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Artykuły astronautyczne / Odp: [AmericaSpace] 'A Finite Number of Heartbeats': The Trauma of Gemini VIII
« Ostatnia wiadomość wysłana przez Orionid dnia Luty 15, 2019, 21:14 »
'Tumbling End Over End': The Trauma of Gemini VIII (Part 2)
By Ben Evans, on March 16th, 2014 [AmericaSpace]

Dave Scott (left) and Neil Armstrong breathe the fresh air of Earth as the hatches of Gemini VIII are opened by a trio of U.S. Air Force Pararescuemen (PJs) after splashdown. Photo Credit: NASA

Forty-eight years ago today, Gemini VIII astronauts Neil Armstrong and Dave Scott accomplished a key goal in America’s bid to land a man on the Moon by successfully rendezvousing and docking with an unmanned Agena target vehicle in Earth orbit. As noted in yesterday’s AmericaSpace article, it was the first time that a manned vehicle had achieved physical contact with another target in space. However, the situation aboard Gemini VIII was far from perfect. A distinct lack of available tracking stations across the flight path had already resulted in decidedly “spotty” communications with the Mission Operations Control Room (MOCR) in Houston, Texas. In fact, only two ship-based stations were supporting the flight, the Rose Knot Victor and the Coastal Sentry Quebec, together with a land site in Hawaii. Shortly before one loss of contact, at around 6:35 p.m. EST on 16 March 1966, Capcom Jim Lovell radioed the Gemini VIII crew. If problems arose, he told them, they should immediately deactivate the Agena with Command 400 and assume manual control with the Gemini. It was a standard call. Lovell could hardly have imagined that a potential disaster would soon engulf the mission.   

Half an hour after docking with the Agena, Dave Scott instructed the target to roll them 90 degrees, and Neil Armstrong, in the commander’s seat, told Lovell that it had “gone quite well.” The call came a few seconds before Gemini VIII passed out of radio contact with the ground. Alone, the astronauts electronically activated the Agena’s tape recorder. Shortly thereafter, their attitude indicator showed that they were in an unexpected, and almost imperceptible, roll of about 30 degrees. “Neil,” called Scott, “we’re in a bank.” Were the Agena’s attitude controls misbehaving? Or was it a problem with the target vehicle’s software? Certainly, Gemini VIII’s own thrusters were now switched off and the assumption could safely be made that the Agena was at fault. What they did not know was that one of their thrusters—the No. 8 thruster—had short-circuited and stuck into its “on” position. Unaware, Scott cut off the Agena’s thrusters, whilst Armstrong reactivated the Gemini’s thrusters in an attempt to stop the roll and bring the combination under control.

For a few minutes, his effort succeeded.

Gradually, the craft stabilized. Then, as Armstrong started to reorient them into their correct position, the unwanted motions resumed … albeit much faster than before and along all three axes. Perplexed, the men jiggled the Agena’s control switches, then those of the Gemini, on and off, in a fruitless attempt to isolate the problem. Glancing at his instrument panel, Scott noticed that their craft’s attitude propellant had dropped to just 30 percent. At this stage, it dawned on the astronauts that the fault was with their craft. “We had to disengage from the Agena,” Scott later wrote in his memoir, Two Sides of the Moon, “and quickly.”

This posed its own problems, since both craft were rapidly rotating and could hit each other. Quickly, Scott set the Agena’s recording devices to allow flight controllers to remotely command it; a crucial step, since, after undocking, the target would otherwise be dead. “No one would ever know what the problem had been or how to fix it,” he wrote. His prompt action saved the Agena and preserved it not only for subsequent investigations, but also for a remarkable “double rendezvous” on the Gemini X mission in July.

Armstrong and Scott were still out of radio communications with the ground. They duly undocked from the Agena and fired a long burst of the Gemini’s thrusters to pull away … whereupon their craft, now free, began to spin much more violently, in roll, pitch, and yaw axes. Since the stuck-on No. 8 thruster was no longer turning the entire combination, the oscillations were correspondingly worse than before. At length, high above southeast Asia, they came into contact with the Coastal Sentry Quebec. Controllers were stunned at 6:58 p.m. when Dave Scott’s urgent call came through.

“We have serious problems here,” he reported. “We’re tumbling, end over end. We’re disengaged from the Agena.”

Jim Fucci, the communicator aboard the ship, was stunned and asked them about the problem. Quickly, and characteristically calm, Armstrong reported that they were continuously increasing in a left roll and unable to turn anything off. Fucci, an old NASA hand with great experience, alerted Houston that Gemini VIII was suffering from “pretty violent oscillations.” The resultant three-way conversation with the MOCR meant that several seconds elapsed before Flight Director John Hodge picked up all the details; Fucci had to repeat that Armstrong was “in a roll and he can’t stop it.”

In orbit, Armstrong threw circuit breakers to cut electrical power and hence the flow of propellant to the attitude thrusters, including troublesome No. 8. However, with no friction or counter-firing thrusters to halt it, the spinning continued … reaching a horrifying 60 revolutions per minute. Checklists, flight plans, and procedural charts were flung around Gemini VIII’s cabin by the resultant centrifugal force, and the unfiltered sunlight blazed through the astronauts’ windows with startling regularity. To Dave Scott, it was like a constant strobe light, hitting them square in the face. Added to this, the rotation was such that the astronauts were close to physically blacking out and they struggled to read their instruments. Physiologically, Armstrong and Scott were suffering from a complete loss of orientation, caused by the effect on their inner ears, together with an involuntary rhythmic motion of their eyes.

Gemini VIII (foreground) enters into the final stages of rendezvous with the Agena target vehicle. Photo Credit: NASA

Aware that the problem was with his own spacecraft, Armstrong had little choice but to use Gemini VIII’s 16 re-entry thrusters to steady them. This was easier said than done … for the re-entry controls were in a particularly awkward position, directly above his head, and, worse, they were on a panel with around a dozen toggles. “With our vision beginning to blur,” wrote Scott, “locating the right switch was not simple.” Fortunately, months of repetitive training had allowed the astronauts to know each switch, intuitively, but Scott was amazed at Armstrong’s flying skill as he reached for the toggle and grappled with the spacecraft’s hand controller, at the same time. Eventually, the effort succeeded, albeit at the expense of 75 percent of Gemini VIII’s propellant. Mission rules decreed that, once the re-entry controls had been activated, the flight was aborted. Ten hours into a planned three-day mission, Armstrong and Scott were on their way home.

