Science
The Long March 5B, a 22-ton Chinese rocket, is falling back to Earth this weekend. Where will it land? – Grid
When you’re asked, “What’s up?” this weekend, here’s your answer: the Long March 5B, a roughly 44,000-pound rocket body that’s spiraling toward Earth.
But scientists are unsure when and where this debris — from China’s launch this past Sunday of its Wentian space-station module — will land. The Aerospace Corporation did release its latest predicted paths for the debris — with the disclaimer that it’s still too early to be certain.
Experts believe that 20 percent to 40 percent of the rocket body’s immense mass will survive its fiery journey through Earth’s atmosphere to the planet’s surface, but not in one piece. Seventy percent of the planet is covered in ocean, so the odds are that whatever is left of the rocket will land in water, but that’s not guaranteed.
The shoulder-shrugs in response to the potential dangers of Long March 5B’s debris are nothing new. Aaron Boley, the co-director of the Outer Space Institute and a planetary astronomer at the University of British Columbia, said about 70 percent of rockets that de-orbit and re-enter Earth’s atmosphere do so in an uncontrolled way, and rocket debris is just part of that risk.
In April, a 6- to 10-foot metal ring fell onto a village in India’s Maharashtra state. In 2020, a 39-foot metal pipe landed on two villages in Ivory Coast. In 2016, two rocket fuel tanks landed on islands of Indonesia. Earlier this month, parts of a SpaceX trunk capsule fell into paddocks in New South Wales, Australia.
“Every time we’re launching rockets, we’re rolling dice,” Boley said. “And the problem is, we’re rolling many dice, many times.”
Rockets are the transport vessel for anything put into orbit, including individual satellites and satellite constellations, telescopes, engineering projects and research modules. In 2021, there were more than 130 successful orbital rocket launches globally — a record — and 2022 is on pace to deliver even more as space development skyrockets.
“In the future, we might have companies launching rockets to build their own space stations, whether it’s for tourism or on-orbit manufacturing,” Boley said.
The trajectories of rockets can take a few shapes. Often, they gradually break apart during ascent, shedding heavy boosters or empty fuel tanks in a controlled process called staging. When staging occurs in the suborbital zone — where Earth’s gravity still has complete or near-complete effect on the dropped machinery — the launch teams can precisely plan where they will land (over an ocean).
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Other mission paths require that some stages of the rocket are abandoned in low-Earth orbit (LEO) — a region loosely considered as being between 180 and 1,250 miles above Earth — where they are left to drift, effectively, as space junk.
The technology is there to curb the danger. Just not everyone uses it.
This is not a technology problem. Some rockets, like SpaceX’s Falcon 9, have re-ignitable engines, which can direct re-entry to an uninhabited (by humans) place on Earth, and sometimes even full-on return trips with landing pads ready and waiting for them.
But not all rockets are outfitted with these technologies, and even if they are, “there is an extra expense associated with recovery,” Boley said. “The customer may decide on a cheaper option, or the launch team may decide that it’s easier to dispose of the object in orbit.”
So the rocket bodies — including the particularly massive Long March 5B, which is not outfitted with reigniting engines — are left to litter LEO. It’s a policy decision many countries, including the U.S., seem fine with.
Over 1,000 rocket bodies and thousands of satellites are currently hurtling through LEO, completing revolutions around the Earth every 90 to 120 minutes.
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Gradually, these slow-burn orbital journeys — tracked most prominently and shared online by the Aerospace Corporation, an independent, government-sponsored nonprofit — are slowed down by drag, the same aerodynamic force that naturally counteracts an airplane or a race car, and fall to the Earth.
“It’s all kind of a funny thing, because an orbit is nothing more than falling toward something and constantly missing. And then eventually, gas drag makes it so, nope, it’s gonna hit this time.”
Where space debris lands is not always left to chance
The eventual landing spots for many of these uncontrolled entries are not always random — with many launched and landing around the equator.
In studying the orbital trajectories of the more than 1,500 rockets that have deorbited over the past 30 years, Boley and a team of researchers at the University of British Columbia estimated that there has been between a 10 and 20 percent chance of casualties due to rocket debris.
This is a far cry from the 0.01 percent risk threshold the United States applies to its launches, a casualty assessment that is often waived. “To my knowledge, there is no paper trail for the decision-making process that led to that [0.01 percent] number having been applied to launches and re-entries,” said Boley.
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“But we can’t paint space people out as bad guys,” said Timiebi Aganaba, an assistant professor and senior global futures scientist at Arizona State University who specializes in environmental and space governance. “[When the policies on space development were set], there were so few launches; it’s just not something that, 10 years ago, anybody would have been talking about.”
But now, as space continues to be commodified and rockets fly more frequently, both Boley and Aganaba agree that rocket debris is a collective action problem. Boley said the solution will require the international community to come together and agree on risk mitigation regulations.
How and when these rules will be made and followed is to be seen. It might take until “someone wins the lottery, so to speak,” of being unfortunately hit by space debris, Boley said. “Odds are it’s not going to be you, but someone’s going to do it.”
This article has been updated. Thanks to Lillian Barkley for copy editing this article.
This visualization shows water features on New York’s Long Island – shown as bright pink splotches. Purple, yellow, green, and dark blue shades represent different land elevations, while the surrounding ocean is a lighter blue. The data was collected on Jan. 21, 2023, by SWOT’s KaRIn instrument. Credit: NASA/JPL-Caltech
The Surface Water and Ocean Topography mission offers the first taste of the detailed perspectives of Earth’s surface water that its cutting-edge instruments will be able to capture.
The international Surface Water and Ocean Topography (SWOT) mission – led by NASA and the French space agency Centre National d’Études Spatiales (CNES) – has sent back some of its first glimpses of water on the planet’s surface, showing ocean currents like the Gulf Stream in unprecedented detail. SWOT is also capturing views of freshwater features such as lakes, rivers, and other water bodies down to about 300 feet (100 meters) wide.
The satellite will measure the elevation of nearly all the water on Earth’s surface and provide one of the most comprehensive surveys yet of our planet’s surface water. SWOT’s measurements of freshwater bodies and the ocean will provide insights into how the ocean influences climate change and the water cycle; how a warming world affects water storage in lakes, rivers, and reservoirs; and how communities can better manage their water resources and prepare for floods and other disasters.
“SWOT’s advanced imagery will empower researchers and advance the way we manage fresh water and the effects of sea level rise across the globe,” said NASA Administrator Bill Nelson. “Water is one of our planet’s most important resources – and it’s proven to be vulnerable to the impacts of climate change. SWOT will provide critical information that communities can use to prepare for the impacts of a warming climate.”
A Whole New View
As seen in these early images, on Jan. 21, 2023, SWOT measured sea level in a part of the Gulf Stream off the coast of North Carolina and Virginia. The two antennas of SWOT’s Ka-band Radar Interferometer (KaRIn) instrument acquired data that was mapped as a pair of wide, colored strips spanning a total of 75 miles (120 kilometers) across. Red and orange areas in the images represent sea levels that are higher than the global average, while the shades of blue represent sea levels that are lower than average.
For comparison, the new data is shown alongside sea surface height data taken by space-based instruments called altimeters. The instruments – widely used to measure sea level – also bounce radar signals off of Earth’s surface to collect their measurements. But traditional altimeters are able to look only at a narrow beam of Earth directly beneath them, unlike KaRIn’s two wide-swath strips that observe sea level as a two-dimensional map.
The spatial resolution of SWOT ocean measurements is 10 times greater than the composite of sea surface height data gathered over the same area by seven other satellites: Sentinel-6 Michael Freilich, Jason-3, Sentinel-3A and 3B, Cryosat-2, Altika, and Hai Yang 2B. The composite image was created using information from the Copernicus Marine Service of ESA (European Space Agency) and shows the same day as the SWOT data.
KaRIn also measured the elevation of water features on Long Island – shown as bright pink splotches nestled within the landscape. (Purple, yellow, green, and blue shades represent different land elevations.)
