Blogarchiv
Raumfahrt - SLS rocket Artemis 1 mission -Update-15

7.12.2022

NASA capsule flies over Apollo landing sites, heads home

NASA's Orion capsule is on its way home from the moon to wrap up a three-week test flight

artemismond-j

NASA's Orion spacecraft beamed back close-up photos of the moon and Earth on Monday, Dec. 5, 2022. The crew capsule and its test dummies will aim for a Pacific Ocean splashdown on Sunday, Dec. 11, 2022, off the coast of San Diego after a three-week test flight, setting the stage for astronauts on the next flight in a couple years. NASA

CAPE CANAVERAL, Fla. -- NASA’s Orion capsule and its test dummies swooped one last time around the moon Monday, flying over a couple Apollo landing sites before heading home.

Orion will aim for a Pacific splashdown Sunday off San Diego, setting the stage for astronauts on the next flight in a couple years.

The capsule passed within 80 miles (130 kilometers) of the far side of the moon, using the lunar gravity as a slingshot for the 237,000-mile (380,000-kilometer) ride back to Earth. It spent a week in a wide, sweeping lunar orbit.

Once emerging from behind the moon and regaining communication with flight controllers in Houston, Orion beamed back photos of a close-up moon and a crescent Earth — Earthrise — in the distance.

“Orion now has its sights set on home," said Mission Control commentator Sandra Jones.

The capsule also passed over the landing sites of Apollo 12 and 14. But at 1,200 miles (1,900 kilometers) up, it was too high to make out the descent stages of the lunar landers or anything else left behind by astronauts more than a half-century ago. During a similar flyover two weeks ago, it was too dark for pictures. This time, it was daylight.

Deputy chief flight director Zebulon Scoville said nearby craters and other geologic features would be visible in any pictures, but little else.

“It will be more of a tip of the hat and a historical nod to the past," Scoville told reporters last week.

The three-week test flight has exceeded expectations so far, according to officials. But the biggest challenge still lies ahead: hitting the atmosphere at more than 30 times the speed of sound and surviving the fiery reentry.

Orion blasted off Nov. 16 on the debut flight of NASA's most powerful rocket ever, the Space Launch System or SLS.

The next flight — as early as 2024 — will attempt to carry four astronauts around the moon. The third mission, targeted for 2025, will feature the first lunar landing by astronauts since the Apollo moon program ended 50 years ago this month.

Apollo 17 rocketed away Dec. 7, 1972, from NASA's Kennedy Space Center, carrying Eugene Cernan, Harrison Schmitt and Ron Evans. Cernan and Schmitt spent three days on the lunar surface, the longest stay of the Apollo era, while Evans orbited the moon. Only Schmitt is still alive.

Quelle: abcNews

----

Update: 9.12.2022

.

Splashdown! Here's how NASA will recover the Artemis I Orion capsule in the Pacific Ocean

30260bec-50fc-44c8-84e6-6bd7f7e0dcd0-ksc-20200313-ph-kaa01-0159-orig

Now, the ocean engineering and marine sciences assistant professor has reported to the Navy amphibious transport ship USS Portland in San Diego. On Sunday, he'll help forecast and analyze wave dynamics to guide NASA officials as they retrieve the rocket's bobbing Orion capsule after it splashes down into the Pacific Ocean.

“It’s just like, whoa. I saw this vehicle drop off the horizon on our beach. We see these beautiful photos of it orbiting the moon. And then, you’ll see it come into the well deck four weeks later," Hunsucker said, referring to the lower level of the ship that will be flooded to load the capsule onboard.

“I’m going to be on the other coast of the United States seeing the same engineering article, picking it up in the ocean," he said.

The 322-foot Artemis I rocket bolted skyward Nov. 16 from pad 39B at Kennedy Space Center, lifting an uncrewed Orion capsule on an epic 1.3-million-mile trek looping twice around the moon.

Concluding its 25½-day mission, Artemis' Orion capsule will slow from a dizzying 25,000 mph – roughly a dozen times faster than a rifle bullet – to 300 mph after entering the Earth’s atmosphere. The capsule's heat shield should reach a roasting 5,000 degrees, or twice the temperature of molten lava.

After a series of parachutes deploy, NASA engineers predict the 11-by-16½-foot capsule should slow to about 20 mph before gliding earthward and striking the sea's surface within eyesight of the recovery ship's crew, 50 to 60 nautical miles off the San Diego coast.

Upon splashdown, Melissa Jones, NASA's Artemis I landing and recovery director, said “we’re frantically trying to get to the capsule” to recover pieces of jettisoned hardware that could sink into the ocean’s depths. This includes the spacecraft's ring-shaped forward bay cover, which protects the parachutes and other soft goods during reentry.

“NASA’s all about data. And we also want to fly crew on the next mission. So this is a key test flight for us, in order for us to get that data back,” Jones said.

Comprised of about 95 people, the Orion landing and recovery team includes Navy amphibious specialists piloting inflatable boats; NASA engineers and technicians from KSC and Johnson Space Center in Houston, Texas; Air Force weather specialists; and Lockheed Martin Space Operations personnel. A helicopter squadron from nearby Naval Air Station North Island will provide aerial spotting.

The Portland will approach the bobbing Orion, and divers will use sensors to conduct “sniff checks” for leaking hydrazine or ammonia from the capsule, Jones said. Then Navy personnel will attach tending lines to Orion and flood the ship’s well deck with about 6 feet of seawater, and a cable will tow the floating spacecraft through the ship's lowered stern gate into a specially designed cradle.

Afterward, the Portland will transport the capsule to a pier at Naval Base San Diego.

Jones said the primary splashdown site is located within a Navy fleet training area – a move designed to keep recreational boats at bay. In August 2020, a makeshift flotilla of private vessels swarmed the SpaceX Crew Dragon Endeavour after it splash-landed in the Gulf of Mexico near Pensacola with astronauts Bob Behnken and Doug Hurley aboard.

The Orion crew module is designed to carry four astronauts to deep space during future missions within a 330-cubic-foot habitable area. Jones said Sunday's recovery team will also hustle to try to recover the capsule's three main parachutes for scientific analysis.

Jones said the recovery team will have about six hours to collect samples and imagery and conduct assessments and tests before towing the uncrewed capsule into the well deck. This will include about 1½ hours of imagery documenting the condition of the heat shield before it touches anything inside the Portland.

Three mannequins equipped with sensors are aboard Orion for test purposes. By contrast, Artemis II will propel four astronauts on a lunar flyby.

Liliana Villarreal, who will direct NASA's capsule-recovery campaign for that mission, said Artemis II astronauts will maneuver out of Orion's hatch in open water before the crew module is winched into a Navy ship – and the astronauts must report to the ship's medical bay within two hours.

"It's completely different. There's a lot of equipment that we have to ensure is turned off before we can do that," Villarreal said. "There are interfaces with the crew's suits that we've got to make sure that we disconnect for the crew to exit the vehicle safely."

Splashdown weather, waves are major factors  

A test version of the Orion capsule is pulled into the flooded well deck of the USS John P. Murtha during an October 2018 NASA splashdown exercise in the Pacific Ocean.
A test version of the Orion capsule is pulled into the flooded well deck of the USS John P. Murtha during an October 2018 NASA …Show more   
NASA/TONY GRAY

Hunsucker has spent the days leading up to Sunday's splashdown working on wave forecasts along the San Diego coast, where Pacific swells can originate across a broad geographic swath ranging from the Gulf of Alaska down into the southern hemisphere.

He has spent the past four years analyzing Orion-recovery wave-forecast data with the Johnson Space Center meteorology group, particularly from NASA's recovery exercises using mock capsules. A critical component of his job: Position the Portland to minimize waves inside the ship's well deck.

"You have this 700-foot-long ship that's impacted by the waves. It starts moving around. Inside of that ship, you have a well deck. It, too, has waves that are generated from the moving of the ship," Hunsucker said.

"My role is to understand how the ocean waves affect the ship's motion, how the ship's motion affects the well-deck waves, and in turn how the well-deck waves affect the crew module," he said.

NASA's Orion recovery team completed a three-day "final rehearsal" exercise at sea last week aboard the Portland using a mockup capsule. Jones said Johnson Space Center personnel will select Sunday's splashdown location based on weather conditions and flight rules outlining "sea state" requirements for wave action and "winds aloft" standards to ensure that the parachutes function properly.

If conditions warrant, Orion could alternately splash down just southeast of the Catalina Islands near Los Angeles, NASA Flight Director Judd Frieling said during a Monday briefing. Or, Orion could land "short" – about 1,200 nautical miles south of San Diego. He described this trio of splashdown sites as a Plan A/Plan B/Plan C slate of options.

The large red balloons attached to the capsule are prominent features of the crew module uprighting system amid rolling ocean waves, said Carla Rekucki, lead test director with NASA’s Exploration Ground Systems program.

Hunsucker, who is working via contract with Jacobs Technology, said the Portland's heading will also depend on the shapes and steepness of incoming waves. He likened the exercise to driving a vehicle through a parking lot riddled with potholes.

"I think we all hope that we land on a beautifully calm, flat, quiescent day," Hunsucker said.

Quelle: Florida Today

----

Update: 10.12.2022

.

NASA Will Test a High Stakes Re-Entry Maneuver With Artemis 1 on Sunday

orion-1-1

The crew of Apollo 8 had a lot of things on their minds when they splashed down in the Pacific Ocean on Dec. 27, 1968, after becoming the first humans to orbit the moon—and one of the biggest was the matter of the sharks. The spacecraft hit the water at 4:51 a.m. Hawaiian-Aleutian time, more than an hour before the Pacific sunrise. A recovery crew of Navy frogmen was standing by on the nearby USS Yorktown, but they dared not jump into the water until day broke—and the astronauts dared not exit their spacecraft—because sharks prowl in the predawn darkness. Only when the sun came up would it be safe to attempt a recovery.

Landing in a daylit part of the world would have clearly been preferable, but back in the Apollo era, returning lunar astronauts could not be so choosy. Once they hit the atmosphere they were essentially in free-fall, flying at a steep angle and eventually splashing down 2,776 km (1,725 mi.) from their point of atmospheric entry. If that happened to be in dark, shark-infested waters, well, that was the price you paid for going to the moon.

Things are different today. When Artemis 1’s Orion spacecraft returns to Earth this Sunday, Dec. 11, after its 25-day lunar orbital mission, it will execute a never-before-tried means of reentry that will allow its guidance system to land it anywhere—and at any time—mission planners choose within an 8,890 km (5,524 mi) range. Want to land in daylight? Done. Want to land just 80 km (50 mi.) off the coast of San Diego at precisely 12:40 p.m. Eastern Time, as is currently planned? Not a problem. That, of course, is provided that that never-before-tried maneuver works as intended—and that is a worry that is surely causing some NASA personnel a few sleepless nights.

Reentering the atmosphere from Earth orbit is a relatively easy thing: a matter of firing retro-rockets and slowing the spacecraft’s velocity below the 28,160 km/h (17,500 mph) speed necessary to maintain orbit. After that, the ship basically falls from the sky.
Returning from the moon is a different matter. In order to reenter the atmosphere safely, the ship must aim for a keyhole in the sky just 24 km (15 mi.) wide. That sounds like a mighty big target, but if the Earth was the size of a basketball and the moon the size of a baseball, and the two were placed 6.7 m (22 ft.) apart—the relative translunar distance at that scale—the reentry target would be no thicker than a piece of paper. Miss it and enter too steeply, and the spacecraft would not survive the heat of reentry; miss it and enter too shallowly and the spacecraft would simply skip off the atmosphere and bounce back into space.
Even a bullseye hit on that tiny target—which all nine Apollo lunar crews pulled off—did not make for a pleasant ride. The astronauts had to endure forces of 6.8 g’s (or 6.8 times Earth’s gravity) on the way down before their speed slowed, their parachutes opened, and they hit the water.
Artemis 1’s return will improve on things by attempting what flight engineers call a “skip entry.” When the Orion capsule enters the 24 km-wide keyhole in the atmosphere it will be traveling at a speed of more than 32,000 km/hr (20,000 mph). The atmospheric friction from entering so fast will cause the temperature on its heat shield to rise throughout the descent process to a peak of 2,760º C (5,000º F).
The uncrewed spacecraft will initially plunge to an altitude of 61,000 m (200,000 ft.)—or about 61 km (38 mi.). Then it will pull off a fancy bit of flying. Rolling 180 degrees—so that future astronauts who were sitting straight up inside would now be upside down—it will change its center of gravity, causing it to skip off the atmosphere, just as it would on a too-shallow reentry, but not so hard and fast that it would fly off into space. Instead, it will climb back up to 99,000 m (325,000 ft)—or 99 km (61 mi)—essentially taking it back into space. After that parabolic maneuver, it will resume its descent, with its guidance system pointing it straight for the waters off of San Diego.

The skip entry not only increases the spacecraft’s reentry footprint, it also reduces the temperature load on the heat shield, as the ship briefly roller coasters back into the chill of space. What’s more, astronauts on board would have an easier ride: dividing the reentry into two parts this way reduces the maximum g-forces from 6.8 to just 4.

The skip entry concept was around in the days of Apollo—and the physics certainly aren’t any different now from what they were then. But the power of the guidance computer aboard the spacecraft—not to mention the computer modeling that has allowed the maneuver to be run and rerun on the ground first—did not exist at the time, making the maneuver too risky a trick to try. This Sunday—54 years after the return of Apollo 8—the entry maneuver will at last be attempted. If all goes well, the next time it’s tried will be in 2024, when Artemis 2 carries a crew of astronauts around the moon—bringing them back to Earth for a smooth and close-to-home splashdown.

Quelle: TIME

----

Update: 11.12.2022

.

Here's how NASA's Artemis 1 Orion spacecraft will splash down to end its moon mission in 8 not-so-easy steps

 
 
226 Views
Raumfahrt+Astronomie-Blog von CENAP 0