Television stations began interrupting their programmes—Batman and, ironically, Lost in Space—to provide live coverage. Original plans had called for Gemini VIII to splash down in the Atlantic and be recovered by the aircraft carrier U.S.S. Boxer, but the emergency guided them instead to a point in the western Pacific, 500 miles (800 km) east of Okinawa. A naval destroyer, the U.S.S. Leonard F. Mason, based off the coast of Vietnam, was assigned to this splashdown zone and her crew began steaming toward the predicted point.

The bitterly disappointed astronauts ran through their pre-retrofire checklist, and tests of Gemini VIII’s thrusters finally identified the fault with No. 8. Scott later described the thrusters as not exhibiting “a consistent, linear problem … it was really screwed up.” In effect, the thruster had been “on” when it should have been “off” and vice versa. Loading the re-entry software into the spacecraft’s 4,000-word computer memory was difficult, particularly as it was already overloaded from the rendezvous with the Agena. This required Scott to erase the rendezvous and docking programs and feed the re-entry data by means of a keypad and auxiliary tape memory unit. Punching in a series of nine lines of seven-digit numbers, he checked and cross-checked his work with Jim Fucci, whose admirable calmness under duress made those critical moments seem like “taking a stroll in the park.”

At 9:45 p.m., Gemini VIII’s retrorockets fired above south-central Africa, in orbital darkness, which gave the astronauts no visual cues for alignment. The spacecraft re-entered over the high peaks of the Himalayas, and, as it descended, Scott could see nothing through his window, save a pinkish-orange glow of superheated plasma outside … then, after a while, came high-level haze and, later, the glint of water. Ten hours and 41 minutes after leaving Cape Kennedy—at 10:22 p.m. on 16 March in Florida, but a little after midday on 17 March in the western Pacific—Gemini VIII hit the choppy waters with a harsh thump. Seasickness was an inevitability as the spacecraft’s windows rhythmically rolled and pitched, but the men stepped smartly through the shutdown of electrical and other systems. They had forgotten to take their anti-seasickness pills. “When Mission Control told us about three-foot waves,” Scott recalled, “they forgot to mention the 20-foot swells!”

First on the scene were U.S. Air Force Pararescuemen (PJs) from 33 Air Rescue Service, scrambled out of Naha Air Force Base, Okinawa, aboard a Grumman HU-16 Albatross flying boat. They successfully parachuted into the Pacific Ocean, applied the capsule flotation collar to stabilize Gemini VIII and were first to tend to the immediate medical needs of Armstrong and Scott. They were followed, several hours later, by the arrival of the Mason. In fact, the destroyer’s crew had been less than enamored when they were assigned to be one of the backup recovery vessels. They had just finished a seven-week tour in Vietnam and had been given a brief spell of liberty in Okinawa. Now they were as relieved as the rest of the world that Armstrong and Scott were safe.

In the weeks that followed, post-flight analysis removed any blame from the shoulders of the astronauts. Still, astronauts Walt Cunningham and Tom Stafford expressed criticism; the former pointed to flaws in both Armstrong and Scott’s performance, and the latter argued that undocking from the Agena had been the wrong decision. Flight Director Gene Kranz, who supervised Gemini VIII’s re-entry, saw things differently. He regarded it as a failure of the ground controllers in having few contingency procedures to cover the docked phase of the mission. Other astronauts, including Frank Borman and Wally Schirra, praised the actions of the crew as having saved the mission from disaster. Without their safe return, the erroneous belief that the Agena was to blame could have diseased Project Gemini’s final months and made it difficult for Project Apollo—with its emphasis on rendezvous and docking—to move confidently ahead. In Scott’s words, it could have been “a showstopper.”

The performance of Neil Armstrong and Dave Scott in March 1966 was nothing short of remarkable. They had completed a flawless docking with the Agena and, but for the stuck-on No. 8 thruster, might have gone on to complete an equally flawless three-day mission. That neither man was to blame for the events of Gemini VIII is amply highlighted by their subsequent careers: Armstrong was reassigned as backup commander of Gemini XI, whilst Scott was named as senior pilot on the backup crew for the first manned Apollo mission. In time, they would venture further, becoming the only Gemini crew whose both members would someday set foot on the Moon.

The author would like to express grateful thanks to Mr. Jeff Morrisette (SGT USAF, CDR USN, Ret.) for his clarification and additional detail regarding the critical role of U.S. Air Force Pararescuemen (PJs) in the safe recovery of the Gemini VIII.

Source: https://www.americaspace.com/2014/03/16/tumbling-end-over-end-the-trauma-of-gemini-viii-part-2/
« Ostatnia wiadomość wysłana przez wini dnia Luty 15, 2019, 21:13 »
Ktoś miał w rękach jakąś dobrą książkę na temat odkryć jakie zostały dokonane dzięki Opportunity i Spirit i mógłby polecić?:)
Artykuły astronautyczne / [AmericaSpace] 'A Finite Number of Heartbeats': The Trauma of Gemini VIII
« Ostatnia wiadomość wysłana przez Orionid dnia Luty 15, 2019, 21:11 »
'A Finite Number of Heartbeats': The Trauma of Gemini VIII (Part 1)
By Ben Evans, on March 15th, 2014

Neil Armstrong (left) and Dave Scott sought to fulfil many of the objectives needed to reach the Moon, including orbital rendezvous and docking. They were the only Gemini crew whose two members both walked on the Moon later in their careers. Photo Credit: NASA

At the dawn of 1966, America’s drive to land a man on the Moon had accelerated into high gear. Five Gemini crews had shown that astronauts could survive in space for long enough to complete the journey and that it was possible to venture outside in a pressurized suit and perfect the tricky technique of orbital rendezvous—all of which would someday be critical in enabling the first steps on another world. On Gemini VIII in March 1966, astronauts Neil Armstrong and Dave Scott sought to press the envelope still further. They would spend three days in space, perform rendezvous and—for the first time—actual physical docking with another object, and execute combined maneuvers, scientific experiments, a two-hour EVA, and a precision re-entry and splashdown. In time, Armstrong and Scott would both leave their bootprints on the dusty lunar surface … yet their ill-fated flight together on Gemini VIII would bring them within a whisker of losing their lives.     

