The Realm of Daphnis

NASA & ESA - Cassini-Huygens Mission to Saturn & Titan patch.

Feb. 14, 2017

Daphnis, one of Saturn's ring-embedded moons, is featured in this view, kicking up waves as it orbits within the Keeler gap. The mosaic combines several images to show more waves in the gap edges than seen in a previously released image, PIA21056.

Daphnis is a small moon at 5 miles (8 kilometers) across, but its gravity is powerful enough to disrupt the tiny particles of the A ring that form the Keeler gap's edge. As the moon moves through the Keeler gap, wave-like features are created in both the horizontal and vertical plane.  For more about these vertical structures see PIA11654 and PIA11547.

Images like this provide scientists with a close-up view of the complicated interactions between a moon and the rings, as well as the interactions between the ring particles themselves, in the wake of the moon’s passage. Three wave crests of diminishing sizes trail Daphnis here. In each subsequent crest, the shape of the wave evolves, as the ring particles within the crests collide with one another.

Close examination of Daphnis’ immediate vicinity also reveals a faint, thin strand of ring material that almost appears to have been directly ripped out of the A ring by Daphnis.

The images in this mosaic were taken in visible light, using the Cassini spacecraft narrow-angle camera at a distance of approximately 17,000 miles (28,000 kilometers) from Daphnis and at a Sun-Daphnis-spacecraft, or phase, angle of 71 degrees. Image scale is 551 feet (168 meters) per pixel.

Cassini spacecraft. Image Credits: NASA/JPL

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

Related links:

PIA21056: http://photojournal.jpl.nasa.gov/catalog/PIA21056

PIA11654: http://photojournal.jpl.nasa.gov/catalog/PIA11654

PIA11547: http://photojournal.jpl.nasa.gov/catalog/PIA11547

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org and ESA's website: http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Image, Text, Credits: NASA/JPL-Caltech/Space Science Institute/Tony Greicius.

Best regards, Orbiter.ch

Lasers Could Give Space Research its 'Broadband' Moment

NASA logo.

Feb. 14, 2017

Thought your Internet speeds were slow? Try being a space scientist for a day.

The vast distances involved will throttle data rates to a trickle. You’re lucky if a spacecraft can send more than a few megabits per second (Mbps) -- a pittance even by dial-up standards.

But we might be on the cusp of a change. Just as going from dial-up to broadband revolutionized the Internet and made high-resolution photos and streaming video a given, NASA may be ready to undergo a similar “broadband” moment in coming years.

Image above: Several upcoming NASA missions will use lasers to increase data transmission from space. Image Credits: NASA's Goddard Space Flight Center/Amber Jacobson, producer.

The key to that data revolution will be lasers. For almost 60 years, the standard way to “talk” to spacecraft has been with radio waves, which are ideal for long distances. But optical communications, in which data is beamed over laser light, can increase that rate by as much as 10 to 100 times.

High data rates will allow researchers to gather science faster, study sudden events like dust storms or spacecraft landings, and even send video from the surface of other planets. The pinpoint precision of laser communications is also well suited to the goals of NASA mission planners, who are looking to send spacecraft farther out into the solar system.

“Laser technology is ideal for boosting downlink communications from deep space,” said Abi Biswas, the supervisor of the Optical Communications Systems group at NASA’s Jet Propulsion Laboratory, Pasadena, California. “It will eventually allow for applications like giving each astronaut his or her own video feed, or sending back higher-resolution, data-rich images faster.”

Science at the speed of light

Both radio and lasers travel at the speed of light, but lasers travel in a higher-frequency bandwidth. That allows them to carry more information than radio waves, which is crucial when you’re collecting massive amounts of data and have narrow windows of time to send it back to Earth.

A good example is NASA's Mars Reconnaissance Orbiter, which sends science data at a blazing maximum of 6 Mbps. Biswas estimated that if the orbiter used laser comms technology with a mass and power usage comparable to its current radio system, it could probably increase the maximum data rate to 250 Mbps.

