{"id":25078,"date":"2021-02-18T17:13:41","date_gmt":"2021-02-18T09:13:41","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/nasa-perseverance-in-epicly-successful-entry-descent-and-landing-at-jezero-crater-mars\/"},"modified":"2021-02-18T17:13:41","modified_gmt":"2021-02-18T09:13:41","slug":"nasa-perseverance-in-epicly-successful-entry-descent-and-landing-at-jezero-crater-mars","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/nasa-perseverance-in-epicly-successful-entry-descent-and-landing-at-jezero-crater-mars\/","title":{"rendered":"NASA, Perseverance in epicly successful entry, descent, and landing at Jezero Crater, Mars"},"content":{"rendered":"

After years of hard work and labor, NASA succeeded in the most complex landing ever attempted on another planet.<\/p>\n

Perseverance safely touchdown at Jezero Crater at an actual time on Earth of 15:43 EST (20:43 UTC) \u2014 with confirmation of landing received 11 minutes 22 seconds later through the Madrid, Spain facility of the Deep Space Network at 15:55 EST (20:55 UTC).<\/p>\n<\/p>\n

Arriving at Mars, and the challenges thereof<\/b><\/p>\n

Historically, there is now \u2014 with Al-Amal, Tianwen-1, Perseverance\u2019s successes \u2014 a better than 50% chance of succeeding in placing a spacecraft at Mars, whether that\u2019s inserting it into orbit or landing it on the surface. <\/p>\n

While that is technically true from a complete historical aspect, it is somewhat misleading based on the technology used for the initial Mars attempts throughout the 1960s and 70s and the newer technology which has seen a far greater success rate in the last two decades. <\/p>\n

Since the start of the 21st century, 18 Mars missions, not counting Perseverance (the success of which cannot be determined until landing), have departed (or tried to depart) for Mars with the purpose of either entering orbit or landing on the planet.  Of those, 14 have been successful and four have failed.<\/p>\n

That gives an international, 21st century success rate above 75% \u2014 far better than the historical average.<\/p>\n

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But those numbers themselves do not tell the full story.  Even 21st century missions with well-built and tested autonomous technology have failed during critical events like landing, as was the European Space Agency\u2019s Schiaparelli lander\u2019s fate in October 2016.<\/p>\n

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Overview of Perseverance. (Credit: NASA\/JPL)<\/p>\n

What\u2019s more, while Perseverance used some of the same systems that helped land the Curiosity rover on Mars in August 2012, Perseverance also used new technology to execute the most extreme landing ever attempted on another planet.<\/p>\n

Perseverance had a very small landing target and carried a need to avoid, in real-time, potentially hazardous terrain inside Jezero Crater \u2014 which is itself a 45 kilometer wide impact basin.<\/p>\n

During the final stages of descent, Perseverance\u2019s onboard landing systems had to navigate steep cliffs, sand dunes, boulder fields, and smaller impact craters to find a safe location to set the rover down. <\/p>\n

The Terrain Relative Navigation and the Range Trigger, both new technologies incorporated into Perseverance\u2019s landing systems, allowed split-second decision-making as well as an ability to abort landing at one location and fly to a different site nearby if needed.<\/p>\n

It was challenging indeed, and while there was no guarantee of success, there were many reasons to believe that NASA engineers, technicians, and mission planners had done everything possible to ensure the rover makes it safely to the surface. <\/p>\n

In Perseverance\u2019s favor were not just the overall 21st century odds but NASA\u2019s overall odds of landing something on the Red Planet \u2014 especially when it comes to rovers, for which the U.S. space agency has a stunning 100% success rate.<\/p>\n

Moreso, the Sojourner, Spirit, Opportunity, and Curiosity rovers have all enjoyed long scientific careers for their designs, with Opportunity outlasting its 90 day planned mission for a final duration of 14 years 138 days.<\/p>\n

Nevertheless, landing on Mars is extremely hard for several reasons, not the least of which being that all commands had to be stored ahead of time as there was no way to communicate in real-time based on the distances between Mars and Earth.<\/p>\n

For Perseverance\u2019s landing, it took 11 minutes 22 seconds for a signal from the rover to reach Earth.<\/p>\n

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The Entry, Descent, and Landing profile for Perseverance. (Credit: NASA\/JPL)<\/p>\n

By the time teams at the Jet Propulsion Lab receive the confirmation signal that Perseverance has entered the Martian atmosphere, the rover had already landed safely five minutes earlier.<\/p>\n

Entry, Descent, and Landing \u2014 Seven Minutes of Terror<\/b><\/p>\n

It was now down to Perseverance\u2019s technology and software to execute the landing program as planned and get the rover safely to the surface.<\/p>\n

Overall, there were 16 main sequence events in the Entry, Descent, and Landing choreography that had to reduce Perseverance\u2019s velocity from 19,332.58 km\/h to 0 km\/h in just six minutes.<\/p>\n

The first elements of this sequence included separation of the cruise stage, which has provided power, data, and communication capabilities during the cruise from Earth, followed by de-spin, which stopped the vehicle\u2019s four rpm spin that stabilized it during the interplanetary cruise.<\/p>\n

The final step prior to atmospheric entry was jettisoning the cruise balance masses to allow the entry capsule to achieve the proper attitudes during landing.<\/p>\n

As atmospheric entry began, the vehicle continued accelerating toward Mars as the tenuous atmosphere around the planet was not yet thick enough to begin reducing the craft\u2019s velocity.<\/p>\n

When the atmosphere became thick enough, active guidance began as the spacecraft encountered pockets of more-dense and less-dense air within Mars\u2019 atmosphere.  This active guidance period kept the craft on course for the landing site by making minor adjustments to the trajectory as it surfs through the atmosphere.<\/p>\n

One minute past peak heating, a heading alignment maneuver engaged to correct any additional crossrange error imparted during atmospheric entry that could not be corrected by active guidance. <\/p>\n<\/p>\n