goodbye comet - recent images from the Solar and Heliospheric Observatory’s Large Angle and Spectrometric Coronagraph Experiment
Behind Saturn, in the context of the featured infrared image, is Saturn’s moon Tethys, visible as the small speck above the unusual hexagonal cloud pattern that encompasses Saturn’s North Pole. Tethys actually orbits Saturn right in the ring plane, which places the 1000-km moon much farther from Cassini than the planet itself.
Greg Matloff has speculated that what may have drawn Sänger to antimatter is specific impulse, which reaches surreal heights if you can produce an exhaust velocity equal to the speed of light (see The Starflight Handbook for more on Matloff’s thinking). The speed of light being about 3 X 108 m/sec, Matloff worked out a specific impulse of 3 X 107 seconds. Recall that specific impulse measures engine efficiency. In other words, a higher specific impulse produces more thrust for the same amount of propellant.
Sänger must have been dazzled by this ultimate specific impulse, which he conceived possible only through the mutual annihilation of matter with antimatter. But recall that when Sänger was developing these ideas, the only form of antimatter known was the positron, or positively charged electron, which had been discovered by Carl Anderson in 1932 (he would win the Nobel for the work in 1936).
With the potential to expand our knowledge of the universe for years to come, researchers are excited about the potential discoveries TESS could bring.
“The cool thing about TESS is that one of these days I’ll be able to go out in the country with my daughter and point to a star and say ‘there’s a planet around that one,’” said TESS Project Scientist Stephen Rinehart.
The National Aeronautics and Space Administration’s (NASA) Orion Multi-Purpose Crew Vehicle (Orion) program has overcome several technical challenges and made design changes to the crew capsule to reduce risk. Known challenges, however,remain—such as development of the service module and the crew capsule heatshield, among others—that could cause cost increases and schedule delays as the program undergoes integration and test. Technical challenges are inherent in complex programs such as Orion, but if not carefully managed, they could result in cost overruns and schedule delays. For example,the program has identified software development as an area of substantial risk with a potential cost impact of more than $90 million and which may result in schedule delays.
GAO found that the Orion program’s cost and schedule estimates are not reliable based on best practices for producing high-quality estimates. Cost and schedule estimates play an important role in addressing technical risks. In September 2015, NASA established a commitment baseline of $11.3 billion and an April 2023 launch readiness date for the program’s second exploration mission. NASA used a joint cost and schedule confidence level (JCL) analysis—a point-in-time estimate that, among other things, includes all cost and schedule elements and incorporates and quantifies known risks—to establish the commitment baselines at a 70 percent confidence level, as required by NASA policy. However, NASA’s JCL analysis was informed by its unreliable cost and schedule estimates. GAO found that the Orion cost estimate met or substantially met 7 of 20 best practices and its schedule estimate met or substantially met1 of 8 best practices. For example, the cost estimate lacked necessary support and the schedule estimate did not include the level of detail required for high-quality estimates.Without sound cost and schedule estimates, decisionmakers do not have a clear understanding of the cost and schedule risk inherent in the program or important information needed to make programmatic decisions.
Asteroids provide fundamental clues to the formation and evolution of planetesimals. Collisional models based on the depletion of the primordial main belt of asteroids predict 10–15 craters >400 km should have formed on Ceres, the largest object between Mars and Jupiter, over the last 4.55 Gyr. Likewise, an extrapolation from the asteroid Vesta would require at least 6–7 such basins. However, Ceres’ surface appears devoid of impact craters >~280 km. Here, we show a significant depletion of cerean craters down to 100–150 km in diameter. The overall scarcity of recognizable large craters is incompatible with collisional models, even in the case of a late implantation of Ceres in the main belt, a possibility raised by the presence of ammoniated phyllosilicates. Our results indicate that a significant population of large craters has been obliterated, implying that long-wavelength topography viscously relaxed or that Ceres experienced protracted widespread resurfacing.
On July 20, 2015, NASA released to the world the first image of the sunlit side of Earth captured by the space agency’s EPIC camera on NOAA’s DSCOVR satellite. The camera has now recorded a full year of life on Earth from its orbit at Lagrange point 1, approximately 1 million miles from Earth, where it is balanced between the gravity of our home planet and the sun.
With the arrival of the SpaceX CRS-9 mission to the Space Station Wednesday morning, the first-ever in-space DNA sequencer experiment has arrived at the international orbiting lab. The experiment is designed to test the feasibility of DNA sequencing in a non-Earth environment as well as serve as a pathfinder for sequencing initiatives on long-duration human missions in the inner solar system and on Mars.
“We began as wanderers, and we are wanderers still. We have lingered long enough on the shores of the cosmic ocean. We are ready at last to set sail for the stars.”
—Carl Sagan
Among the confirmed is a planetary system comprising four promising planets that could be rocky.
These four planets, all between 20 and 50 percent larger than Earth by diameter, are orbiting the M dwarf star K2-72, found 181 light-years away in the direction of the Aquarius constellation. The host star is less than half the size of the sun and less bright. The planets’ orbital periods range from five-and-a-half to 24 days, and two of them may experience irradiation levels from their star comparable to those on Earth. Despite their tight orbits – closer than Mercury’s orbit around our sun – the possibility that life could arise on a planet around such a star cannot be ruled out, according to lead author Ian Crossfield, a Sagan Fellow at the University of Arizona’s Lunar and Planetary Laboratory in Tucson.
In 2010, NASA’s Wide-field Infrared Survey Explorer (WISE) mission observed the entire sky twice. Astronomers used these data to point out the X-shaped structure in the bulge of the Milky Way, contained in the small circle at center, as well as the inset image. The circled central portion covers roughly the area of sky that would be blocked by a basketball when held out at arm’s length.
dragon spacecraft launch to iss on july 18th, 2016
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