National Geographic Society

Hubble's WFPC-2, now on display at Air and Space
—Picture copyright Smithsonian Institution

"The difference between an artifact and an instrument is that, now that it's an artifact, you can't touch it anymore."

So General Jack Dailey told astronaut John Grunsfeld during the opening of a new gallery in the Smithsonian's National Air and Space Museum—now home to several significant artifacts from the Hubble Space Telescope.

Just a few short months ago, Grunsfeld was part of the shuttle mission sent to repair and upgrade the aging Hubble. The crew's tasks included removing the Wide-Field Planetary Camera 2 (WFPC-2) and the Corrective Optics Space Telescope Axial Replacement (COSTAR) so they could be replaced with more advanced instruments.

(See some of the first pictures from the upgraded Hubble.)

COSTAR, sometimes called Hubble's contact lenses
—Picture by Eric Long/NASM, copyright Smithsonian Institution

Air and Space made the phone booth-size COSTAR part of its new gallery, called Moving Beyond Earth, a high-tech setup full of interactives, computer feeds, and huge visual projections.

The gallery also houses the HST Power Control Unit Trainer, a life-size replica of Hubble's electrical nerve center. Grunsfeld was among the astronauts who used the trainer to practice replacing the unit during a 2002 servicing mission.

—Picture by Eric Long/NASM, copyright Smithsonian Institution

WFPC-2, meanwhile, gets a place of honor in the museum's Space Hall. The camera, about the size of a baby grand piano, "turned Hubble into the Great American comeback story," NASA's Edward J. Weiler told reporters during the gallery opening.

The now beloved space telescope had a few early setbacks, including the grim discovery shortly after launch that its primary mirror was deformed, making its science images pretty much useless.

WFPC-2 got installed during the first-ever Hubble servicing mission in December 1993, complete with its own built-in corrective optics that compensated for the faulty mirror.

(FYI, new instruments installed since then also carried their own corrective optics, eventually rendering COSTAR obsolete. It was removed to make room for a device called a spectrograph, designed to study the origins of the universe.)

The same mission added COSTAR, a bundle of tiny mirrors that sent corrected, focused light to the rest of Hubble's instruments. But WFPC-2 specifically went on to provide scientists with some of the most iconic Hubble pictures that both dazzled the public and offered new insights into the universe.

"Museums remind us of the choices we make as a culture." —David DeVorkin

(See WFPC-2's last "pretty picture" before the camera was removed in May 2009.)

"Hubble has more than fulfilled its promise," said senior curator of space history David DeVorkin.

But astronaut Grunsfeld, who joked about his title of "chief Hubble hugger," reminded the audience that it wasn't really the instruments that saved Hubble, it was the people.

"Museums remind us of the choices we make as a culture," DeVorkin added. During Hubble's development, people made the choice to build a space telescope that could see objects ten billion times fainter than the human eye.

People also made the choice to make that telescope something that could be regularly serviced rather than used until it broke and then abandoned.

And when Hubble suffered from its initial setback, people made the choice to find ways to fix what was quickly labeled as a national failure.

"It's a message of persistence," Dailey said. "Don't quit. Hubble is a perfect example of that."

After a successful four-year mission studying the ringed planet, the Cassini probe was still orbiting Saturn in near perfect health in June 2008. So NASA dug deep and found the funding to keep Cassini gainfully employed.

The extension, dubbed the Equinox Mission, is primarily focused on changes wrought on Saturn by the onset of equinox, when the sun shines directly on the gas giant's equator, which happens just once every 15 years.

In the past Saturn, its rings, and its moons were all illuminated from the south. But tomorrow the equinox comes, and afterward the sunlight will glide over to Saturn's northern face.

Over the long term, Cassini will be able to watch the planet's seasonal changes—at least until the currently funded mission ends in September 2010.

But the time immediately around the equinox is especially exciting, because changes in the planet's position combined with light coming in at different angles are exposing all sorts of 3-D effects in the normally "two-dimensional" rings.

Last week, for example, Cassini images revealed a new itteh bitteh moon hovering just outside Saturn's B ring.

—Image courtesy NASA/JPL/Space Science Institute, little white arrow courtesy moi

The small, light-colored object is so close to the dense rings—the scientists guess it's a mere 660 feet (200 meters) above—that it was effectively hidden until now.

The unique interplay of light brought on by the upcoming equinox caused the little moon to cast a long shadow on the rings. In general, Saturn's moons cast shadows on the rings only before and after an equinox, so pictures like this are incredibly rare.

That means it's a treat even when bigger, known moons decorate the rings with their own shadowy dances, since the shadows allow Cassini scientists to create unprecedented images with scientific punch.

Here, the moon Tethys casts its spiky shadow across the A and B rings in a mosaic of 17 pictures taken about 2 minutes, 17 seconds apart.

