Sep 13 2017
From The Space Library
RELEASE 17-077 Three New Crew Members Arrive at International Space Station
After a six-hour flight, NASA astronauts Mark Vande Hei, Joe Acaba and Alexander Misurkin of Roscosmos arrived at the International Space Station at 10:55 p.m. EDT Tuesday, Sept. 12, where they will continue important scientific research.
The three crewmates launched aboard the Soyuz MS-06 spacecraft from the Baikonur Cosmodrome in Kazakhstan at 5:17 p.m. (3:17 a.m. Baikonur time Wednesday), orbited Earth four times, and docked at the space station. The hatches between the spacecraft and station will open at 12:40 a.m. Wednesday.
The arrival of Vande Hei, Acaba and Misurkin restores the station's crew to six, as they join Expedition 53 Commander Randy Bresnik of NASA and Flight Engineers Sergey Ryazanskiy of Roscosmos and Paolo Nespoli of ESA (European Space Agency.) The new Expedition 53 crew members will spend more than four months conducting approximately 250 science investigations in fields such as biology, Earth science, human research, physical sciences and technology development.
Bresnik, Ryazanskiy and Nespoli are scheduled to remain aboard the station until December, and Vande Hei, Acaba and Misurkin are slated to return in February 2018.
This marks the first long-term increase in crew size on the U.S. segment from three to four, allowing NASA to maximize time dedicated to research. Highlights of upcoming investigations include demonstrating the benefits of manufacturing fiber optic filaments in a microgravity environment, a new study looking to slow or reverse muscle atrophy in astronauts during spaceflight, and exploring the ability of a synthetic bone material that adheres bone to metal within minutes to accelerate bone repair.
The crew members also are scheduled to receive Orbital ATK’s next commercial resupply mission in November, delivering several tons of research, supplies and vehicle hardware.
For more than 16 years, humans have lived and worked continuously aboard the International Space Station, advancing scientific knowledge and demonstrating new technologies, making research breakthroughs not possible on Earth that will enable long-duration human and robotic exploration into deep space. A global endeavor, more than 200 people from 18 countries have visited the unique microgravity laboratory that has hosted more than 2,100 research investigations from researchers in more than 95 countries.
RELEASE 17-078 Cassini Spacecraft Makes Its Final Approach to Saturn
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.
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.
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 86 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 86 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.
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: [1]
Live mission commentary and video from JPL Mission Control will air on NASA Television 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.