“Our ability to measure freshwater resources on a global scale through satellite data is of prime importance as we seek to adjust to a changing climate,” said CNES Chairman and CEO Philippe Baptiste. “In this respect, the first views from SWOT give us a clearer picture than ever before. These data will prove highly valuable for the international scientific community in the fields of hydrology, oceanography, and coastal studies.”
This initial inland image is a tantalizing indication of how SWOT can measure details of smaller lakes, ponds, and rivers in ways that satellites could not before. Such data will be used to produce an extraordinary accounting of the freshwater on Earth’s surface in ways useful to researchers, policymakers, and water resource managers.
“The KaRIn instrument took years to develop and build, and it will collect information on bodies of water across the globe – data that will be freely and openly available to everybody who needs it,” said Parag Vaze, SWOT project manager at NASA’s Jet Propulsion Laboratory in Southern California.
More About the Mission
Launched on Dec. 16, 2022, from Vandenberg Space Force Base in central California, SWOT is now in a period of commissioning, calibration, and validation. Engineers are checking out the performance of the satellite’s systems and science instruments before the planned start of science operations in summer 2023.
The data for these first images was collected by SWOT’s KaRIn instrument, the scientific heart of the satellite. KaRIn has one antenna at each end of a boom that’s 33 feet (10 meters) long. This enables the instrument to look off to either side of a center line directly below the satellite as it bounces microwave signals off Earth’s surface. The returning radar signals arrive at each antenna slightly out of sync, or phase, from one another. When these signals are combined with other information about the antennas and the satellite’s altitude, scientists will be able to map the height of water on Earth’s surface with never-before-seen clarity. KaRIn encountered an issue earlier this year with one of its subsystems; engineers have now resolved the situation, and the instrument is up and running.
SWOT was jointly developed by NASA and CNES, with contributions from the Canadian Space Agency (CSA) and the UK Space Agency. JPL, which is managed for NASA by Caltech in Pasadena, California, leads the U.S. component of the project. For the flight system payload, NASA provided the KaRIn instrument, a GPS science receiver, a laser retroreflector, a two-beam microwave radiometer, and NASA instrument operations. CNES provided the Doppler Orbitography and Radioposition Integrated by Satellite (DORIS) system, the dual frequency Poseidon altimeter (developed by Thales Alenia Space), the KaRIn radio-frequency subsystem (together with Thales Alenia Space and with support from the UK Space Agency), the satellite platform, and ground operations. CSA provided the KaRIn high-power transmitter assembly. NASA provided the launch vehicle and the agency’s Launch Services Program, based at Kennedy Space Center, managed the associated launch services.
To learn more about SWOT, visit: https://swot.jpl.nasa.gov/
The Earth witnessed a powerful solar storm in nearly six years, causing auroras all over the US, the National Oceanic and Atmospheric Administration (NOAA) said. NOAA had earlier announced moderate G2 storm and G3 conditions between March 23 and 25, but updated it to G4. A severe G4 storm can affect the power grid system with possible widespread voltage control problems; and spacecraft operations with increased possibility of surface charging, and atmospheric drag risk on Low Earth Orbiting (LEO) satellites.
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Five of the sun’s eight major planets will be lined up on the western horizon this Tuesday just after sunset.
The astronomical delight will comprise Mercury, Venus, Mars, Jupiter and Uranus — all in a visible line from the horizon to the crescent moon.
NASA astronomer Bill Cooke says the best way to get a glimpse is to stand somewhere with a clear view of the western horizon.
The planets will stretch from the horizon to halfway up the night sky.
Mercury and Jupiter (the first and fifth planets from the sun) will dip below the horizon around 30 minutes after sunset, that is 7:37 p.m. on Tuesday.
The five-planet spread can be seen anywhere on Earth.
Venus, Mars and Jupiter will be the brightest, particularly Venus, and Mars will be closest to the moon. Mercury and Uranus will be the dimmest, so a set of binoculars will be useful.
Uranus is the rarest seen of the planetary lineup.
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