Rosetta-Philae lander on Comet 67P/Churyumov-Gerasimenko - artist concept

Scene: Spacecraft hurtling through space, approaching a giant 4-kilometer flying mountain of ice and rock. The two hurtle on together, flying closer and closer to the hot, radiant Sun. Things get dicey as the comet, under fire from the Sun's intense rays, begins to come apart, erupting with great jets of gas and dust liberated from eons of frozen preservation.

Then, the spacecraft deploys a lander, maneuvering dangerously close to the hard ice and unpredictable blasts of shrapnel from within. The lander manages to safely set down, shooting harpoon anchors into the ice to fasten it securely to the comet in the low gravity environment.

(If you're envisioning explosions right and left, great shards of sharp ice ejecting skyward, frozen cutting shrapnel flying in every direction and bouncing off the lander's armored hull, please continue; it could add to the dramatic effect….)

Then… (wavy curtain distortions indicating that we're entering a dream state) …the hatch opens and out steps Bruce Willis, a custom-made comet-smashing bazooka in one hand, a rocket-powered grappling hook that would make Batman proud in the other…. (End wavy curtain distortions; back to reality, alas….)

Sounds like a thrilling blockbuster movie. But it gets better! (Yes, minus the wavy curtains….)

The European Space Agency's (ESA) Rosetta spacecraft is currently hibernating its way through space, en route to comet (get your pen ready) 67P/Churyumov-Gerasimenko, which is also currently in comet-hibernation far out in space. At this moment, in fact, the comet is almost as far from the Sun as it gets: about 5.6 Astronomical Units, or a little beyond the orbit of Jupiter. The comet and the spacecraft will rendezvous in 2014, then together swing closest to the Sun in mid-2015, at a distance somewhat within Mars' orbit (1.29 AU).

The TRUE mission of Rosetta, and its lander Philae, are not to save the comet from destruction, or to destroy it—but a kind of combination of the two: to observe and study it while the comet is in the process of falling apart, under duress from the Sun. The Rosetta orbiter and Philae lander will accompany the comet from a point in space still relatively distant from the Sun, and follow it along its eccentric orbit sunward. The comet and its stalking spacecraft will swing by the Sun, then outward into deep space again.

All the while, we will witness, for the first time, the process of a comet heating up under increasingly intense solar radiation, up close—not only up close from orbit, but with an observer "on the ground" as well.

We've watched comets do their Inner Solar System dance with the Sun since prehistoric times. The image of a comet that probably comes to your mind is what humans have watched in the skies, periodically, since long before telescopes: the fuzzy knot of the comet's coma—the shroud of gas surrounding the icy nucleus—and the long blurry, feather-like smear of its tail, blown off into space by the solar wind. This is the characteristic appearance of comets that human eyes are able to see, at least the ones that come close enough to the Sun to be warmed and exude a tail (or tails—usually one tail of gas, another of dust) and close enough to Earth to become a fixture in our night skies.

In recent years we've begun to witness comets up close with several fly-by spacecraft missions: comets Halley, Hartley 2, Wild 2, and some others. The Stardust mission actually captured dust particles from the tail of its comet quarry and returned the sample to Earth.

Rosetta will not only be our first up-close look at Comet 67P (etc.), it will be the first mission to follow the progress of a comet as it swings by the Sun, erupting in all its comet glory, then back out again toward another deep freeze cycle. It will also be the first landing on a comet ever. Should be pretty exciting.

I expect the time-compressed movie constructed from images taken by Rosetta and Philae to show a lot of explosions, sharp icy shrapnel bouncing off of armor…oh, and of course a treasure trove of less flashy but more substantial scientific knowledge of the life and times of a frozen time capsule that hasn't changed much since the formation of the Solar System five billion years ago….

Gullies in wall of Hale Crater. Credit: NASA/MRO

Here's a quick status on the active ones:

Mars Reconnaissance Orbiter: The most recent arrival at Mars (2006), MRO's 5-year mission (hmmm—sound vaguely familiar?) is to study the history of water and climate on Mars, as well as to serve as a telecommunications relay for other spacecraft. Armed with a suite of powerful instruments to study the atmosphere, surface, and subsurface of Mars—including a camera, HiRISE, that can almost read the license plates on Martian automobiles—MRO has to date sent back more data than all other Mars missions combined. It's not been a glitchless flight, however: in 2009, MRO's computer reset itself four times for unknown reasons; the last reset, in August, was followed by a 4-month operational hiatus as Earth-side controllers performed some careful programming updates to help guard against effects of any future resets. MRO resumed operation in December.

