From the size of a milk crate to the size of a car, NASA’s Mars rovers have gotten bigger and more powerful since the first such landing in 1997. The latest effort, Curiosity, landed at Gale Crater in 2012 and is expected to last the better part of a decade. But its durability and powerful rock-analyzing laboratory came at a price of $2 billion.

Curiosity’s science return so far includes finding extensive evidence of organics and water in its zone, although critics have said its drill is under-used. NASA is now planning a similarly sized rover to leave for Mars in 2020. But is there a way to add more science without overburdening on cost?

PHOTOS: Satellite ‘Flock’ Launched From ISS Cubesat Cannon

As multi-million dollar spacecraft crawl across our solar system, they could bring smaller passengers with them. These tiny vehicles are called CubeSats and they’ve done a great job colonizing low Earth orbit since 2003. (At least one launched that year, from the University of Tokyo, was still operational as of 2014.) Their ability to survive beyond our planet is untested — even though from experience, the community knows what parts are most likely to survive. Nevertheless, NASA, the European Space Agency and several other groups are thinking about how to make this exploration happen in the next few years.

The first out of the gate will likely go to Mars. Just last week, NASA announced two tiny CubeSats called MarCO will join the 2016 stationary InSight lander. While InSight works on the surface, MarCO will fly overhead and attempt to send information to Earth about the entry and landing in real time.

Artist’s conception of the European Space Agency mission called the Asteroid Impact Mission (AIM), which could carry up to six CubeSats with it. APL

If these satellites make it, they will be the first attempt to have carry-on spacecraft at Mars since the doomed Mars Polar Lander struck the surface in 1999. Riding with MPL were two tiny probes called Deep Space 2 that were supposed to slam below the surface and look for water ice.

ANALYSIS: Cubesats May Hitchhike on Mission to Europa

“We know they landed, but we don’t know in what condition,” said Robert Staehle, the assistant division manager for advanced concepts in NASA’s Jet Propulsion Laboratory’s instruments division, in an interview with Discovery News. In a few words, his job is to send instruments all over the solar system: Earth, Mars, the icy moon of Europa, wherever. And he knows of at least 15 funded projects at JPL that involve CubeSats.

Staehle is also lead investigator of a concept called MarsDrop (a collaboration with the Aerospace Corporation) a microlander that would target riskier areas of Mars. While a rover has its uses, it wouldn’t go far on a volcano or inside a crater. Mini-landers could instead explore the surface, Staehle argues, by riding along with a bigger mission to take them to the Red Planet.

ANALYSIS: Cubesats: A Space Junk Hazard?

But there are questions about how well these small spacecraft could survive. CubeSats take advantage of advances in computer technology, but their delicate circuit boards are not necessarily resistant to radiation despite the industry selecting parts that have performed well in the past, he points out. (Small missions are also subject to less testing, adding to the uncertainty.) Outside of Earth’s protective cocoon, the radiation risk grows exponentially. So part of MarCO’s role will be to test how long the electronics can survive baked in a harsh space environment.

Artist’s conception of CubeSats at Jupiter (right) and its moon Europa.NASA/JPL

Mars isn’t the only spot being targeted. Vermont Technical College’s CubeSat Laboratory is working on a CubeSat that could one day form the design basis of a tiny lunar spacecraft. NASA is planning a mission to Europa in the 2020s to examine its ice from orbit, and learn more about the probable ocean underneath. In October, it announced that 10 universities have been selected to do preliminary CubeSat proposals to ride along. They would do everything from probe landing sites to measure the magnetic field.

Around the same time, the European Space Agency wants to explore a pair of asteroids with its Asteroid Impact Mission. There are up to six CubeSat slots available on this mission for smaller passengers. And waiting for a launch date is JPL’s Interplanetary NanoSpacecraft Pathfinder In Relevant Environment (INSPIRE), which (among other science) will do studies of the sun outside of Earth’s magnetic field.

NEWS: Space Station’s Cubesat Launcher has Mind of its Own

Because these spacecraft are built cheaply and not tested as much as conventional ones, the unexpected can sometimes happen. Staehle recalls the time that three CubeSats launched into low Earth orbit. Two of them, built by the University of Michigan (with a JPL payload called COVE, for CubeSat On-Board processing Validation Experiment) and Montana State University, had magnets to align with the Earth’s magnetic field. It’s a common technique to keep the satellites pointed in the right direction. But in this case, they used a magnet that was a little stronger than usual. The result? After the satellites deployed, they flew back and stuck together.

“You could argue that was the first automated rendezvous and docking between CubeSats, but that was not the mission objective,” Staehle joked. Because the two satellites were transmitting and receiving on similar frequencies, the University of Michigan’s CubeSat was unable to receive the command to turn on the JPL experiment. Instead of a formal investigation, the crews of the satellites informally collaborated and made design changes. For $250,000 — a bargain in space spending — the University of Michigan CubeSat and JPL payload were rebuilt from spares and relaunched in December 2013 with no problem.

Mars Sojourner stands ready to explore the Red Planet in 1997. NASA

The history of CubeSats can be traced back to the NASA “Faster, Better, Cheaper” program of the 1990s, which postulated that more science could be done with smaller missions. These involved small teams, fewer formal checks and a commitment to use commercial microelectronics to keep launch costs down.

It led to successes such as Mars Pathfinder, which touched down safely with its Sojourner rover in 1997. But it also was criticized for not having enough checks and balances in place to save the Mars Polar Lander or Mars Climate Orbiter, which both died upon arrival later that decade.

“My personal opinion is it has been very successful,” Staehle said, pointing out that the idea of doing more with less has persisted even 20 years later. “We used to have two planetary missions a decade, and some years we now have two a year.”

He argues, however, that there is a role for both cheap and big missions in the coming decades. The big ones can spend their usual years exploring a distant planet or moon, while the little ones riding along can have a hyper-focused secondary mission that may only last a few days, weeks or months. Both provide science, but with two different flavors. The next question, then, is how well the little missions will do in fulfilling their mandate.