The pair had been together since the end of August 1965, and neither man was under any illusion about the complexity of their task. The EVA was particularly crucial. Unlike America’s first spacewalker, Ed White, who had moved around for barely a few minutes, Dave Scott would maneuver to the rear of Gemini VIII, reverse himself into a backpack, known as the Extravehicular Support Package (ESP), and attach a tether to enable him to venture up to 90 feet away. He would spacewalk through orbital daytime and nighttime, retrieve an emulsion package, activate a micrometeoroid collector on the Agena target spacecraft, and test a reactionless power wrench. It was only the second time an American had left his craft in space, and Scott’s work was laden with risk; if he hit difficulties, there would be no way for Armstrong to see or reach him. Aware of this risk, Armstrong had requested realistic training models of the Gemini’s aft adaptor section and a series of rehearsals in an altitude chamber. By the eve of launch, Scott had practiced his movements on 200 parabolic aircraft flights and more than 20 hours on an air-bearing table.

Scott knew that to operate effectively within a space suit he needed to maintain his physical fitness and strength. This was particularly true from conversations with Ed White, who had experienced difficulty closing the Gemini’s hatch at the end of his own EVA. A lever had been fitted to make it a bit easier, but White cautioned Scott that the suit was stiff and heavy and demanded enormous reserves of stamina for any movement, let alone two hours of physical work. Scott jogged, played handball, and pumped iron in the gym, and this brought him face to face with Neil Armstrong’s wry humor. When it came to physical exertion, Armstrong had one cardinal rule: Human beings had a finite number of heartbeats and should not waste them with frivolity! One day, during Gemini VIII training, as a sweat-drenched Scott worked out, Armstrong set the exercise bicycle on its lowest possible setting and began pedaling. …

Gemini VIII was launched on 16 March 1966, atop a Titan II booster, from Pad 19 at Cape Kennedy. Photo Credit: NASA

The training uncovered obstacles that might have threatened Scott’s life. The air-bearing table, for example, allowed him to literally “fly” across a surface and demonstrate a hand-held maneuvering gun. The gun was filled with Freon, a relatively dense refrigerant, and the strength of its impulse caused Scott to worry about how it might perform in space. In one test at low temperatures, the Freon caused the gun’s poppet valve to stick “open” when triggered. Had this occurred in the frigid cold of orbital flight, the escaping gas might have caused Scott to tumble uncontrollably. Elsewhere, there were concerns that an injector in the space suit’s chest pack might freeze and prevent the flow of oxygen, and trials inside the cramped Gemini cabin left some engineers literally “tangling” with the problem of a jumble of floating umbilicals, tethers, and jumper cables. Not until December 1965 did Scott feel confident that he could complete the task.

On the morning of 16 March 1966, the two astronauts awoke in their crew quarters at Cape Kennedy and breakfasted on filet mignon, eggs, and toast with butter and jelly. The skies above Cape Kennedy were clear, blue, and cloud-speckled, and conditions seemed perfect for the launch of their Agena-D target vehicle—a pencil-shaped craft, mounted atop an Atlas rocket—at 10:00 a.m. EST and their own launch at 11:40 a.m. As they donned their suits, a watch belonging to aviation pioneer Jimmy Mattern was strapped around Armstrong’s wrist, and pieces of wood and cloth from an old Douglas World Cruiser, the New Orleans, were packed with Scott’s personal effects. Both were on loan from the museum at Wright-Patterson Air Force Base. At Pad 19, where Gemini VIII sat atop its Titan II booster, a glitch with Scott’s parachute harness required backup commander Charles “Pete” Conrad to ferret around for a toothpick to remove epoxy resin from the catcher mechanism.

As the clock struck 10, the Atlas-Agena combination thundered away from Pad 14, inserting the vehicle perfectly into orbit. By now alone in the cramped cabin of Gemini VIII, the astronauts were elated. The first stage of their mission was running smoothly. “Cradled in my contoured seat,” Dave Scott wrote in his autobiography, Two Sides of the Moon, “it felt almost as if I was being held in someone’s arms.” The Gemini felt as snug and crisp as a brand-new Ferrari, and the pure oxygen atmosphere provided a cool sense of freshness and cleanness to the cabin.

Under the direction of Flight Director John Hodge, Gemini VIII itself rose from the pad at 11:41 a.m. The astronauts felt  “a solid feeling, a sharp kick in the tail” as the Titan delivered them smoothly into space. Scott’s heart rate peaked at 128 beats per minute, with Armstrong’s reaching 146; post-mission analysis would determine that the difference was attributable to a “keying-up” of the commander’s physical and psychological awareness, rather than an indicator of undue stress. Armstrong told his biographer, James Hansen, that the ascent was “very definite” and that although the Titan’s thrust was noticeable, it did not interfere with their communications. By the time the first stage separated and the second stage ignited, Scott described the ride as “smooth as glass” and, minutes later, was amused to let go of his checklist and watch it drift across the cabin … together with a small metal washer which hovered in front of his face.

Nothing could have prepared either man for his first glimpse of Earth. By now they had crossed the vast gulf of the Atlantic Ocean, and as Armstrong rolled Gemini VIII they beheld the deep trench of the Mediterranean Sea, with Italy clearly visible, and far on the horizon the unmistakable shapes of the Middle East and the Red Sea. In those euphoric seconds, Scott realised that his camera would do no justice to this scene; privately he hoped that NASA would someday send an artist or a poet into orbit to describe it better. Nonetheless, he broke out his camera and starting shooting. Armstrong, too, was overwhelmed. He had flown the X-15 rocket aircraft to an altitude of more than 40 miles (64 km) and had seen the curvature of the Home Planet, but this was four times higher and something quite different.