—Image courtesy NASA/JPL/Space Science Institute

The changing degrees of light and dark in the same parts of each shadow can tell scientists just how dense the planet's rings are in certain regions.

Saturn's moons also sometimes interact directly with the rings, as seen in this picture of the moon Prometheus creating dark "steamers" through the thin outer F ring.

—Image courtesy NASA/JPL/Space Science Institute

The 53-mile-wide (86-kilometer-wide) moon dips into the F ring when its orbit takes it farthest from the planet. The moon's gravity then pulls material out of the rings as it moves closer to Saturn. (Watch a movie of Prometheus "bouncing" off the F ring.)

So far we've only seen this phenomenon lit from the south, but it's due to happen again late this fall, after the equinox. Scientists hope light coming in from the north will, pardon the cliché, literally shed new light on the moon's effects on the F ring.

As for the equinox itself, Cassini will likely have its eye trained on Saturn to see the gas giant make its roughly 170,000-mile-wide (273,000-kilometer-wide) rings ... disappear!

As wide as the rings are, they're just 30 feet (9 meters) thick. As the planet turns on its axis during the equinox, the edge of the rings will line up with the light from the sun.

It's like turning a piece of white paper edge-on against a mostly white wall and then shining a light directly at it. For all you can see, the paper will seem to vanish.

—Image courtesy NASA/Hubble Heritage

Astronomer Galileo Galilei saw this happen in December 1612 (although through his low-power 'scope, he thought the rings were actually two moons on either side of the planet!).

He was appropriately baffled at the vanishing act, writing in a letter: "I do not know what to say in a case so surprising, so unlooked for and so novel."

Sadly the folks at home won't be able to witness the spectacle this year, as Saturn is also in solar conjunction—basically behind the sun as seen from Earth.

So let's all hope Cassini keeps working overtime and catches the equinox in action!

Shortly after the Chandra X-ray Observatory opened its eye for the first time in 1999, the orbiting probe snapped its first picture of a supernova remnant about 190,000 light-years away that's lovingly called 1E 0102.2-7219—or E0102 for short.

—Image courtesy NASA/CXC/SAO

Yesterday, ten years to the day after the probe's July 23 launch, the Chandra team released this updated version of the supernova's portrait:

—X-ray (NASA/CXC/MIT/D.Dewey et al. & NASA/CXC/SAO/J.DePasquale); Optical (NASA/STScI)

In the immortal word of Keanu Reeves: Whoa.

The brilliant new picture (click here for a larger version) combines Chandra's x-ray data with a visible-light image from its orbiting partner the Hubble Space Telescope. Together the two orbiters show the supernova's hot outer blast wave as a blue halo around the cooler inner material, with bright stars glittering in the background.

The green blob in the lower right is a cloud of gas and dust being illuminated by one very massive star (not pictured), probably not unlike the one that went boom and created E0102.

While the x-ray data add some great visual details to the shot, Chandra also contributed to the scientific analysis of the remnant. The x-rays, for instance, have helped astronomers get a better picture of the geometry of the explosion.

That's because x-rays with different levels of energy shine differently for Chandra. Since energy levels are linked to direction, scientists can tell how the object's components are moving relative to each other.

To us, E0102 may look like a colorful cotton ball in space. But Chandra reveals that the supernova is actually shaped more like a cylinder, and we're simply seeing the rounded face. There's a nifty animation of this here, in case pictures speak loader than words...

Btw, in its ten years of data collection, it seems Chandra has done its share of capturing puffballs in outer space. Here's a "rogues gallery" of some of the more famous explosions:

Tycho's Remnant

• About 7,500 light-years away
• Danish astronomer Tycho Brahe saw light from the initial explosion in 1572
• Chandra snapped it in April 2003

—X-ray: NASA/CXC/SAO, Infrared: NASA/JPL-Caltech; Optical: MPIA, Calar Alto, O.Krause et al.

Kepler's Remnant

• About 13,000 light-years away
• Astronomer Johannes Kepler was among the first to see it as a new object in the sky in 1604
• Chandra studied it from April to August 2006

—Image courtesy NASA/CXC/NCSU/S.Reynolds et al.

Cassiopeia A

• About 10,000 light-years away
• Discovered in the constellation Cassiopeia via radio observations in 1947
• Chandra snapped it in December 2007

—Image courtesy NASA/CXC/MIT/UMass Amherst/M.D.Stage et al.

SN1006

• About 7,000 light-years away
• The brightest supernova ever seen from Earth, witnessed in Asia, Europe, and the Middle East in A.D. 1006
• Chandra snapped it in April 2003

—X-ray: NASA/CXC/Rutgers/G.Cassam-Chenai, J.Hughes et al.; Radio: NRAO/AUI/NSF/GBT/VLA/Dyer, Maddalena & Cornwell; Optical: Middlebury College/F.Winkler, NOAO/AURA/NSF/CTIO Schmidt & DSS