Speaking of Hubble...

Archive: May 2012

Crash of the Titans

May 31, 2012 by Frank Summers
ILLUSTRATION CREDIT: NASA, ESA, Z. Levay and R. van der Marel (STScI), and A. Mellinger

ILLUSTRATION CREDIT: NASA, ESA, Z. Levay and R. van der Marel (STScI), and A. Mellinger

Imagine what goes through the mind of a baseball batter as he stares down a speeding pitch. The baseball is hurtling toward him, but difference between a strike and a ball depends on precisely gauging the amount of sideways motion. He’ll want to swing for the fences if it’s out over the plate, or jump back out the box if it’s headed for his ear.

Astronomers have been pondering a similar situation for about a hundred years. We can easily measure whether the neighboring Andromeda galaxy is moving toward or away from us (we call this “radial” motion). The result, known to Edwin Hubble in the 1920s, is that Andromeda is approaching our Milky Way galaxy at the tremendous speed of more than 250,000 miles per hour.

However, it is extremely difficult to measure the sideways (or “tangential”) motion of a galaxy. We have been left wondering: what is Andromeda’s full trajectory? Will the two galaxies simply pass by each other like cars on opposite sides of an interstate highway, or will there be a colossal pileup involving hundreds of billions stars in each galaxy?

It has taken Hubble’s namesake telescope, with its exquisite resolution, and some innovative imaging and computational measurement techniques to finally answer this question. By measuring minute shifts in the stars of Andromeda over the course of about a decade of observations, we now know that Andromeda has very little sideways motion. It is heading straight for the Milky Way, and, unlike the baseball batter, our galaxy can’t get out of the way.

SIMULATION: NASA, ESA, G. Besla (Columbia University), and R. van der Marel (STScI)

The two galaxies have been destined by gravity to crash together in about four billion years. Their thin and beautiful spiral disks will become warped, stretched, and distorted beyond recognition. The centers of the galaxies will smash through one another not just once, but several times as the galaxies merge. Eventually, about six billion years from now, the two spirals will become one elliptical galaxy, mixed together for all eternity.

Our visualization of this galactic gravitational dance is the first scientific look into the far-flung future of our galaxy. Our news release features artistic visions of what the view might be from within the Milky Way during the collision. The stars and the band of the Milky Way across the night sky seem static and constant on human time scales. But taking an astronomer’s perspective, and looking forward billions of years, they have quite a dynamic future ahead of them.

Examining Venus in a Lunar Mirror

May 25, 2012 by Frank Summers

Hubble can't look at the Sun directly, so it will observe the Venus transit with sunlight reflected off the Moon.

On June 5, 2012, the last Transit of Venus will happen in your lifetime. Unless, of course, you plan on living until December 2117 to catch the next one. Because it is the “last chance of a lifetime,” folks are clamoring about when and how to observe it. But I’ve found that many people have even more basic questions like “What exactly is happening?” “Why should I care?” and “Won’t Hubble get the pretty pictures for us?”

First off, the event is that the planet Venus will pass directly between Earth and the Sun. For several hours, Venus will appear as a dark dot moving across the Sun’s brilliant face. The precise alignment required for such a transit happens very rarely: pairs of Venus transits are separated by eight years, with 105.5- or 121.5-year separations between pairs. The first of this current pair occurred in 2004. The 2012 transit of Venus is only the eighth since the telescope was invented in 1609.

Historically, Venus transits were very important in measuring the precise distance to the Sun. A single measurement of a transit provides the relative sizes and distances to Venus and the Sun. Multiple measurements from multiple places on Earth enable astronomers to triangulate the true distance to the Sun. In the 1700s and 1800s, no other astronomical observation could provide this measurement, and grand expeditions were funded to observe Venus transits.

Today, we have radar measurements of the distance to Venus, so transits are not the unique opportunity they once were. For Hubble, however, the 2012 transit of Venus will be a unique opportunity of a totally different dimension.

Exciting discoveries can be made by studying an extrasolar planet that transits in front of its star. Some of the star’s light passes through the planet’s atmosphere, and we can determine the composition of that atmosphere. The same argument applies to the transit of Venus. However, since we know the composition of Venus’ atmosphere, observing its transit can provide an invaluable calibration and substantiation of the techniques used on extrasolar planets.

But, Hubble never looks at the Sun. Our star’s dazzling light would irreparably damage the telescope’s optics. Instead, Hubble will use the Moon as a giant mirror, studying its reflected sunlight to glean information about the Venus transit. It is a difficult observation, but one that mimics some of the complexity of observing extrasolar planets.

Who would have thought that the path to searching for habitable planets in the universe would involve examining Venus in a lunar mirror?

A Virtual Universe Awaits Future Astronomers

May 18, 2012 by Ray Villard
HubbleSite: NSF Grant to Fund "National Virtual Observatory"

Data from ground-based and orbiting telescopes will be united in the National Virtual Observatory.

Being an astronomer in the year 2030 will be notably different than it is today. Yes, scientists will still be pondering, among other mysteries, the evolving universe, life on other worlds, and the nature of dark energy.