Gemini VIII’s target, the Agena vehicle, is launched from Cape Kennedy atop an Atlas rocket on 16 March 1966. Photo Credit: NASA

There was little time to gaze in wonder at the astonishing scene. Armstrong and Scott were trailing the Agena by a little over 1,000 miles (1,600 km), and they were scheduled to rendezvous and dock with it, later that same day, before performing the EVA. Ninety minutes into the mission, they fired Gemini VIII’s thrusters to slightly lower their orbital apogee. A second burn raised their perigee and a third, at 2:27 p.m., placed them into roughly the same orbital plane as the Agena. “A fundamental requirement of rendezvous,” Armstrong told Hansen, “is to get your orbit into the same plane as the target’s orbit, because if you’re misaligned by even a few degrees, your spacecraft won’t have enough fuel to get to its rendezvous target.” By launching in a tightly defined time span and entering orbit within a few tenths of a degree of the target, Gemini VIII was thus poised. Betwixt the thrusters burns, Armstrong and Scott broke for lunch … and broke would probably be an apt choice of word. Space food was hardly home cooking. The chicken and gravy casserole, despite having been rehydrated, was quite dry, and the men’s chocolate brownie cookies stuck together and crumbled apart. Fortunately, they were running on reserves of adrenaline and eating was the last thing on their mind.

At length, the Agena was detected by radar at a distance of about 200 miles (320 km), and another burn of Gemini VIII’s thrusters, high above Madagascar, aligned them with perfection for the “terminal” phase of the rendezvous. An hour later, at 4:21 p.m., Scott visually sighted the target, less than 80 miles (130 km) away, its rendezvous beacon blinking against the black sky. Drifting into orbital nighttime, they lost sight of it for a while, although its beacon was still apparent, and when they re-established visual contact Armstrong prepared for docking. He was now braking Gemini VIII by eyesight alone, firing off short spurts of the thrusters … and, at length, the men’s craft came into position, close to the Agena, with no relative velocity. Thirty minutes later, after checking that the target was undamaged, they prepared to move in for the final rendezvous and docking.

Gemini VIII’s nose edges into the docking collar of the Agena target. Although this mission achieved a successful rendezvous and docking, it fell victim to violent oscillations, due to a stuck-on thruster, which almost cost Neil Armstrong and Dave Scott their lives. Photo Credit: NASA

The complexity and importance of this maneuver cannot be underestimated. No previous physical docking had ever been accomplished by a manned craft, and, with NASA planning Lunar Orbital Rendezvous as part of its scheme to land on the Moon, the work of Armstrong and Scott was absolutely critical. As the commander guided his ship gingerly closer, he experienced no problems; in fact, fellow astronaut Wally Schirra—who performed a rendezvous the previous December—had assured him that flying close to another vehicle was very easy when the correct positioning had been achieved. For 25 minutes, Armstrong and Scott electronically checked the Agena’s systems, antennas, and lights by radio command and by now were so close that they could read a small instrument panel above its docking collar. At 6:15 p.m., less than seven hours after launch, Armstrong became the first human being to dock with another craft in orbit. An electronic motor aboard the Agena retracted the collar, pulled the Gemini’s nose into the target, and connected their electrical systems. The instrument panel on the Agena displayed a green “rigid” confirmation.

Both vehicles were electrically and mechanically mated. They had done it.

“Flight, we are docked,” Armstrong announced, with more than a hint of triumph, “and it’s really a smoothie!” There was no noticeable oscillations in the combined craft. In the Mission Operations Control Room in Houston sheer pandemonium broke out. The achievement of Gemini VIII had cleared another hurdle on the road to the Moon.

Armstrong’s “smoothie,” though, would be the last time that anyone on the ground or in orbit would breathe easily. Within minutes, Gemini VIII would change from a perfect flight into a very real battle for survival.

Source: https://www.americaspace.com/2014/03/15/a-finite-number-of-heartbeats-the-trauma-of-gemini-viii-part-1/
« Ostatnia wiadomość wysłana przez Orionid dnia Luty 15, 2019, 21:09 »
Artykuły astronautyczne / Odp: [JPL] Rover Team Beaming New Commands to Opportunity on Mars
« Ostatnia wiadomość wysłana przez Orionid dnia Luty 15, 2019, 21:09 »
NASA declares Opportunity rover dead after 15 years on Mars
February 13, 2019 Stephen Clark [Spaceflight Now]

Opportunity’s front hazard-avoidance camera captured this image of the rover’s shadow July 26, 2004. Credit: NASA/JPL-Caltech

Eight months after last hearing from the Opportunity rover, NASA officials announced the end of the craft’s 15-year mission Wednesday, closing out an ambitious chapter of Mars exploration that proved the Red Planet once harbored running water and demonstrated the promise of mobile robotic scouts to survey other worlds.

The rover succumbed to a sky-darkening global dust storm, and last communicated to Earth on June 10, 2018. Mission officials hoped to regain contact with Opportunity after the dust storm cleared, but daily listening sessions and more than 1,000 tries to send commands to the rover produced no results.

Thomas Zurbuchen, head of NASA’s science mission directorate, declared the end of Opportunity’s mission in a press conference Wednesday at the Jet Propulsion Laboratory in Pasadena, California.

“I was there yesterday, and I was there with the team as these commands went out into the deep sky, and I learned this morning that we had not heard back, and our beloved Opportunity remains silent,” Zurbuchen said. “I am standing here with a sense of deep appreciation and gratitude to declare the Opportunity mission as complete, and with it the Mars Exploration Rover mission as complete.”

Opportunity landed on Mars on Jan. 24, 2004, to begin a mission that was not planned to last more than 90 days. Instead, Opportunity returned data for more than 14 years — nearly 60 times longer than its designed lifetime — and logged more than 28 miles (45 kilometers) on its odometer, farther than any other robot has driven on another world.

“I have to tell you, this is an emotional time,” Zurbuchen said.

Opportunity and its twin rover, Spirit, launched in 2003 from Cape Canaveral aboard a pair of Delta 2 rockets. After reaching the Red Planet in January 2004, both of the 384-pound (174-kilogram) rovers — each about the size of a golf cart — set out to explore their surroundings, climbing hills and descending into craters in search of geologic clues about the ancient history of Mars.

Spirit ended its mission in March 2010, after getting stuck in sand with its solar panels in an unfavorable orientation to generate power during a harsh Martian winter.

