I’m Studying Up On Mars


Tomorrow will be busy for me. We’ve got two slooh.com shows about the close encounter between Comet Siding Spring and Mars.

I host, surrounded by cometary experts. I still have to know the science.

This is an unprecedented event. We’ve never seen a comet get so close to a planet.

That worries NASA.

Actually, let me modify that. Their worry is later.

First, cards on the table. NASA is always interested in ‘visitors’ to our part of the solar system. But there’s a lot more buzz for Comet Siding Spring C/2013 A1. It will come close to Mars and to billions of dollars of hardware circling Mars, plus rovers on-the-ground.

Comet-Siding-Spring-Trajectory-Mars-br2Siding Spring is speeding in from the Oort Cloud, a theorized mass of billions of comets 100,000 times farther from the Sun than we are. It will zip by Mars at a closing speed 35 miles per second–186,000 mph.

The comet misses Mars. We’ve all got that, right?

Later, Mars passes through the debris field left in the comet’s wake. Scientists expect some fragments will be drawn toward the planet where we have satellites and stuff.

NASA’s official “Best Estimate” says the particles miss. Their conservative estimate says 90-100 minutes after the closest approach a stream of small debris will come, then quickly go.

Our satellites all had their orbits disrupted, putting them on the far side of Mars when this happens.

T-0 is officially called the “time of the particle fluence center.”

NASA is praying one or more of the rovers will take a photo or two of the comet brightly shining through the Martian atmosphere. That’s pretty damn cool. It will likely happen and will surely include a part of the rover, lest we forget whodunit.

We’ll also get images from whatever sensors can be turned around on satellites.

I’m not sure how much of this is actually advancing science and how much is showing off. An opportunity and challenge like this shouldn’t be squandered, but this is more photo-op than anything. After all, we’re landing on a comet next month!

Everything is now set. It’s too late for change to matter. Any debris that hits the Red Planet was jettisoned off the comet years ago.

Distance and time are very different in space. You can’t think in minutes and seconds or inches and feet. Our best orbital predictions say C/2013 A1 won’t be back for around a million years.

Incredible Engineering: Rosetta Wakes Up

Comet_approach_node_full_imageNothing is impossible. I say that without fear of contradiction because of what the European Space Agency and NASA have been doing for the last decade. It’s the Rosetta mission.

Rosetta’s job is to monitor a comet, 67P/Churyumov-Gerasimenko, by placing an orbiter around it and a lander on it! It will do this as the comet races toward the inner Solar System.

Rosetta_trajectory_English[1]As you might imagine, catching a comet isn’t easy. Rosetta was launched in 2004 and has made three Earth passes, plus one trip around Mars, all to gain speed and set-up its rendezvous.

To conserve power while coasting through space, Rosetta’s been ‘sleeping.’ Here’s how they list it on the mission timeline.

July 2011 Aphelion/Enter Hibernation

Rosetta_approaching_its_ultimate_destination_Comet_67P_Churyumov-Gerasimenko_node_full_imageAphelion means its furthest point from the Sun. Hibernation… you get that.

Today Rosetta gets its wake-up call! It needs to start processing data. It needs to prepare for its May meet-up with Comet 67P/Churyumov-Gerasimenko.

This is another unbelievably complex and intricate engineering challenge that should be impossible. What could possibly be more difficult than this?

Comet Ison Taught Me A Lot

743538main_image001_0As a meteorologist on TV I was often called on to be a science generalist. From earthquakes to volcanoes to comets, I had to know enough get on the air and provide context. It was a part of the job I relished.

Comets appeared from time-to-time, allowing me to get some shaved ice and dirt and give a quick lesson. There are not many people who get the opportunity to teach science on TV. It was an honor.

What I knew would not have been enough for Comet Ison. This comet was unusual. I learned a lot.

Astronomers first caught sight of Ison in September 2012 when was 585 million miles away. Even at that distance it was bright enough to hint at big things ahead.

Automated spotting programs make comet discoveries easier. Computers look for objects that are moving while the rest of the star field stays relatively in place.

By October a paper delivered to the American Astronomical Society’s 45th Annual Division for Planetary Sciences meeting noted Comet Ison was rotating in such a way that only one side was getting heated by the Sun and it was already spurting water ice into space.