But how they explore the universe is already changing. This is partly driven by the fact that we are riding an exponential curve of increasing telescope size and detector sensitivity, but much more importantly, huge amounts of observational data are being harvested and archived faster than astronomers can analyze.

In addition, amateur astronomers are becoming more heavily involved in this analysis than in recent decades because of the “democratization” of space via huge, publicly accessible astronomical databases.

The consequences are that we are on the cusp of a knowledge explosion in astronomy, where discoveries expand at an unprecedented rate across the globe. Our knowledge of the universe is becoming, well, inflationary.

One prime example is the Barbara A. Mikulski Archive for Space Telescopes (MAST), housed at the Space Telescope Science Institute. This remarkably vast database contains astronomical observations from 15 NASA space astronomy missions, including the Hubble Space Telescope and the James Webb Space Telescope.

MAST presently contains approximately 200 terabytes of data that are used and reused many times by astronomers. New data are constantly flowing into the archive, but even more data is flowing out. Today, more than half of published scientific papers containing Hubble data used archival observations. This number has increased steadily over the past five years.

Facilities like MAST will lead to a new breed of “office-chair astronomer” who explores a “virtual universe” of vast, interconnected online databases. This is called the Virtual Observatory, and it is now in its developmental period.

What’s more, “citizen scientists” — those without formal degrees in astronomy — will have open and free access to the same data mines to make their own discoveries.

In 2030, a typical day for an astronomer on a university campus will have her start her work by looking at a list of science papers that have been intelligently selected by a software tool that surfed the Internet overnight. She clicks on an object in an online science paper and the Virtual Observatory database delivers views in X-ray, visible light, and infrared and radio observations. She queries the archive to perform an intelligent search, pulling up information relevant to the questions she’s asking about the object.

She never goes to a mountain top observatory to do follow-up observations of the object. Instead this is all carried out autonomously, following acceptance of her observing proposal. Automatically processed and calibrated observations are quickly delivered for high-level analysis after the observation. This online pipeline processing of data is a procedure pioneered on the Hubble Space Telescope mission, which has amassed 60 terabytes of observations to date.

Her observation goes into the Virtual Observatory archive after a brief proprietary period. Her unrefereed science results are soon published online. Peers and lay readers comment on the results, which are disseminated through social media. Her formally accepted paper is next published freely in an open-access online journal. Students in impoverished third-world universities have the same access to her results as a Harvard astrophysicist does.

Armchair astronomers will focus on complex and innovative queries of the Virtual Observatory to automatically search and extract precise sets of observations made by a variety of telescopes. Researchers will make new discoveries purely by being able to cleverly combine data from different wavelengths, spectra, and transient changes in space.

Many thousands more inquiring minds will be able to explore the databases, too. A prototype for this is the Galaxy Zoo project, where members of the public classify galaxies found in astronomical data. In 2007, Dutch schoolteacher Hanny van Arkel was participating in the Galaxy Zoo project when she found a huge, ghostly, glowing blob of gas, an oddity illuminated by a beam of light from a black hole in the core of a nearby galaxy.

We are just beginning to ride the wave of incredible new insights into our universe.

Cinematic Scientific Visualizations

May 9, 2012 by Frank Summers
A sequence from "Hubble 3D" takes us on a journey to the heart of the orion nebula. CREDIT: "Hubble 3D" © 2010 Warner Bros. Courtesy Warner Bros. and IMAX Corporation

In this frame from the movie "Hubble 3D," the viewer enters the central region of the Orion Nebula. CREDIT: "Hubble 3D" © 2010 Warner Bros. Courtesy Warner Bros. and IMAX Corporation

Within our Office of Public Outreach, I lead a team that produces three-dimensional visualizations based on Hubble images and data. Most notably, our team worked on the IMAX filmHubble 3D.” In collaboration with our partners at the National Center for Supercomputing Applications (NCSA) and the Spitzer Science Center, we worked on 12 minutes of scientific visualizations for the movie.

At a conference last week, I was invited to speak about our work on the project. I began with a reference to the old adage of “truth and beauty” as twin goals of artistry that both complement and conflict with each other. I noted that our documentary work must grow out of the truth side, while commercial (and fictional) films develop more from the beauty side. In fact, the incredible sophistication of movie computer graphics has raised audience expectations to a level that make standard scientific presentations look antiquated.

Taking Hubble to the big screen required many months of exacting work. I detailed the transformation of raw data into images, the variety of methods employed to create three-dimensional computer models, and the intensive computational requirements for these giant-screen, stereo 3D visualizations. I wanted to emphasize both the scientific underpinnings as well as the artistic effort necessary to produce the shots and sequences.

After my talk, one audience member sheepishly admitted that, when he saw the film, he had assumed the all of the sequences were fantasy Hollywood computer graphics. I was at first taken aback that our painstaking scientific basis was not recognized, but later I felt complemented that the sophistication of our work had risen enough to be considered “too good to be true.”

