Meteor showers are among the most beautiful phenomena to brighten Earth's sky, but could the fast moving space rocks that accompany major events threaten or delay future Artemis moon missions as NASA and its partners plan for a lunar landing attempt?

NASA estimates that approximately 48.5 tons (44,000 kilograms) of naturally occurring space debris falls into Earth's atmosphere each day. These fragments range in size from tiny micrometeoroids a fraction of a millimeter in diameter to larger particles that create spectacular shooting stars and fireballs as they burn up during atmospheric entry.

The space around Earth gets even more crowded during meteor showers, as Earth careens through one of the many debris streams continuously shed by asteroids and comets as they make lazy circuits around the sun.

Can micrometeoroids endanger a spacecraft?

Micrometeoroids travel through space at hypervelocity speeds averaging 22,000 miles per hour (34,405 kilometers per hour), according to NASA. At that pace, even a tiny micrometeoroid has the ability to impart a significant kinetic blow upon striking a spacecraft en route to the moon, with potentially disastrous results for the astronaut crew inside.

Fast moving debris has the potential to penetrate or deform a spacecraft's hull, damaging critical systems or even triggering a catastrophic rupture. There is also the risk that a micrometeoroid could punch a hole in one of the heat-resistant outer tiles on the Orion spacecraft, NASA's crew capsule for the agency's Artemis moon missions, undermining its ability to survive the intense furnace of reentry, per NASA.

The Chinese Space Agency was given a stark reminder of the dangers posed by space debris in November last year, when taikonaut Chen Dong discovered a crack in the viewport of his Shenzhou-20 spacecraft, which forced the three person crew to use a different return craft for their journey.

Thankfully, modern spacecraft such as the Orion capsule used for NASA's Artemis moon missions have been designed to mitigate the threat posed by micrometeoroid impacts, in so far as is possible. "Orion spacecraft material selection and thicknesses have been optimized for [micrometeoroid and orbital debris] (MMOD) protection and risk balancing," said Mike Heckwolf, Orion crew and mission risk integrator at Lockheed Martin's in an email to Space.com.

"Hypervelocity impact testing is conducted to confirm impact physics, to characterize damage survivability, and verify performance of the Orion spacecraft MMOD design," continued Heckwolf. "The Artemis mission trajectory and Orion flight attitude are carefully assessed to minimize MMOD risk."

Meteor storms and outbursts raise the stakes

As is so often the case, the best protection against disaster is prevention. NASA and its partners regularly perform risk assessments on the micrometeoroid environment both ahead of and during a mission, though only the most severe events present cause for concern.

"Only a handful of the more than 1,000 known meteor showers exceed the sporadic background by more than 5% — like the Geminids, for example — [which is] the strongest annual shower," explained NASA Meteoroid Environments Office lead Bill Cooke, in an email to Space.com.

The major mission disrupters come in the form of meteor storms and outbursts, which see a dramatic increase in the quantity of interplanetary debris choking the Earth-moon environment. "If a major meteor shower outburst or storm is forecast during a mission or crew activity, the mission would be delayed or the crew kept inside until the outburst or storm is over," said Cooke.

Storm forecasts on the horizon

Hundreds or even thousands of shooting stars may be seen burning through Earth's skies each hour during one of these intense meteor storm events, though the distance separating micrometeoroids in space would still likely be measured on the order of miles.

Thankfully, forecasters are able to predict when meteor storms or outbursts are likely to occur, many years before they brighten our skies.

"Currently there are four possible meteor outbursts predicted to occur during the next ten years," said Robert Lunsford of the American Meteor Society in an email to Space.com. "These involve the Perseids (August 12, 2028) and the Leonids (November 17, 2033 and November 18 & 19, 2034. The strongest of these appears to be the Perseid outburst, which could range from 500 to 1000 meteors per hour."

Artemis 4 — NASA's first crewed mission to the lunar surface since the Apollo-era — is currently slated to launch in early 2028, though it's possible that an unforeseen delay could push that window backwards.

