Thursday, March 5, 2015

Mars Lost an Ocean’s Worth of Water

This artist’s impression shows how Mars may have looked about four billion years ago. The young planet Mars would have had enough water to cover its entire surface in a liquid layer about 140 metres deep, but it is more likely that the liquid would have pooled to form an ocean occupying almost half of Mars’s northern hemisphere, and in some regions reaching depths greater than 1.6 kilometres. Credit: ESO/M. Kornmesser

A primitive ocean on Mars held more water than Earth’s Arctic Ocean, and covered a greater portion of the planet’s surface than the Atlantic Ocean does on Earth, according to new results published today. An international team of scientists used ESO’s Very Large Telescope, along with instruments at the W. M. Keck Observatory and the NASA Infrared Telescope Facility, to monitor the atmosphere of the planet and map out the properties of the water in different parts of Mars’s atmosphere over a six-year period. These new maps are the first of their kind. The results appear online in the journal Science today. About four billion years ago, the young planet would have had enough water to cover its entire surface in a liquid layer about 140 metres deep, but it is more likely that the liquid would have pooled to form an ocean occupying almost half of Mars’s northern hemisphere, and in some regions reaching depths greater than 1.6 kilometres. “Our study provides a solid estimate of how much water Mars once had, by determining how much water was lost to space,” said Geronimo Villanueva, a scientist working at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the new paper. “With this work, we can better understand the history of water on Mars.”

A Missing Link in the Family Tree of Cosmic Black Holes

Left: Optical image of the galaxy NGC 2276, taken with the Hubble Space Telescope.  Right: The image is a zoom into the radio structure of the newly found source NGC 2276-3c in one of the galaxy’s spiral arms at high resolution. The radio image, observed with the European VLBI Network shows details of only a few light years in extension. Adapted from Mezcua et al. 2015, MNRAS 448, 1893

A black hole discovered wandering all by itself inside one of the spiral arms of the galaxy NGC 2276 may present an important clue that would fill the gap in the evolutionary story of black holes. This discovery has been reported recently by a research team which is led by Mar Mezcua from the Harvard Centre for Astrophysics in Boston and includes Andrei Lobanov from the Max-Planck-Institut für Radioastronomie (MPIfR) in Bonn. They identify this elusive black hole, called NGC 2276-3c. The astronomers had to look at it simultaneously at radio waves with the European Very Long Baseline Interferometry Network, or EVN, and in X-rays with NASA’s Chandra Space Observatory. The combination of X-ray and radio data enables the researchers to ‘weigh’ the black hole, which has turned out to be as heavy as about 50,000 Suns. With this mass, it fills a gap between stellar black holes found in our own Galaxy and supermassive black holes residing in centers of most of the massive galaxies. Such intermediate-mass black holes are probably the seeds from which supermassive black holes will form.

ALMA Performs Its First Very Long Baseline Observations

ALMA, the Atacama Large Millimeter/submillimeter Array, has successfully combined its immense collecting area and sensitivity with that of APEX (Atacama Pathfinder Experiment) to create a new, single instrument through a process known as Very Long Baseline Interferometry (VLBI).  This first successful observation using VLBI with ALMA used a baseline of 2.1 km, and was an essential proof-of-concept test for the planned Event Horizon Telescope, which eventually will include a global network of millimetre-wavelength telescopes. Credit: Clem & Adri Bacri-Normier (wingsforscience.com)/ESO

ALMA, the Atacama Large Millimeter/submillimeter Array, has successfully combined its immense collecting area and sensitivity with that of APEX (Atacama Pathfinder Experiment) to create a new, single instrument through a process known as Very Long Baseline Interferometry (VLBI). “The entire team is immensely gratified at achieving this success on the first VLBI attempt with ALMA. It marks a huge step toward making first images of a black hole with the Event Horizon Telescope," said Shep Doeleman, the principal investigator of the ALMA Phasing Project and assistant director of the Massachusetts Institute of Technology’s Haystack Observatory and astrophysicist at the Smithsonian Astrophysical Observatory.

