Monthly Archives: September 2017

Gas giants Saturn, Jupiter, et al, Space Science, Space Systems

Videos: Cassini nears its final orbit around Saturn

On Friday, the Cassini probe will end its 13 year mission at the ringed planet when its final orbit takes the spacecraft into Saturn’s atmosphere: Cassini Spacecraft Makes Its Final Approach to Saturn | NASA

NASA’s Cassini spacecraft is on final approach to Saturn, following confirmation by mission navigators that it is on course to dive into the planet’s atmosphere on Friday, Sept. 15.

Cassini is ending its 13-year tour of the Saturn system with an intentional plunge into the planet to ensure Saturn’s moons – in particular Enceladus, with its subsurface ocean and signs of hydrothermal activity – remain pristine for future exploration. The spacecraft’s fateful dive is the final beat in the mission’s Grand Finale, 22 weekly dives, which began in late April, through the gap between Saturn and its rings. No spacecraft has ever ventured so close to the planet before.

Milestones in Cassini’s final dive toward Saturn.

The mission’s final calculations predict loss of contact with the Cassini spacecraft will take place on Sept. 15 at 7:55 a.m. EDT (4:55 a.m. PDT). Cassini will enter Saturn’s atmosphere approximately one minute earlier, at an altitude of about 1,190 miles (1,915 kilometers) above the planet’s estimated cloud tops (the altitude where the air pressure is 1-bar, equivalent to sea level on Earth). During its dive into the atmosphere, the spacecraft’s speed will be approximately 70,000 miles (113,000 kilometers) per hour. The final plunge will take place on the day side of Saturn, near local noon, with the spacecraft entering the atmosphere around 10 degrees north latitude.

When Cassini first begins to encounter Saturn’s atmosphere, the spacecraft’s attitude control thrusters will begin firing in short bursts to work against the thin gas and keep Cassini’s saucer-shaped high-gain antenna pointed at Earth to relay the mission’s precious final data. As the atmosphere thickens, the thrusters will be forced to ramp up their activity, going from 10 percent of their capacity to 100 percent in the span of about a minute. Once they are firing at full capacity, the thrusters can do no more to keep Cassini stably pointed, and the spacecraft will begin to tumble.

Graphic showing the relative altitudes of Cassini’s final five passes through Saturn’s upper atmosphere, compared to the depth it reaches upon loss of communication with Earth. Credits: NASA/JPL-Caltech

When the antenna points just a few fractions of a degree away from Earth, communications will be severed permanently. The predicted altitude for loss of signal is approximately 930 miles (1,500 kilometers) above Saturn’s cloud tops. From that point, the spacecraft will begin to burn up like a meteor. Within about 30 seconds following loss of signal, the spacecraft will begin to come apart; within a couple of minutes, all remnants of the spacecraft are expected to be completely consumed in the atmosphere of Saturn.

Due to the travel time for radio signals from Saturn, which changes as both Earth and the ringed planet travel around the Sun, events currently take place there 83 minutes before they are observed on Earth. This means that, although the spacecraft will begin to tumble and go out of communication at 6:31 a.m. EDT (3:31 a.m. PDT) at Saturn, the signal from that event will not be received at Earth until 83 minutes later.

“The spacecraft’s final signal will be like an echo. It will radiate across the solar system for nearly an hour and a half after Cassini itself has gone,” said Earl Maize, Cassini project manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “Even though we’ll know that, at Saturn, Cassini has already met its fate, its mission isn’t truly over for us on Earth as long as we’re still receiving its signal.”

Cassini’s last transmissions will be received by antennas at NASA’s Deep Space Network complex in Canberra, Australia.

Cassini is set to make groundbreaking scientific observations of Saturn, using eight of its 12 science instruments. All of the mission’s magnetosphere and plasma science instruments, plus the spacecraft’s radio science system, and its infrared and ultraviolet spectrometers will collect data during the final plunge.

Cassini’s path into Saturn’s upper atmosphere, with tick marks every 10 seconds.
Credits: NASA/JPL-Caltech

Chief among the observations being made as Cassini dives into Saturn are those of the Ion and Neutral Mass Spectrometer (INMS). The instrument will directly sample the composition and structure of the atmosphere, which cannot be done from orbit. The spacecraft will be oriented so that INMS is pointed in the direction of motion, to allow it the best possible access to oncoming atmospheric gases.