In the unlikely event that Artemis 4, or any subsequent mission's launch should fall close to a projected outburst, they could well be delayed in the name of safety, and it wouldn't be the first time that NASA has postponed a mission to ensure its success in the face of a micrometeoroid risk.

As noted by Cooke, the STS-51 space shuttle Discovery mission was delayed in 1993 to avoid the peak of the Perseid meteor shower, and an uncrewed science mission out of Vandenberg Space Force Base was delayed in 2000 to sidestep a Leonid meteor shower outburst.

The agency also has protocols in place to reduce the threat of micrometeoroid impacts to its flagship orbital telescopes during major meteor showers. The James Webb Space Telescope and Hubble Space Telescope, for example, routinely point their large primary mirrors away from meteor showers radiants (the points in space from which they originate) during intense events.

NASA's strategies for dealing with micrometeoroid impacts will be further tested in the coming decade, as the agency and its partners seek to establish a permanent presence on and around Earth's moon.

Would you like to know more? Then be sure to read our explainer article on NASA's Artemis Program, along with the latest on the agency's upcoming Artemis 3 mission to test vital technologies for the Artemis 4 landing near the lunar south pole.

The first emergency operation in the history of China's human spaceflight program came to an end on Monday (Jan. 19) when an uncrewed Shenzhou 20 capsule parachuted into the Dongfeng landing site in north China's Inner Mongolia Autonomous Region.

The spacecraft had spent 270 days in orbit, docked for nine months to the country's Tiangong space station.

And that wasn't the plan.

Delayed due to damage from a space-junk strike

Shenzhou 20's original return date had been delayed due to concerns over tiny cracks found in the craft's viewport window. That damage was thought to be caused by a strike by space debris.

On-site inspection of the returned capsule on Monday found that its exterior was "generally normal" and the items secured inside the vessel were in good condition, the China National Space Administration (CNSA) said.

The recovery crew quickly took steps to protect the damaged porthole on the return capsule upon its touchdown on terra firma. That action was driven by the need for post-landing assessment work about the damage the Shenzhou 20 capsule suffered in space.

Emergency mission

The Shenzhou 20 incident sparked an emergency mission to launch the uncrewed Shenzhou 22 spacecraft to Tiangong on Nov. 24. Now docked to the orbiting facility, that vehicle will serve the currently orbiting Shenzhou 21 crew on their expected return at the conclusion of their six-month mission later this year.

The Shenzhou 20 crew returned to Earth on Nov. 14 aboard the Shenzhou 21 capsule, after Chinese space officials deemed it too risky to fly them down on the damaged Shenzhou 20 spacecraft.

"Furthermore, in conjunction with the emergency launch of the Shenzhou 22 spacecraft, a porthole crack repair device was expedited and sent to the launch site," CNSA officials said. "Astronauts installed it inside the Shenzhou 20 capsule, effectively improving the spacecraft's heat protection and sealing capabilities during reentry."

Unique factors

The state-run China Central Television (CCTV) reported that Xu Peng, the on-site commander at the Shenzhou 20 capsule touchdown site, said that this return to Earth was unique in a number of ways.

"This marks the first time the Dongfeng Landing Site has carried out a spaceship recovery mission during the coldest season of the year, with cold weather posing a test for both our search and rescue teams and equipment," Xu said. "We made special cold-protection preparations in advance to ensure that both personnel and the equipment remained in good condition throughout the mission."

Xu also noted another unique factor of this uncrewed return recovery operation: Ground recovery teams made use of new capsule recovery methods, such as drones and other high-tech equipment.

"Adjustments were made to our recovery forces," Xu said. "The helicopter unit did not participate in this mission, and the drone and unmanned ground vehicle units made their debut. This new model, combining unmanned search equipment with ground personnel, was applied in the recovery of the uncrewed capsule."

Landing parachute

Furthermore, Xu added that, as the Shenzhou 20 return capsule came down without astronauts, there was no onboard crew member to manually separate the landing parachute.

"As a result, the main parachute did not automatically detach upon landing, and in strong winds, it could have dragged the return capsule along the ground. This requires our ground personnel to reach the landing point and cut the parachute as quickly as possible," Xu said.

