Jet Propulsion Laboratory engineers will forgo an opportunity to tell the spacecraft carrying the rover Curiosity how to get to Mars two hours before it lands.
It's the last time they can talk to the spacecraft before the dramatic landing sequence that involves a 100-pound parachute and sky crane, which is designed to lower the rover from a rocket-powered "backpack."
"Everything was looking good all day," said John Essmiller, a guidance and control engineer on the mission, from the JPL campus.
Essmiller said the spacecraft will get to Mars' Gale Crater by predicting its location. Engineers have the chance to tweak its position two hours before landing, but they don't plan to, said Essmiller. After that, it's on its own.
He described it as knowing in your head how long it takes to arrive at the entrance of a door when you're a few feet away from it. Engineers have to tell the spacecraft where it is in space, or it won't know its location.
Tomas Martin-Mur, the mission's navigation team chief, previously said "There is no GPS on Mars."
Any adjustment the engineers could make tonight would be equivalent to telling the spacecraft "You are here."
The spacecraft will land to the best of its ability in the area of the Gale Crater JPL picked, but engineers are prepared for small errors that could park Curiosity slightly out of the landing site, said Essmiller.
"The sensors give it some insight to where it is," he said. "But the vehicle doesn't have eyes to gauge how far away it is [from Mars]."
What will the engineers be doing when less than two hours are left until landing?
"Waiting patiently," said Essmiller.
-- Tiffany Kelly, Times Community News