astronomy@iowa

If all goes well on March 6, the Kepler telescope will blast off from Cape Canaveral’s launch pad 17-B aboard a Delta II rocket and usher in a new era of space exploration. NASA’s Kepler mission will begin an unprecedented 3 1/2 year mission to locate Earth-like extrasolar planets. While over 250 planets outside our solar system have been discovered to date, the vast majority of those planets are massive “gas giants” similar to the outer planets found in our solar system. In some cases, however, these giant worlds are located much closer to their stars—roughly the distance Earth is from the Sun—and thus dubbed “hot jupiters.” Regardless of the distance, though, their large masses make them easier to find than planets of more modest mass so the discovery of rocky, earth-like planets lags far behind the discovery of these hot gas giants. Kepler’s mission is to improve the odds of finding those smaller, terrestrial bodies.

Kepler is the first telescope specifically designed to locate Earth-like planets by measuring the periodic dimming of a star as it is eclipsed by its planets. If the plane of a planet’s orbit is aligned with the telescope, the planet will transit the star’s disk and cause it to decrease in brightness. While astronomers are not sure how many Earth-like planets might exist around other stars, they hope that a survey of 100,000 stars in the Cygnus-Lyra region of the Milky Way will turn up  dozens or hundreds of rocky planets. If any of those planets are located in the “Goldilocks zone” (where temperatures are neither too cold nor too hot, but just right for liquid water to exist), they may be habitable. Kepler’s photometer is so sensitive that it can detect a decrease in a star’s magnitude of only 20 parts in a million. As described by James Fanson, Kepler project manager, if turned on Earth at night, the telescope could detect the dimming of a porch light as a person walks in front of the light! To accomplish this feat of technology, Kepler will have use the most sensitive detector ever launched into space—a 95 megapixel array.

According to Debra Fischer of San Francisco State University, Kepler is essential to our understanding of the kind of planets that form around other stars. Scientists chose to name the mission after the German astronomer Johannes Kepler in honor of his fundamental discoveries in the fields of optics and celestial mechanics. Although he initially studied theology, Kepler became fascinated with the work of Nicolaus Copernicus and while a professor of mathematics, openly embraced Copernicus’ sun-centered model of the heavens in his 1596 book Mysterium Cosmographicum. Throughout 2009, we celebrate the 400th anniversary of the publication of his first two laws of planetary motion. Kepler’s three laws of planetary motion are the cornerstone of celestial mechanics and can be used to describe all closed orbits.

For further information: Kepler Mission home page, highlights of the life of Kepler, and suggestions for further reading.

On September 17, the International Astronomical Union announced that 2003 EL61 would be classified as the fifth named dwarf planet and officially designated Haumea. The name was chosen after meetings of the IAU’s Committee on Small Body Nomenclature and the Working Group for Planetary System Nomenclature. The number of dwarf planets is now five: Ceres, Eris, Haumea, Makemake and Pluto.

The 2,200 km ellipsoidal body—deformed due to a four-hour rotation period—is just beyond the orbit of Pluto and has two satellites. Orbiting among the Trans-Neptunian objects, Haumea is currently 50 astronomical units from the Sun but can get as close as 35 A.U. The astronomical unit is the average Earth-Sun distance and a standard measure of distance within the solar system.

In Hawaiian mythology, Haumea is the goddess of childbirth and fertility.

One hundred thousand orbits, that is…

On August 11 the Hubble Space Telescope completed its 100,000th orbit of Earth since being placed in orbit by the space shuttle Discovery in 1990. In the last 18 years the telescope has logged over 2.7 billion miles (that’s over 5,700 trips to the Moon!) while speeding at 5 miles per second.

To Commemorate 18 years of astronomical service, the Space Telescope Science Institute (STScI) is giving away 18 prints of the star cluster NGC 2074 taken to commemorate the orbital milestone. Visit the official website hubblesite.org and submit a valid email address after clicking the “Learn more” link for a chance to be one of the lucky winners to receive a 16×20-inch print.

Hurry, the drawing ends August 18.

Everything seems to be “Go” for an October 5 launch of the Interstellar Boundary Explorer satellite. Problems with the Pegasus rocket that will lift the satellite from its perch under the belly of a modified Lockheed L-1011 jumbo jet appear to have been resolved and IBEX has been delivered to Vandenberg Air Force Base for several weeks of testing before being mated to the Pegasus launch vehicle. Eventually the assembled vehicle will be flown under the Orbital Sciences Corporation’s L-1011 to the pacific island of Kwajalein for the October launch. By using the facilities at Kwajalein atoll for the mission launch instead of Cape Canaveral or Vandenberg AFB, mission planners will be able to utilize the additional eastward rotational velocity near Earth’s equator to increase fuel load by a precious few pounds and thus increase the final orbit of the 175-pound IBEX. To obtain the best data, the spacecraft must fly as far out of Earth’s magnetosphere as possible.

