In 1969, during the Apollo 11 Moon landing, astronauts looked out of the shuttle window for distinguishing features of the landscape that they recognised from maps of the moon, enabling them to steer clear of known craters and boulders and ensure they did not land on a potentially disastrous area.
50-years on and this process is now automated thanks to new technology developed by NASA. The process, called ‘Terrain Relative Navigation’ (TRN) analyses images of the planet’s surface during descent and provides the shuttle’s pilots with insights into surface hazards to avoid while landing.
TRN is a feature on NASA’s newest Mars rover, Perseverance, which will test the technology on its maiden voyage to the Red Planet in 2021, paving the way for future crewed missions to the moon and beyond.
How will Perseverance land and where does TRN fit into the process?
As Perseverance enters the Martian atmosphere, it will naturally slow down due to drag. However, this will heat the external surface of the shuttle to around 1,300 degrees Celsius (the internal temperature will remain at room temperature due to temperature regulation technology).
While descending through the atmosphere, pockets of air will hit Perseverance, which could knock it off course. Working against the air pockets, the on-board thrusters kick in to adjust its angle and direction to ensure it remains on course. This is a standard guided entry technique.
The shuttle’s heatshield will naturally slow the spacecraft down to approximately 1,000mph. At this point, Perseverance’s ‘Range Trigger Technology’ will calculate its distance to the landing target using radar technology and analysing the bounce signals from the surface.
At approximately 7 miles away from the surface, the shuttle’s 70.5ft supersonic parachute will open and help slow the rover down to 200mph. At this point, the heatshield will separate and expose the Terrain Relative Navigation system for the first time.
The TRN system uses a high-powered camera to identify core surface features and compare them to an on-board map of Mars to determinate exactly where it is heading. Before the launch, mission team members will have mapped out the safest areas to land, and the TRN system will determine which one is safest and within reach. The shuttle will then prepare for its next landing stage.
Once slowed to 200mph, the shuttle will separate from the parachute and slow down further using it’s ‘descent stage engines’. These are 8 powerful thrusters, pointed down at the ground, and are activated at approximately 6,900 feet above the surface.
The descent stage engines will slow Perseverance down to its final descent speed of approximately 1.7mph where it will initiate the ‘Skycrane Manoeuvre’ – this is where the shuttle’s legs and wheels lock into position for the final touchdown.
The progress made in space exploration technology has been astronomical in the last half-decade. Many articles have reported how the components in a modern-day phone, such as an iPhone are more advanced than those used in the Apollo 11 spacecraft, including memory cards and processors.
Terrain Relative Navigation is another piece of revolutionary technology which will only improve the Entry, Descent and Landing process for future space missions. At Soumac, we find the intricate workings of a modern shuttle’s systems out-of-this-world and are fascinated thinking about the advanced circuit boards which are used on spacecraft such as Perseverance.