Mars Odyssey 2001: NASA's 2001 Odyssey is still going fine after nine years—although the computer glitchiness out around Mars seems to be catching: Odyssey's computer put itself into a safe mode last November 2009 in response to a memory error. This was corrected and Odyssey has resumed doing science. Among Odyssey's major discoveries was the detection of huge expanses of water ice just under the surface of polar lowlands, and the surveying of deposits of water-related minerals in various locations around the planet.

Mars Express: Arriving at Mars in 2004, Mars Express became the European Space Agency's first mission to another planet, which was recently extended to 2012. Though the Beagle 2 lander component of the mission fell to Mars and was never heard from again, the Mars Express orbiter has sent back years of captivating images and important data, including the confirmation of methane in Mars' atmosphere (whose source is in all likelihood subsurface, and the origin of which—organic or inorganic processes—is being debated).

Mars Exploration Rover Opportunity: After six years of crawling around Meridiani Planum discovering chemical and geological evidence for past water on Mars, Opportunity is now on a long march to a large impact crater, which it will reach (if it can keep on running) in about two years. Currently, the rover has stopped to RAT out chemical and geological information from a rock called Marquette Island—the RAT is its rock abrasion tool, or rock grinder. Still going….

Mars Exploration Rover Spirit: Also still alive after six years—almost 25 times longer than it was planned to run—Spirit has been stuck in a sand bog for the last six months. With a couple of wheels on the fritz, Earth-side operators have been confounded in trying to free the robot—but Spirit has continued to make scientific measurements anyway…and in fact made a significant discovery in the course of trying to get unstuck.

Phoenix lander: Although it's been in the deep dark freeze of a Martian winter since November 2008, the Phoenix lander has an outside chance of survival. Now that light is returning to Phoenix's landing site, NASA is listening for the robot's radio signal, in case the return of solar power means that Phoenix will rise from the frost and live again! So far, no such signal….

Next up: The Mars Science Laboratory rover, "Curiosity."

37.8148 -122.178

The California freshwater shrimp is 10-legged crustacean in the family Atyidae.

Found only in a handful of Bay Area creeks, the shrimp is a detritus feeder that prefers glides (calm, slow-flowing sections of streams) with undercut banks, exposed roots, and overhanging vegetation. Adult females produce relatively few eggs-about 50-120-that stick to the mother's pleopods during winter incubation. The young measure about 6 millimeters and are released in late spring or early summer. They grow rapidly, reaching up to 2.5 inches as adults and ranging in color from translucent to rusty red.

The species' closest cousin, the Pasadena freshwater shrimp (Syncaris pasadenae), went extinct in the 1930s, leaving the California freshwater shrimp as the only representative of its genus. The California freshwater shrimp was listed under the ESA in 1988. Recently the U.S. Fish & Wildlife Service issued its 5-year review of the shrimp's status. The report concludes that the species is not ready for delisting, as it still faces many of the same threats as 20 years ago: loss of habit due to agricultural activities and development, water pollution, water diversions-even the construction of recreational summer dams for swimming and fishing.

But there is also good news in the report. At the time it was listed, the shrimp was known from 17 streams; it now has been found in 23. In one of these, the number of shrimp surveyed increased from 1,878 in 1991 to 4,407 in 2000. Many of the streams in which the shrimp is found have watershed management plans in place. And the report also acknowledged the ongoing work of STRAW to restore more than 50,000 linear feet of stream bank, creating new habitat for the shrimp-not to mention other native species.

When Congress passed and Richard Nixon signed the ESA in 1973, a little freshwater shrimp was not at the forefront of their minds. But there is an inspiring sense of democracy in the ESA as written: It empowers citizens to petition or sue the government to protect species. And it doesn't discriminate between the big, showy species and the small and obscure-but equally unique and imperiled-ones.

According to the US Fish & Wildlife Service, since 1973 the ESA has protected 99% of listed species from extinction. National Endangered Species Day is coming up May 16. Find out about ways to help celebrate.

Ann Dickinson is Communications Manager for The Bay Institute (www.bay.org), a nonprofit research, education, and advocacy organization dedicated to protecting and restoring San Francisco Bay and its watershed, "from the Sierra to the sea."