One of the items carried in the uncrewed Shenzhou 20 capsule was a retired spacewalking spacesuit. That spacesuit was used for more than four years in orbit, far exceeding its original design life, reported CCTV. Over that time, the suit had supported 11 Chinese astronauts across eight crewed missions, enabling 20 successful spacewalks to be conducted.

Heated discussions

The Shenzhou 20 crew inspected their vehicle after it sustained damage in orbit. They observed that the porthole had an unexpected mark on the edge of the outermost glass — a triangular shape, about two centimeters long, according to a report by the state-run Xinhua news agency.

The Shenzhou capsule porthole consists of three layers of glass. "The outermost layer is a heat-resistant window, which can withstand the high-temperature ablation caused by the spacecraft's high-speed motion and intense friction with the air during its reentry into the atmosphere," the Xinhua report stated.

"The middle layer is a pressure-bearing window, and the inner layer is a protective window, which can ensure the airtightness of the cabin and the stability of the spacecraft's structure, but their heat resistance is less than half that of the heat-resistant window," reported Xinhua.

A Shenzhou 20 "Problem Analysis and Safety Assessment Report" was written based on laboratory tests that addressed a key question: Can a cracked heat shield withstand the extreme environment of atmospheric reentry? The consensus? "Life comes first, and safety comes first."

Rolling backup mode

Since the Shenzhou 12 mission, China's human spaceflight program has adopted a "rolling backup mode" of "one launch, one backup."

But, as noted in the Xinhua report, that "standby" spacecraft mode has never actually been needed. "This time, the standby status unexpectedly turned into emergency combat, and the tests followed one after another," Xinhua reported.

Actions taken — from the crew report, followed by ground worry and appraisal, to launch of the uncrewed Shenzhou 22 — was completed in 16 days.

Meanwhile, a Shenzhou 23 spacecraft has arrived at China's Jiuquan Satellite Launch Center, and its Long March 2F Y23 booster is about to be shipped, the CNSA pointed out.

"With the return of the Shenzhou 20 spacecraft, the main tasks of this emergency space operation for the Chinese space station have been successfully completed," CNSA officials stated.

The fate of Spain's newest communications satellite is up in the air.

SpainSat NG-2 was the second military communications satellite launched for Spain last year. It was on its way to an operational location in geostationary orbit when it was struck by a "space particle," according to a Jan. 2 statement from Indra Group, the majority stakeholder of Hisdesat, which owns and operates the SpainSat NG-2 satellite on behalf of Spain’s Ministry of Defense.

SpainSat NG-2 launched on a SpaceX Falcon 9 rocket from Cape Canaveral Space Force Station in Florida on Oct. 23. The satellite was meant to complete a secure communications constellation duo, but now may not get that chance.

SpainSat NG-1 also launched on a Falcon 9, heading to orbit last January. The Airbus-built 2-billion-euro ($2.3 billion USD) pair of satellites was designed as an "advanced government communications system in Europe," according to Airbus. Since its launch in October, SpainSat NG-2 has been slowly making its way toward geostationary orbit, but its status since the collision remains unknown.

According to Indra Group, the space particle impact occurred at about 31,000 miles (50,000 kilometers) in altitude. That's higher than geostationary orbit, which lies 22,236 miles (35,786 km) above Earth.

"Hisdesat implemented a contingency plan to ensure that the Ministry of Defense and other clients are not affected," Indra Group said in the statement.

"The technical team is analyzing the available data to determine the extent of the damage," the statement continued. "If necessary, SpainSat NG-2 will be replaced as soon as possible."

SpaceX's astronaut taxi may get a shield upgrade.

NASA is considering asking SpaceX to boost the existing shielding on the company's Crew Dragon capsule after something blasted a tiny hole in a Russian Soyuz spacecraft in December 2022, agency officials said during a press conference on Wednesday (Jan. 25).  

