Alien conspiracy theorists have certainly ruined the word “probe.” But there's really only one kind of extraterrestrial probing happening in our solar system, and it’s us Earthlings who are doing it.
On Monday an intrepid spacecraft called OSIRIS-REx officially rendezvoused with a 500-meter-wide asteroid. The spacecraft will spend months at the asteroid, then descend to gather samples and return them to Earth.
Humanity witnessed another casual miracle of engineering just the week before—the landing of InSight on Mars. This probe will measure seismic Marsquakes and drill into the surface measure the thermal flux under the surface. This is a geology mission, one meant to gather never-before-seen data on the internal structure of the Red Planet.
“I think we’re in a Golden Age of space exploration,” Bruce Banerdt, the InSight principal investigator for JPL, told Seniorhelpline on the morning of the Mars landing.
Alone But Together
Although our robotic explorers are working millions of miles apart, together they're pursuing the same central mystery: how did the solar system form? Each probe is providing new hard, forensic evidence for planetary scientists, geologists, and astronomers to form a unified view of Earth's origins, and how other planets could be home to its abundance of life.
“We've had missions all across the solar system...it's been pretty spectacular,” says Tim Linn, senior space engineer at Lockheed Martin who’s division is running seven missions from its facilities in Colorado.
Talk to the NASA scientists and contractors who built these spacecraft and it becomes clear that it's a great time to be in the space exploration game.
“If you look back through the history of planetary science, there were a few big missions every so often that did spectacular things, but there were long gaps in between the missions,” says Linn. “There was a pretty big push for the early Mars missions and some Venus missions, and then there was the Pioneer and Voyager spacecraft, but there was not a lot happening in the late 60's and through the 70's. Not very much happened in the 80's, and then not too much happened in the 90's either.”
But concentrating scientific minds (and government budgets) toward Mars changed everything.
A New Martian Mission
On July 4th, 1997, NASA's Pathfinder spacecraft landed safely on the surface of Mars, effectively turning a page in the history of space exploration.
"That kick-started the Mars program that led to Mars Global Surveyor, Mars Odyssey, Mars Reconnaissance Orbiter, a lot of landers,” says Beau Bierhaus, a veteran space mission engineer at Lockheed. "And it's just been a snowball rolling downhill since then."
And in the case of Mars, there is strength in numbers. During last week's InSight landing, the Mars Recon Orbiter and Odyssey both served as communication relays (along with two twin CubeSats that launched with InSight earlier this year). If anything went wrong during the landing, their view of the disaster would be the key forensic evidence used to find out what happened.
When the science begins in earnest next year, even more predecessor probes will take part in the mission.
“Mid-next summer, MAVEN is actually tweaking their trajectory now, so they're going to be another asset for future relays,” says Linn. “Not only for InSight, but for also Curiosity, which is still doing amazing science on the surface of Mars.”
Having an earlier arrival on the scene is a huge advantage in these operations. “The spacecraft are lasting longer,” JPL’s Barnerdt says. “It used to be that you’d put one up and it would fail or finish, and then you’d launch another. Now the missions overlap.”
The science also benefits from multiple missions, producing questions that the next mission can try to answer. For example, evidence of water and ice on Mars have led to questions about past habitability, so InSight will use geological tools to learn how Mars formed. More importantly, these are clues to why Mars became hostile to life while Earth has been so very nurturing.
The next big NASA probe will land in 2020. This will be a geologic treasure hunt as the rover scouts around for rocks that have signs of microbial life and them stash them for a future retrieval mission, though that mission remains currently unfunded. The targeted area is the Jezero Crater, which scientists think was once a river delta courtesy of spectroscopic images captured by the various orbiters.
Mars makes it clear that more can be gained from scientific campaign instead of one-off missions. “We can study these places in depth, and not just do reconnaissance, which is what we did the first 20 years,” Barnerdt said. “In the scientific sense, it allows us to pass the baton and not just move on to the next place.”
More Than Just Mars
It makes sense that Mars, with its similarities, would be instructive when it comes to understanding Earth. But destinations like asteroid and gas giants are less obvious subjects.
The asteroid Bennu, the target of the OSISRIS-REx probe, is a flash-frozen sample of the solar system’s original material. Earth has been subject to tremendous pressures and temperatures over its 4.5-billion-year history, changing those early building block materials.
“O-REx is getting those early ingredients that led to the formation of Earth,” says Beau Bierhaus, a veteran space mission engineer at Lockheed. ”And so these missions are cool and interesting, and we get to solve these really neat engineering challenges, but fundamentally they really are going after these really big questions.”
He says that the asteroid probe is “one of the missions that's part of that fleet of spacecraft that are really kind of revolutionizing our understanding of our solar system and earth's place in the solar system.”
Bierhaus is also working the Juno spacecraft, which has been doing flybys past Jupiter since 2016. This planet couldn't be more different than our Earth. It is giant planet 11 times larger than Earth with a gaseous center instead of a rocky core. But studying this celestial body has some direct bearings on those big questions concerning Earth’s earliest history.
“One of the reasons why Juno is so important is because it's getting information about the size and mass of Jupiter's core tells us a whole lot about the early solar system and how mass is exchanged between the inner and the outer solar system,” Bierhaus says. “Jupiter was sort of the gateway. What material was delivered to Earth was, in part, dependent upon how big Jupiter's core was and how fast it formed.”
While the probes are flying fast and furious, there’s always the matter of paying for future missions. NASA has not yet funded a Mars mission after 2020. Space telescopes and the effort to return to the Moon will take attention and funding away from exploration campaigns. Hopefully, the useful engineering lessons from the “Golden Era” of space exploration will make future missions less expensive and more probable.
But no matter what future unfolds, these vehicles are forever changing the understanding of our cosmic neighborhood. They have also secured homo sapien’s place as the master probers of this solar system—extraterrestrials take note.