“We were meant to get to this point, to wear these rovers out, to leave behind no unutilized capability on the surface of Mars, but we had no idea it would take this long,” said John Callas, Opportunity’s project manager at JPL. “But even still, this is a hard day, and this is hard for me because I was there at the beginning.”

“Spirit and Opportunity may be gone, but they leave us a legacy, and that’s a legacy of a new paradigm for solar system exploration,” said Mike Watkins, director of JPL. “A robotic geologist on Mars, and an integrated science and engineering (and) operations team here on Earth all set out together on a mission of discovery. They didn’t know what they would find, they didn’t know what direction they would go, sometimes from one day to the next, and they made it work. And they made it work longer than any of us thought possible, by both brilliant scientific deduction of where to go and brilliant engineering to keep the rovers alive.”

“It’s a team that makes success like this,” Zurbuchen said. “It’s a team that creates exploration, transformative exploration, for science and engineering, and it’s a team that is celebrating here today, emotionally.”

Members of Opportunity’s ground team gathered late Tuesday to send the final commands to the rover in an attempt to restore communications. Credit: NASA/JPL-Caltech

Skies over the Opportunity rover blackened last June as a global dust storm enveloped Mars and starved the robot’s solar panels of sunlight. It was the most extreme dust storm observed by Spirit or Opportunity since their landings in 2004.

Ground controllers regularly listened for a call from Opportunity after losing communications with the rover, using giant dish antennas from NASA’s Deep Space Network to try and detect a signal. Engineers hoped the rover would automatically wake up and radio Earth when the dust storm cleared, but that did not happen. Managers then prepared commands to send up to Opportunity “in the blind,” hoping that a gust of wind would clear the solar panels of dust and bring the robot back to life.

Opportunity’s ground team sent up the last such command Tuesday night. After the signal took 13-and-a-half minutes to reach Mars — traveling at the speed of light — Opportunity should have sent a response back to engineers keeping vigil in a control room at JPL. Silence reigned.

“We tried valiantly over these last eight months to try to recover the rover, to get from signal from it,” Callas said Wednesday. “We’ve listened every single day with the Deep Space Network, with our sensitive receivers, and we sent over 1,000 recovery commands trying to exercise every possibility of getting a signal from the rover. But with time, the skies are darkening, it’s getting colder on Mars, we recently passed through the historic dust-cleaning season on Mars to see if that would help … That brought us to last night, we sent our final commands, and we heard nothing, so it comes time to say goodbye.”

NASA spent around $800 million — in 2003 economic conditions — to build and launch the Spirit and Opportunity rovers.

“Spirit and Opportunity were robotic field geologists,” said Steve Squyres, lead scientist for the twin rovers from Cornell University. “Geology is a forensic science. A geologist is like a detective at the scene of a crime. Something happened at this place on Mars billions of years ago. What was it? What was it like there back then? And you’re looking for clues, and the clues are in the rocks. So we equipped these vehicles with the tools that they needed to read those clues.”

Opportunity’s panoramic camera captured this self-portrait on Mars in 2014. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

After a six-month journey from launch, Opportunity dropped to an airbag-cushioned landing at Meridiani Planum, a smooth equatorial plain, and rolled into a 72-foot-wide (22-meter) crater, a fortuitous interplanetary “hole-in-one” that presented scientists with a treasure trove of layered bedrock exposed by an ancient asteroid impact.

“The first day that we landed, it was geologic pay dirt right from the very beginning,” Squyres said.

“I remember the emotions,” Zurbuchen said. “I saw that Cornell professor (Squyres) jumping up and down like my 4-year-old on his birthday when entry, descent and landing was complete, and the rover said, ‘I’m here.'”

Within weeks, Opportunity discovered evidence that liquid water once flowed across the Martian surface at the Eagle Crater site.

“But it wasn’t nice stuff,” Squyres said Wednesday. “You know, we were running around saying, ‘Water on Mars! Water on Mars!’ It was really sulfuric acid on Mars. The pH was very low, this was very acidic stuff, it was very salty. This was not evidence of an evolutionary paradise, but it was a fascinating, fascinating environment.”

Opportunity drove to two bigger nearby craters — Endurance and Victoria — for an extended mission, then Squyres and his deputies decided to dispatch the rover across a barren stretch of Meridiani Planum, riddled with sand dunes, toward 14-mile-wide (22-kilometer) Endeavour Crater.

The cross-country trip took three years.

Opportunity’s navigation camera took this image of its tracks on the journey to Endeavor Crater on Aug. 4, 2010. Credit: NASA/JPL-Caltech

“When we got there, the mission started all over again,” Squyres said “New rocks, new stories, looking in the very distant past.”

“We were able, at the rim of Endeavour Crater, to find rocks that were probably the oldest observed by either one of the rovers,” he said. “And those told a story of water coursing through the rocks, but with a neutral pH. It was water you could drink, so we were about to piece together a new story there. That was one of the mission’s most significant discoveries, and it came 11 years into our 90-day mission.”

Opportunity took 217,594 raw images on Mars, nearly double the number captured by Spirit.

Abigail Fraeman, Opportunity’s deputy project scientist, was a junior in high school when the rover returned the first set of images soon after landing in Eagle Crater. She was at JPL for the landing, thanks to an educational project provided by the Planetary Society.

“It was those first images from Opportunity that inspired me to become a planetary scientist,” she said. “They revealed a view of Mars that we had never seen before.

“I’ve been hearing a lot of people’s stories,” Fraeman said. “What strikes me as so cool is that this story is not unique for me. There really are hundreds, if not thousands, of students who were just like me, who witnessed these rovers and followed along (with) their mission from the images they released to the public over the last 15 years, and because of that went to pursue careers in science, education and math.”

Callas counted the intergenerational team as “one of the most rewarding legacies” of the Spirit and Opportunity rovers. Scientists and engineers brought up with the Mars rovers will go on to support future space missions, such as the Curiosity rover still exploring Mars, or the Mars 2020 mission set for departure to the Red Planet next year, he said.

“We built them for Mars. That’s the place where they were designed to go. That’s their home, that’s where I would like them to stay. Also, if you had the opportunity to bring 180 kilograms of stuff back from the surface of Mars, the last thing I want to bring is something I know exactly what it’s made of,” joked Steve Squyres, Mars Exploration Rover principal investigator from Cornell University, in response to a question about retrieving the rovers and returning them to Earth.

