NASA ultimately called off the 2016 launch, made the fix to the seismometer, and readied InSight for its new launch window. Part of the long delay was because Mars and Earth align favorably for spacecraft launches once every 26 months when the planets are relatively close in their respective orbits.
The stationary InSight is heavily based on the Phoenix lander that touched down in 2008 at Vastitas Borealis, near the north pole of the planet. Some similarities include the structural layout of the lander, which includes three legs that will touch the surface, as well as the descent thrusters that will help InSight touch down.
But there are several upgrades to enhance InSight's science since Phoenix landed on the planet a decade ago. The flight electronics, or avionics, are based on the design for the much newer orbiting MAVEN Mars mission, which launched from Earth in 2013.
InSight also has an X-band communications system that transmits directly to the Deep Space Network, a large set of antennas on Earth. It will constantly send out its position. As Mars wobbles in its orbit around the sun, those wobbles will provide information about the Red Planet's core, including its size and composition. This information will help scientists assesses the cores of other rocky planets, such as Earth and Venus.
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The spacecraft also has a heat probe that will dig 16 feet (five meters) under the surface to measure subterranean heat flow. This could provide more information on volcanic activity on Mars, which is another huge mystery. Mars possesses several mighty volcanoes in its Tharsis region, including the enormous Olympus Mons that dwarfs the height and width of Earth's Mount Everest. These volcanoes appear dormant now, but they were active some time ago.
InSight will be the first Mars mission to launch from Vandenberg Air Force Base in California. Previous Mars missions launched from Florida, where the Earth's rotation at the equator helped boost the rocket speed to help the spacecraft escape Earth orbit. While Vandenberg doesn't have this advantage, NASA chose the West Coast because its launch manifest wasn't as crowded. Luckily, the Atlas V rocket hefting InSight into space has more than enough power to send the spacecraft on its way.
The spacecraft will also have two tiny companions riding along in the rocket. The Mars Cube One, or MarCO, CubeSats will fly behind InSight and transmit information about InSight's landing. These will be the first CubeSats to fly so far from Earth. NASA will fly additional CubeSats on a test of its mighty Space Launch System rocket when it flies around the moon in sometime around 2020. Other CubeSats may be passengers on NASA's planned Europa Clipper mission, which will target an icy moon of Jupiter in the 2030s.