Launch of Russian Cargo Mission Scrubbed

ROSCOSMOS - Russian Vehicles patch.

October 12, 2017

Image above: The Progress 68 resupply rocket stands at it launch pad at the Baikonur Cosmodrome in Kazakhstan. Image Credit: Roscosmos.

Launch of the Russian Progress 68 cargo craft has been scrubbed for today. The next launch attempt will be no earlier than Saturday Oct. 14 at 4:46 am EDT (2:46 p.m. local time in Baikonur).

Rollout of Soyuz-2.1a with Progress MC-07 (68P). Video Credit: Roscosmos

Following a 34-orbit, two-day trip, Progress 68 would arrive at the Pirs Docking Compartment of the International Space Station for docking on Monday, Oct. 16. Roscosmos technicians in Baikonur are analyzing the cause of the scrubbed launch.

Related articles:

Roscosmos Press Release: http://en.roscosmos.ru/20699/

NASA to Televise International Space Station Cargo Ship Launch, Docking
https://www.nasa.gov/press-release/nasa-to-televise-international-space-station-cargo-ship-launch-docking-0

Related links:

Expedition 53: https://www.nasa.gov/mission_pages/station/expeditions/expedition53/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/Mark Garcia.

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Reconstructing Cassini's Plunge into Saturn

NASA - Cassini Mission to Saturn patch.

October 12, 2017

As NASA's Cassini spacecraft made its fateful dive into the upper atmosphere of Saturn on Sept. 15, the spacecraft was live-streaming data from eight of its science instruments, along with readings from a variety of engineering systems. While analysis of science data from the final plunge will take some time, Cassini engineers already have a pretty clear understanding of how the spacecraft itself behaved as it went in. The data are useful for evaluating models of Saturn's atmosphere the team used to predict the spacecraft's behavior at mission's end, and they help provide a baseline for planning future missions to Saturn.

Image above: Cassini spacecraft is shown during its Sept. 15, 2017, plunge into Saturn's atmosphere in this artist's depiction. Image Credits: NASA/JPL-Caltech.

Chief among these engineering data, or telemetry, are measurements indicating the performance of the spacecraft's small attitude-control thrusters. Each thruster was capable of producing a force of half a newton, which is roughly equivalent to the weight of a tennis ball on Earth.

During the final moments of its plunge, Cassini was traveling through Saturn's atmosphere, which was about the same density as the tenuous gas where the International Space Station orbits above Earth. In other words, there's barely any air there at all. Despite the fact that this air pressure is close to being a vacuum, Cassini was traveling about 4.5 times faster than the space station. The higher velocity greatly multiplied the force, or dynamic pressure, that the thin atmosphere exerted on Cassini. It's like the difference between holding your hand outside the window of a car moving at 15 mph versus one moving at 65 mph.

Data show that as Cassini began its final approach, in the hour before atmospheric entry it was subtly rocking back and forth by fractions of a degree, gently pulsing its thrusters every few minutes to keep its antenna pointed at Earth. The only perturbing force at that time was a slight tug from Saturn's gravity that tried to rotate the spacecraft.

Animation above: Cassini Grand Finale, penetration of Saturn's upper atmosphere. Animation Credits: NASA/JPL-Caltech/Space Science Institute.

"To keep the antenna pointed at Earth, we used what's called 'bang-bang control,'" said Julie Webster, Cassini's spacecraft operations chief at NASA's Jet Propulsion Laboratory, Pasadena, California. "We give the spacecraft a narrow range over which it can rotate, and when it bangs up against that limit in one direction, it fires a thruster to tip back the other way." (This range was indeed small: just two milliradians, which equals 0.1 degree. The reconstructed data show Cassini was subtly correcting its orientation in this way until about three minutes before loss of signal.)

At this point, about 1,200 miles (1,900 kilometers) above the cloud tops, the spacecraft began to encounter Saturn's atmosphere. Cassini approached Saturn with its 36-foot-long (11-meter) magnetometer boom pointing out from the spacecraft's side. The tenuous gas began to push against the boom like a lever, forcing it to rotate slightly toward the aft (or backward) direction. In response, the thrusters fired corrective gas jets to stop the boom from rotating any farther. Over the next couple of minutes, as engineers had predicted, the thrusters began firing longer, more frequent pulses. The battle with Saturn had begun.

