With just a day to go, NASA's InSight spacecraft is aimed at bull's-eye touchdown on Mars, zooming in like an arrow with no turning back.
The InSight's journey of six months and 300 million miles (482 million kilometers) comes to a precarious grand finale Monday afternoon.
The robotic geologist designed to explore Mars' insides, surface to core – must go from 12,300 mph (19,800 kph) to six minutes flat as it pierces the Martian atmosphere, pops out a parachute, fires its descent engines and, hopefully, lands on three legs.
It is NASA's attempt to land on Mars in six years, and all those involved are understandably anxious.
NASA's top science official mission, Thomas Zurbuchen, confided Sunday that his stomach was already churning. The hardest thing is sitting on his hands and doing nothing, he said, except hoping and praying everything goes perfectly for InSight.
"Landing on Mars is one of the hardest single jobs that people have to do in planetary exploration," noted InSight's lead scientist Bruce Banerdt. "It's such a difficult thing, it's such a dangerous thing that there is always a fairly uncomfortably large chance that something could go wrong."
Earth's success rate at Mars is 40 percent, counting every attempted flyby, orbital flight and landing by the U.S., Russia and other countries dating all the way back to 1960.
But the U.S. Mars landings in the past four decades has been pulled off seven successful. With only one failed touchdown, it's an active record. No other country managed to set and operate a spacecraft on the dusty red surface.
InSight could hand NASA's eighth win.
It's shooting for Elysium Planitia, a plain near the Martian equator that the InSight team hopes is a flat as a parking lot in Kansas with few, if any, rocks. This is the no rock-collecting expedition. Instead, the stationary 800-pound (360-kilogram) lander will use its 6-foot (1.8-meter) robotic arm to place a mechanical mole and seismometer on the ground.
The self-hammering mole will burrow 16 feet (5 meters) down to measure the planet's internal heat, while the ultra-high-tech seismometer listens for possible marsquakes. Nothing like this has been attempted before our smaller next-door neighbors, nearly 100 million miles (160 million kilometers) away.
No experiments have ever been moved robotically from the spacecraft to the actual Martian surface. No lander has deeper than several inches, and no seismometers have ever worked on Mars.
By examining the deepest, darkest interior of Mars – still preserved from its earliest days – scientists have formed a 4.5 billion years ago and why they turned out so different. What are the big questions that are made Earth so hospitable to life.
Mars once had flowing rivers and lakes; the deltas and lakebeds are now dry, and the planet cold. Venus is a furnace because of its thick, heat-trapping atmosphere. Mercury, closest to the sun, has a surface that is positively baked.
The planetary know-how gained from InSight's $ 1 billion, two-year operations could even spill over to rocky world beyond our solar system, according to Banerdt. "The findings help explain the types of conditions in these so-called exoplanets" and how they fit into the story that we're trying to figure out for how planets forms, "he said.
Concentrating on planetary building blocks, InSight has no life-detecting capability. That will be left for future rovers. NASA's Mars 2020 mission, for instances, will collect rocks for eventual returns that can hold evidence of ancient life.
Because it's been so long since NASA's last Martian landfall – the Curiosity rover in 2012 – Mars mania is gripping not only the space and science communities, but everyday folks.
Viewing parties are planned to coast to museums, planetariums and libraries, as well as in France, where InSight's seismometers were designed and built. The giant NASDAQ screen in New York's Times Square will start NASA Television broadcasting an hour before InSight's scheduled for 3 p.m. EST touchdown; so will the National Air and Space Museum's Udvar-Hazy Center in Chantilly, Virginia, and the Denver Museum of Nature and Science. The InSight spacecraft was built near Denver by Lockheed Martin.
But the real action, at least on Earth, will unfold at NASA's Jet Propulsion Laboratory in Pasadena, California, home to InSight's flight control team. NASA is providing a special 360-degree online broadcast from inside the control center.
Confirmation of touchdown could take minutes – or hours. At the minimum, it's eight-minute communication lag between Mars and Earth.
A pair of briefcase size satellites trailing InSight since lift in the radio signals to Earth, with a potential lag time of under nine minutes. These experimental CubeSats will fly right past the red planet without stopping. Signals also could travel straight from InSight to radio telescopes in West Virginia and Germany. It will take longer to hear from NASA's Mars orbiters.
Project manager Tom Hoffman said he was trying to stay outwardly calm as the hours tick down. Once InSight phones home from the Martian surface, though, he expects to behave much like three young grandsons at the Thanksgiving dinner, running around like crazy and screaming.
"Just to see who's sitting near me … I'm going to unleash my inner 4-year-old on you, so be careful," he said.