The Sun and entire solar system are moving through a region of space referred to as the local interstellar medium, which is composed of material ejected by stellar winds, novae and supernovae. The boundary between the local interstellar medium and the Sun’s sphere of influence is just now being studied and of considerable interest to astronomers now that the Voyager 1 spacecraft reached the termination shock in December 2004 at a distance of 94 Astronomical Units from the Sun (1 A.U. is the average distance between the earth and Sun.) The termination shock is the boundary layer where the particles from the solar wind begin interacting with material from the interstellar medium causing the solar wind to abruptly slow from a supersonic flow to a subsonic flow. Beyond the termination shock as some unknown distance is the heliopause—the layer at which the pressure of the solar wind is balanced by the pressure of the interstellar medium hitting the solar wind—and beyond that is the bow shock, where the interstellar medium first encounters the Sun’s influence.

The sole scientific objective of the IBEX mission is to discover the interaction between the local interstellar medium and the solar wind by answering several questions: What is the strength and structure of the termination shock, how are energetic protons accelerated by the termination shock, what are the properties of the solar wind flow beyond the termination shock, and how does the interstellar flow interact with the solar wind beyond the heliopause? The IBEX spacecraft will do this by investigating energetic neutral atoms of hydrogen generated primarily in the region beyond the heliopause. Because neutral atoms are unaffected by the presence of electric or magnetic fields, the detectors on IBEX will be able to map the points of origin of the neutral atoms it observes.

For more information about the Interstellar Boundary Explorer mission check out the IBEX website or get more immediate updates on IBEX at Twitter.

On July 31 laboratory tests aboard the Phoenix lander confirmed the existence of water in a Martian soil sample. The evidence came from vapors produced by the heating of the sample in an oven onboard the lander. Tentative evidence of water had previously been seen by the Mars Odyssey orbiter as well as disappearing chunks of white material in the soil below Phoenix early this summer.

Because of the success of the mission and overall good health of the spacecraft systems, the Phoenix mission has been extended an additional five week. Funding will now extend through September 30.

Additional information can be found on the mission website phoenix.lpl.arizona.edu.

When the Phoenix lander made its final descent to the Martian surface Sunday evening, something new in the half-century history of the space program happened—the landing of a spacecraft on an alien world was witnessed and photographed. NASA’s Mars Reconnaissance Orbiter photographed Phoenix with its HiRISE camera. The camera is actually a telescope with a 19.7-inch aperture and a focal ratio of f/24. That’s ideal for making high resolution observations and the telescope is capable of seeing detail as small as 12 inches from an altitude of 185 miles.

Although photographed against the backdrop of a 6-mile wide crater, Phoenix was never in any danger as it was still at a very high altitude. The spacecraft eventually drifted to a safe touchdown on a barren landscape strewn with small boulders.

For additional information and photographs, visit the website of the High Resolution Imaging Science Experiment.

If all goes well Sunday the Red Planet will receive a new guest. A little past 6:30 p.m. CDT the Phoenix lander is scheduled to touch down on the high plains of Mars’ northern hemisphere. Given the track record, however—over half of the 39 recent missions to Mars have ended in failure—one can understand the trepidation with which the mission scientists and engineers look towards Sunday’s landing. Designing a spacecraft that must survive a careening descent that takes it from 13,000 mph to a mere 5 mph in seven minutes would make anyone nervous.

Unlike the tireless little rovers that captured the public imagination a few years ago, Phoenix will not be a rover. You see, no matter where one looks, the Martian high plains look pretty much the same. There’s not much reason to go anywhere, just set up operations and get to work. One thing that scientists hope to discover is what role water has played in the Red Planet’s soil. We know there is water at the Martian poles, but scientists hope to find what other chemicals and minerals are present in the soil and what clues can be determined about climate change on the planet. The spacecraft is capable of digging about five or six inches below the surface and while its instruments can’t detect the presence of life, they may discover evidence that it did once exist. Of course the holy grail of planetary astronomy would be the actual detection of life currently thriving below the martian surface. Considering that the total biomass below the surface of Earth surpasses the biomass above ground, digging into the red soil isn’t a bad idea if we want to find signs of life.

The mission will last a short three months before the sunlight striking the northern high plains grows too feeble to provide power to the spacecraft’s solar array.

Mission home page: Phoenix Mars Mission
Image credit: NASA/JPL-Calech/University of Arizona