The strike, likely by a micrometeoroid, occurred while the Soyuz was docked to the International Space Station (ISS), where it remains today. The impact caused a coolant leak that rendered the Soyuz vehicle, known as MS-22, unsafe to carry astronauts home except in case of emergency. 

So Russia's space agency Roscosmos has decided to launch an empty Soyuz on Feb. 20 to bring the three MS-22 crewmembers back to Earth. That journey is expected to occur in September, about six months after the trio's original planned homecoming date.

Related: International Space Station: Live updates

The discussions with SpaceX are in the early stages; the shield-boost idea was just raised Tuesday (Jan. 24) at a regularly scheduled commercial crew meeting, said Steve Stich, program manager for NASA's Commercial Crew Program. 

"We started to talk about a little bit — Is there anything we can do now?" he said in Wednesday's press conference, which provided an update on ISS operations and the next SpaceX mission to the station, Crew-6, which is scheduled to lift off on Feb. 26.

SpaceX's Sarah Walker said the company is aligned with NASA's goals. Walker, who is director of Dragon mission management, also emphasized that all analyses to date show that the Crew Dragon docked at the ISS now, called Endurance, is doing just fine.

"The Dragon systems are healthy and operating nominally," Walker said during Wednesday's press conference of Endurance, which launched to the orbiting lab this past October on SpaceX's Crew-5 mission for NASA.

Roscosmos officials say that the damaged Soyuz MS-22 could accommodate two of its three crewmembers if an emergency necessitated the evacuation of the ISS. The ride back to Earth would be warm with no coolant, however. The two who would make that trip on MS-22 are cosmonauts Sergey Prokopyev and Dmitry Petelin. The third crewmember, NASA astronaut Frank Rubio, would join the four Crew-5 astronauts on Endurance in a "lifeboat" scenario.

NASA considered numerous safety questions before approving Rubio's seat liner for a move from Soyuz MS-22 to Endurance, agency officials said Wednesday, including making sure there was enough oxygen in the SpaceX craft, that carbon dioxide could be minimized and that landing would happen safely. 

SpaceX originally designed the Crew Dragon vehicle to carry as many as seven people. But Endurance was outfitted with just four seats, and securing Rubio as an unexpected fifth crewmember required clever repurposing of supplies in orbit.

"We looked at taking some cargo straps from, actually, the CRS-26 vehicle," Stich said, referring to a SpaceX Dragon cargo capsule that's docked to the ISS right now. "We were able to put the straps over Frank and then the seat liner, if we needed to, and then secure him to the floor of the Dragon," he added.

The empty Soyuz vehicle, known as MS-23, will launch during a stretch that NASA associate administrator Kathy Lueders called "one of the busiest increments in the history of station" during Wednesday's press conference.

Among the many scheduled crewed launches to the ISS in the first half of 2022 are Crew Flight Test, the first astronaut mission for Boeing's Starliner capsule; SpaceX's Crew-6; and Ax-2, the second crewed mission to the orbiting lab by private company Axiom Space. 

Crew-6 will see the Dragon Endeavour fly the first United Arab Emirates astronaut on a long-duration mission (Sultan Al Neyadi). The other crewmates are NASA astronauts Stephen Bowen and Warren Hoburg and Russian cosmonaut Andrey Fedyaev.

The Soyuz MS-22 crew will also see their time in space doubled to a year in orbit as they await the launch of a crewed Soyuz later in 2023 to relieve their duties on the ISS. The current forecast for MS-22's landing is in late September. 

Elizabeth Howell is the co-author of "Why Am I Taller?" (ECW Press, 2022; with Canadian astronaut Dave Williams), a book about space medicine. Follow her on Twitter @howellspace. Follow us on Twitter @Spacedotcom or Facebook.

A newly released photograph from NASA's Lunar Reconnaissance Orbiter (LRO) was taken at the same moment that the spacecraft was struck by a meteoroid traveling faster than a bullet, the agency announced this week.

The collision did not harm the health or operation of the spacecraft, and NASA scientists only became aware of the incident because of the picture, which looks as though it was taken by a very jittery camera.  

