ground stations are expensive to deploy, and come with geographical — and sometimes political — constraints on where they can be positioned. Laser links will allow the Starlink satellites to pass internet traffic from spacecraft to spacecraft around the world, without needing to relay the signals to a ground station connected to a terrestrial network.
“Inter-satellite laser communications means Starlink can carry data at speed of light in vacuum all around Earth before touching ground,” tweeted Elon Musk, SpaceX’s founder and CEO. “Over time, some amount of communication can simply be from one user terminal to another without touching the internet.”
The completion of the first Starlink shell enables the network to provide high-speed, low-latency internet services to lower latitudes, such as the southern United States. The partial deployment of satellites into the first orbital shell initially provided service over northern regions of the United States, Canada, and Europe, as well as higher-latitude regions in the southern hemisphere.
SpaceX is currently providing interim internet services through the Starlink satellites to consumers who have signed up for a beta testing program.
Musk tweeted Saturday that the Starlink network should work for maritime customers by mid-2022, once SpaceX has launched enough laser-equipped satellites. “Until then, it will be patchy when far from land,” he tweeted.
SpaceX’s newest 53 Starlink internet satellites have deployed from the Falcon 9 rocket’s second stage in orbit.
SpaceX has launched 1,844 Starlink satellites to date.https://t.co/HsIOf3qPfu pic.twitter.com/FfVVC7bpc7
— Spaceflight Now (@SpaceflightNow) November 13, 2021
In September, SpaceX launched the first batch of 51 Starlink satellites into a 70-degree inclination orbit on a Falcon 9 rocket from Vandenberg Space Force Base. That orbital shell will eventually contain 720 satellites at an altitude of 354 miles (720 kilometers).
Aside from the 53-degree and 70-degree orbital shells, SpaceX’s other Starlink layers will include 1,584 satellites at 335 miles (540 kilometers) and an inclination of 53.2 degrees, and 520 satellites spread into two shells at 348 miles (560 kilometers) and an inclination of 97.6 degrees.
SpaceX has regulatory approval from the Federal Communications Commission for approximately 12,000 Starlink satellites. The company’s initial focus is on launching 4,400 satellites on a series of Falcon 9 rocket flights. SpaceX’s next-generation launcher, a giant rocket called the Starship that has not yet reached orbit, may eventually be tasked with launching hundreds of Starlink satellites on a single mission.
The launch Friday brought the total number of Starlink spacecraft SpaceX has launched to 1,844 satellites, including failed and decommissioned platforms, adding to the largest fleet ever put into orbit. It was the 31st dedicated Falcon 9 launch for the Starlink network.
SpaceX builds the Starlink satellites, each with a mass of about a quarter-ton, in a factory in Redmond, Washington.
A tabulation by Jonathan McDowell, an astronomer and respected tracker of spaceflight activity, shows SpaceX currently has 1,454 operational Starlink satellites, with nearly 100 additional craft moving into their operational positions in orbit.
Saturday’s launch was the 25th flight of a Falcon 9 rocket this year, but just the fifth of the second half of 2021. SpaceX launched 20 Falcon 9 missions from January through the end of June, a rapid launch cadence primarily driven by Starlink missions.
The pace has slowed since June as SpaceX struggled to finish development of Starlink’s inter-satellite laser terminals. SpaceX’s external customers also had no payloads ready to fly.
Three of SpaceX’s missions since June have carried Dragon capsules into space — crew and cargo missions for NASA to the space station, and the privately-funded Inspiration4 crew mission to low Earth orbit. The other two Falcon 9 launches since June have deployed Starlink satellites.
SpaceX has at least five more missions scheduled before the end of the year.
The next Falcon 9 launch will blast off from Vandenberg Space Force Base in California on Nov. 23 (California time) with NASA’s DART spacecraft, which will demonstrate a deflection technique that could protect Earth from a future asteroid impact threat.
At least four Falcon 9 missions are scheduled in December from Florida’s Space Coast, launching more Starlink satellites, NASA’s IXPE X-ray astronomy telescope, the Turksat 5B communications payload, and another NASA cargo mission to the space station.
Nov. 7—At the end of the first orbital test flight for its 164-foot Starship, SpaceX envisions a reentry into the atmosphere at speeds approaching Mach 25, or 19, 000 miles per hour, followed by 15 minutes of hypersonic flight.
During this time, the spacecraft will hurtle sideways, generating tremendous heat before adjusting to an upright position for a “soft ” rocket-powered ocean landing 62 miles north of Kauai.