That might still sound stunningly slow to Internet users. But on Earth, data is sent over far shorter distances and through infrastructure that doesn’t exist yet in space, so it travels even faster.

Increasing data rates would allow scientists to spend more of their time on analysis than on spacecraft operations.

“It’s perfect when things are happening fast and you want a dense data set,” said Dave Pieri, a JPL research scientist and volcanologist. Pieri has led past research on how laser comms could be used to study volcanic eruptions and wildfires in near real-time. “If you have a volcano exploding in front of you, you want to assess its activity level and propensity to keep erupting. The sooner you get and process that data, the better.”

That same technology could apply to erupting cryovolcanoes on icy moons around other planets. Pieri noted that compared to radio transmission of events like these, "laser comms would up the ante by an order of magnitude.”

Clouding the future of lasers

That’s not to say the technology is perfect for every scenario. Lasers are subject to more interference from clouds and other atmospheric conditions than radio waves; pointing and timing are also challenges.

Lasers also require ground infrastructure that doesn’t yet exist. NASA's Deep Space Network, a system of antenna arrays located across the globe, is based entirely on radio technology. Ground stations would have to be developed that could receive lasers in locations where skies are reliably clear.

Animation above: Conceptual animation depicting a satellite using lasers to relay data from Mars to Earth. Animation Credits: NASA's Goddard Space Flight Center.

Radio technology won’t be going away. It works in rain or shine, and will continue to be effective for low-data uses like providing commands to spacecraft.

Next steps

Two upcoming NASA missions will help engineers understand the technical challenges involved in conducting laser communications in space. What they’ll learn will advance lasers toward becoming a common form of space communication in the future.

The Laser Communications Relay Demonstration (LCRD), led by NASA's Goddard Space Flight Center in Greenbelt, Maryland, is due to launch in 2019. LCRD will demonstrate the relay of data using laser and radio frequency technology. It will beam laser signals almost 25,000 miles (40,000 kilometers) from a ground station in California to a satellite in geostationary orbit, then relay that signal to another ground station. JPL is developing one of the ground stations at Table Mountain in southern California. Testing laser communications in geostationary orbit, as LCRD will do, has practical applications for data transfer on Earth.

NASA and Photonics: Making the Connection

Video above: NASA is using photonics to solve some of the most pressing upcoming challenges in spaceflight, such as better data communications from space to Earth. Video Credits: NASA's Goddard Space Flight Center/Amber Jacobson, producer.

Deep Space Optical Communications (DSOC), led by JPL, is scheduled to launch in 2023 as part of an upcoming NASA Discovery mission. That mission, Psyche, will fly to a metallic asteroid, testing laser comms from a much greater distance than LCRD.

The Psyche mission has been planned to carry the DSOC laser device onboard the spacecraft. Effectively, the DSOC mission will try to hit a bullseye using a deep space laser -- and because of the planet’s rotation, it will hit a moving target, as well.

Related article:

Photonics Dawning as the Communications Light For Evolving NASA Missions
http://go.nasa.gov/2gBzbyx

Related links:

Deep Space Optical Communications (DSOC): https://gameon.nasa.gov/projects/deep-space-optical-communications-dsoc/

Tracking and Data Relay Satellites: http://www.nasa.gov/directorates/heo/scan/services/networks/txt_tdrs.html

Laser Communications Relay Demonstration (LCRD): http://www.nasa.gov/mission_pages/tdm/lcrd/index.html

Technology: https://www.nasa.gov/topics/technology/index.html

Image (mentioned), Animation (mentioned), Video (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Andrew Good.

Best regards, Orbiter.ch

Spitzer Hears Stellar 'Heartbeat' from Planetary Companion

NASA - Spitzer Space Telescope patch.

Feb. 14, 2017

A planet and a star are having a tumultuous romance that can be detected from 370 light-years away.