For the next couple of days, as Saturn looms ever larger, Cassini expects to take a last look around the Saturn system, snapping a few final images of the planet, features in its rings, and the moons Enceladus and Titan. The final set of views from Cassini’s imaging cameras is scheduled to be taken and transmitted to Earth on Thursday, Sept. 14. If all goes as planned, images will be posted to the Cassini mission website beginning around 11 p.m. EDT (8 p.m. PDT). The unprocessed images will be available at: https://saturn.jpl.nasa.gov/galleries/raw-images

This unprocessed image of Titan was taken by NASA’s Cassini spacecraft during the mission’s final, distant flyby on Sept. 11, 2017. Credits: NASA/JPL-Caltech/Space Science Institute

Live mission commentary and video from JPL Mission Control will air on NASA Television and the agency’s website from 7 to 8:30 a.m. EDT (4 a.m. to 5:30 a.m. PDT) on Sept. 15. A post-mission news briefing from JPL is currently scheduled for 9:30 a.m. EDT (6:30 a.m. PDT), also on NASA TV.

A new NASA e-book, The Saturn System Through the Eyes of Cassini, showcasing compelling images and key science discoveries from the mission, is available for free download in multiple formats at: https://www.nasa.gov/ebooks

An online toolkit of information and resources about Cassini’s Grand Finale and final plunge into Saturn is available at: https://saturn.jpl.nasa.gov/grandfinale

Follow the Cassini spacecraft’s plunge on social media using #GrandFinale, or visit:

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

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More about the Cassini mission and its ending:

Activism, Mars, Space Settlement

Videos: Mars Society conference presentations

Videos of a dozen or so presentations at last week’s Mars Society conference are now available in the The Mars Society YouTube channel. (There are also videos with the complete daily live streams from the conference as in the earlier post.) Here is a sampling of the talks:

** Dr. Robert Zubrin – Opening Remarks:

** George Whitesides – CEO, Virgin Galactic:

** Loretta Hildalgo-Whitesides – Astrobiologist, space advocate, co-creator of Yuri’s Night, the World Space Party:

** Greg Benford – Legendary Sci-Fi Author:

** Vera Mulyani – CEO, Mars City Design:

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Astronomy

ESO: Observation of titanium oxide in atmosphere of gas giant exoplanet

The latest report from ESO (European Southern Observatory):

Inferno World with Titanium Skies
ESO’s VLT makes first detection of titanium oxide in an exoplanet

An artist’s impression showing the exoplanet WASP-19b, in which atmosphere astronomers detected titanium oxide for the first time. In large enough quantities, titanium oxide can prevent heat from entering or escaping an atmosphere, leading to a thermal inversion — the temperature is higher in the upper atmosphere and lower further down, the opposite of the normal situation. [Larger images.]
Astronomers using ESO’s Very Large Telescope have detected titanium oxide in an exoplanet atmosphere for the first time. This discovery around the hot-Jupiter planet WASP-19b exploited the power of the FORS2 instrument. It provides unique information about the chemical composition and the temperature and pressure structure of the atmosphere of this unusual and very hot world. The results appear today in the journal Nature.

Astronomers using ESO’s Very Large Telescope have detected titanium oxide in an exoplanet atmosphere for the first time. This discovery around the hot-Jupiter planet WASP-19b exploited the power of the FORS2 instrument. It provides unique information about the chemical composition and the temperature and pressure structure of the atmosphere of this unusual and very hot world. The video is available in 4K UHD.

A team of astronomers led by Elyar Sedaghati, an ESO fellow and recent graduate of TU Berlin, has examined the atmosphere of the exoplanet WASP-19b in greater detail than ever before. This remarkable planet has about the same mass as Jupiter, but is so close to its parent star that it completes an orbit in just 19 hours and its atmosphere is estimated to have a temperature of about 2000 degrees Celsius.

Artist impression of the light passing through the atmosphere of the extrasolar planet WASP-19b. Astronomers detected titanium oxide, together with water and traces of sodium, in the atmosphere of the hot-Jupiter planet WASP-19b. Part of the stellar light is absorbed in the atmosphere by these molecules, while other parts get scattered or go through almost unchanged. Credit: ESO/M. Kornmesser

As WASP-19b passes in front of its parent star, some of the starlight passes through the planet’s atmosphere and leaves subtle fingerprints in the light that eventually reaches Earth. By using the FORS2 instrument on the Very Large Telescope the team was able to carefully analyse this light and deduce that the atmosphere contained small amounts of titanium oxide, water and traces of sodium, alongside a strongly scattering global haze.

“Detecting such molecules is, however, no simple feat,” explains Elyar Sedaghati, who spent 2 years as ESO student to work on this project. “Not only do we need data of exceptional quality, but we also need to perform a sophisticated analysis. We used an algorithm that explores many millions of spectra spanning a wide range of chemical compositions, temperatures, and cloud or haze properties in order to draw our conclusions.”

