A NASA spacecraft will fly by one of the most intriguing ocean worlds in our solar system on Thursday.
The Juno spacecraft, which has been orbiting Jupiter since 2016, was scheduled to make its closest approach yet to the moon Europa at 5:36 a.m. ET, flying within 222 miles (358 kilometers) of its icy surface.
Juno will capture some of the highest resolution images ever taken of Europa’s ice shell. The spacecraft also is expected to gather data about the moon’s interior, where a salty ocean is thought to exist.
The ice shell that makes up the moon’s surface is between 10 and 15 miles (16 and 24 kilometers) thick, and the ocean it likely sits on top of is estimated to be 40 to 100 miles (64 to 161 kilometers) deep.
Juno’s Microwave Radiometer instrument will study the ice crust to determine more about its temperature and composition. It’s the first time this kind of information will be collected about Europa’s frozen shell.
The data and images captured by Juno could help inform NASA’s Europa Clipper mission, which will launch in 2024 to perform a dedicated series of 50 flybys around the moon after arriving in 2030. Europa Clipper may be able to help scientists determine whether the interior ocean exists and if the moon — one of many orbiting Jupiter — has the potential to be habitable for life.
This illustration shows Europa Clipper after its arrival at the icy moon, with Jupiter in the background.
NASA
Clipper will eventually transition from an altitude of 1,700 miles (2,735 kilometers) to just 16 miles (26 kilometers) above the moon’s surface. While Juno has largely focused on studying Jupiter, Clipper will be dedicated to observing Europa.
“Europa is such an intriguing Jovian moon, it is the focus of its own future NASA mission,” said Scott Bolton, Juno principal investigator at the Southwest Research Institute in San Antonio in a statement.
“We’re happy to provide data that may help the Europa Clipper team with mission planning, as well as provide new scientific insights into this icy world.”
All of Juno’s instruments will be collecting data during the flyby, including those that can measure the top layers of Europa’s atmosphere and how Europa interacts with Jupiter’s magnetic field. The team is hoping to spot a water plume rising up from cracks in the ice shell. Previous missions have spied plumes of water vapor erupting into space through the ice shell.
“We have the right equipment to do the job, but to capture a plume will require a lot of luck,” Bolton said. “We have to be at the right place at just the right time, but if we are so fortunate, it’s a home run for sure.”
Images taken of Europa during the flyby can be compared with those taken by previous missions to study how the moon’s surface might have changed over the last 20 years.
Europa is about 90% of the size of Earth’s moon, and Juno’s flyby will be the closest a NASA spacecraft has come to it since the Galileo mission flew by in 2000.
Juno is in the extended part of its mission, which was set to end in 2021. The spacecraft is now focused on performing flybys of some of Jupiter’s moons. The spacecraft visited Ganymede in 2021 and will zoom by Io in 2023 and 2024. Its mission is now set to end in 2025.
The Europa maneuver will also shorten Juno’s orbit around Jupiter from 43 to 38 days.
Europa was last visited by NASA's Galileo spacecraft.
NASA
“The relative velocity between spacecraft and moon will be 14.7 miles per second (23.6 kilometers per second), so we are screaming by pretty fast,” said John Bordi, Juno deputy mission manager at NASA’s Jet Propulsion Laboratory in Pasadena, California, in a statement.
“All steps have to go like clockwork to successfully acquire our planned data, because soon after the flyby is complete, the spacecraft needs to be reoriented for our upcoming close approach of Jupiter, which happens only 7½ hours later.”
Their Soyuz MS-21 spacecraft is scheduled to undock from the Prichal module of the ISS at 3:34 a.m. EDT (0734 GMT) and arrive in Kazakhstan, outside of the remote town of Dzhezkazgan, at 6:57 a.m. EDT (1057 GMT or 4:57 a.m. local time), NASA officials(opens in new tab) said.
Live streaming of the undocking and re-entry will be available here at Space.com, via NASA Television(opens in new tab), as well as on the agency's website, app, and social media. Undocking coverage will start at 3:15 a.m. EDT (0715 GMT) and landing coverage at 5:45 a.m. EDT (0945 GMT).
Expedition 67 featured numerous spacewalks to prepare and integrate the European Robotic Arm on the Russian side of the space station, adding on to robotic capabilities used by Canada's Canadarm2 and Japan's Kibo module arm. (One Aug. 17 spacewalk was cut short due to problems with Artemyev's suit, which were resolved before the next excursion.)
