Shuttling into History

The Last Flights of the STS Fleet

A tribute image to the space shuttle Endeavour, set to launch on April 29, 2011 on its last mission. Courtesy NASA.

As NASA winds down its space shuttle missions — Endeavour launches on April 29 and Atlantis is scheduled for late June — it’s kind of hard to think that after those flights, there will be no direct access to space via NASA. The shuttles, like the Apollo spacecraft before them and the Gemini before those, have cemented themselves into the world’s consciousness and the U.S. national psyche.

They’ve made the ISS possible, they’ve carried many important science experiments into space, and they’ve proved that people can return to low-earth orbit again and again. It’s an honorable history and even though I won’t get a chance to ride a shuttle into orbit (that was once a dream of mine), I’m still proud of it and what it stands for.

Of course, the honor comes at the price of two sets of shuttle crews’ lives. As Gus Grissom once said, “The conquest of space is worth the risk of life.”  I don’t think he thought his own life was to end so soon, and neither did the people aboard Challenger and Columbia have an inkling that theirs would end so spectacularly. But, they would have wanted the flights to continue; to do anything less would have detracted from the scientific cause to which they dedicated their lives.

I remember getting up well before dawn to see the first shuttle launch of Columbia on April 12, 1981. It seemed to us (after watching the much slower Saturn V launches of the Apollo era) that the shuttle was an agile system. It cleared the tower in just a few seconds and less than a minute later was arcing out over the ocean and into history. The first shuttle launch I saw in person was in the summer of 1993. As luck would have it, I was working on an HST instrument team, and so got a chance to see a second shuttle launch later that year when STS-61, flown by Endeavour, took off on the first Hubble Space Telescope servicing mission. That was an early morning launch and after it was over, we also had the chance to see HST fly over, giving us a first-hand feel for the orbital configuration the shuttle had to achieve in order to rendezvous with the telescope.

Watching a shuttle launch is an amazing experience. The sound comes well after the sight of the launch, and it hits you like a wall of “sensation”.  I remember car alarms going off in the nearby parking lot at Press Site, and people were yelling in amazement.

Watching a shuttle land — as we did at White Sands in New Mexico in 1982 — was like watching an aerodynamic brick drop out of the sky and achieve a smooth landing.  I still remember watching it glide to a soft landing, accompanied by T-38 chase jets. I can imagine it was pretty exciting for the folks onboard the shuttle and NOTHING like a landing that you or I might experience at an airport.

As I watch the preparations for the final flights, I can’t help but feel this palpable sense of history passing in front of our eyes. The shuttles have been part of our lives for some 30 years now. It’s tough to imagine that the last launches are coming up fast — and that soon NASA will have no home-grown access to space for its astronauts. They will, instead, be relying on the Russians to get them to and from low-earth orbit. And that, in the final analysis, is one of the most historically intriguing outcomes of the end of the shuttles. Our space program was spurred in large part in the late 1950s and 1960s by an incredibly rancorous competition with the then-Soviet Union. I often wonder what those early spacefarers at NASA and the Soviet space program would say if they knew today that NASA and Roscosmos were cooperating to get people to and from space together!

If you have a chance, be sure and watch the final launches of the space shuttles — either via NASA TV online, on TV, or if you can–in person. They’re incredibly powerful experiences.  I hope that the next generation of space travelers will once again have a vehicle that can easily take them to orbit.  I know that some are on the drawing boards and in testing.  Hopefully, the historical changing of the guard from shuttles to those craft won’t take too long. I still want my ride!

It Was 21 Years Ago…

That Hubble Went out to Play

To celebrate the 21st anniversary of the Hubble Space Telescope's deployment into space, astronomers at the Space Telescope Science Institute in Baltimore, Md., pointed Hubble's eye at an especially photogenic pair of interacting galaxies called Arp 273. This image is a composite of Hubble Wide Field Camera 3 data taken on December 17, 2010, with three separate filters that allow a broad range of wavelengths covering the ultraviolet, blue, and red portions of the spectrum. Hubble was launched April 24, 1990, aboard Discovery's STS-31 mission. Click to enlarge (and you WANT to see this one bigger).

And what a time it’s been!  As you can see by this image, the most famous of the Great Observatories is still crankin’ out some stunning visions of the cosmos.  Take this image, for example. It’s a pair of interacting galaxies, slightly farther along in their gravitational dance than the two I wrote about in my last entry. They are an interesting looking grouping called Arp 273.

