Caught ya! The Moon Transits the Earth as Seen by DSCVR

A Step to a Satellite Based Panopticon

Record Melting of Greenland & Antarctic Glaciers

"The new elevation maps are snapshots of the current state of the ice sheets. The elevations are very accurate, to just a few metres in height, and cover close to 16 million km2 of the area of the ice sheets. This is 500,000 square kilometres more than any previous elevation model from altimetry", says lead-author Dr. Veit Helm, glaciologist at the Alfred Wegener Institute in Bremerhaven.

For the new digital maps, the AWI scientists had evaluated all data by the CryoSat-2 altimeter SIRAL. Satellite altimeter measure the height of an ice sheet by sending radar or laser pulses in the direction of the earth. These signals are then reflected by the surface of the glaciers or the surrounding waters and are subsequently retrieved by the satellite. This way the scientists were able to precisely determine the elevation of single glaciers and to develop detailed maps.

On the basis of further CrysoSat-2 the scientists also documented how the elevation has changed over the 2011-2014 period. Ice sheets gain mass through snowfall and lose it due to melting and accelerating glaciers, which carry ice from the interior of the ice sheet to the ocean. "We need to understand where and to which extent the ice thickness across the glaciers has changed. Only then can we can analyse the drivers of these changes and find out how much ice sheets contribute to global sea level rise", says Veit Helm.

The team derived the elevation change maps using over 200 million SIRAL data points for Antarctica and around 14.3 million data points for Greenland. The results reveal that Greenland alone is reducing in volume by about 375 cubic kilometres per year. "When we compare the current data with those from the ICESat satellite from the year 2009, the volume loss in Greenland has doubled since then. The loss of the West Antarctic Ice Sheet has in the same time span increased by a factor of 3. Combined the two ice sheets are thinning at a rate of 500 cubic kilometres per year. That is the highest rate observed since altimetry satellite records began about 20 years ago," says AWI glaciologist Prof. Dr. Angelika Humbert, another of the study's authors.

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Sangeang Api Ash Plume

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What Earth Looked Like to ESA's Rosetta Mission

Analysis of Rosetta/VIRTIS spectra of earth using observations from ENVISAT/AATSR, TERRA/MODIS and ENVISAT/SCIAMACHY, and radiative-transfer simulations

Authors:

Hurley et al

Abstract:

Rosetta, the Solar System cornerstone mission of ESA's Horizon 2000 programme, consists of an orbiter and a lander, and is due to arrive at the comet 67P/Churyumov–Gerasimenko in May 2014. Following its 2004 launch, Rosetta carried out a series of planetary fly-bys and gravitational assists. On these close fly-bys of the Earth, measurements were taken by the Visible Infrared Thermal Imaging Spectrometer (VIRTIS). Analysis of these spectra and comparison with spectra acquired by Earth-observing satellites can support the verification of the inflight calibration of Rosetta/VIRTIS.

In this paper, measurements taken by VIRTIS in November 2009 are compared with suitable coincident data from Earth-observing instruments (ESA-ENVISAT/AATSR and SCIAMACHY, and EOS-TERRA/MODIS). Radiative transfer simulations using NEMESIS (Irwin et al., 2008) are fit to the fly-by data taken by VIRTIS, using representative atmospheric and surface parameters. VIRTIS measurements correlate 90% with AATSR's, 85–94% with MODIS, and 82–88% with SCIAMACHYs.

The VIRTIS spectra are reproducible in the 1–5 μm region, except in the 1.4 μm deep water vapour spectral absorption band in the near-infrared in cases in which the radiance is very low (cloud-free topographies), where VIRTIS consistently registers more radiance than do MODIS and SCIAMACHY. Over these cloud-free regions, VIRTIS registers radiances a factor of 3–10 larger than SCIAMACHY and of 3–8 greater than MODIS. It is speculated that this discrepancy could be due to a spectral light leak originating from reflections from the order-sorting filters above the detector around 1.4 μm.

New Map of Antarctica's Bedrock

Fires, in New Mexico, From Space

Tres Lagnus above.

Thompson Ridge Fire too.

Planetary Resources to Launch Testbed Arkyd-3 Nanosat in 2014

A billionaire-backed asteroid-mining company aims to start putting its big plans into action soon, launching its first hardware into space by this time next year.

Planetary Resources, which counts Google execs Larry Page and Eric Schmidt among its investors, plans to loft a set of tiny "cubesats" to Earth orbit in early 2014, to test out gear for its first line of asteroid-prospecting spacecraft.

"Our belief and our philosophy is that the best testbed is space itself," Chris Voorhees, Planetary Resources' vice president of spacecraft development, said Wednesday (April 24) during a Google+ Hangout event. [Planetary Resources' Asteroid-Mining Plans (Images)]

"Despite the fact that we're a deep-space company, we're going to use Earth orbit as much as possible," Voorhees added. "For us, it's a valuable learning experience, and that's what we plan on doing one year hence."

The cubesats slated for launch in 2014 will measure 12 inches long by 4 inches wide by 4 inches tall (30 by 10 by 10 centimeters), company officials said. These "Arkyd-3" satellites will test out technologies for Planetary Resources' Arkyd-100 scouts, which the firm hopes to launch to low-Earth orbit on asteroid-hunting missions in 2015.

The Arkyd-3 "is the testbed manifestation of our Arkyd-100 spacecraft. It just happens to be flying," Voorhees said.