NASA's Spitzer Space Telescope has detected unusual pulsations in the outer shell of a star called HAT-P-2. Scientists' best guess is that a closely orbiting planet, called HAT-P-2b, causes these vibrations each time it gets close to the star in its orbit.

"Just in time for Valentine's Day, we have discovered the first example of a planet that seems to be causing a heartbeat-like behavior in its host star," said Julien de Wit, postdoctoral associate at the Massachusetts Institute of Technology, Cambridge. A study describing the findings was published today in Astrophysical Journal Letters.

The star's pulsations are the most subtle variations of light from any source that Spitzer has ever measured. A similar effect had been observed in binary systems called "heartbeat stars" in the past, but never before between a star and a planet.

Image above: This illustration shows how the planet HAT-P-2b, left, appears to cause heartbeat-like pulsations in its host star, HAT-P-2. Image Credits: NASA/JPL-Caltech.

Weighing in at about eight times the mass of Jupiter, HAT-P-2b is a relatively massive planet. It's a "hot Jupiter," meaning an exoplanet that is extremely warm and orbits its star tightly. But this hot Jupiter is tiny in relation to its host star, which is about 100 times more massive. That size difference makes the pulsation effect all the more unusual (For comparison, our sun is about 1,000 times more massive than Jupiter).

"It's remarkable that this relatively small planet seems to affect the whole star in a way that we can see from far away," said Heather Knutson, assistant professor of geological and planetary sciences at Caltech in Pasadena, California.

Known to the exoplanet community since 2007, HAT-P-2b was initially interesting to astronomers because of its "eccentric," or elliptical orbit. The planet spends most of its time relatively far from the star, but comes around for a close encounter every 5.6 days. Those are indeed hot dates for this planet, as it receives as much as 10 times the amount of light per unit area at closest approach than at its farthest point in the orbit.

Each time the planet swings around for that close approach, it appears to gives its star a little "kiss" as the gravitational forces of these two bodies interact. The star, in turn, beats like a heart as the planet travels around in its orbit again. For a less lovey-dovey analogy: The planet's gravity hits the star like a bell on closest approach, making it ring throughout the planet's orbit. 

"We had intended the observations to provide a detailed look at HAT-P-2b’s atmospheric circulation," said Nikole Lewis, co-author and astronomer at Space Telescope Science Institute, Baltimore. "The discovery of the oscillations was unexpected but adds another piece to the puzzle of how this system evolved."

Spitzer Space Telescope. Image Credits: NASA/JPL-Caltech

Spitzer watched the planet-star interactions from the vantage point of our own solar system, in the telescope's Earth-trailing orbit around the sun, for about 350 hours between July 2011 and November 2015. Because of the system's alignment with respect to Earth, Spitzer was able to observe the planet cross directly in front of the star (in a process called a "transit") as well as behind it (called a "secondary eclipse"). These eclipses of the planet allowed scientists to determine that the pulsations originate from the star, not the planet. The point of closest approach occurs between the transit and secondary eclipse.

The planetary system still has scientists stumped. Calculations by co-author Jim Fuller, Caltech postdoctoral scholar, predicted that the pitter-patter of the star's vibrations should be quieter and at a lower frequency than what Spitzer found.

"Our observations suggest that our understanding of planet-star interactions is incomplete," said de Wit. "There's more to learn from studying stars in systems like this one and listening for the stories they tell through their 'heartbeats.'"

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena, California. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit:

http://spitzer.caltech.edu

http://www.nasa.gov/spitzer

Related link:

"Heartbeat stars": http://www.jpl.nasa.gov/news/news.php?feature=6659

Images (mentioned), Text, Credits: NASA/Martin Perez/JPL/Elizabeth Landau.

Happy Valentine, Orbiter.ch

NASA to Launch Raven to Develop Autonomous Rendezvous Capability

NASA Goddard Space Flight Center logo.