Comet Ison is/was a sungrazer. Sungrazer’s are comets which get close enough to the Sun to be intensely affected by its gravity and heat. We’d never spotted a sungrazer so far out. Probably from the Oort Cloud, this was Ison’s first trip to the rodeo.

Until Ison, all the comets I’d talked about stayed far enough away from the Sun and had ‘visited’ this part of the solar system often enough that they weren’t in peril. This one was headed inside the Roche limit.

The Roche limit, sometimes referred to as the Roche radius, is the distance within which a celestial body, held together only by its own gravity, will disintegrate due to a second celestial body’s tidal forces exceeding the first body’s gravitational self-attraction. – Wikipedia

So, if Ison was a mass of rocks, pebbles and dirt held together by ice and its own internal gravity, the Sun would probably break it apart. That’s what happened. If Ison was an asteroid or some other giant space boulder we’d probably be looking at it still. Whatever does exist today is a small fraction of its former self.

I know this now. I didn’t know this a week ago or when I was talking about much colder comets on TV.

We see comets and their signature tail because heat (usually not very much heat) allows ice to melt which in turn allows gases to vent and dust to be set free. A comet’s tail is blown by the solar wind, a field of energy blasted into space from the Sun. The tail points away from the Sun and has no relation to the direction the comet is actually moving.

If all the ice has melted and the nucleus disintegrated there’s nothing left to view. That seems to be the case. There will be no “Comet of the Century” in the December sky.

We’re very lucky it’s 2013. There are a few satellites, some far from Earth, specifically designed to monitor activity like this. They provided amazing images as Ison whipped its way around the Sun and back toward deep space.

Over the next few months, as astronomers and other specialists look at the tsunami of data produced, we’ll learn more. It’s likely we’ll find Ison’s exact makeup and what caused its demise. I wouldn’t be surprised to see some animations simulating Ison’s final interactions with the Sun.

This comet was a tease. We were told it could be the big one. Obviously, it was not.

It wasn’t a disappointment to me. My knowledge has expanded. I might have been a terrible student as a kid, but grown-up Geoff loves to learn.

Over the last few weeks I’ve heard a lot of those in the know compare comets to cats. The both have tails and they both do what they want to do.

Ciao, Ison.

Billions Of Stars

starry telescope

I just read an article from The Royal Astronomical Society. British. Nearly 200 years old. Well respected.

RAS says, “Astronomers anticipate 100 billion Earth-like planets.” That’s a lot.

It’s also a meaningless number.

Distant space travel is impractical. We’ll never visit a planet beyond our solar system.

I’m sorry. I don’t mean to be a wet blanket but, it’s true.

Humans can only live within a tight range of parameters. We need oxygen and moderate temperatures. We need food. We need to return to Earth! Carrying enough supplies to accomplish that is orders of magnitude beyond any capability we have now.

Time is a problem too. The nearest star, Proxima Centauri, is 4.24 light years away. Our farthest satellite, Voyager 1, is a little over 17 light hours away and it’s been in space since 1977!

To go light years would take centuries!

We know about a few extrasolar planets. Not as much as you think.

We know they’re there, orbiting some distant stars through mathematics. We don’t actually see them. We do see the gravitational effect they exert on their star. These space wobbles are covered nicely by the laws of physics.

But that’s all we’re really seeing–stars wobble. All we know about any planet beyond our solar system is implied from the actions of things we can see.

It’s cool that astronomers can make these projections. Alas, they have no practical application or purpose.

Why Newt’s Wrong About The Moon

Space is also big. Other planets are far. Other solar systems are crazily far even at the speed of light.

I’ve been reading about Newt Gingrich’s call for American bases on the Moon before the end of his second term. His heart is in the right place, but that mission isn’t going to happen. Few are willing to say it, but the real future of space exploration doesn’t include men.

The simple truth is once you leave the surface of the Earth it’s extremely difficult to provide a living environment that allows work. There is no walking in your shirtsleeves on a nice summer’s day anywhere but Earth!

Space is also big. Other planets are far. Other solar systems are crazily far even at the speed of light. Voyager 1 was launched in 1977 and it’s still within our own solar system.

NASA figured this out a long time ago. They send turnkey projects into space. A rover on Mars doesn’t need a driver. It arrives mostly assembled and finishes the job on its own!

NASA’s expertise could be scaled up to build larger projects deployed away from Earth. It’s possible there are commercial implications though I don’t see any.

Space travel without humans is no less meaningful. It’s a lot less romantic.