With its thrusters firing almost continuously, the spacecraft held its own for 91 seconds against Saturn's atmosphere -- the thrusters reaching 100 percent of their capacity during the last 20 seconds or so before the signal was lost. The final eight seconds of data show that Cassini started to slowly tip over backward. As this happened, the antenna's narrowly focused radio signal began to point away from Earth, and 83 minutes later (the travel time for a signal from Saturn), Cassini's voice disappeared from monitors in JPL mission control. First, the actual telemetry data disappeared, leaving only a radio carrier signal. Then, 24 seconds after the loss of telemetry, silence.

Animation above: Cassini Grand Finale, disintegration of the spacecraft. Animation Credits: NASA/JPL-Caltech/Space Science Institute.

These data explain why those watching the signal -- appearing as a tall green spike on a squiggly plot of Cassini's radio frequency -- in mission control and live on NASA TV -- saw what appeared to be a short reprieve, almost as though the spacecraft was making a brief comeback. The spike of the signal first began to diminish over a few seconds, but then rose briefly again before disappearing with finality.

"No, it wasn't a comeback. Just a side lobe of the radio antenna beam pattern," Webster said. Essentially, the reprieve was an unfocused part of the otherwise narrow radio signal that rotated into view as the spacecraft began to slowly tip over.

"Given that Cassini wasn't designed to fly into a planetary atmosphere, it's remarkable that the spacecraft held on as long as it did, allowing its science instruments to send back data to the last second," said Earl Maize, Cassini project manager at JPL. "It was a solidly built craft, and it did everything we asked of it."

(Click on the image to see animation)

Animated graphics above: This animation shows the last 30 seconds of Cassini's X- and S-band radio signals as they disappeared from mission control on Sept. 15, 2017. The video has been sped up by a factor of two. Animation Credits: NASA/JPL-Caltech.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter.

More information about Cassini:

https://www.nasa.gov/cassini

https://saturn.jpl.nasa.gov

http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Image (mentioned), Animations (mentioned), Text, Credits: NASA/JPL/Preston Dyches.

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SpaceX - EchoStar 105/SES-11 Mission Success

SpaceX - Falcon 9 / EchoStar 105/SES-11 Mission patch.

Oct. 11, 2017

Falcon 9 carrying EchoStar 105/SES-11 payload, launch from Kennedy Space Center

On October 11th, SpaceX successfully launched the EchoStar 105/SES-11 payload from Launch Complex 39A (LC-39A) at NASA’s Kennedy Space Center, Florida. The satellite was deployed approximately 36 minutes after liftoff into its targeted orbit. EchoStar. Liftoff, from Launch Complex 39A at the Kennedy Space Center took place at the opening of a two-hour window at 18:53 Eastern Time (22:53 UTC).

Echostar 105 / SES-11 Launch replay

Following stage separation, Falcon 9’s first stage successfully landed on the “Of Course I Still Love You” droneship, which is stationed in the Atlantic Ocean. Falcon 9’s first stage for the EchoStar 105/SES-11 mission previously supported SpaceX’s 10th resupply mission to the International Space Station (CRS-10) in February of this year.

EchoStar 105/SES-11 hybrid communications satellite

A SpaceX Falcon 9 rocket launches the SES-11/EchoStar 105 hybrid communications satellite to replace the AMC-15 and AMC-18 satellites. As SES-11, the spacecraft’s C-band capacity will provide replacement capacity for SES of Luxembourg for AMC-18. EchoStar Corp. of Englewood, Colorado, will market the Ku-Band transponder capacity, with coverage of the 50 U.S. states, the Gulf of Mexico and the Caribbean, as EchoStar 105, replacing AMC-15.

For more information about SpaceX, visit: http://www.spacex.com/

Images, Video, Text, Credits: SpaceX/SES/EchoStar Corp.

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Spacewalk Review Ahead of Thursday’s Cargo Delivery

ISS - Expedition 53 Mission patch.

October 11, 2017

Image above: NASA Television will provide live coverage of the launch and docking of a Russian cargo spacecraft delivering almost three tons of food, fuel and supplies to the International Space Station. Image Credit: NASA.

Two astronauts checked in with ground engineers today after completing the second of three spacewalks yesterday that are planned for this month. Meanwhile, a Russian cargo ship stands at its launch pad ready to blast off Thursday morning on a short delivery trip to the International Space Station.

Commander Randy Bresnik and Flight Engineer Mark Vande Hei called down to Mission Control today to discuss the elements of Tuesday’s successful spacewalk. During the excursion, they began the lubrication process on the Canadarm2’s newly-installed latching end effector and swapped out a degraded video camera. Today, the spacewalkers are servicing their spacesuits’ water system and recharging the batteries.

Image above: The Russian Progress 68 resupply rocket stands at it launch pad at the Baikonur Cosmodrome in Kazakhstan. Image Credit: Roscosmos.