During a change of command ceremony on Wednesday (Sept. 28), outgoing Expedition 67 commander Artemyev seemed to allude to the ongoing war. "In the end, our war will end everywhere," he said.
Expedition 68 commander Samantha Cristoforetti is the first European woman to helm the ISS and the fifth European to do so overall. After Artemyev, Matveev and Korsakov depart, she'll share the ISS with NASA astronauts Robert Hines, Jessica Watkins and Kjell Lindgren and Frank Rubio, along with cosmonauts Sergey Prokopyev and Dmitri Petelin.
The next crewed launch to the ISS is expected to happen no sooner than Oct. 5. Crew-5, a mission that will take place aboard a SpaceXCrew Dragon spacecraft, is slated to launch from NASA's Kennedy Space Center in Florida.
The multinational Crew-5 will include a seat for Anna Kikina, the first Russian cosmonaut to fly to the ISS on a commercial American spacecraft, along with NASA's Nicole Mann (who will become the first Native American woman in space), NASA's Josh Cassada and Japan's Koichi Wakata.
Crew-5's launch has been delayed at least two days due to the potential "catastrophic" arrival of Hurricane Ian in Florida, as some officials have termed the storm. NASA has emphasized that the new launch date is tentative and depends on the center's recovery after the hurricane, which has brought Category 4 winds to the state.
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NEW YORK (AP) — A big catch of fish fossils in southern China includes the oldest teeth ever found — and may help scientists learn how our aquatic ancestors got their bite.
The finds offer new clues about a key period of evolution that’s been hard to flesh out because until now scientists haven’t found many fossils from that era. In a series of four studies, published Wednesday in the journal Nature, researchers detail some of their finds, from ancient teeth to never-before-seen species.
The fossils date back to the Silurian period, an important era for life on earth from 443 million years ago to 419 million years ago. Scientists believe our backboned ancestors, who were still swimming around on a watery planet, may have started evolving teeth and jaws around this time.
This let the fish hunt for prey instead of “grubbing around” as bottom feeders, filtering out food from the muck. It also sparked a series of other changes in their anatomy, including different kinds of fins, said Philip Donoghue, a University of Bristol paleontologist and an author on one of the studies.
“It’s just at this interface between the Old World and the New World,” Donoghue said.
But in the past, scientists haven’t found many fossils to show this shift, said Matt Friedman, a University of Michigan paleontologist who was not involved in the research. They’ve been relying on fragments from the time — a chunk of spine here, a bit of scale there.
The fossils from China are expected to fill in some of those gaps as researchers around the world pore over them.
A field team discovered the fossil trove in 2019, Min Zhu, a paleontologist at the Chinese Academy of Sciences who led the research, said in an email. On a rainy day, after a frustrating trip that hadn’t revealed any fossils, researchers explored a pile of rocks near a roadside cliff. When they split one rock open, they found fossilized fish heads looking back at them.
After hauling more rocks back to the lab for examination, the research team wound up with a huge range of fossils that were in great condition for their age.
The most common species in the bunch is a little boomerang-shaped fish that likely used its jaws to scoop up worms, said Per Erik Ahlberg of Sweden’s Uppsala University, an author on one of the studies.
Another fossil shows a sharklike creature with bony armor on its front — an unusual combination. A well-preserved jawless fish offers clues to how ancient fins evolved into arms and legs. While fossil heads for these fish are commonly found, this fossil included the whole body, Donoghue said.
And then there are the teeth. The researchers found bones called tooth whorls with multiple teeth growing on them. The fossils are 14 million years older than any other teeth found from any species — and provide the earliest solid evidence of jaws to date, Zhu said.
Alice Clement, an evolutionary biologist at Australia’s Flinders University who was not involved with the research, said the fossil find is “remarkable” and could rewrite our understanding of this period.
The wide range of fossils suggests there were plenty of toothy creatures swimming around at this time, Clement said in an email, even though it’s the next evolutionary era that is considered the “Age of Fishes.”
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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.
The latest SpaceX launch created a striking view along the U.S. East Coast.
