NASA’s InSight lander has performed a perfect and critical entry and descent through the Martian atmosphere to gently touchdown on Mars’ Elysium Planitia. The landing came after a flawless six and a half month cruise through the interplanetary space between Earth and Mars and was humanity’s first successful landing on Mars in over six years following 2012’s August landing of NASA’s Curiosity rover at Gale Crater.

Confirmation of landing came through the Deep Space Network at 15:01 EST (2001 UTC) on Monday, 26 November following the 7 minute descent and landing of InSight on the Martian surface – during which the science platform slowed itself from 12,300 mph (19,800 kph) to just 5 mph (8 kph).

The Martian Challenge:

From the 1600s to the 1960s, all the information humanity had on Mars came solely from ground-based telescopes – a feat in itself. But with the dawn of rocketry came a new means of exploring the tantalizing Red Planet that had for so long captured our imaginations and fancy.

Since the beginning of the space age, the exploration of Mars figured prominently in the space programs of the United States and Russia (formerly the Union of Soviet Socialist Republics) – expanding in the 1990s to include Japan, in the 2000s to include the European Space Agency (ESA), and in the 2010s to include India and China.

On 10 October 1960, Earth’s first space probe to Mars was launched by the USSR. Named Mars 1M No.1, the mission ended shortly after liftoff in a launch failure. And with that failure, the reality of up-close exploration of Mars was realized.

Mars was never going to be easy, and it was going to challenge us in ways we didn’t expect. Since 10 October 1960, 56 missions (some bundled together resulting in two missions launching together) to Mars – be they flybys, orbiters, landers, rovers, and/or sample returns – have been launched by NASA, Russia/USSR, Japan, ESA, China, and India.

Of those 56 missions, 56 to date, including InSight and the Mars Cube One flights, have attempted to successfully arrive at Mars and either flyby, insert themselves into orbit, or land on the surface.

Of those 56 attempts, the results stand as thus:

Successes Partial Successes Failures

27 8 21

This gives an overall global average for Mars mission success of 48% if only complete successes are taken. To say the least, the figures tell a clear story of how difficult in-situ exploration of Mars is, and the figures for landers and rovers are even more daunting.

In all, 19 lander/rover missions have been attempted to Mars, including InSight. Of those, 8 have ended in failures, 3 in partial successes, and only 8 in successes – a 42% success rate.

Despite those daunting global odds, NASA has a nearly unbelievable success rate with Mars lander/rover missions. Including InSight, NASA has sent 11 landers/rovers to Mars with an 82% success rate. Only the Mars Polar Lander and Deep Space 2 hard landers (two components of the same mission) crash-landed on the Red Planet in 1999 due to improper hardware testing.

Despite that failure (and a few others), NASA’s overall Martian success rate is an impressive 80%, with accomplishments including:

First completely successful mission to Mars with Mariner 4

First successful Martian orbiter with Mariner 9

First completely successful Martian landing with Viking 1

First successful Martian rover with Sojourner

Longest-surviving Human technology on another world with the Mars Exploration Rover Opportunity.

InSight’s landing – preparing for all possibilities years ahead of time:

InSight was the 19th lander to attempt a touchdown on the Martian surface.

Slamming into Mars’ atmosphere at 12,300 mph (5.5. km/second), the 1,340 lb (608 kg) craft used a combination of hypersonic aerobraking with its heat shield, a hypersonic parachute, and 12 retro-rocket descent thrusters to slow itself to just 5 mph (8 kph) in 7 minutes for landing on the western Elysium Planitia.

Despite similarities and heritage technology with NASA’s Phoenix polar lander, InSight had a much more challenging Entry, Descent, and Landing – known as EDL – sequence than Phoenix did in 2008.

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InSight entered the Martian atmosphere at a slower relative velocity than Phoenix, 12,300 mph (5.5 km/second) vs. 12,500 mph (5.6 km/sec), respectively, and landed 4,900 feet (1.5 km) higher in elevation than Phoenix did – meaning InSight had less time to slow itself down for a safe landing than Phoenix had.

But mission designers also had to account for – years in advance – the possibility that InSight, once launched, might have to land during or just after a dust storm. Dust storms during the Martian northern hemisphere’s autumn season (the current season at InSight’s landing location) are not uncommon, and mission planners had to account for that possibility during InSight’s initial design phase years ago.

Yet during that design phase, no one could have known that the mission’s launch would be delayed from 2016 to 2018 nor that after the lander’s launch, Mars would experience a global dust storm that – in some aspects – was the most intense ever observed.

Nonetheless, the kind of dust storms Mars just endured were always a possibility that InSight would have to contend with; to that end, the lander was given a thicker heat shield than Phoenix’s in case of high-altitude suspended dust which could have caused greater wear through sandblasting of the heat shield.

Likewise, InSight’s hypersonic parachute suspension lines were made of stronger, heavier material than Phoenix’s to account for the possibility that Mars’ atmosphere might be thicker than predicted due to suspended dust in the atmosphere.

More so, InSight controllers received daily weather updates of the Elysium Planitia landing site from NASA’s Mars Reconnaissance Orbiter – allowing controllers the chance to upload last-minute tweaks to the timing of InSight’s parachute deployment and activation of its landing radar system to account for landing-day weather characteristics.

Of note, InSight was also designed to be able to land during a Martian dust storm – something it did not have to do Monday but was nonetheless baked into the craft’s design given that, once launched, the science platform’s landing date and time were fixed and could not be postponed.