Bresnik will conduct another spacewalk Oct. 18 with NASA astronaut Joe Acaba to finalize the servicing on the Canadarm2 robotic arm. The duo will also perform some electrical maintenance work and replace another degraded video camera. NASA TV will broadcast the third and final spacewalk on Oct. 18 beginning at 6:30 a.m.

International Space Station (ISS). Animation Credit: NASA

Three tons of food, fuel and supplies are loaded inside a Russian resupply ship (ISS Progress 68) ready to lift off to the orbital complex Thursday at 5:32 a.m. The 68P will take just two orbits around Earth and dock to the station less than three-and-a-half hours later. This will be the shortest delivery mission for a Progress mission which usually takes a near six-hour trip, and in the past has taken up to two days to assist in the resupply of the complex.

Related article:

NASA to Televise International Space Station Cargo Ship Launch, Docking
https://www.nasa.gov/press-release/nasa-to-televise-international-space-station-cargo-ship-launch-docking-0

Related links:

Expedition 53: https://www.nasa.gov/mission_pages/station/expeditions/expedition53/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), Animation (mentioned), Text, Credits: NASA/Mark Garcia.

Best regards, Orbiter.ch

Giant Exoplanet Hunters: Look for Debris Disks

JPL - Jet Propulsion Laboratory logo.

Oct. 11, 2017

Image above: This artist's rendering shows a large exoplanet causing small bodies to collide in a disk of dust. Image Credits: NASA/JPL-Caltech.

There's no map showing all the billions of exoplanets hiding in our galaxy -- they're so distant and faint compared to their stars, it's hard to find them. Now, astronomers hunting for new worlds have established a possible signpost for giant exoplanets.

A new study finds that giant exoplanets that orbit far from their stars are more likely to be found around young stars that have a disk of dust and debris than those without disks. The study, published in The Astronomical Journal, focused on planets more than five times the mass of Jupiter. This study is the largest to date of stars with dusty debris disks, and has found the best evidence yet that giant planets are responsible for keeping that material in check.

"Our research is important for how future missions will plan which stars to observe," said Tiffany Meshkat, lead author and assistant research scientist at IPAC/Caltech in Pasadena, California. Meshkat worked on this study as a postdoctoral researcher at NASA's Jet Propulsion Laboratory in Pasadena. "Many planets that have been found through direct imaging have been in systems that had debris disks, and now we know the dust could be indicators of undiscovered worlds."

Astronomers found the likelihood of finding long-period giant planets is nine times greater for stars with debris disks than stars without disks. Caltech graduate student Marta Bryan performed the statistical analysis that determined this result.

Researchers combined data from 130 single-star systems with debris disks detected by NASA's Spitzer Space Telescope, and compared them with 277 stars that do not appear to host disks. The two star groups were between a few million and 1 billion years old. Of the 130 stars, 100 were previously scanned for exoplanets. As part of this study, researchers followed up on the other 30 using the W. M. Keck Observatory in Hawaii and the European Southern Observatory's Very Large Telescope in Chile. They did not detect any new planets in those 30 systems, but the additional data helped characterize the abundance of planets in systems with disks.

The research does not directly resolve why the giant exoplanets would cause debris disks to form. Study authors suggest the massive gravity of giant planets causes small bodies called planetesimals to collide violently, rather than form proper planets, and remain in orbit as part of a disk.

"It's possible we don't find small planets in these systems because, early on, these massive bodies destroyed the building blocks of rocky planets, sending them smashing into each other at high speeds instead of gently combining," said co-author Dimitri Mawet, a Caltech associate professor of astronomy and a JPL senior research scientist.

On the other hand, giant exoplanets are easier to detect than rocky planets, and it is possible that there are some in these systems that have not yet been found.

Our own solar system is home to gas giants responsible for making "debris belts" -- the asteroid belt between Mars and Jupiter, shaped by Jupiter, and the Kuiper Belt, shaped by Neptune. Many of the systems Meshkat and Mawet studied also have two belts, but they are also much younger than ours -- up to 1 billion years old, compared to our system's present age of 4.5 billion years. The youth of these systems partly explains why they contain much more dust -- resulting from the collisions of small bodies -- than ours does.

One system discussed in the study is Beta Pictoris, which has been directly imaged from ground-based telescopes. This system has a debris disk, comets and one confirmed exoplanet. In fact, scientists predicted this planet's existence well before it was confirmed, based on the presence and structure of the prominent disk.