“Why did these rovers last so long? Why did Opportunity last so long? There are two main technical reasons,” Callas said. “One is that we had expected that dust falling out of the air would accumulate on the solar arrays and eventually choke off power after about 90 days. But what we didn’t expect that wind would come along periodically and blow the dust off the arrays. This on a seasonal cycle actually became pretty reliable, and allowed us to survive not just the first winter, but all the winters we experienced on Mars, and to keep going and exploring.

“The other thing was that these rovers actually have the finest batteries in the solar system,” Callas said. “They had over 5,000 charge-discharge cycles on them, and they still had about 85 percent of their capacity. I mean, we’d all love it our cell phone batteries lasted this long, but that really was an enabling capability, that with the dust cleaning and the batteries allowed us to have that critical energy that we needed to get through the coldest, darkest parts of the winter on Mars, and to keep exploring.”

Opportunity suffered from a type of amnesia. A flaw in the rover’s flash memory forced ground controllers to retrieve imagery, science data and housekeeping telemetry before Opportunity went into hibernation every night, then start fresh again the next morning.

Multiple images from the Opportunity rover from June 2018 were stitched together to create this panoramic mosaic, days before the rover’s last contact with Earth. Credit: Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer

“We had many challenges along the way,” Callas said. “When we first landed on Mars, one of the things that happened was we had a heater on the robotic arm on the rover that got stuck on. So every night that heater would come on and waste energy from the rover. If we left it alone like that, the mission wouldn’t have lasted long beyond the 90 days.

“So we developed this technique called deep sleep, which is every night we would turn everything off on the rover, including all the survival heaters, and the rover would get cold, but it would stay just warm enough that in the morning when the sun would come up, we would power everything back up,” he said. “It never got below its allowable temperatures.

“This is kind of like if you have a light in your bedroom stuck on, and you can’t sleep, so what you do is you go outside and you turn off the master breaker for your house,” Callas said. “But that means your refrigerator starts to warm up, but by the morning time when you wake up and you turn the breaker back on, the ice cream hasn’t melted too badly. And you do that every single night. Now imagine doing that for 5,000 nights. That’s what we had to do for this vehicle. But it also, partially perhaps, explains why we weren’t able to recover the rover.

If the rover’s batteries were fully depleted, its internal clock would have reset.

“With a loss of power, the clock in the rover gets scrambled, and it wouldn’t know when to deep sleep,” Callas said. “So it probably wasn’t sleeping at night when it needed to, and that heater was stuck on, draining away whatever energy the solar arrays were accumulating from the sun to charge those batteries. So that might be part of this explanation, in addition to the fact that now it’s much colder and darker on Mars (as winter approaches).”

Source: https://spaceflightnow.com/2019/02/13/nasa-declares-opportunity-rover-dead-after-15-years-on-mars/
Artykuły astronautyczne / Odp: [JPL] Rover Team Beaming New Commands to Opportunity on Mars
« Ostatnia wiadomość wysłana przez Orionid dnia Luty 15, 2019, 21:09 »
Historic Opportunity Rover Mission on Mars Comes to Silent End
By Paul Scott Anderson, on February 13th, 2019 [AmericaSpace]

Opportunity casts its shadow in this image from sol 180 (July 26, 2004), taken by the rover’s front hazard-avoidance camera, on the edge of Endurance Crater. Photo Credit: NASA/JPL-Caltech]Opportunity casts its shadow in this image from sol 180 (July 26, 2004), taken by the rover’s front hazard-avoidance camera, on the edge of Endurance Crater. Photo Credit: NASA/JPL-Caltech

It’s been a long 15 years, but the inevitable has finally happened: the Opportunity rover’s days of exploring Mars are over. The sad news was announced this morning at 2 pm ET in a NASA press briefing, bringing an official end to one of the most successful Mars missions in history.

“It is because of trailblazing missions such as Opportunity that there will come a day when our brave astronauts walk on the surface of Mars,” said NASA Administrator Jim Bridenstine. “And when that day arrives, some portion of that first footprint will be owned by the men and women of Opportunity, and a little rover that defied the odds and did so much in the name of exploration.”

Opportunity, like its twin, Spirit, was designed for a hoped-for nominal mission of 90 Martian days (sols) when it landed in 2004, but lasted for an incredible 15 years. That is 60 times its projected life span.

The mission plan also called for Opportunity to travel at least 1,100 yards (1,000 meters), but ended up roving more than 28 miles (45 kilometers) altogether.

The last image ever sent back by Opportunity, on June 10, 2018, showing the darkened sky due to the dust storm. Photo Credit: NASA/JPL-Caltech/Cornell

“For more than a decade, Opportunity has been an icon in the field of planetary exploration, teaching us about Mars’ ancient past as a wet, potentially habitable planet, and revealing uncharted Martian landscapes,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate. “Whatever loss we feel now must be tempered with the knowledge that the legacy of Opportunity continues – both on the surface of Mars with the Curiosity rover and InSight lander – and in the clean rooms of JPL, where the upcoming Mars 2020 rover is taking shape.”

The trouble began in June 2018, when Opportunity’s location – and most of the planet – was hit with a massive dust storm. June 10 was the last time that the rover was heard from. Up until last night, NASA engineers sent over 1,000 radio commands to try to revive the rover, to no avail. The final transmission was sent via the 70-meter Mars Station antenna at NASA’s Goldstone Deep Space Complex in California.

“We have made every reasonable engineering effort to try to recover Opportunity and have determined that the likelihood of receiving a signal is far too low to continue recovery efforts,” said John Callas, manager of the Mars Exploration Rover (MER) project at JPL.

Eagle Crater, where Opportunity first landed on Jan. 24, 2004. The rover’s tracks can be seen on the right side of the image. Photo Credit: NASA/JPL-Caltech

<a href="http://www.youtube.com/watch?v=1Ll-VHYxWXU" target="_blank">http://www.youtube.com/watch?v=1Ll-VHYxWXU</a>

Opportunity: NASA Rover Completes Mars Mission. Video Credit: NASA/JPL

Opportunity had survived dust storms and other hazards before, but this time was different unfortunately.