The larger of the spiral galaxies in the group, known as UGC 1810, has a disk that is distorted into a rose-like shape by the gravitational tidal pull of the companion galaxy below it, known as UGC 1813. Not only are these two cosmic behemoths changing each other’s shapes, but in the process, they’re spurring huge swaths of star-forming factories in the process. Those are the blublogs at the top of UGC 1810, and the bluish clouds of light at the tip of the lower galaxy.  The image (embiggenate to see it better) shows a tenuous tidal bridge of material between the two galaxies that are separated by tens of thousands of light-years from each other.

Even more unusual are the off-center spiral patterns of each galaxy.  Even if you didn’t know anything else about these galaxies, just one look at the off-kilter spirals would tell you that something has happened. In this case, one galaxy has dived through the center of the other. The smaller one probably sliced right through its larger companion above it in this image.

Notice how the spiral arms of UGC 1810 (the upper one) are warped off-kilter with respect to each other.  The inner set is offset out of the plane of the galaxy.  This must have been a titanic interaction!

As if this wasn’t weird enough, there’s also a possible mini-spiral in the upper right arms of UGC 1810.

Astronomers have seen many interacting galaxies — enough to be able to understand something of how and why they form. In this case, the larger galaxy of the pair is about five times more massive than its smaller companion.   In unequal pairs such as this, the relatively rapid passage of a companion galaxy produces the lopsided or asymmetric structure in the main spiral. Also in such encounters, the starburst activity typically begins in the minor galaxy earlier than it does in the major galaxie. These effects could be due to the fact that the smaller galaxies have consumed less of the gas present in their nucleus — and that gas is what you need for stars to form. The gravitational shock waves spur “bursts” of star formation as the gas is compressed and heated during the interaction.

Arp 273 lies in the constellation Andromeda and is roughly 300 million light-years away from Earth. This image is just one of a stream of cosmic visions sent back by Hubble during its 21 years on orbit.  Currently, the telescope is in great shape and should continue its work for some time to come.

Disturbed Galaxies

I Blame Gravity

The galaxies in this cosmic pairing, captured by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile, display some curious features, demonstrating that each member of the duo is close enough to feel the distorting gravitational influence of the other. Courtesy ESO. Click to enlarge.

Take a look at the galaxies in this image. The one on the left, called NGC 3169, looks a little unsettled, not quite perfectly formed. The one on the right (NGC 3166) seems more blobby and its spiral arms aren’t quite as well-defined as, say, our Milky Way’s.

The reason they look this way?

Gravity. Both galaxies each have an extremely strong gravitational pull, and that plays a part in the cosmic dance they are undergoing.

As each galaxy feels the gravitational influence of the other, a push-pull tug-of-war is warping the spiral shape of one galaxy while fragmenting dust lanes in the other.

Spiral galaxies like NGC 3169 and NGC 3166 usually have arms of stars and dust that are arranged in a swirl around their central regions.  They stay in such configurations for quite a long time, until they have close encounters with other galaxies.

When galactic interactions happen, the combined gravity of the objects jumbles things up.  The classic spiral shape is stretched and pulled and sometimes torn apart, particularly when the galaxies merge. That’s what gravity does when massive systems of stars get close to each other during their mutual, lengthy cosmic dances.

The Advanced Camera for Surveys (ACS), the newest camera on NASA/ESA Hubble Space Telescope, has captured a spectacular pair of galaxies engaged in a celestial dance of cat and mouse or, in this case, mouse and mouse. Located 300 million light-years away in the constellation Coma Berenices, the colliding galaxies have been nicknamed "The Mice" because of the long tails of stars and gas emanating from each galaxy. Otherwise known as NGC 4676, the pair will eventually merge into a single giant galaxy. Courtesy Hubble Space Telescope.

Unlike the two galaxies shown in the Hubble image above, NGC 3169 and NGC 3166 aren’t yet in a full-out merger. Their close passage toward each other has only begun the transformation they may ultimately undergo. NGC 3169’s arms, shining bright with big, young, blue stars, have been teased apart, and lots of luminous gas has been drawn out from its disc. In NGC 3166’s case, the dust lanes that also usually outline spiral arms are in disarray. Unlike its bluer counterpart, NGC 3166 is not forming many new stars. In a few million years, these two galaxies could look very, very different — and, when their merger (if they have one) is complete, there’ll be an elliptical galaxy left where two majestic spirals once existed.  That’s what gravity will do to large-scale stellar systems!  For more information on this gorgeous image, visit the ESO web site writeup. There’s way more to these galaxies than meets the casual glance.