"The meteoroid was traveling much faster than a speeding bullet," Mark Robinson, principal investigator for the LRO camera system, said in a statement from the agency. "In this case, [the LRO camera] did not dodge a speeding bullet, but rather survived a speeding bullet!" [Latest Moon Photos from NASA's Lunar Reconnaissance Orbiter]

The image perplexed LRO scientists at first, because LRO normally sends back "beautifully clear images of the lunar surface," according to the statement. The LRO camera (LROC) system consists of three cameras, including two narrow-angle cameras (NACs) that scan the surface right to left, and then stack those images together to create larger images, similar to the way a line printer works. The motion of the spacecraft moves the camera forward, so that it can slowly scan the entire lunar surface. The image in question features one very smeared right-to-left band that suggests the camera was jerked while scanning the lunar surface.

When the wobbly image appeared, scientists ruled out other potential causes (such as internal vibrations) because this blurring effect was not seen in the images from the other cameras taken at the same time. The team concluded that it must have been a small meteoroid that struck the camera. The scientists wanted to know how fast the meteor was traveling when it hit the camera, based on how much the camera moved (determined by the degree of distortion picked up in the image). It just so happened that they already had a piece of computer software that could help them do just that.

Before LRO launched, NASA commissioned a computer program to show how the cameras would fare during launch, when the payload would undergo intense vibration and lots of stress. The team used that same program to try to re-create the distorted image, and figure out how large the meteorite was and how fast it was traveling. They concluded that the space rock must have been about half the size of a pinhead (0.03 inches, or 0.8 millimeters), traveling at a velocity of about 4.3 miles per second (7 kilometers per second), with the "density of an ordinary chondrite meteorite," or 0.09 lbs. per cubic inch (2.7 grams per cubic centimeter), according to the statement.

The collision occurred on Oct. 13, 2014, but because the issue didn't interrupt the mission in any way, the team is only now reporting the incident as "a fascinating example of how engineering data can be used, in ways not previously anticipated, to understand what is happening to the spacecraft over 236,000 miles (380,000 kilometers) from the Earth," John Keller, LRO project scientist from NASA's Goddard Space Flight Center, said in the statement.

"A meteoroid impact on the LROC NAC reminds us that LRO is constantly exposed to the hazards of space," Noah Petro, deputy project scientist for LRO, said in the statement. "And as we continue to explore the moon, it reminds us of the precious nature of the data being returned."

Following the release of the LRO image, Alex Parker, a planetary scientist at the Southwest Research Institute in Colorado who is not involved with LRO, converted the vibrations of the camera into sound waves, recreating what it might have sounded like when the micrometeoroid struck the spacecraft (although the lack of an atmosphere around LRO means soundwaves have nothing to travel through). Young posted the sound file he created on Twitter.

Follow Calla Cofield @callacofield. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.

In this historical photo from the U.S. space agency, an overhead view of the Skylab Orbital Workshop in Earth orbit as photographed from the Skylab 4 Command and Service Modules (CSM) during the final fly-around by the CSM on Feb. 8, 1974, before returning home. The space station is contrasted against the pale blue Earth.

During launch on May 14, 1973, some 63 seconds into flight, the micrometeor shield on the Orbital Workshop (OWS) experienced a failure that caused it to be caught up in the supersonic air flow during ascent. This ripped the shield from the OWS and damaged the tie downs that secured one of the solar array systems.

Complete loss of one of the solar arrays happened at 593 seconds when the exhaust plume from the S-II's separation rockets impacted the partially deployed solar array system. Without the micrometeoroid shield that was to protect against solar heating as well, temperatures inside the OWS rose to 126 degrees fahrenheit.

[Far Out Space Station Concepts by NASA (Gallery )]

The gold "parasol" clearly visible in the photo, was designed to replace the missing micrometeoroid shield, protecting the workshop against solar heating. The replacement solar shield was deployed by the Skylab I crew. This enabled the Skylab Orbital Workshop to fulfill all its mission objects serving as home to additional crews before being deorbited in 1978.

Each weekday, SPACE.com looks back at the history of spaceflight through photos (archive).