Feb. 14, 2017

Launching soon, aboard the 10th SpaceX commercial resupply mission, will be a technology module called Raven, which will bring NASA one step closer to having a relative navigation capability. When affixed outside the International Space Station, Raven will test foundational technologies that will enable autonomous rendezvous in space, meaning they will not necessitate any human involvement — even from the ground.

Raven is Heading to the International Space Station

Video above: A technology module known as Raven will launch aboard SpaceX 10 to the International Space Station, bringing NASA one step closer to an autopilot capability. Raven will test foundational technologies that will enable autonomous rendezvous in space, meaning they will not necessitate any human involvement. This technology, when matured, will provide autonomous rendezvous capability for future missions. The future of autonomous navigation capability is getting closer to being a reality. Video Credits: NASA's Goddard Space Flight Center/Stuart Snodgrass, producer.

To envision why autonomous rendezvous is important in space missions, imagine this scenario: one spacecraft following another satellite, steadily closing the gap — with each vehicle traveling more than 16,000 miles per hour in the darkness of space. The satellite that is being serviced, the client, is a multi-ton craft that is running out of fuel. The fully robotic servicing satellite, the servicer, named Restore-L follows in pursuit, carrying life-extending propellant and tools.

The client, not designed to be serviced, does not have markings to making it easier for the servicer to find and secure it. The servicer has to do this on its own, using an advanced machine vision system, perfected using the data collected by Raven aboard the space station. Successful servicing first depends on the servicer’s ability to accurately locate and match speed with the client satellite.

Image above: The Raven technology module, prelaunch. Image Credits: NASA’s Goddard Space Flight Center/Chris Gunn.

To further complicate this scenario, the servicer is far from Earth, creating a communications delay for command and data exchange to and from space. The delay prevents ground operators from quickly and accurately providing commands to the servicer in order to prevent a possible collision within the last few feet of the rendezvous.

Therefore, the servicer has to perform relative navigation with its client, and it needs to do so autonomously (by itself, with no human guidance), and in real time.

“Two spacecraft autonomously rendezvousing is crucial for many future NASA missions and Raven is maturing this never-before-attempted technology,” said Ben Reed, deputy division director, for the Satellite Servicing Projects Division (SSPD) at NASA’s Goddard Space Flight Center in Greenbelt, Maryland — the office developing and managing this demonstration mission.

Raven will demonstrate the capability of a groundbreaking relative navigation system, housed within its carry-on luggage-sized frame, which will allow a spacecraft server to find, and if necessary, catch its intended target. Raven aims to lead to a fully developed, mature system available for future NASA missions.

Image above: Artist’s representation of Raven tracking a vehicle approaching the International Space Station. Image Credits: NASA’s Goddard Space Flight Center.

Five days after launch, Raven will be removed from the unpressurized “trunk” of the SpaceX Dragon spacecraft by the Dextre robotic arm, and attached on a payload platform outside the space station. From this perch, Raven will begin providing information for the development of a mature real-time relative navigation system.

During its stay aboard the space station, Raven’s components will join forces to independently image and track incoming and outgoing visiting space station spacecraft. To do this, Raven’s sensors will feed data they “see” to a processor, which will run sets of instructions (also known as special pose algorithms) to gauge the relative distance between Raven and the spacecraft it is tracking. Then, based on these calculations, the processor will autonomously send commands that swivel the Raven module on its gimbal, or pointing system, to keep the sensors trained on the vehicle, while continuing to tracking it. While these maneuvers take place, NASA operators on the ground will evaluate how Raven’s technologies work together as a system, and will make adjustments to increase Raven’s tracking performance.

Over its two-year lifespan, Raven will test these critical technologies that are expected to support future NASA missions for decades to come. One upcoming application for this technology is its use in the Restore-L servicing mission which will navigate to refuel Landsat 7, a U.S. government Earth-observing satellite already in orbit. An additional application is the potential use for systems on NASA’s Journey to Mars. Raven is on track to advance and mature the sensors, machine vision algorithms, and processing necessary to implement a robust autonomous rendezvous and docking system for NASA. SSPD is developing and managing both the Raven and Restore-L demonstration missions.