A Falcon 9 rocket launched 52 Starlink spacecraft from Florida's Cape Canaveral Space Force Station Saturday at 7:32 p.m. EDT (2332 GMT). Due to clear conditions across the coastline, it was visible at least as far north as Long Island.
Viewers close by the launchpad witnessed Falcon 9's first stage falling back to Earth for a soft landing atop the SpaceX "droneship" A Shortfall of Gravitas, which was stationed in the Atlantic Ocean.
SpaceX is working on expanding its Starlink megaconstellation, which is now signing up customers in remote places like Antarctica. The company has already sent nearly 3,400 Starlinks into space and has a plan to bring thousands more aloft.
The Falcon 9's upper stage deployed the 52 Starlinks as planned, SpaceX confirmed via Twitter(opens in new tab). Saturday's launch was SpaceX's 43rd orbital mission this year, adding another notch to the company's annual liftoff record. (Its previous high of 31 was set in 2021.)
As SpaceX shoots for 100 launches in 2023, the company plans to bring up Starlink Version 2 (V2) satellites that officials say will be more capable than today's sets. For example, V2 satellites will interface directly with smartphones, including with T-Mobile customers via a project called "Coverage Above and Beyond," SpaceX founder and CEO Elon Musk announced last month.
The clutches of V2 satellites will go into space on board the giant, next-generation Starship vehicle that will be tasked with deep space, moon and Mars missions if the company's plans come to fruition. Starship's first orbital test flight is "highly likely" to occur in November, Musk said recently.
Hundreds of miles away, the Saturday sunset launch generated spectacular photography from professionals and amateurs alike, who shared their images on social media.
INCREDIBLE imagines of the @spacex launch from a C-17 cockpit over the Atlantic Ocean. Thank you for the pictures @mavliocca pic.twitter.com/fSO8zHTlKHSeptember 25, 2022
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A @SpaceX #falcon9 #Starlink launch tonight seen from…NEW YORK!!! WOWWWWWW!!! pic.twitter.com/ykTfLtG2bjSeptember 24, 2022
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Watched the Starlink launchTo cap-off an all-day drive.Totally worth it.Fourteen-hour drive,Just to drive home tomorrow.At least something launched!#haiku #doublehaiku #haikutoyoutoo #rocketlaunchhaiku #rocketlaunch #spacex #starlink pic.twitter.com/OofK7VQZ0LSeptember 25, 2022
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This is what a @SpaceX Falcon 9 rocket launch from Cape Canaveral Florida looks like in New Hampshire pic.twitter.com/0JIcjjN3hHSeptember 24, 2022
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One more shot from last night's #Falcon9 #Starlink launch. It’s the 2nd stage firing after separation; and some glinting off the 1st stage before it returns and lands on #ASOG off the #NC coast. @SpaceX #sobx #spacex #northcarolina @TimBuckleyWX @considercosmos pic.twitter.com/U6yOirTy9uSeptember 25, 2022
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SpaceX Starlink launch spotted from Long Island New York! @CBSNewYork @NBCNewYork @News12LI @LeeGoldbergABC7 pic.twitter.com/fdF3Gjg8npSeptember 24, 2022
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Spectacular post-sunset blastoff of SpaceX’s Falcon 9 rocket and 52 Starlink satellites this evening pic.twitter.com/FU0uk6BR4JSeptember 25, 2022
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United Launch Alliance’s (ULA) Delta IV Heavy rocket made its last West Coast launch on Saturday, carrying out a mission for the National Reconnaissance Office, as it moves one flight closer to retirement. Liftoff of the NRO Launch 91 (NROL-91) mission from Space Launch Complex 6 — at the Vandenberg Space Force Base in California — took place at 3:25 PM PDT (22:25 UTC).
Delta IV Heavy is the most powerful version of the Delta IV, one of two rockets developed under the US Air Force’s Evolved Expendable Launch Vehicle (EELV) program to meet the US Government’s launch needs in the early 21st century. Delta IV, alongside its former competitor-turned-stablemate Atlas V, is now being phased out as a new generation of launchers prepare to take their place.
One of the first steps in that transition was winding down Delta IV operations, with the last Delta IV Medium+ launch taking place in 2019. Delta IV Heavy, with its significantly higher payload capacity, has been kept in service to carry out a handful of national security launches that cannot be performed by Atlas V.
Saturday’s mission, NROL-91, is the final Delta IV launch from California’s Vandenberg Space Force Base, with the rocket’s remaining missions to be executed from the East Coast at Cape Canaveral.
While the National Reconnaissance Office (NRO) keeps details of its satellites classified, the use of a Delta IV Heavy and the fact the launch is taking place from Vandenberg speak volumes. Delta IV Heavy missions carry satellites that have too great a mass for the most powerful Atlas V configurations to place into their destined orbits, indicating the satellite is very heavy, bound for a high orbit, or both. From its location on the West Coast, Vandenberg is an ideal launch site for low Earth orbit (LEO) reconnaissance satellites operating in polar and near-polar orbits, as well as some signals intelligence satellites in elliptical orbits.
Those signals intelligence satellites are typically launched by smaller rockets, so the combination of rocket and launch site suggests that NROL-91 will deploy one of the agency’s large imaging satellites, part of a program identified in previously leaked documents as Crystal. The NRO does not acknowledge the names or types of satellites it operates; instead, they are assigned an NROL designation prior to launch and a numerical USA designation upon reaching orbit. The satellite launched by the NROL-91 mission is expected to take on the designation USA-337, the next available number in this sequence.
Crystal, also known as KH-11, is the successor to a long line of Keyhole reconnaissance satellites that the NRO has operated since the 1960s. Earlier members of this series used small capsules to return photographic film to Earth for development. When it was introduced in 1976, the KH-11 did away with these, instead downlinking images electronically. Since then, the satellites have undergone further upgrades, with several different blocks of spacecraft identified.
NROL-91 will be the nineteenth Crystal satellite to be launched, and the fifth to fly aboard a Delta IV. Previous satellites had flown aboard Titan rockets, initially the Titan III(23)D and Titan III(34)D, and later the Titan IV. The fourteenth KH-11, USA-186, was the payload for the final Titan IV launch and was at the time also expected to be the last Crystal satellite. Failures in the procurement of the successor Future Imagery Architecture (FIA) saw additional Crystal spacecraft constructed, with the first bearing a conspicuous phoenix on its mission patch.
Declassified image taken by a KH-11 satellite, showing Iran’s Semnan launch site (Credit: NRO/US Government)
The Crystal satellites are believed to give the NRO its highest-resolution pictures of the Earth’s surface. They are rumored to resemble the Hubble Space Telescope but pointed toward the Earth, rather than out into space. Most have operated in a Sun-synchronous orbit (SSO) — a particular type of low, near-polar, orbit that allows them to cover most of the Earth’s surface, ensuring they pass over each point at the same local solar time every day, ensuring consistent lighting conditions.
Up until now, the only KH-11 not operated in Sun-synchronous orbit has been USA-290. Deployed by the NROL-71 mission in January 2019, it was the last-but-one KH-11 to launch prior to NROL-91. With an orbital inclination of 73.6 degrees, its orbit is lower than the other operational satellites, meaning that it does not pass as close to the Earth’s poles.
Hazard areas published ahead of the NROL-91 mission, to warn aviators and mariners to stay away from areas where debris from the launch is expected to fall, suggest that this mission is targeting the same inclination as USA-290, rather than the more typical SSO.
With Saturday’s launch marking the last Delta IV flight from Vandenberg, it is not clear whether this also means that NROL-91 was the final launch of a Crystal satellite. The now-abandoned optical element of the FIA program sought to develop a smaller, cheaper high-resolution imaging satellite using more modern technology. Future missions could follow this model, or alternatively, Crystal satellites could continue launching aboard a different rocket — such as Falcon Heavy or ULA’s next-generation vehicle, Vulcan.
Delta IV during rollout from the Horizontal Integration Facility to the launch pad ahead of the NROL-91 mission (Credit: United Launch Alliance)
The Delta IV Heavy is a two-stage expendable launch vehicle, with its first stage consisting of three Common Booster Cores (CBCs). A five-meter-diameter Delta Cryogenic Second Stage (DCSS) sits atop this, with the satellite housed within the payload fairing at the top of the rocket. Both stages of the rocket use cryogenic propellants: liquid hydrogen and liquid oxygen.