It had been hoped that the rover simply “went to sleep” when the power in its solar panels became too low, and would revive later after the dust storm had ended. But it didn’t. Opportunity had also recently been in a period where stronger seasonal winds would blow off dust more easily, as had happened numerous times before, but that also did not work. So why didn’t Opportunity wake up?

As noted by Emily Lakdawalla on Twitter:

Emily Lakdawalla
 · Feb 13, 2019
Replying to @elakdawalla
Callas attributes the rover's longevity to 2 main technical things: the lucky seasonal winds providing dust-cleaning events, and the phenomenal overperformance of the lithium-ion batteries, which were at 85% capacity til the end.

Emily Lakdawalla
Ah, I hadn't realized this. Callas says that one plausible explanation for rover's failure now is that dust storm caused low power mode that scrambled its clock so it didn't know when to turn on deep sleep mode to preserve energy... 1/2
8:19 PM - Feb 13, 2019

Emily Lakdawalla
 · Feb 13, 2019
Replying to @elakdawalla
Ah, I hadn't realized this. Callas says that one plausible explanation for rover's failure now is that dust storm caused low power mode that scrambled its clock so it didn't know when to turn on deep sleep mode to preserve energy... 1/2

Emily Lakdawalla
...Opportunity (but not Spirit) had to go into a "deep sleep" mode every Martian night because one of the electric heaters in an arm joint was stuck on from landing day. If it didn't go into deep sleep, the stuck-on heater may just have drained the battery continuously. 2/2
8:20 PM - Feb 13, 2019

It may be that simple, that Opportunity just wasn’t able to be revived due to other mechanical and/or software problems, even if its solar panels had been cleaned off of dust.

Opportunity landed on Jan. 24, 2004 in Meridiani Planum, 20 days after its twin, Spirit, landed in Gusev Crater. Spirit kept exploring until May 2011, after it became stuck in deep sand and was unable to free itself.

Opportunity escaped its own similar predicament, Purgatory Dune, back in 2005.

Opportunity’s landing site was a treasure trove of geologic wonders, with bright patches of bedrock seen in the first images sent back. That bedrock provided evidence for past water in the region, as did the famous “blueberries” – hematite concretions, never seen before on Mars. Opportunity also found the first evidence for ancient salty playa lakes and groundwater on this now mostly-dry world. Important discoveries, since the rover’s overall mission was to determine the past habitability of this region of Mars.

Spirit and Oppy@MarsRovers
 Oppy proved beyond a doubt that ancient Mars had lots of liquid water. These hematite spheres, nicknamed "blueberries," formed in the presence of H2O. https://go.nasa.gov/2E8bmx2 #ThanksOppy
8:16 PM - Feb 13, 2019

Spirit and Oppy@MarsRovers
 ...and we watched the skies darken.
Ultimately, it was the most intense dust storm in recorded Martian history that brought this epic mission to a close. https://go.nasa.gov/2E9PG3Y #ThanksOppy
8:22 PM - Feb 13, 2019

“From the get-go, Opportunity delivered on our search for evidence regarding water,” said Steve Squyres, principal investigator of the rovers’ science payload at Cornell University. “And when you combine the discoveries of Opportunity and Spirit, they showed us that ancient Mars was a very different place from Mars today, which is a cold, dry, desolate world. But if you look to its ancient past, you find compelling evidence for liquid water below the surface and liquid water at the surface.”

The rover explored vast plains, deep craters and steep hills, and watched dust devils, as it continued its exploration over the years. Some of the most notable moments include:

 - Set a one-day Mars driving record March 20, 2005, when it traveled 721 feet (220 meters).
 - Returned more than 217,000 images, including 15 360-degree color panoramas.
 - Exposed the surfaces of 52 rocks to reveal fresh mineral surfaces for analysis and cleared 72 additional targets with a brush to prepare them for inspection with spectrometers and a microscopic imager.
  - Found hematite, a mineral that forms in water, at its landing site.
  - Discovered strong indications at Endeavour Crater of the action of ancient water similar to the drinkable water of a pond or lake on Earth.

“When I think of Opportunity, I will recall that place on Mars where our intrepid rover far exceeded everyone’s expectations,” Callas said. “But what I suppose I’ll cherish most is the impact Opportunity had on us here on Earth. It’s the accomplished exploration and phenomenal discoveries. It’s the generation of young scientists and engineers who became space explorers with this mission. It’s the public that followed along with our every step. And it’s the technical legacy of the Mars Exploration Rovers, which is carried aboard Curiosity and the upcoming Mars 2020 mission. Farewell, Opportunity, and well done.”

Dust devil seen by Opportunity on March 31, 2016. Photo Credit: NASA/JPL-Caltech

Opportunity’s final resting place, in Perseverance Valley on the edge of Endeavour Crater. This photo was taken by NASA’s Mars Reconnaissance Orbiter. Photo Credit: NASA/JPL-Caltech/Univ. of Arizona

“Opportunity’s final days were spent in Perseverance Valley, an ancient gully thought to have been carved by water or ice, on the edge of Endurance Crater.

“I cannot think of a more appropriate place for Opportunity to endure on the surface of Mars than one called Perseverance Valley,” said Michael Watkins, director of JPL. “The records, discoveries and sheer tenacity of this intrepid little rover is testament to the ingenuity, dedication, and perseverance of the people who built and guided her.”

Meanwhile, NASA’s other Mars rover, Curiosity, continues its mission in Gale Crater and the InSight lander is now ready to start investigating the deep interior of Mars.

Opportunity was beloved by many people – scientists and the public alike – and so became more than just a robot. This quote in Rebecca Boyle’s obituary to Opportunity sums it up nicely:

“It’s odd to think about grief being associated with a machine. But it’s a part of our lives.” – Mark Lemmon

More information about Opportunity is available on the mission website.