Donna Cox, my counterpart at NCSA, and I developed the phrase “cinematic scientific visualizations” to describe what our teams strive to produce. In that pursuit, we use not only the same software as used in astronomy research, but also the same software used in producing Hollywood blockbusters. Our goal is an elusive balance of accuracy and aesthetics.

While our artistry is well above the standard of science, we have neither the money, the manpower, nor the time to achieve the amazing complexity and detail that Hollywood routinely produces. In the end, however, that doesn’t matter.

The connection back to the underlying science is the crucial element that elevates our work. The knowledge that there is truth behind the beauty is what makes Hubble imagery all that more powerful.

Mining Asteroids? Why Not!

May 3, 2012 by Alberto Conti
The asteroid Eros

The asteroid Eros

Last week, a new company entered the increasingly crowded market for private space exploration and exploitation. Planetary Resources‘ goal is to “establish a new paradigm for resource discovery and utilization that will bring the solar system into humanity’s sphere of influence.” This ambitious mission statement is backed up by “visionaries, pioneers, rocket scientists and industry leaders with proven track records on — and off — this planet.”

Among the founders of Planetary Resources is Peter Diamandis, who is very well known is space circles for many ambitious and successful undertakings. Perhaps the most well-known is the $10 million Ansari X PRIZE for private-sector manned spaceflight, a prize won in October 2004 by Microsoft co-founder Paul Allen and famed aviation designer Burt Rutan for SpaceShipOne, the world’s first non-governmental, piloted spacecraft. However, it is perhaps not as well known that Peter is also the co-founder of the International Space University (ISU): “an international institution of higher learning, dedicated to the development of outer space for peaceful purposes through international and multidisciplinary education and research programs.”

I was privileged to be part of the ISU summer programs in Barcelona (1994) as a student, and in Stockholm (1995) as a teaching assistant. As one of the 180 or so students in Barcelona, I worked on an intense, nine-week course for postgraduate students and professionals. The course tackled space-related disciplines that covered astrophysics, space policy and law, life sciences and more. Our final product was a Solar System Exploration Design Project, in which we ran thought experiments on how we should colonize and explore our own solar system. We developed mission concepts for lunar probes, comet sample returns, missions to the outer planets, and even the search for life!

Of particular relevance to the announcement by Planetary Resources was our Near Earth Asteroid Mission. Our mission statement — remember this was 1994 — was to “affirm the relevance of solar system exploration to human society using a smaller, cheaper, and faster science mission to evaluate the resource and hazard potential of small near-Earth asteroids.” Even back then, young professionals thought that investigating Near-Earth Objects (NEOs) was a rather promising idea.

Scientifically, NEOs represent the remnants from the early formation of our own solar system. As such, their physical, chemical and geological properties hold clues to the origin and evolution of our solar system. However, from a resource potential, NEOs are truly remarkable. Unlike on Earth, where heavier metals sink to the core, metals in NEOs are distributed throughout their body, making them easier to extract. They contain valuable and useful materials like iron, nickel, water, and rare platinum group metals, often in significantly higher concentration than found in mines on Earth.

Some NEOs could even be the remnants of extinct comet nuclei and therefore contain large quantities of water ice and other volatiles under a thin shell of silicate dust.

So how would you built a mission to rendezvous and orbit an NEO in preparation for full-scale mining? In our project, we identified three possible mission scenarios, in order of increasing complexity:

  • Flyby — short observation time, but ideal for quick reconnaissance
  • Rendezvous — long observations time, ample opportunity to study composition and landing sites
  • Contact/Penetrator Probe — direct sampling of internal composition

Each mission would be equipped with cameras for determining size, shape, rotation and surface features; X-ray and Gamma-ray spectrometers to inspect surface and near-surface elemental composition; infrared reflectance spectral mappers for detailed mineralogical composition; and a number of other desirable instruments such as magnetometers, altimeters, dust collectors, mass spectrometers, etc.

Our design was inspired by the Clementine mission, which flew in 1994, and tested advanced sensors and spacecraft components under extended exposure to the harsh space environment during observations of the Moon. (The project was named Clementine after the song “Oh My Darling, Clementine” as the spacecraft would be “lost and gone forever” following its mission.)

Clementine was only a partial success; its planned flyby of an NEO did not take place due to an instrument malfunction. However, many of the technologies and techniques used by Clementine to obtain high-resolution images of our Moon, using innovative ideas and with limited costs, helped the development of later solar system observatories.

It is now almost two decades later, and the landscape of space exploration has changed. NASA is starting to partner with the private sector to enable new initiatives in support of its 50-year-old mission. At the same time, innovative entrepreneurs are seeking to capitalize on the convergence of cheap and reliable technologies for mining operations, which, for the first time in our history, will be located on a different solar system body than our own.

The time seems to be favorable for the exploitation of resources well beyond our immediate atmosphere. This race will undoubtedly produce a cascade of products and ideas focused on enabling our species to explore our immediate planetary neighborhood.

Let the race begin!