For more information about Raven, visit: https://sspd.gsfc.nasa.gov/Relative_Navigation_System.html

Related links:

Robotics: https://www.nasa.gov/topics/technology/robotics/index.html

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images (mentioned), Video (mentioned), Text, Credits: NASA's Goddard Space Flight Center, by Peter Sooy/Rob Garner.

Greetings, Orbiter.ch

NASA’s TDRS-M Space Communications Satellite Begins Final Testing

NASA - TDRS Program logo.

Feb. 13, 2017

The Tracking and Data Relay Satellite (TDRS) project has begun final testing on a new satellite that will replenish NASA's Space Network. The spacecraft is scheduled to launch from NASA’s Kennedy Space Center in Cape Canaveral, Florida, on Aug. 3, 2017, on an Atlas V rocket.

The addition of TDRS-M to the fleet will provide the Space Network (SN) the ability to support space communication for an additional 15 years. The network consists of TDRS satellites that transmit data to and from ground stations on Earth for NASA missions and expendable launch vehicles. Without the Space Network, scientists, engineers and control room staff would be unable to readily access data from missions like the Hubble Space Telescope and the International Space Station.

Coming Soon: The Latest Tracking and Data Relay Satellite, TDRS-M

Video above: TDRS-M will enable groundbreaking science and expand the current fleet of satellites. TDRS puts the "space" in Space Network. In geosynchronous orbit around Earth, the TDRS constellation ensures reliable, global communications coverage to more than 35 NASA spacecraft. TDRS-M will be the 12th satellite the TDRS team has launched since 1983. Video Credits: NASA's Goddard Space Flight Center/Stuart Snodgrass, producer.

“The Space Network is critical to numerous NASA missions that are fundamentally changing the way we think about science,” said Bill Marinelli, TDRS development manager with the Space Communications and Navigation (SCaN) program office at NASA Headquarters, which provides programmatic oversight to the TDRS mission. “By expanding the fleet of satellites that support communications from these missions, TDRS-M will enable NASA to continue scientific exploration and discovery for years to come.”

Image above: Engineers deployed TDRS-M’s antennas during a routine test at Boeing’s plant in El Segundo, California. Image Credit: Boeing.

Designed, built and environmentally tested at Boeing’s satellite development center in El Segundo, California, the spacecraft is currently undergoing a final series of tests to ensure it is flight-ready. TDRS-M will continue to undergo electronics, compatibility and deployment tests into the spring as the team prepares to ship the spacecraft to NASA’s Kennedy Space Center in Cape Canaveral, Florida, for its mid-summer launch.

Image above: TDRS-M undergoes vibration testing. Image Credit: Boeing.

NASA developed the idea for the Space Network in the 1970s to improve upon the ground-based space communications networks the agency had used since its inception. With ground networks, spacecraft could only connect with the antennas for short periods of time while they were in sight of the ground terminal. Then they would be without a communications connection for long periods of time. By contrast, a space-based network with satellites placed around the globe would provide nearly continuous coverage.

In coming months, engineers will test TDRS-M to ensure it connects with the Space Network’s various ground stations. NASA built the initial White Sands Ground Terminal (WSGT) in Las Cruces, New Mexico, in the 1970s and launched the first TDRS in 1983. In the 1980s, NASA identified the need for and built the Second TDRS Ground Terminal (STGT) at White Sands, forming the White Sands Complex. Today, the network has added two additional ground terminals in Guam and Blossom Point, Maryland, and currently has nine TDRS in orbit around Earth. Two of the original spacecraft have now been retired. The two most recent satellites, TDRS-K  and TDRS-L, were launched from Kennedy Space Center to replenish the fleet in January 2013 and January 2014, respectively. After the scheduled TDRS-M launch later this year, the TDRS project will have successfully launched 12 satellites in support of the Space Network.