First flown in November 2002, Delta IV has made 42 flights prior to the NROL-91 mission, of which 13 have used the Heavy configuration. Other versions of the Delta IV have included the long-retired Delta IV Medium, which consisted of a single CBC, a four-meter DCSS, and several intermediate Medium+ configurations which augmented the Medium’s CBC with two or four solid rocket boosters and could fly with either version of the second stage.
Of the previous 42 missions, Delta IV has completed 41 successfully. Its only failure was the maiden flight of the Delta IV Heavy in 2004, during which all three CBCs shut down prematurely due to cavitation in the propellant lines. The rocket, which was carrying a mass simulator and a pair of small satellites, reached a lower orbit than had been planned.
Each Common Booster Core is powered by an Aerojet Rocketdyne RS-68A engine, capable of providing 312 kilonewtons of thrust at sea level. The upper stage and payload are mounted above the center core, while the others are attached to the port and starboard sides of the vehicle.
While the CBCs provide an initial boost through Earth’s atmosphere, the DCSS is responsible for completing the insertion of the NROL-91 payload into orbit. It is powered by a single cryogenic engine from Aerojet Rocketdyne’s RL10 family.
The NROL-91 payload, encapsulated in its fairing, is installed atop the rocket (Credit: United Launch Alliance)
Although the Delta IV program is being wound down, Saturday’s launch marks the first flight of a new engine variant, the RL10C-2-1, which replaces the RL10B-2 used on previous Delta IV missions. The RL10C was developed to reduce production costs by increasing standardization between the RL10A engines used on Atlas and the RL10Bs used on Delta. The RL10C-2-1 is expected to be used on the remaining Delta IV launches, as well as future Space Launch System (SLS) missions with the Interim Cryogenic Propulsion Stage (ICPS), which is derived from DCSS.
For NROL-91, Delta IV flew with a bisector, or two-part, payload fairing made of composite materials. This is one of two fairings that can be flown on Delta IV Heavy and has been used on previous Crystal launches. Most other national security missions have used a trisector — three-part — design of metallic construction, derived from a fairing previously used on the Titan IV.
Delta IV launches from Vandenberg Space Force Base take place from Space Launch Complex 6 (SLC-6), and with Saturday’s launch marking the last Delta IV mission from Vandenberg, this is expected to be the last time the complex is used in its current configuration. With no launch providers having made public plans to use SLC-6 going forward, the complex will likely be decommissioned and mothballed in the immediate future, closing another chapter in the eventful history of this launch pad.
SLC-6 was originally built in the 1960s but did not see a launch until 1995, after the first two programs that were meant to use it were both canceled at late stages of development. The first of these was the Titan IIIM, an upgraded version of the Titan III rocket that was to have launched the Manned Orbiting Laboratory (MOL), a crewed reconnaissance platform developed by the US Air Force. Construction of the launch complex began in March 1966 and was nearing completion when MOL was abandoned in 1969.
After MOL’s cancellation, SLC-6 was selected as a launch site for Space Shuttle missions to polar orbit. Such orbits could not safely be reached from the Kennedy Space Center, so a launch pad on the West Coast was deemed necessary for planned military Shuttle missions. After the pad had undergone extensive modifications, the orbiter Enterprise was used for fit checks in early 1985, and the complex was accepted into service later that year.
Space Shuttle Enterprise at SLC-6 in February 1985 (Credit: US Air Force)
The loss of Challenger in 1986, and the reviews of the Space Shuttle program that followed, saw plans for polar orbit missions canceled. At the time of the accident, the first launch from SLC-6 had been a few months away, with Discovery slated to deploy an experimental reconnaissance satellite during the STS-62-A mission. With Shuttle launches restricted to the Kennedy Space Center, SLC-6 was again placed into mothballs.
It would not be until the 1990s, when Lockheed selected SLC-6 for its Lockheed Launch Vehicle (LLV) rocket, later named Athena, that SLC-6 would finally host a launch. Four missions, two using the Athena I configuration followed by two using the Athena II configuration, were flown between August 1995 and September 1999. These launches did little to help SLC-6’s cursed reputation: the first and third missions failed to achieve orbit, while the second successfully deployed NASA’s Lewis satellite only for the spacecraft to malfunction and lose power less than three days later.
In a strange twist of fate, NROL-91 lifted off 23 years to the day after the fourth and final Athena launch from SLC-6, which successfully deployed a commercial Ikonos imaging satellite.
