NASA’s Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) spacecraft is currently cruising to Mars. On May 22, 2018, it performed its first course correction guiding it to the Red Planet.
NASA’s InSight spacecraft is on its way to Mars. Image credit: NASA / JPL-Caltech.
InSight will be the first mission to peer deep beneath the Martian surface, studying the planet’s interior by measuring its heat output and listening for marsquakes, which are seismic events similar to earthquakes on Earth.
It will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will help planetary researchers better understand how other rocky planets, including Earth, were and are created.
InSight was launched on May 5, 2018, with a United Launch Alliance Atlas V 401 rocket from Space Launch Complex 3 at Vandenberg Air Force Base in California.
On May 22, the spacecraft fired its thrusters for the first time to change its flight path.
This activity, called a trajectory correction maneuver, will happen a maximum of six times to guide the lander to Mars.
An artist’s impression of the InSight lander on Mars. Image credit: NASA / JPL-Caltech.
Precise calculations are required for InSight to arrive at exactly the right spot in Mars’ atmosphere at exactly the right time, resulting in a landing on November 26, 2018.
Every step of the way, a team of navigators at NASA’s Jet Propulsion Laboratory estimates the position and velocity of the spacecraft.
“This first maneuver is the largest we’ll conduct,” said InSight’s deputy mission design and navigation manager Fernando Abilleira.
“The thrusters will fire for about 40 seconds to impart a velocity change of 8.5 mph (3.8 m/sec) to the spacecraft. That will put us in the right ballpark as we aim for Mars.”
“Navigation is all about statistics, probability and uncertainty,” he added.
“As we gather more information on the forces acting on the spacecraft, we can better predict how it’s moving and how future maneuvers will affect its path.”
The recent 40-second burn relied on four of eight thrusters on the spacecraft.
A separate group of four is autonomously fired on a daily basis to keep the spacecraft’s solar panels trained on the Sun and its antennas pointed at Earth.
While necessary to maintain orientation, these small, daily firings also introduce errors that navigators have to account for and counterbalance.
“Everyone has been working hard since launch to assess what these small forces have done to the trajectory,” said InSight’s navigation team chief Allen Halsell.
“People have worked lots of hours to look at that. For engineers, it’s a very interesting problem, and fun to try to figure out.”
When the spacecraft is just a few hours from Mars, the planet’s gravitational pull, or gravity well, will begin to reel the spacecraft in.
At that point, the InSight team will prepare for the next milestone after cruise: entering Mars’ atmosphere, descending to the surface and sticking InSight’s landing.