In a different scenario, the presence of two dust belts in a single debris disk suggests there are likely more planets in the system whose gravity maintains these belts, as is the case in the HR8799 system of four giant planets. The gravitational forces of giant planets nudge passing comets inward toward the star, which could mimic the period of our solar system's history about 4 billion years ago known as the Late Heavy Bombardment. Scientists think that during that period, the migration of Jupiter, Saturn, Uranus and Neptune deflected dust and small bodies into the Kuiper and asteroid belts we see today. When the Sun was young, there would have been a lot more dust in our solar system as well.

"By showing astronomers where future missions such as NASA's James Webb Space Telescope have their best chance to find giant exoplanets, this research paves the way to future discoveries," said Karl Stapelfeldt of JPL, chief scientist of NASA's Exoplanet Exploration Program Office and study co-author.

For more information about exoplanets, visit: https://exoplanets.nasa.gov

Image (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Elizabeth Landau.

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Secrets of hidden ice canyons revealed

ESA - Cryosat Mission logo.

11 October 2017

We are all aware that Antarctica’s ice shelves are thinning, but recently scientists have also discovered huge canyons cutting through the underbelly of these shelves, potentially making them even more fragile. Thanks to the CryoSat and Sentinel-1 missions, new light is being shed on this hidden world.

Antarctica is surrounded by ice shelves, which are thick bands of ice that extend from the ice sheet and float on the coastal waters. They play an important role in buttressing the ice sheet on land, effectively slowing the sheet’s flow as it creeps seaward.

Hidden ice canyons in the making

The ice sheet that covers Antarctica is, by its very nature, dynamic and constantly on the move. Recently, however, there has been a worrying number of reports about its floating shelves thinning and even collapsing, allowing the grounded ice inland to flow faster to the ocean and add to sea-level rise.

While scientists continue to study the changing face of Antarctica, monitor cracks in the surface of the ice that might signal the demise of a shelf and learn how these changes are affecting the biology of coastal waters, they are also aware of dramatic changes taking place below the surface, hidden from view.

There are huge inverted canyons in the underside of ice shelves, but little is known about how they form and how they affect the stability of the ice sheet.

One type is thought to be caused by subglacial water that drains from beneath the ice sheet and runs into the ocean. In this region, the ocean water is stratified, with the warmer water at the bottom. However, as the colder meltwater pours down into the ocean it then rises because it is less dense than the seawater – but as it rises it drags up the warm bottom water which causes the underbelly of the floating ice shelf to melt.

Ice shelf appears flat

Another type is thought to be caused by the way ocean water circulates under the shelf.

Scientists have been using ESA’s CryoSat to study changes in the surface of the ice shelf and the Copernicus Sentinel-1 mission to study how shelves flow to learn more about what’s going on hidden from view.

Their focus has been on the Dotson ice shelf in West Antarctica.

Noel Gourmelen from the University of Edinburgh said “We have found subtle changes in both surface elevation data from CryoSat and ice velocity from Sentinel-1 which shows that melting is not uniform, but has centred on a 5 km-wide channel that runs 60 km along the underside of the shelf.

“Unlike most recent observations, we think that the channel under Dotson is eroded by warm water, about 1°C, as it circulates under the shelf, stirred clockwise and upward by Earth’s rotation.

“Revisiting older satellite data, we think that this melt pattern has been taking place for at least the entire 25 years that Earth observation satellites have been recording changes in Antarctica.

Dotson ice shelf from Sentinel-1

“Over time, the melt has calved in a broad channel-like feature up to 200 m deep and 15 km across that runs the entire length of the underside of Dotson ice shelf.

“We can see that this canyon is deepening by about 7 m a year and that the ice above is heavily crevassed.

“Melt from Dotson ice shelf results in 40 billion tonnes of freshwater being poured into the Southern Ocean every year, and this canyon alone is responsible for the release of four billion tonnes – a significant proportion.

ESA's Ice Mission CryoSat

”The strength of an ice shelf depends on how thick it is. Since shelves are already suffering from thinning, these deepening canyons mean that fractures are likely to develop and the grounded ice upstream will flow faster than would be the case otherwise.

“It is the first time that we’ve been able to see this process in the making and we will now expand our area of interest to the shelves all around Antarctica to see how they are responding. We couldn’t do this without CryoSat and the European Commission’s Copernicus Sentinel missions,” added Dr Gourmelen.