Athena was far smaller than the rockets that SLC-6 had been designed to serve, but Boeing’s need to find a West Coast launch site for its Delta IV rocket would bring the pad a new lease of life. The first of 10 Delta IV flights from the pad — including the NROL-91 mission — took place in June 2006 when a Delta IV Medium+(4,2) flew the NROL-22 mission, deploying a signals intelligence satellite.
A Delta IV Medium+(5,2) launches from SLC-6 in 2012 (Credit: United Launch Alliance)
The Delta IV Medium and Medium+(4,2) each made a single flight from SLC-6, while the Medium+(5,2), with a five-meter upper stage, made three flights from the pad. Including Saturday’s launch, the Delta IV Heavy configuration has used the pad five times, with all of its launches deploying Crystal satellites.
Overall, NROL-91 is the fourteenth launch to take place from SLC-6. In keeping with previous Delta IV missions, the rocket has been assigned a flight number, or Delta number, which indicates its place in the history of the Delta series of rockets. These numbers have counted — with a handful of exceptions — up from the first Thor-Delta launch in 1960. While the Delta IV is a completely different rocket even compared to the Delta II that retired a few years ago, the tradition has been maintained, and the rocket that performed Saturday’s launch is be Delta 387.
Saturday’s countdown saw the Delta IV rocket filled with cryogenic propellants while critical systems are powered up and tested as the count proceeds toward liftoff. The ignition sequence for the three RS-68A engines began seven seconds before liftoff with the starboard booster before the port and center cores ignited two seconds later. This staggered start helps mitigate the effects of hydrogen build-up around the base of the vehicle, which has scorched the rocket or set fire to insulation on previous missions.
Liftoff occurred at T0. After Delta IV cleared the tower, it began a series of pitch and yaw maneuvers to attain its planned orbit, with the first of these beginning about 10 seconds after liftoff. Flying downrange, Delta 387 throttled down its center core to its partial thrust setting. It passed through the area of maximum dynamic pressure, or Max-Q, 89.6 seconds into the mission and reached Mach 1, the speed of sound, about 1.4 seconds later.
With the side boosters firing at full thrust and the center core operating in partial thrust mode, the port and starboard cores depleted their propellant first. As they approached burnout, they began to throttle back before shutting down at the three-minute and 56.3-second mark in the mission. The spent boosters separated 2.2 seconds later, falling away from the center core as it throttled up to full thrust.
Booster Engine Cutoff (BECO), the end of first-stage flight, occurs five minutes and 37 seconds after liftoff. Six and a half seconds after BECO, the first stage separates and the DCSS begins preparations to ignite its RL10C-2-1 engine, including deployment of the extendible nozzle. RL10 ignition occurs under 13 seconds after stage separation. 10 seconds into the burn, Delta IV’s payload fairing separates, and the NROL-91 payload is exposed to space for the first time.
With fairing separation complete, NRO missions tend to enter a news blackout, with further mission details remaining classified other than a brief press release to confirm the successful deployment of the satellite. The DCSS can be expected to continue firing its engine for about 12 minutes as it inserts the satellite directly into orbit. Spacecraft separation will occur shortly afterward, before the DCSS restarts its engine for a deorbit burn.
With Delta 387’s mission complete, only two more Delta IV missions remain to be launched. These are both slated to fly from the Cape Canaveral Space Force Station, with the NROL-68 mission slated for liftoff early next year and NROL-70 to follow in the first months of 2024. The first flight of Vulcan, ULA’s replacement for both its Delta IV and Atlas V rockets, is also currently scheduled for the first half of next year.
While these milestone launches are still some months away, ULA will be back in action on Friday with an Atlas V slated to deploy a pair of communications satellites for commercial operator SES. This is one of three Atlas V launches currently slated for the tail end of 2022, with deployment of JPSS-2, a military weather satellite, slated for the start of November and the US Space Force 51 (USSF-51) mission tracking no earlier than December.
(Lead photo: Delta IV Heavy and NROL-91 ascend toward orbit. Credit: Jack Beyer for NSF)
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NASA on Monday will attempt a feat humanity has never before accomplished: deliberately smacking a spacecraft into an asteroid to slightly deflect its orbit, in a key test of our ability to stop cosmic objects from devastating life on Earth.
The Double Asteroid Redirection Test (DART) spaceship launched from California last November and is fast approaching its target, which it will strike at roughly 14,000 miles per hour (23,000 kph).
To be sure, neither the asteroid moonlet Dimorphos, nor the big brother it orbits, called Didymos, pose any threat as the pair loop the Sun, passing some seven million miles from Earth at nearest approach.
But the experiment is one NASA has deemed important to carry out before an actual need is discovered.
"This is an exciting time, not only for the agency, but in space history and in the history of humankind quite frankly," Lindley Johnson, a planetary defense officer for NASA told reporters in a briefing Thursday.
If all goes to plan, impact between the car-sized spacecraft, and the 530-foot (160 meters, or two Statues of Liberty) asteroid should take place on September 26 at 7:14pm Eastern Time (2314 GMT), and can be followed on a NASA livestream.
By striking Dimorphos head on, NASA hopes to push it into a smaller orbit, shaving ten minutes off the time it takes to encircle Didymos, which is currently 11 hours and 55 minutes—a change that will be detected by ground telescopes in the days that follow.
The proof-of-concept experiment will make a reality what has before only been attempted in science fiction—notably films such as "Armageddon" and "Don't Look Up."
Technically challenging
As the craft propels itself through space, flying autonomously for the mission's final phase like a self-guided missile, its main camera system, called DRACO, will start to beam down the very first pictures of Dimorphos.
"It's going to start off as a little point of light and then eventually it's going to zoom and fill the whole entire field of view," said Nancy Chabot of Johns Hopkins Applied Physics Laboratory (APL), which hosts mission control in a recent briefing.
"These images will continue until they don't," added the planetary scientist.
Minutes later, a toaster-sized satellite called LICIACube, which separated from DART a couple of weeks earlier, will make a close pass of the site to capture images of the collision and the ejecta—the pulverized rock thrown off by impact.
LICIACube's picture will be sent back in the weeks and months that follow.
Also watching the event: an array of telescopes, both on Earth and in space—including the recently operational James Webb—which might be able to see a brightening cloud of dust.
Finally, a full picture of what the system looks like will be revealed when a European Space Agency mission four years down the line called Hera arrives to survey Dimorphos's surface and measure its mass, which scientists can only guess at currently.
Being prepared
Very few of the billions of asteroids and comets in our solar system are considered potentially hazardous to our planet, and none in the next hundred or so years.
But "I guarantee to you that if you wait long enough, there will be an object," said Thomas Zurbuchen, NASA's chief scientist.
We know that from the geological record—for example, the six-mile wide Chicxulub asteroid struck Earth 66 million years ago, plunging the world into a long winter that led to the mass extinction of the dinosaurs along with 75 percent of species.
An asteroid the size of Dimorphos, by contrast, would only cause a regional impact, such as devastating a city, albeit with a greater force than any nuclear bomb in history.
Scientists are also hoping to glean valuable new information that can inform them about the nature of asteroids more generally.
How much momentum DART imparts on Dimorphos will depend on whether the asteroid is solid rock, or more like a "rubbish pile" of boulders bound by mutual gravity, a property that's not yet known.
We also don't know its actual shape: whether it's more like a dog bone or a donut, but NASA engineers are confident DART's SmartNav guidance system will hit its target.
If it misses, NASA will have another shot in two years' time, with the spaceship containing just enough fuel for another pass.
But if it succeeds, then it's a first step towards a world capable of defending itself from a future existential threat, said Chabot.
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The NASA InSight Lander has “heard” and detected the vibrations of four space rocks as they slammed into Mars over the past two years.
It’s the first time a mission has picked up both seismic and acoustic waves from an impact on Mars, and InSight’s first detection of impacts since landing on the red planet in 2018.
Fortunately, InSight wasn’t in the path of these meteoroids, the name for space rocks before they hit the ground. The impacts ranged from 53 to 180 miles (85 to 290 kilometers) away from the stationary lander’s position in Mars’ Elysium Planitia, a smooth plain that’s just north of its equator.
A meteoroid impact formed these craters on Mars in September 2021. This image, taken by the Mars Reconnaissance Orbiter, enhances the displaced dust and soil in blue to make details more visible.
NASA/JPL-Caltech/University of Arizona
A meteoroid hit the Martian atmosphere on September 5, 2021, and then exploded into at least three shards, each one leaving behind a crater on the red planet’s surface.
The Mars Reconnaissance Orbiter then flew over the site to confirm where the meteoroid landed, spotting three darkened areas. The orbiter’s color imager, the High-Resolution Imaging Science Experiment camera, took detailed close-ups of the craters.
Researchers shared their findings about the new craters in a study that published Monday in the journal Nature Geoscience.
“After three years of InSight waiting to detect an impact, those craters looked beautiful,” said study coauthor Ingrid Daubar, assistant professor of Earth, environmental, and planetary sciences at Brown University in Providence, Rhode Island, in a statement.
Data from InSight also revealed three other similar impacts, one on May 27, 2020, and two additional ones in 2021 on February 18 and August 31.
The agency released a recording of a Martian meteoroid impact Monday. During the clip, listen for a very science fiction-sounding “bloop” three times as the space rock enters the atmosphere, explodes into pieces and hits the surface.
Scientists have actually questioned why more impacts haven’t been detected on Mars because the planet is located next to our solar system’s main asteroid belt, where many space rocks emerge to hit the Martian surface. The Martian atmosphere only has 1% of the thickness of Earth’s atmosphere, meaning that more meteoroids zip through it without disintegrating.
During its time on Mars, InSight has used its seismometer to detect more than 1,300 marsquakes, which take place when the Martian subsurface cracks due to pressure and heat. The sensitive instrument can detect seismic waves that occur thousands of miles away from InSight’s location – but the September 2021 event is the first time scientists used the waves to confirm an impact.
It’s possible the noise of the Martian wind or seasonal changes that occur in the atmosphere hid the additional impacts . Now that researchers understand what an impact’s seismic signature looks like, they expect to find more when they comb through InSight’s data from the last four years.
The meteoroid impacts create quakes with a magnitude of 2.0 or less. So far, InSight’s largest detected quake was a magnitude 5 event in May.
Impact craters help scientists understand the age of a planet’s surface. Researchers can also determine how many of the craters formed early on in the tumultuous history of the solar system.
“Impacts are the clocks of the solar system,” said lead author Raphael Garcia, academic researcher at the Institut Supérieur de l’Aéronautique et de l’Espace in Toulouse, France, in a statement. “We need to know the impact rate today to estimate the age of different surfaces.”
Studying InSight’s data can provide researchers with a way to analyze the trajectory and size of the shock wave produced when the meteoroid enters the atmosphere as well as once it hits the ground.
“We’re learning more about the impact process itself,” Garcia said. “We can match different sizes of craters to specific seismic and acoustic waves now.”
InSight’s mission is coming to an end as dust builds up on its solar panels and reduces its power. Eventually, the spacecraft will shut down, but the team is unsure of when that will happen.
The most recent readings have suggested it could shut down between this coming October and January 2023.
Until then, the spacecraft still has a chance to add to its research portfolio and stunning collection of discoveries on Mars.
The James Webb Space Telescope is still snapping its first pictures of Solar System planets, and the latest batch could be particularly useful. NASA and the ESA have shared early images of Mars, taken on September 5th, that promise new insights into the planet's atmosphere. Data from the near-infrared camera (NIRCam) is already offering a few surprises. For starters, the giant Hellas Basin is oddly darker than nearby areas at the hottest time of the day, NASA's Giuliano Liuzzi and Space.comnoted — higher air pressure at the basin's lower altitude has suppressed thermal emissions.
The JWST imagery also gave space agencies an opportunity to share Mars' near-infrared atmospheric composition using the telescope's onboard spectrograph array. The spectroscopic 'map' (pictured at middle) shows the planet absorbing carbon dioxide at several different wavelengths, and also shows the presences of carbon monoxide and water. A future research paper will provide more detail about the Martian air's chemistry.
It was particularly tricky to record the images. Mars is one of the brightest objects the James Webb telescope can see — a problem for an observatory designed to study the most distant objects in the universe. Researchers countered this by capturing very short exposures and using special techniques to analyze the findings.
This is only the initial wave of pictures and data. It will take more observations to reveal more about Mars. However, the spectral info already hints at more information about the planet's materials. Liuzzi also thinks JWST studies could settle disputes over the presence of methane on Mars, potentially signalling that the Red Planet harbored life in its distant past.
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