It will sink in the Navy’s Pacific Missile Range Facility, according to plans for the historic flight, and join dozens of warships that have gone down over past decades during Navy “sink exercises ” in waters 15, 000 feet deep.
Most recently that included the retired frigate USS Ingraham, which was targeted in mid-August by Marines firing Naval Strike Missiles from Kauai and pummeled by munitions from aircraft and a submarine.
Hawaii’s role in the orbital test of the biggest rocket ship ever built—394 feet with the “Super Heavy ” booster and Starship upper stage combined—has largely been revealed through regulatory filings.
Eventually, Starship is expected to carry crews to Earth orbit, the moon and Mars.
NASA, for its part, wants to fly a WB-57 high-altitude research jet close enough to the 30-foot-wide Starship’s hypersonic reentry to gauge the surface temperature of the “Starbrick ” thermal tiles that will take the brunt of the heat. Controllable fins will keep Starship in the right position.
Current state-of-the-art thermal protection systems, or TPS, including ablators, ceramic tiles and reinforced carbon fiber “typically require significant maintenance between flights, ” meaning inspection, replacement time and cost, an Aug. 24 NASA report stated.
“Starship TPS is intended to provide a dramatic leap forward by demonstrating operational reuse requiring minimal to no maintenance between flights, ” NASA said.
The space agency also offers a possible window for the Starship launch, saying it is “targeting (a ) Starship reentry observation opportunity near March 2022.”
The timing is perhaps a more realistic estimation compared to a series of overly optimistic predictions by SpaceX founder Elon Musk, who tweeted on Oct. 22 : “If all goes well, Starship will be ready for its first orbital launch next month, pending regulatory approval.”
Musk needs approval from the Federal Aviation Administration, and an environmental assessment is ongoing. The first orbital mission would include the stacked rocket launching from the SpaceX Boca Chica “Starbase ” in Cameron County, Texas, with the Super Heavy booster first stage landing in the Gulf of Mexico and Starship second stage splashing down off Kauai after traveling nearly around the Earth in orbit.
Super Heavy is expected to be equipped with up to 37 “Raptor ” engines powered by liquid oxygen and liquid methane, according to the draft programmatic environmental assessment released in September. Starship will employ up to six Raptor engines.
The flight is expected to take 90 minutes. As Starship enters its landing approach, likened to a speed-reducing belly flop, a sonic boom will be created.
“It is SpaceX’s intent to recover and reuse Starship and Super Heavy boosters, ” a June FAA biological assessment states. But the space company may require “expending ” either in the ocean “during early launches as the program develops.”
Its first proposed mission includes “the Starship second stage landing off the coast of Hawaii in the Pacific Ocean, ” the FAA said in an Oct. 18 document.
“SpaceX expects Super Heavy and Starship would break up on impact ” and sink because the spacecraft are mostly made from steel, a separate FAA report said.
Musk’s space flight operation has not identified all potential options for future landing sites and “may plan to land the Starship on islands in the Pacific Ocean, ” which would be analyzed in future reports if plans develop, according to the environmental assessment.
Ted Ralston, a retired aerospace engineer, said Hawaii would likely be ruled out for a land-based return. Rather, SpaceX may have in mind sparsely populated or uninhabited islands in the Western Pacific with little commercial air traffic, he said.
Eventually, SpaceX wants to launch and land its Super Heavy boosters and Star ships back at Boca Chica—and it is adding steel arms at its 450-foot “Mechazilla ” launch tower to “catch ” the returning vehicles.
“Getting the permits to do the landings in Texas of the type that they are thinking of doing, which is a ballistic reentry, might be more complicated than getting that kind of permission in a more inviting atmosphere in the Western Pacific, ” Ralston said. “And then you get the thing developed under say, three or four flights—now you’ve proven it. Now you can move it back to Texas. So you kind of look for the path of least resistance and develop and establish capability and credibility, and with that you can back your claim that you are OK to go back to the FAA.”
It would be relatively easy to barge the landed Star ships from a Pacific island back to Texas, he said.
PMRF is the world’s largest instrumented range capable of supporting surface, subsurface and space operations. The Navy said the facility has over 1, 100 square miles of instrumented underwater range and over 42, 000 square miles of controlled airspace.
In August, U.S. Indo-Pacific Command said PMRF was “in discussions (with SpaceX ) for limited support and use of their range ” for the ocean touchdown.
