Sciency Words: Heartbeat Tone

Hello, friends!  Welcome back to Sciency Words, a special series here on Planet Pailly where we talk about those weird and wonderful terms scientists use.  Today’s Sciency Word is:


Last week, I watched NASA’s live coverage of the Perseverance rover landing on Mars.  Naturally, I had a notepad ready, and I picked up quite a few new scientific terms.  My absolute favorite—the one that brought the biggest smile to my face—was “heartbeat tone.”  I love the idea that Perseverance (a.k.a. Percy, the Mars Rover) has a heartbeat.

As this article from Planetary News describes it, Percy’s heartbeat tone is “similar to a telephone dial tone.”  It’s an ongoing signal just telling us that everything’s okay.  Nothing’s gone wrong, and everything’s still working the way it’s supposed to.

Of course, other NASA spacecraft use heartbeat tones as well.  According to two separate articles from Popular Mechanics, the Curiosity rover on Mars and the Juno space probe orbiting Jupiter also send heartbeat tones back to Earth.  And that article about Juno offers us a little bit of detail about what Juno’s heartbeat actually sounds like: a series of ten-second-long beeps, sort of like very long dashes in Morse code.

Based on my research, it seems like the earliest NASA spacecraft to use heartbeat tones (or rather, the earliest spacecraft to have this heartbeat terminology applied to it) was the New Horizons mission to Pluto, which launched in 2005.  As this article from Spaceflight 101 explains it, New Horizons’ onboard computers monitor for “heartbeat pulses” that are supposed to occur once per second.  If these pulses stop for three minutes or more, backup systems kick in, take over control of the spacecraft, and send an emergency message back to Earth.

So, I could be wrong about this, but I think this “heartbeat pulse” or “heartbeat tone” terminology started with New Horizons.  To be clear: I’m sure spacecraft were sending “all systems normal” signals back to Earth long before the New Horizons mission.  I just think the idea of using “heartbeat” as a conceptual metaphor started with New Horizons.  But again, I could be wrong about that, and if anyone has an example of the term being used prior to New Horizons, I would love to hear about it in the comments below!

P.S.: I recently wrote a post about whether or not planets have genders.  With that in mind, I was amused to note in NASA’s live coverage that everyone kept referring to Perseverance using she/her pronouns.  However, the rover has stated a preference for they/them on Twitter.  So going forward, I will respect the rover’s preferred pronouns.

Oh, Please, Please, Please Tell Me There’s Life on Mars!

There are plenty of people who don’t want evolution to be true or who don’t want to believe in global warming, and they’ll latch onto any shred of evidence to support their worldview.  This is sometimes called confirmation bias: the inability to believe anything that challenges your preexisting conclusions.  Scientists and science enthusiasts like myself are supposed to be immune to confirmation bias.  We’re supposed to keep an open mind to new discoveries and new ideas.  We’re supposed to be skeptics.  Except I have a small confession: I have a little confirmation bias of my own.

Mars Near Opposition 1995-2005: 1995

I am firmly convinced there is life on Mars.  I don’t think it’s anything more substantial than bacteria eking out an existence near the polar regions, but that’s still life, damn it.  Maybe, if I’m lucky, something more complex is buried underground, protecting itself from deadly solar radiation and simultaneously from probing, human eyes.

At the moment, scientific evidence seems to support my belief.  The Curiosity rover has found certain chemicals on Mars that suggest life could have evolved there.  Curiosity also recently discovered evidence that there are small quantities of liquid water present in Martian soil, and since Martian sand storms often spread across the whole planet, scientists say it’s likely these traces of water are present everywhere.

A Global Dust Storm on Mars
Mars before a sandstorm and Mars durning a sandstorm.


There’s also the unresolved mystery of the methane gas in Mars’s atmosphere.  Several different probes have detected it, but no one knows where it’s coming from.  It’s possible bacterial life forms produce it.  Unfortunately, the Curiosity rover is now telling us this methane doesn’t exist.  The rover can’t find any sign of it.  This challenges my faith in the existence of Martian bacteria, so when I read about these new test results I quickly commented that Curiosity must have made a mistake.

What will happen if Curiosity’s next experiment further challenges my beliefs?  I’ll tell you what will happen: I’ll be heartbroken.  I don’t think I’ll break down in tears, but I’ll probably feel a tiny bit depressed for a few days if not a few weeks.  I’ll probably go into denial and argue that the new data only means the possibility of life currently existing on Mars is diminished, but it’s still not impossible.  I might also start talking about how native Martian life might be so different from life on Earth that we wouldn’t recognize it even if we did find it.

I try to be a good skeptic.  I try not to jump to conclusions, no matter how awesome those conclusions might be.  So much as I may want there to be life on Mars, I have to try to curb my enthusiasm.  I have to prepare myself for the possibility that I’m wrong.  But it’s really difficult.  I can understand what creationists and global warming deniers are going through.  It’s hard to overcome confirmation bias, no matter what your confirmation bias is about.

P.S.: There is totally life on Mars, and I think some Martian creature probably threw a rock at the Curiosity rover.  Click here to find out more.

The Office of Planetary Protection

I have said before that one day science fiction won’t be science fiction anymore; it will just be fiction.  To some degree, we already live in a sci-fi world.  Look at all the diseases we can now cure, or look at the International Space Station, or just look at everything our cell phones can do.  Today, we’re going to take a look at something else that may sound like science fiction but is in fact 100% real: the Office of Planetary Protection.

The Office of Planetary Protection is sort of like the Environmental Protection Agency for the Solar System.  Its job is to ensure that NASA doesn’t violate the Outer Space Treaty of 1967, which stipulates among other things that any probe sent to another planet must not contaminate that planet with Earth-born bacteria.  The point of this is not only to protect alien ecosystems (if they exist) but also to ensure that if we do discover life on another planet, we can be certain it’s genuine alien life and not something that stowed away on one of our own space vehicles.

Take Mars as an example.  While it’s clear there isn’t anything like deer or grizzly bears on Mars, or even anything as small as a mouse or insect, there could be native Martian bacteria.  These microscopic organisms might live in areas like Newton Crater, where scientists have observed what appears to be liquid water seeping through the soil.  This water might be enough to support an entire ecosystem of microorganisms.

The Planetary Protection Office has another job as well: protecting us from any life forms that might threaten our own ecosystem.  Many nations, including the United States, are planning “sample return missions,” meaning they want to send a spacecraft to another world, have it collect samples, and send those samples back to Earth for further analysis in a laboratory.  Obviously we want to avoid an outbreak of alien bacteria similar to what happened in Michael Crichton’s The Andromeda Strain.  The Planetary Protection Office will make sure that doesn’t happen.

But just as the EPA is the source of a lot of controversy, so too is the Office of Planetary Protection.  Some scientists complain that planetary protection rules are making space exploration prohibitively expensive.  Sending a probe to Mars is costly enough without having to pay so much extra to sterilize every single delicate, mechanical component.  Given the current state of the economy and the current state of NASA’s budget, some say we shouldn’t waste money protecting alien ecosystems that might not even exist.  There are also questions about how effective the Planetary Protection Office really is given the fact that some of the Curiosity rover’s tools may have been contaminated before its launch in 2011.

Dr. Catharine Conley, the person currently in charge of NASA’s Planetary Protection Office, at least has a sense of humor about her work.  She owns a pair of Ray-Ban sunglasses, just like Will Smith from Men in Black.  She got them as a gift her first day on the job.  Despite the controversies, I feel safer knowing she’s there, keeping planet Earth safe from alien bacteria and keeping the alien bacteria safe from us.