Wheeling to a Halt

Yesterday, the Kepler mission team and NASA announced that the spectacular planet-discovery spacecraft is un-repairable. The news is not unexpected, but scientists and engineers had been working to find ways to stabilize the spacecraft and continue on its world-finding expedition.  Here’s what happened: two of its four gyroscopic reaction wheels failed. Since the spacecraft’s high pointing accuracy depends on having a stable platform, any wobble induced by failing gyros would make it impossible to accurate measure light from distant stars and analyze it for the existence of planets—particularly the Earth-size ones it was built to find.

The spacecraft is, for planet-searching purposes, dead in the water. But, it’s not a dead telescope.  Its instruments are still working and there are still ways it can be used to do other kinds of observational science provided the other reaction wheels don’t fail and thrusters can be used to keep the spacecraft stable. If that works out, Kepler would enter what engineers are calling a “two-wheel” mission that might include certain kinds of exoplanet searches that don’t require the extreme stability that four wheels provide.

Kepler completed its primary mission last November and had just entered its extended four-year mission when the gyroscope problems became unmanageable.  The mission has been spectacularly successful, giving us new looks at planets ranging from super-Earths to super-Jupiters. Those are words that have entered our language, defining new worlds and opening up ideas for further explorations to find signs of life on worlds where it could have arisen and evolved.  Kepler has confirmed the existence of 135 planets around other stars. At least 3,500 planet “candidates” await confirmation from continued observations by ground-based observatories.  And, the team expects hundreds, if not thousands, of new discoveries are lurking in the data sets including finding evidence of  more Earth-size planets that orbit in the habitable zone of Sun-like stars.

The Kepler mission has been an incredible success. Sure, it’s disappointing to see its gyros fail, but working in space is a tough environment for spacecraft. And, to paraphrase a familiar phrase from a Monty Python movie: It’s not dead yet. I hope that its team will find ways to use the spacecraft to aid in other astronomical and astrophysical observations. It’s a marvelous machine, and we can still get some good bang for the buck out of it in other ways.

Perseid Meteor Shower Inbound

This time every year we get to enjoy the Perseid Meteor shower. It begins in late July and normally peaks around in the second week of August. This year the best viewing time is early in the morning of August 12th, and you’ll have to stay up to the wee hours (or get up early) to catch the peak of the shower during that time. Or, you can Perseid-gaze late at night, although you may not see quite as many as you would if you looked during the peak hours. Simply find a time when you can step outside around midnight and wait for a bright flash of light to flare through the sky from roughly the direction of the constellation Perseus. It appears very low above the eastern horizon, but you’ll likely spot meteors in many parts of the sky.

If you do see one (and chances are you’ll see more than one if you stay out any length of time), you’ll be witnessing a piece of solar system history flash across your field of view. It will be a tiny piece of debris left behind by the Comet Swift-Tuttle as it rounds the Sun. Comets date back to the earliest history of the solar system, so these debris pieces are at least 4.5 billion years old (if not older)!

Earth’s orbit takes our planet through that material about this time every year, and those little pieces of dust and grains of sand from the comet get swept up through our atmosphere. Most of them vaporize on the way down, and thus never reach the surface of our planet. These flares are called meteors; the tiny objects that cause them are called meteoroids.

So, dress warmly, prepare to stay up a little later than usual (or get up a couple of hours before dawn), and wait for the Perseids to send a few bits of solar system history across the sky for you to enjoy!

Want to know what else is up this month? Check out Our Night Sky over at AstroCast.TV—a quick tour I take each month through the highlights of stargazing.  This month we explore the planets, the Perseids, some familiar constellations and some deep-sky objects.