Titanium oxide is rarely seen on Earth. It is known to exist in the atmospheres of cool stars. In the atmospheres of hot planets like WASP-19b, it acts as a heat absorber. If present in large enough quantities, these molecules prevent heat from entering or escaping through the atmosphere, leading to a thermal inversion — the temperature is higher in the upper atmosphere and lower further down, the opposite of the normal situation. Ozone plays a similar role in Earth’s atmosphere, where it causes inversion in the stratosphere.

“The presence of titanium oxide in the atmosphere of WASP-19b can have substantial effects on the atmospheric temperature structure and circulation.” explains Ryan MacDonald, another team member and an astronomer at Cambridge University, United Kingdom. “To be able to examine exoplanets at this level of detail is promising and very exciting.” adds Nikku Madhusudhan from Cambridge University who oversaw the theoretical interpretation of the observations.

The astronomers collected observations of WASP-19b over a period of more than one year. By measuring the relative variations in the planet’s radius at different wavelengths of light that passed through the exoplanet’s atmosphere and comparing the observations to atmospheric models, they could extrapolate different properties, such as the chemical content, of the exoplanet’s atmosphere.

Credit: ESO/http://spaceengine.org. Music: John Dyson

This new information about the presence of metal oxides like titanium oxide and other substances will allow much better modeling of exoplanet atmospheres. Looking to the future, once astronomers are able to observe atmospheres of possibly habitable planets, the improved models will give them a much better idea of how to interpret those observations.

“This important discovery is the outcome of a refurbishment of the FORS2 instrument that was done exactly for this purpose,” adds team member Henri Boffin, from ESO, who led the refurbishment project. “Since then, FORS2 has become the best instrument to perform this kind of study from the ground.”

Events, Space Science, Space Systems

Videos: 40th Anniversary of the Voyager missions

To mark the 40 years of the flights of the two Voyager spacecraft through the solar system and into interstellar space, NASA held an event with several of the scientists involved in the project to discuss what it has accomplished:

This segment with William Shatner is about public messages transmitted to Voyager 1:

From the caption:

On Sept. 5, 2017—the 40th anniversary of Voyager 1’s launch—NASA revealed the winning #MessageToVoyager and beamed it into space. “Message to Voyager” is a social media campaign inspired by the messages of goodwill carried on the Golden Record aboard each Voyager spacecraft.

NASA invited the public to submit short, uplifting messages to the Voyager 1 spacecraft and all that lies beyond it. These messages were a maximum of 60 characters and were tagged #MessageToVoyager. NASA tracked more than 30,000 submissions. The Voyager team together with JPL and NASA headquarters selected their 10 favorites, which were then put to a public vote. The winning message was sent into interstellar space by a command that originated from the Deep Space Network (DSN) mission control at NASA’s Jet Propulsion Laboratory with help from the original Captain Kirk, actor William Shatner; Tracy Drain, Juno mission deputy chief engineer; Jeff Berner, DSN chief engineer; and Annabel Kennedy, DSN command engineer.

To see all 10 finalist messages and get more details about the #MessageToVoyager campaign, visit https://voyager.jpl.nasa.gov/message/

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Astronomy, SETI, Space Science

Project Blue: Crowd-funding a telescope to find habitable worlds

The BoldlyGo Institute and several other institutions are supporting Project Blue, a private initiative to develop a space telescope specialized to look for habitable planets around other stars. The Project has opened a crowd-funding campaign to pay for the design of the spacecraft: Project Blue: A Telescope to Find Habitable Worlds | Indiegogo 

Our generation has a unique opportunity to discover Earthlike planets around other stars, and Project Blue could make this breakthrough. We’re creating detailed plans for the spacecraft, and we want you to be a part of advancing our mission to the Launchpad!

We believe a sister Earth could exist not too far from the place we call home and, thanks to recent breakthroughs, the technology now exists to find out. We at Project Blue aim to search the Alpha Centauri system for planets like Earth, and we want your help to launch our engineering design effort, like creating blueprints for a house before construction begins. We are looking to raise $175,000 to complete this engineering phase and to establish our industry partnerships. And we want to get you involved in the mission right at the start so that, together, we can all take a bold leap into shaping humanity’s future!

The observatory would be much smaller, and much cheaper, than the Hubble or similar big science spacecraft:

Project Blue is a space telescope mission that seeks to find and photograph a habitable world, another Earthlike planet where life can potentially thrive. Our goal is simple — to build & launch a telescope so powerful it can detect a blue planet in the nearby Alpha Centauri star system. Thanks to recent technological innovations, our telescope is small enough to fit on a coffee table, but powerful enough to pick up a planet over a billion times dimmer than its star — from four light years away! With this telescope we aim to take the first ever optical image of a potentially habitable exoplanet, and the team hopes that the results will show a ‘pale blue dot’ similar to the famous photo of Earth taken by the Voyager probe.

With sufficient public support, the spacecraft could go into orbit by 2023: