Keeping NASA’s Planetary Discoveries In Perspective

multi_transits_many_full_0

The headlines are breathless and shouted. “NASA’s Kepler Mission Announces a Planet Bonanza, 715 New Worlds.”

Big deal? Maybe it is. Likely it isn’t.

The Kepler mission points an orbiting telescope at a small slice of the sky. Day-after-day it watches the light from the stars in that slice, looking for variations in intensity.

When a planet crosses in front of its star as viewed by an observer, the event is called a transit. Transits by terrestrial planets produce a small change in a star’s brightness of about 1/10,000 (100 parts per million, ppm), lasting for 1 to 16 hours. This change must be periodic if it is caused by a planet. In addition, all transits produced by the same planet must be of the same change in brightness and last the same amount of time, thus providing a highly repeatable signal and robust detection method. – NASA

The planets aren’t actually being seen. That’s why the image at the top of this entry is an artist’s conception, not a photo. Kepler is instead looking for a predictable dimming as planets pass between the stars and Earth.

The rest is speculation! We have no idea what the planets are made of or conditions on their surface.

NASA looks for planets in the ‘habitable zone.’ That doesn’t mean they’re habitable! These objects are incredibly far away. Our data is thin.

NASA readily admits what is doesn’t know, but since that’s not the glamorous part of the release we seldom hear it.

One of these new habitable zone planets, called Kepler-296f, orbits a star half the size and 5 percent as bright as our sun. Kepler-296f is twice the size of Earth, but scientists do not know whether the planet is a gaseous world, with a thick hydrogen-helium envelope, or it is a water world surrounded by a deep ocean.

Even the Earth, the benchmark for habitable planets, is only ‘habitable’ over a small portion of its surface. We can’t live in the ocean, or tall mountaintops, or where it’s too hot or cold, or too dry or wet. We’re picky eaters in the world of habitation!

So, what does the Kepler mission and these discoveries mean to us? From a practical standpoint, little. Maybe nothing!

These planets are too far to ever consider visiting. Our lives won’t change. We’ll learn enough to solidify some theories, no more.

Kepler is an amazing engineering accomplishment. That’s indisputable. It has taken complex planetary theories and made them observable. No small trick. Just don’t expect an exoplanet photo or financial payoff soon… or ever.

Here’s What’s Happening With Kepler

KeplerSpacecraftInSky-br

NASA has all sorts of payloads in orbit. Most are low profile research projects, usually monitoring Earth from above. That’s not Kepler.

The Kepler Space Telescope orbits the Sun, just like we do. Its $600,000,000 mission is finding habitable distant planets! It is among NASA’s highest profile missions.

Here’s a typical Kepler discovery:

NASA’s Kepler mission has discovered a new planetary system that is home to the smallest planet yet found around a star like our sun, approximately 210 light-years away in the constellation Lyra.

Kepler has broken. The telescope is fine, but Kepler has lost its ability to steadily point a tiny piece of space. These are long exposures. Perfectly still is required.

As designed, stability is provided by reaction wheels. They’re motor driven flywheels which position the spacecraft gyroscopically. Kepler needs three. Only two of the four on-board are working.

Unlike Hubble, Kepler can’t be serviced by astronauts. The Shuttle is gone. Kepler’s heliocentric orbit makes it unreachable anyway.

NASA is not optimistic.

with the failure of a second reaction wheel, it’s unlikely that the spacecraft will be able to return to the high pointing accuracy that enables its high-precision photometry. However, no decision has been made to end data collection.

Kepler had successfully completed its primary three-and-a-half year mission and entered an extended mission phase in November 2012.

Even if data collection were to end, the mission has substantial quantities of data on the ground yet to be fully analyzed, and the string of scientific discoveries is expected to continue for years to come.

It’s just a shame to lose the hardware. The hope is always they run forever. Not this time.