To work for the NASA Jet Propulsion Lab (JPL) it would probably be helpful if you had some juggling skills.
“At JPL we have 24 flying missions in deep space,” said spacecraft engineer Terry Himes, who has had a hand on most of those craft. Himes gave a talk titled “Mars Insider” recently at the Museum of Flight.
“Our job as spacecraft engineers is to keep the health and welfare of the spacecraft,” Himes said, and that’s a job that doesn’t always line up with the science goals of the mission.
“The science guys want to go to the worst possible places on the planet,” Himes laughed. “They want to go to horrifying places and land in crevasses and do all kids of crazy stuff. We (engineers) want to land on flat, sandy plains.”
Thus choosing a place to land is a battle from day one and can often be a lengthy discussion, Himes said. For the Mars Science Lab Curiosity, for example, the science team wanted to land as close as possible to Mount Sharp on Mars so they could explore the geology there. They were able to land in a tight spot by using the controlled descent of Curiosity’s incredible landing method. Himes noted that the target landing area for Mars missions, known as the “landing ellipse,” has been shrinking over the years. While Viking had a landing ellipse 300 kilometers long, they dropped Curiosity into a target of just 18 kilometers.
“It’s like hitting a golf ball in San Diego and making a hole-in-one in New York,” Himes said.
Once a lander is on the ground there’s another daily discussion about what it will do next. This is typically based on photos sent back from the activities of the previous sol, or Martian day. They consider interesting nearby objects, any hazards in the area, and the overall health of the rover. Himes noted that Curiosity’s wheels have taken a beating from hard and sharp rocks on Mars. He also related a funny story about the wheels.
A message in the sand
NASA had told the spacecraft team that they couldn’t put a logo or any other mention of JPL on Curiosity because the project involved all of NASA and scientists from other countries, too. They got around that by putting cutout grooves in the wheels that are Morse code for the letters, so that every time those wheels turn they leave J-P-L in the Martian sand.
“Don’t mess with engineers,” Himes laughed.
A little InSight about Mars
The next project for Himes will be InSight, which after a recent delay is now scheduled to launch next May and land on Mars in November of 2018. InSight, which is short for Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport, will help us figure out how rocky planets form and evolve. The craft will be a modified version of Phoenix, another mission Himes worked on, which found ice near the north pole of Mars in 2008. InSight will have a couple of new instruments.
The first is the Heat flow and Physical Properties Probe, or HP3, which Himes says they’re calling simply “The Mole.”
“It’s a heat transfer mechanism,” Himes said. “We’re going to go into the surface of Mars and conduct heat experiments, see how much heat is there.” The mole will be driven some five meters into the ground on Mars.
The other instrument is the Seismic Experiment for Interior Structure, or SEIS, a “very broad band” seismometer sensitive enough to detect meteor strikes way on the other side of the planet. These two instruments will give scientists information about the inner workings of Mars.
There are a couple more Mars missions on the drawing board. Mars 2020 will be a lander much like Curiosity—NASA can save some cash by re-using spacecraft designs if they can serve the purpose—and it will look for signs of past microbial life on Mars, explore the possibility for creating oxygen in the Red Planet’s atmosphere, and do a variety of other experiments.
NeMO, the “next Mars orbiter,” will provide another communication link should a current orbiter fail, and it also could be part of a plan to return pieces of Mars to Earth.
“Mars 2020 may be depositing samples that it gathers in canisters and leaving them around,” Himes said, “and then NeMO may have something that’s going to go down to the surface, pick them up, and come back, and return to Earth.” Himes noted that plans for NeMO are still quite preliminary.
As these missions are developed it seems likely that Himes will be in the middle of it all.