Tag: the-spacecraft

NASA will test a key deep space navigation tool this year

The Deep Space Atomic Clock (DSAC) is finally ready for testing, and NASA’s JPL has begun preparing it for launch this year after working on it for two decades. Current space vehicles and observatories already use atomic clocks for navigation — they are, after all, some of the most accurate timekeeping devices ever. However, the way they work isn’t ideal for use in vessels going beyond Low-Earth Orbit. See, the atomic clocks space agencies and companies use today need to be paired with ground-based antennas. The antenna sends signals to a spacecraft, and the vessel sends them back to Earth. Current clocks use the difference in time between sending and receiving a signal to calculate a space vehicle’s location, path and velocity. It then relays commands to the spacecraft based on those calculations. While signals travel at the speed of light, that process can still take hours — the farther the spacecraft is, the longer it has to wait for a signal. Deep Space Atomic Clock solves that issue by being onboard the spacecraft itself, which means it doesn’t need to rely on two-way tracking. It can use the signal sent from Earth to calculate for its host’s position and velocity without having to toss that signal back. That means vehicles can move and change course more quickly than current ones can, and they can focus on completing mission objectives rather than spend time readjusting antennas. In addition, DSAC will allow ground-based antennas to keep track of multiple satellites in one area — say the Martian orbit — since they don’t need to wait for vehicles to respond. DSAC will launch this year attached to General Atomic’s Orbital Test Bed spacecraft, which will blast off aboard the US Air Force Space Technology Program mission. It can head to space as a hosted payload , because it’s about the size of a four-slice toaster, much smaller than current fridge-sized atomic clocks — the agency could shrink it down even further for future missions. JPL’s ultimate goal is achieving a .03 nanosecond accuracy, but it’ll call the upcoming test a success if the prototype can maintain time accurately to within two nanoseconds. Source: NASA

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NASA will test a key deep space navigation tool this year

Cassini has taken another spectacular image of its home planet

NASA As it continues to make some of its final flybys of the Saturn system, the Cassini spacecraft hasn’t entirely forgone looking back toward its home planet, Earth. And last week the spacecraft’s camera snapped a shot of Earth and the Moon (visible in a close-cropped view) from a distance of 1.4 billion km away. Some of Saturn’s rings are also visible in the new images, including the A ring (at top) with the Keeler and Encke gaps visible, and the F ring (at bottom). The Sun is behind the disk of Saturn from Cassini’s perspective, so the rings are backlit in this view. Read 1 remaining paragraphs | Comments

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Cassini has taken another spectacular image of its home planet

NASA’s Cassini spacecraft sent photos of Saturn’s north pole

As Cassini winds down its 20-year mission to Saturn, the spacecraft will maneuver into a series of weeklong orbits, allowing it to get a closer look at the planet’s famous rings as it flies by. Although there are still a few days before Cassini grazes Saturn’s rings, its cameras have already sent back some initial shots of some interesting features near the planet’s northern hemisphere. The images below, for example, show the same view of a hexagonal-shaped jetstream over the planet’s north pole , as seen from about 400, 000 miles above the planet and through four different spectral filters sensitive to wavelengths of light ranging from violet to infrared. (The curved lines you see beyond the edge of the planet are the rings, of course.) Although the images Cassini sends back are relatively small — just 256 by 256 pixels square in their original format — NASA calculated that each pixel represents about 95 miles of space and each side of the jetstream is about as wide as Earth itself. Cassini will pass by the outer edges of the planet’s rings on December 11 and it should start sending back images of the rings themselves a few days later. After that, Cassini will continue circling Saturn until April 22, when it will get a closer look at the moon Titan and another orbital adjustment in the process. That final orbit will swing the spacecraft back between the planet and its rings 22 more times before it finally takes a dive into the atmosphere and loses signal around September 15, 2017.

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NASA’s Cassini spacecraft sent photos of Saturn’s north pole