InSight’s landing sequence:

From 12,300 mph (19,800 kph) to 5 mph (8 kph) in just 7 minutes.

As NASA and ESA had done for the last several Mars arrivals and landings, NASA’s fleet of Mars orbiters served as communications relays for InSight as it sent out a continuous stream of data via its UHF antenna during Entry, Descent, and Landing.

1 DAY AWAY from my #MarsLanding. The “seven minutes of terror” is one of the most intense parts of my mission. It starts when I reach the top of the Martian atmosphere (~80 miles above the surface) and lasts about 6 ½ minutes until I land safely. More: https://t.co/RIpdIlqSek pic.twitter.com/vkZNsJjXEt — NASAInSight (@NASAInSight) November 25, 2018

NASA’s Mars Reconnaissance Orbiter and Mars Odyssey crafts once again served as the primary engineering communications paths for InSight back to the Deep Space Network on Earth and then on to the Jet Propulsion Laboratory in Pasadena, California, to InSight’s controllers.

InSight’s team had no control over the craft during landing, instead watching the data to see if InSight had executed its autonomous landing program as designed.

During InSight’s landing, Earth and Mars were roughly 90,533,240 miles (145,699,130 km) apart, and it took telemetry transmitted from Mars 8 minutes 6 seconds to arrive at Earth.

That meant that at the time NASA received confirmation that InSight had entered the Martian atmosphere, the craft had already been on the Martian surface for over a minute and had already transmitted its “I’m alive and functioning” signal back to Earth.

Given the time it took to receive these signals, all times given by NASA and listed here for InSight’s critical landing steps are in Earth Receive Time – which is 8 minutes 6 seconds after the event actually occurred.

InSight’s Entry, Descent, and Landing timeline with Earth Receive Times for Monday, 26 November 2018 is:

Time (EST) Time (UTC) Event 2:40 pm 1940 InSight entry capsule separation from cruise stage 2:41 pm 1941 InSight entry capsule orients for atmospheric entry 2:47 pm 1947 ATMOSPHERIC ENTRY at 12,300 mph (19,800 kph) 2:49 pm 1949 Peak heating of 2,700°F (1,500°C) 2:49:15 pm 1949:15 Peak deceleration. May cause temporary comm blackout 2:51 pm 1951 Parachute deployment at 850 mph (1,367 kph) 2:51:15 pm 1951:15 Heat shield separation 2:51:25 pm 1951:25 InSight lander leg deployment 2:52 pm 1952 Landing radar system activation 2:53:20 pm 1953:20 Separation of backshell/parachute 2:53:20.5 pm 1953:20.5 IGNITION of 12 retro-rocket/descent engines 2:53:23 pm 1953:23 Orientation to proper landing attitude 2:53:45 pm 1953:45 Begin final decelaration to 5 mph (8 kph) 2:54 pm 1954 TOUCHDOWN on Elysium Planitia 3:01 pm 2001 Receive “Beep” confirming InSight is alive & functioning 8:35 pm 0135 (27 Nov) Confirmation of InSight solar array deployment

Communications – delayed returns and hopeful real-time data:

During Entry, Descent, and Landing operations, InSight continuously broadcasted its data via a UHF radio to the Mars Reconnaissance Orbiter (MRO), but MRO did not transmit that data to Earth right away. Instead, MRO collected the data, stored it, and will transmit it to Earth roughly 3 hours after InSight’s EDL sequence.

Moreover, Mars Odyssey was not within range of InSight during the EDL sequence, but will pass within range of InSight’s landing location roughly 6 hours after landing – at which time Odyssey will connect with InSight and transmit confirmation to Earth that InSight’s solar arrays have deployed as planned.

To this end, while MRO and Odyssey are the engineering communications relays for InSight, they did not relay the platform’s landing information in real-time.

Back on Earth, two observatories, however, did listen for InSight’s UHF live transmission signals during entry and landing, one in Germany and one in West Virginia in the United States. These two observatories provided some real-time information on cruise stage separation, entry, and parachute deployment, but not much else.

Therefore, the only signal Earth received directly from InSight was its X-band ‘beep’ once the lander touched down – a beep that told controllers that InSight was alive and functioning on the surface.

That “beep” arrived at Earth at 15:01 EST (2001 UTC) – 8 minutes 6 seconds after InSight sent it.

So how did we get information real-time from InSight?

Enter the Mars Cube One mission CubeSats.

Given the “delayed gratification” in terms of real-time information expected from InSight via MRO, Odyssey, and the two Earth observatories, NASA designed two CubeSats – Mars Cube One – to fly along with InSight and serve as a technology demonstration to receive InSight’s UFH data signals during Entry, Descent, and Landing, convert them to X-band signals, and immediately retransmit them back to Earth.

The MarCOs – officially called MarCO-A and MarCO-B, though Jet Propulsion Lab engineers nicknamed them WALL-E and Eva – worked perfectly… marking a huge advancement in CubeSat interplanetary and comm relay ability and use.

Thus, the MarCOs provided the only real-time data transmission of the entire EDL sequence from InSight.

Nonetheless, InSight’s success was not tied to the successful operation of the MarCO CubeSats, and InSight could have landed perfectly even if the MarCOs had failed to relay its data back to Earth.

Unlike InSight, the MarCO Cubesats did not enter Mars’ atmosphere nor did they enter orbit. They flew by Mars and continued off into heliocentric orbit of the Sun.