Related links:

CryoSat: http://www.esa.int/Our_Activities/Observing_the_Earth/CryoSat

Access CryoSat data: https://earth.esa.int/web/guest/missions/esa-operational-eo-missions/cryosat

AGU Geophysical Research Letters Channelized melting drives thinning under Antarctic ice shelves: http://onlinelibrary.wiley.com/doi/10.1002/2017GL074929/abstract

University of Edinburgh–School of Geosciences: http://www.ed.ac.uk/geosciences

Support to Science Element: http://due.esrin.esa.int/stse/

Images, Video, Text, Credits: ESA/N. Gourmelen/contains modified Copernicus Sentinel data (2017), processed by A. Hogg/CPOM.

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This is a Test: Asteroid Tracking Network Observes Oct. 12 Close Approach

Asteroid Watch logo.

Oct. 10, 2017

On Oct. 12, a small asteroid designated 2012 TC4 will safely pass by Earth at a distance of approximately 26,000 miles (42,000 kilometers). This is a little over one-tenth the distance to the Moon and just above the orbital altitude of communications satellites. This encounter with TC4 is being used by asteroid trackers around the world to test their ability to operate as a coordinated international asteroid warning network.

Animation above: On Oct. 12, 2017, a small (15-30 meter) asteroid known as 2012 TC4 will safely fly past Earth. Based on continuing observations, scientists have determined that it will pass the Earth at a distance of about 26,000 miles (42,000 kilometers). Animation Credits: NASA/JPL-Caltech.

2012 TC4 is estimated to be 45 to 100 feet (15 to 30 meters) in size. Orbit prediction experts say the asteroid poses no risk of impact with Earth. Nonetheless, its close approach to Earth is an opportunity to test the ability of a growing global observing network to communicate and coordinate their optical and radar observations in a real scenario.

This asteroid was discovered by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) on Hawaii back in 2012. Pan-STARRS conducts a near-Earth object (NEO) survey funded by NASA’s NEO Observations Program, a key element of NASA’s Planetary Defense Coordination Office. However, 2012 TC4 traveled out of the range of asteroid-tracking telescopes shortly after it was discovered.

Based on the observations they were able to make in 2012, asteroid trackers predicted that it should come back into view in the fall of 2017. Observers with the European Space Agency and the European Southern Observatory were the first to recapture 2012 TC4, in late July 2017, using one of their large 8-meter aperture telescopes.  Since then, observers around the world have been tracking the object as it approaches Earth and reporting their observations to the Minor Planet Center.

This “test” of what has become a global asteroid-impact early-warning system is a volunteer project, conceived and organized by NASA-funded asteroid observers and supported by the NASA Planetary Defense Coordination Office (PDCO).

As explained by Michael Kelley, program scientist and NASA PDCO lead for the TC4 observation campaign, “Asteroid trackers are using this flyby to test the worldwide asteroid detection and tracking network, assessing our capability to work together in response to finding a potential real asteroid-impact threat."

No asteroid currently known is predicted to impact Earth for the next 100 years.

Asteroids passing Earth. Image Credit: ESA

Asteroid TC4’s closest approach to Earth will be over Antarctica at 1:40 AM EDT. Tens of professionally run telescopes across the globe will be taking ground-based observations from visible to near-infrared to radar. Amateur astronomers may contribute more observations, but the asteroid will be very difficult for backyard astronomers to see, as current estimates are that it will reach a visual magnitude of only about 17 at its brightest, and it will be moving very fast across the sky.

Many of the observers who are participating in this exercise are funded by NASA’s NEO Observations Program but observers supported by other countries’ space agencies and space institutions around the world are now involved in the campaign.

Vishnu Reddy, an assistant professor at the University of Arizona's Lunar and Planetary Laboratory in Tucson, is leading the 2012 TC4 campaign. Reddy is principal investigator for a NASA-funded near-Earth asteroid characterization project. "This campaign is a team effort that involves more than a dozen observatories, universities and labs around the globe so we can collectively learn the strengths and limitations of our near-Earth object observation capabilities," he said. "This effort will exercise the entire system, to include the initial and follow-up observations, precise orbit determination, and international communications."

In September, asteroid observers were able to conduct a “pre-test” of a coordinated tracking for the close approach of a much larger asteroid known as 3122 Florence. Florence, one of the largest known NEOs, at 2.8 miles (4.5 kilometers) in size, passed by Earth on Sept. 1 at 18 times the distance to the Moon. Coordinated observations of this asteroid revealed, among other things, that Florence has two moons.

Related link:

Asteroids: https://www.nasa.gov/mission_pages/asteroids/main/index.html

NASA Planetary Defense Coordination Office (PDCO): https://www.nasa.gov/planetarydefense

Animation (mentioned), Image (mentioned), Text, Credits: NASA/Tricia Talbert.

Greetings, Orbiter.ch