Planet 'Reared' by Four Parent Stars

This artist's conception shows the 30 Ari system, which includes four stars and a planet. Image Credit: Karen Teramura, UH IfA

Growing up as a planet with more than one parent star has its challenges. Though the planets in our solar system circle just one star -- our sun -- other more distant planets, called exoplanets, can be reared in families with two or more stars. Researchers wanting to know more about the complex influences of multiple stars on planets have come up with two new case studies: a planet found to have three parents, and another with four. The discoveries were made using instruments fitted to telescopes at the Palomar Observatory in San Diego: the Robo-AO adaptive optics system, developed by the Inter-University Center for Astronomy and Astrophysics in India and the California Institute of Technology in Pasadena, and the PALM-3000 adaptive optics system, partially funded by NASA and developed by NASA's Jet Propulsion Laboratory in Pasadena, California, and Caltech.

Single Site on Mars Advanced for 2016 NASA Lander

This map shows the single area under continuing evaluation as the InSight mission's Mars landing site, as of a year before the mission's May 2016 launch. The finalist ellipse marked is within the northern portion of flat-lying Elysium Planitia about four degrees north of Mars' equator. Image Credit: NASA/JPL-Caltech

NASA’s next mission to Mars, scheduled to launch one year from today to examine the Red Planet’s deep interior and investigate how rocky planets like Earth evolved, now has one specific site under evaluation as the best place to land and deploy its science instruments. The mission called InSight -- an acronym for "Interior Exploration using Seismic Investigations, Geodesy and Heat Transport" -- is scheduled to launch from Vandenberg Air Force Base, California. The launch period runs from March 4 to March 30, 2016, and will mark the first California launch of an interplanetary mission. Installation of science-instrument hardware onto the spacecraft has begun and a key review has given thumbs up to integration and testing of the mission's component systems from several nations participating in the international project.

Wednesday, March 4, 2015

Cosmic Showers Halt Galaxy Growth

Abell 2597, shown here, is a galaxy cluster located about one billion light years from Earth. This image contains X-rays from NASA's Chandra X-ray Observatory (blue), optical data from the Hubble Space Telescope and the Digitized Sky Survey (yellow) and emission from hydrogen atoms (red) from the Walter Baade Telescope in Chile. Credit: X-ray: NASA/CXC/Michigan State Univ/G.Voit et al; Optical: NASA/STScI & DSS; H-alpha: Carnegie Obs./Magellan/W.Baade Telescope

Using NASA's Chandra X-ray Observatory, astronomers have found that the growth of galaxies containing supermassive black holes can be slowed down by a phenomenon referred to as cosmic precipitation. Cosmic precipitation is not a weather event, as we commonly associate the word -- rain, sleet, or snow. Rather, it is a mechanism that allows hot gas to produce showers of cool gas clouds that fall into a galaxy. Researchers have analyzed X-rays from more than 200 galaxy clusters, and believe that this gaseous precipitation is key to understanding how giant black holes affect the growth of galaxies. "We know that precipitation can slow us down on our way to work," said Mark Voit of Michigan State University (MSU) in East Lansing, lead author of the paper that appears in the latest issue of Nature. "Now we have evidence that it can also slow down star formation in galaxies with huge black holes."

China Prepares for Mars, Asteroid Exploration

China's mission control center. Credit: Xinhua

China has been researching the technical feasibility of exploring Mars and asteroids, a top space scientist and national political advisor revealed on Tuesday. Ye Peijian, from the China Academy of Space Technology and chief scientist with the country's lunar probe mission, said Chinese space researchers had tackled some of the technical difficulties associated with the exploration of Mars and asteroids. However, he added, the projects are only at the technical preparation stage, which suggests that it will be some time before an official project is announced.