Who can hate a Roomba? Astronomers, that's who.

The robotic vacuums we all know and love ensure we don’t have to clean our own homes ourselves to get them spotless. (God forbid.) Now, the Roomba's maker, iRobot, wants to do for lawn care what it did for vacuuming. According to filings with the FCC spotted by IEEE Spectrum, iRobot is designing a robotic mower—news that should elate lazy people the world over.

But one group is really, really unhappy about this boon to the slothful: Astronomers. Some of them are so upset, in fact, that their objections might put the kibosh on the whole thing. How could this be? In a scenario that sounds straight out of the Golden Age of sci-fi, it all comes down to robots versus telescopes, and how they all communicate.

The saga started in February, when iRobot filed a waiver request with the FCC seeking approval to use a portion of the radio spectrum to help guide its robomower. The problem with grass-cutting bots, according to iRobot’s filing, is the only way to get them to work is to dig a trench along the perimeter of a lawn and install a wire that creates the electronic fence needed to ensure the automatons don’t wander beyond the property line.

As a less arduous solution, iRobot proposes using stakes, driven into the ground, to act as beacons. The beacons will talk to the lawnbot, helping it map the area and stay within the designated boundaries. A typical user with a typical lawn (a quarter to a third of an acre) might need between four and nine beacons.

But the system requires special permission from the FCC due to its restrictions on fixed outdoor infrastructure. In a nutshell, the FCC doesn't want people creating ad hoc networks of transmitters, which could interfere with existing authorized services like cellular and GPS systems. In its filings, iRobot says it should be exempt because it doesn't set out to establish a broad communications network—its lawnbot networks would be tightly contained.

Astronomers say that's not good enough. The frequency band proposed for the lawnbot (6240-6740 MHz) is the very same one several enormous radio telescopes operate on. Astronomers want the FCC to protect their share of the radio spectrum so their telescopes continue observing methanol, which abounds in regions where celestial bodies are forming.

“The Observatory’s telescopes … do a kind of celestial cartography that measures distances to star-forming regions with high precision, charting the course of galactic evolution,” representatives of the National Radio Astronomy Observatory wrote in public comments to the FCC objecting to iRobot's application to the agency.

Stay Off Our Lawn

The solution iRobot proposes is to add a note in its user manual: “Consumer use only; use must be limited to residential areas.” This, the company argues, should ensure the lawnbots won’t be doing their thing near observatories. But Harvey Liszt, spectrum manager with the NRAO, says a written warning likely won't work. “What’s to stop the guy who spends thousands of dollars on this product from using it in residential areas near our telescopes?” he asks.

Liszt says lawyers representing iRobot got in touch with the NRAO in January to explain the tech specs before requesting the FCC waiver. Liszt responded to the message saying that the distances within which the 'bots would operate would be quite large, and he was not confident that iRobot could police each of its users. “We didn’t talk anymore, then I saw the filing,” Liszt says. “I replied, and I was fairly surprised by how hard they pushed back.”

The communication breaks down between the NRAO and iRobot when the two entities do their calculations for the range the lawnbot beacons affect. Liszt and the NRAO claim a 55-mile exclusion zone is necessary to protect radio telescopes from harmful interference, while iRobot says 12 miles is sufficient. In a later response, iRobot added that NRAO observatories usually are surrounded by desert or forests, not environments where residential lawn equipment is used—a claim the NRAO called “silly.” In its latest filing with the FCC, Liszt included pictures of some sites with telescopes he believes could be exposed to lawnbot beacon interference.

“NRAO is not trying to stop this, NRAO just wants people to respect where its telescopes are,” says Liszt.

The folks at iRobot declined to be interviewed for this story, saying the company’s policy is not to discuss specifics around unannounced products or technologies.

"It’s a very strange process," says Liszt of the back-and-forth playing out via the FCC's public comments. "But the topic really grabs the public’s interest—it's telescopes against robots. I think there may well be larger issues here that the FCC will base their decision on."