Since arriving at near-Earth asteroid Bennu in December 2018, NASA’s OSIRIS-REx mission has been studying this small world of boulders, rocks, and loose rubble – and looking for a place to touch down. The goal of OSIRIS-REx is to collect a sample of Bennu in mid-2020, and return it to Earth in late 2023.
Bennu turned out to be rockier than anticipated, but mission planners have now identified four sites on its surface that are smooth enough for OSIRIS-REx to collect a sample. The mission will down-select to the final two sites – a primary and a backup – in December 2019. Like the mythological Bennu bird for which the asteroid is named, all of the candidate sample sites refer to birds that can be found in Egypt.
Its size and surface gravity are much larger than Earth’s, and its radiation environment may be hostile, but a distant planet called K2-18b has captured the interest of scientists all over the world. For the first time, researchers have detected water vapor signatures in the atmosphere of a planet beyond our solar system that resides in the “habitable zone,” the region around a star in which liquid water could potentially pool on the surface of a rocky planet.
Given the high level of activity of its red dwarf star, K2-18b may be more hostile to life as we know it than Earth, as it is likely to be exposed to more high-energy radiation. The planet, discovered by NASA’s Kepler Space Telescope in 2015, also has a mass eight times greater than Earth’s. That means the surface gravity on this planet would be significantly higher than on our planet.
Space is an important and valuable domain that has changed from a safe environment to one that is congested and threatened. A growing number of satellite system owners and operators need new capabilities to protect their assets and manage their interests in Space. Lockheed Martin’s iSpace software addresses this need by providing command and control and battle management capabilities for customers in all arenas – defense, international, commercial, and civil – that operate in the space domain.
This Hubble time-lapse movie shows the orbits of some of Saturn’s icy moons as they circle the planet over an 18-hour period. The video is composed of 33 Hubble snapshots of the planet, taken June 19 to 20, 2019, by the Wide Field Camera 3.
Saturn’s signature rings are still as stunning as ever. The image reveals that the ring system is tilted toward Earth, giving viewers a magnificent look at the bright, icy structure. Hubble resolves numerous ringlets and the fainter inner rings.
This image reveals an unprecedented clarity only seen previously in snapshots taken by NASA spacecraft visiting the distant planet. Astronomers will continue their yearly monitoring of the planet to track shifting weather patterns and identify other changes. The second in the yearly series, this image is part of the Outer Planets Atmospheres Legacy (OPAL) project. OPAL is helping scientists understand the atmospheric dynamics and evolution of our solar system’s gas giant planets.
Scientists have discovered that a mysterious pressure dubbed “dark energy” makes up about 68 percent of the total energy content of the cosmos, but so far we don’t know much more about it. Exploring the nature of dark energy is one of the primary reasons NASA is building the Wide Field Infrared Survey Telescope (WFIRST), a space telescope whose measurements will help illuminate the dark energy puzzle. With a better understanding of dark energy, we will have a better sense of the past and future evolution of the universe.
Astronomers have measured the rate of of the universe’s expansion by using ground-based telescopes to study relatively nearby supernova explosions. The mystery escalated in 1998 when Hubble Space Telescope observations of more distant supernovae helped show that the universe actually expanded more slowly in the past than it does today. The expansion of the universe is not slowing down due to gravity, as everyone thought. It’s speeding up.
While we still don’t know what exactly is causing the acceleration, it has been given a name — dark energy. This mysterious pressure remained undiscovered for so long because it is so weak that gravity overpowers it on the scale of humans, planets and even the galaxy. It is only on an intergalactic scale that dark energy becomes noticeable, acting like a sort of weak opposition to gravity.
What exactly is dark energy? More is unknown than known, but theorists are chasing down a couple of possible explanations. Cosmic acceleration could be caused by a new energy component, which would require some adjustments to Einstein’s theory of gravity — perhaps the cosmological constant, which Einstein called his biggest blunder, is real after all.
Alternatively, Einstein’s theory of gravity may break down on cosmological scales. If this is the case, the theory will need to be replaced with a new one that incorporates the cosmic acceleration we have observed. Theorists still don’t know what the correct explanation is, but WFIRST will help us find out.
Discovering how dark energy has affected the universe’s expansion in the past will shed some light on how it will influence the expansion in the future. If it continues to accelerate the universe’s expansion, we may be destined to experience a “Big Rip.” In this scenario, dark energy would eventually become dominant over the fundamental forces, causing everything that is currently bound together — galaxies, planets, people — to break apart. Exploring dark energy will allow us to investigate, and possibly even foresee, the universe’s fate. Watch this video to learn more about dark energy and how WFIRST will study it.
Video Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger (USRA): Lead Producer/Krystofer Kim (USRA): Lead Animator/Chris Smith (USRA): Animator/Sophia Roberts (AIMM): Narrator/Francis Reddy (University of Maryland College Park): Lead Science Writer/Claire Andreoli (NASA/GSFC): Lead Public Affairs Office
Understanding how fire spreads and behaves in space is crucial for the safety of future astronauts and for understanding and controlling fire here on Earth.
The primary focus of microgravity combustion experiments has been related to either fire safety in space or better understanding of practical combustion on Earth and in space. The reduced gravity creates flames that look a lot different from the ones seen here on Earth: with the near absence of gravity on the space station, flames tend to be spherical. On Earth, hot gasses from the flame rise while gravity pulls cooler, denser air to the bottom of the flame. This creates both the shape of the flame, as well as a flickering effect. In microgravity, this flow doesn’t occur. This reduces the variables in combustion experiments, making them simpler and creating spherical shaped flames.
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