NASA ENGINEERS TESTED the first robotic moon rover last week as its prototype practiced descending off a test model of a lunar lander ramp at the Ames Research Center in Silicon Valley.
Volatiles Investigating Polar Exploration Rover (VIPER) is a mobile robot that will go to the moon’s south pole in search of water. The testing is a critical step for the rover’s trip to ensure its smooth exit from the lander on the moon.
SpaceX’s Falcon Heavy launch vehicle and Astrobotic’s Griffin Lander will deliver VIPER to the moon’s surface. The rover will be controlled by drivers at Ames. The testing last week was to check how things would go after the lander is on the moon and the ramps are deployed.
“One of the things we learned is that we’re pretty good at being able to egress.”Mercedes Herreras Martinez, VIPER mission risk manager
It is one of the most critical phases of the mission, which is egress — coming off the lander by driving down the ramps, according to Mercedes Herreras Martinez, risk manager for the mission.
“We’re trying to make sure we understand all the little challenges of coming off the ramps,” she said.
The wheels need to be well-adjusted to the ramps and have a good grip. The lander might not land completely leveled, which could be another challenge.
One of the tests was to put marks in the ramps to know where the rover is during its descent. They also tested having drivers in a different building and driving the prototype down the ramps. Additionally, to test fault management, they made the ramps bend inwards, bringing them closer and closer and tested driving down it.
“One of the things we learned is that we’re pretty good at being able to egress,” Martinez said. According to her, the egress can be complicated, and the team needs to pay attention to a lot of different things to make it happen.
The rover will then come off the lander by driving down the ramps, and then that is when the journey of the mission starts.
The primary objective of the 100-day mission is to try to understand where and how much water and other resources there are on the moon by building a resource map. The rover will be remotely controlled so there will be a few seconds’ delay in the signals.
The rover will have three spectrometers and one drill. The drill will take samples at different depths and put them at the bottom of the rover for the spectrometers to look at and measure the concentration of water.
There are a few areas on the moon, called science stations, where there might be increased scientific interest or likelihood of finding water, Martinez explained. The rover will do three drills in different places at these spots and then move on to the next.
It is very critical that communication with the rover stays healthy, she said.
“One of the key challenges of the south pole of the moon is that Earth is very low on the horizon,” Martinez said. “The radio signal is very, very much close to the lunar terrain, so when that happens there can be interference.”
There are other challenges for the mission and testing conditions on Earth do not exactly match the moon’s conditions. There is no vacuum and it’s not the same temperature.
“But we try to invest our resources in the things that are the easiest but very high return value,” Martinez said. “In this case, it was mostly trying to test all the structural interface between the rover and the lander and make sure that the driving is smooth.”
The temperature requirements, loads and the vacuum are tested separately.
The team has tested challenging scenarios, Martinez said, “but we have demonstrated that we are able to come off the ramps even if the lander isn’t landing in the best orientation.”