Image above: Artist’s concept of the third-generation TDRS spacecraft. Image Credits: NASA's Goddard Space Flight Center.

The TDRS project at NASA’s Goddard Space Flight Center is responsible for the design, build, integration and testing of the spacecraft. After launch, on-orbit testing and spacecraft acceptance by the TDRS project, the Space Network will integrate TDRS-M into the TDRS constellation.

The TDRS project office at Goddard Space Flight Center manages the development effort in conjunction with the Space Communications and Navigation (SCaN) office within the Human Exploration and Operations (HEO) Mission Directorate at NASA Headquarters in Washington.

Related links:

Tracking and Data Relay Satellite (TDRS): https://tdrs.gsfc.nasa.gov/tdrs

Space Network: https://tdrs.gsfc.nasa.gov/sn

SCaN (Space Communications and Navigation): https://www.nasa.gov/directorates/heo/scan/index.html

Images (mentioned), Video (mentioned), Text, Credits: NASA’s Goddard Space Flight Center, by Ashley Hume/Rob Garner.

Greetings, Orbiter.ch

F for Fabulous

NASA - Cassini Mission to Saturn patch

Feb. 13, 2017

When seen up close, the F ring of Saturn resolves into multiple dusty strands. This Cassini view shows three bright strands and a very faint fourth strand off to the right.

The central strand is the core of the F ring. The other strands are not independent at all, but are actually sections of long spirals of material that wrap around Saturn. The material in the spirals was likely knocked out from the F ring's core during interactions with a small moon. To read more about the spiral, see The F Ring's Spiral Arm: https://saturn.jpl.nasa.gov/resources/2701/

This view looks toward the unilluminated side of the rings from about 38 degrees above the ring plane.  The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Dec. 18, 2016.

The view was acquired at a distance of approximately 122,000 miles (197,000 kilometers) from Saturn and at a Sun-Ring-spacecraft, or phase, angle of 47 degrees. Image scale is 0.7 miles (1.2 kilometers) per pixel.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org and ESA's website: http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Image, Text, Credits: NASA/JPL-Caltech/Space Science Institute/Martin Perez.

Best regards, Orbiter.ch

Scientists Shortlist Three Landing Sites for Mars 2020

NASA logo.

Feb. 13, 2017

Image above: Three potential landing sites for NASA's next Mars rover. Image Credit: NASA.

Participants in a landing site workshop for NASA’s upcoming Mars 2020 mission have recommended three locations on the Red Planet for further evaluation. The three potential landing sites for NASA’s next Mars rover include Northeast Syrtis (a very ancient portion of Mars’ surface), Jezero crater, (once home to an ancient Martian lake), and Columbia Hills (potentially home to an ancient hot spring, explored by NASA’s Spirit rover).

More information on the landing sites can be found at:

http://mars.nasa.gov/mars2020/mission/timeline/prelaunch/landing-site-selection/

Mars 2020 is targeted for launch in July 2020 aboard an Atlas V 541 rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida. The rover will conduct geological assessments of its landing site on Mars, determine the habitability of the environment, search for signs of ancient Martian life, and assess natural resources and hazards for future human explorers. It will also prepare a collection of samples for possible return to Earth by a future mission.

NASA's Jet Propulsion Laboratory will build and manage operations of the Mars 2020 rover for the NASA Science Mission Directorate at the agency's headquarters in Washington.

For more information about NASA's Mars programs, visit: http://www.nasa.gov/mars

Related article:

One Role of Mars Orbiter: Check Possible Landing Sites
http://orbiterchspacenews.blogspot.ch/2017/02/one-role-of-mars-orbiter-check-possible.html

Related links:

Mars 2020: http://mars.nasa.gov/mars2020/

Mars 2020 Rover: http://www.nasa.gov/mars2020

Image (mentioned), Animation, Text, Credits: NASA/Tony Greicius/JPL/DC Agle.

Greetings, Orbiter.ch