Source: https://www.americaspace.com/2019/02/13/historic-opportunity-rover-mission-on-mars-comes-to-silent-end/#more-107243
Artykuły astronautyczne / Odp: [JPL] Rover Team Beaming New Commands to Opportunity on Mars
« Ostatnia wiadomość wysłana przez Orionid dnia Luty 15, 2019, 21:07 »
NASA declares Opportunity Mars rover mission over
by Jeff Foust — February 13, 2019 [SpaceNews]

NASA said Feb. 13 it was ceasing efforts to restore contact with the Opportunity Mars rover, ending its mission, originally slated to last 90 days, after more than 15 years. Credit: NASA/JPL illustration

WASHINGTON — NASA announced Feb. 13 that it was ending efforts to restore contact with the Opportunity Mars rover, bringing its mission to an end more than 15 years after it landed on the planet.

At an event at the Jet Propulsion Laboratory, project officials and NASA leadership said they were declaring the overall Mars Exploration Rovers project over after months of attempts by spacecraft controllers failed to reestablish communications with Opportunity after a major dust storm cut off power to the rover in June.

“I am standing here, with a sense of deep appreciation and gratitude, to declare the Opportunity mission as complete, and with it the Mars Exploration Rovers mission as complete,” said Thomas Zurbuchen, NASA associate administrator for science. That decision came after Opportunity failed to respond to a final set of commands transmitted to it by the Deep Space Network Feb. 12.

Opportunity last contacted Earth in early June as “an historic” global dust storm reached its location on Mars, said John Callas, project manager for the Mars Exploration Rovers at JPL. That storm darkened the skies and cut off of the rover’s solar power.

“We tried valiantly over these last eight months to try to recover the rover, to get some signal from it,” he said. However, the onset of winter at the rover’s location on Mars, a region called Perseverance Valley, meant less sunlight and colder temperatures, making it increasingly unlikely the rover could be recovered.

“It brought us to last night, and we sent our final commands, and we heard nothing,” he said. “So, it comes time to say goodbye.”

Opportunity was the second of the twin Mars Exploration Rovers to land on Mars, arriving in January 2004 about three weeks after Spirit landed. The rovers had 90-day lifetimes, but each far exceeded that. Spirit’s mission ended in May 2011 after traveling eight kilometers, while Opportunity logged 45 kilometers before losing contact last June.

Callas said the extreme longevity of the rovers could be credited in part to winds that cleared dust that had accumulated on the solar panels that, if not removed, would have diminished the power those panels generate. The rovers’ batteries also exceeded expectations, retaining 85 percent of their original capacity after more than 5,000 charge/discharge cycles.

A glitch with Opportunity that dates back to very early in its mission may have contributed to its demise. Callas said a heater in the rover’s robotic arm got stuck on shortly after landing, depleting the rover’s batteries during the night. “If we left it alone like that, the mission wouldn’t have lasted long beyond the 90 days,” he said.

To correct the problem, engineers developed a “deep sleep” mode to turn off all the heaters each night. When the dust storm hit, the loss of power “scrambled” Opportunity’s internal clock, keeping it from engaging that deep sleep mode each night. “It probably wasn’t sleeping at night when it needed to, and that heater was stuck on, draining away whatever energy the solar arrays were accumulating from the sun,” he said.

The JPL event was billed as a media briefing but was more of a celebration of the rover, with project scientists and engineers reminiscing about the mission. Only a few minutes at the end of the hour-long event was devoted to media questions.

Steve Squyres, the Cornell University planetary scientist who was principal investigator for the Mars Exploration Rovers, divided Opportunity’s mission into two parts. The first, lasting about nine years, covered initial exploration of its landing site, turning up evidence of water, albeit rather acidic, early in the planet’s history.

The project then made the decision to make a long trek to a distant crater, Endeavour. “When we got there the mission started all over again,” he said. That included finding evidence of past water on Mars that had a neutral pH, rather than acidic. “That was one of the mission’s most significant discoveries. It came 11 years into our 90-day mission.”

Asked later in the briefing whether either of the Mars Exploration Rovers might one day be retrieved to place in a museum, Squyres noted that huts from the early exploration of Antarctica, more than a century ago, have been preserved there. The same, he suggested, should be the case for the rovers. “We built them for Mars. That’s the place they were designed to go. That’s their home. That’s where I would like them to stay,” he said.

Another opinion, though, came from Ellen Stofan, a planetary geologist and director of the National Air and Space Museum. Speaking at the Commercial Space Transportation Conference here Feb. 13, shortly after the JPL event, she discussed ongoing renovations of the museum and plans for new exhibits.

“What I’m looking forward to in the museum, the artifact that I most want, is something from one of the Mars rovers that one of the first crews on Mars has been able to bring back to Earth,” she said. “I’ll put that right next to my Mars rock.”

Source: https://spacenews.com/nasa-declares-opportunity-mars-rover-mission-over/
Księżyc / Odp: Chang'e 4
« Ostatnia wiadomość wysłana przez Orionid dnia Luty 15, 2019, 21:07 »
LRO obserwuje Chang’e 4

(...) Pod koniec stycznia, na początku drugiego dnia księżycowej misji Chang’e 4 został sfotografowany z orbity przez Lunar Reconnaissance Orbiter (LRO). Ten satelita NASA krąży wokół Srebrnego Globu od 2009 roku i dostarcza wspaniałych ujęć naszego naturalnego satelity.

Na najlepszych obrazach wykonanych przez LRO można zobaczyć lądownik Chang’e 4 oraz łazik Yutu-2. Oba urządzenia mają zaledwie kilka pikseli wielkości, ale są wyraźnie inne od otoczenia. Zdjęcia także pokazują mnogość kraterów różnej wielkości w pobliżu regionu lądowania Chang’e 4, choć bezpośrednio obszar, w którym osiadł lądownik jest stosunkowo płaski.

Mars / Odp: Mars Rover 2020
« Ostatnia wiadomość wysłana przez artpoz dnia Luty 15, 2019, 20:30 »
Jak się nie wyrobią, to też nic wielkiego się nie stanie. Najwyżej poczekamy jeszcze te 2 lata. Curiosity się opóźnił, ale ważne, że wszystko zadziałało i do tej pory bada sobie Marsa.
Księżyc / Odp: Chang'e 4
« Ostatnia wiadomość wysłana przez juram dnia Luty 15, 2019, 20:04 »
Podziałka na dole zdjęcia jest błędnie opisana - pojedynczy pasek ma długość 50 metrów a nie 100.
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