Thursday, May 30, 2013
NASA / JPL - Caltech / MSSS
A One-Ton Robotic Rover Paves the Way for the Future...
Radiation Measured by NASA's Curiosity on Voyage to Mars has Implications for Future Human Missions (Press Release)
WASHINGTON -- Measurements taken by NASA's Mars Science Laboratory (MSL) mission as it delivered the Curiosity rover to Mars in 2012 are providing NASA the information it needs to design systems to protect human explorers from radiation exposure on deep-space expeditions in the future.
MSL's Radiation Assessment Detector (RAD) is the first instrument to measure the radiation environment during a Mars cruise mission from inside a spacecraft that is similar to potential human exploration spacecraft. The findings will reduce uncertainty about the effectiveness of radiation shielding and provide vital information to space mission designers who will need to build in protection for spacecraft occupants in the future.
"As this nation strives to reach an asteroid and Mars in our lifetimes, we're working to solve every puzzle nature poses to keep astronauts safe so they can explore the unknown and return home," said William Gerstenmaier, NASA's associate administrator for human exploration and operations in Washington. "We learn more about the human body's ability to adapt to space every day aboard the International Space Station. As we build the Orion spacecraft and Space Launch System rocket to carry and shelter us in deep space, we'll continue to make the advances we need in life sciences to reduce risks for our explorers. Curiosity's RAD instrument is giving us critical data we need so that we humans, like the rover, can dare mighty things to reach the Red Planet."
The findings, which are published in the May 31 edition of the journal Science, indicate radiation exposure for human explorers could exceed NASA's career limit for astronauts if current propulsion systems are used.
Two forms of radiation pose potential health risks to astronauts in deep space. One is galactic cosmic rays (GCRs), particles caused by supernova explosions and other high-energy events outside the solar system. The other is solar energetic particles (SEPs) associated with solar flares and coronal mass ejections from the sun.
Radiation exposure is measured in units of Sievert (Sv) or milliSievert (one one-thousandth Sv). Long-term population studies have shown exposure to radiation increases a person's lifetime cancer risk. Exposure to a dose of 1 Sv, accumulated over time, is associated with a 5 percent increase in risk for developing fatal cancer.
NASA has established a 3 percent increased risk of fatal cancer as an acceptable career limit for its astronauts currently operating in low-Earth orbit. The RAD data showed the Curiosity rover was exposed to an average of 1.8 milliSieverts of GCR per day on its journey to Mars. Only about 5 percent of the radiation dose was associated with solar particles because of a relatively quiet solar cycle and the shielding provided by the spacecraft.
The RAD data will help inform current discussions in the United States medical community, which is working to establish exposure limits for deep-space explorers in the future.
"In terms of accumulated dose, it's like getting a whole-body CT scan once every five or six days," said Cary Zeitlin, a principal scientist at the Southwest Research Institute (SwRI) in San Antonio and lead author of the paper on the findings. "Understanding the radiation environment inside a spacecraft carrying humans to Mars or other deep space destinations is critical for planning future crewed missions."
Current spacecraft shield much more effectively against SEPs than GCRs. To protect against the comparatively low energy of typical SEPs, astronauts might need to move into havens with extra shielding on a spacecraft or on the Martian surface, or employ other countermeasures. GCRs tend to be highly energetic, highly penetrating particles that are not stopped by the modest shielding provided by a typical spacecraft.
"Scientists need to validate theories and models with actual measurements, which RAD is now providing," said Donald M. Hassler, a program director at SwRI and principal investigator of the RAD investigation. "These measurements will be used to better understand how radiation travels through deep space and how it is affected and changed by the spacecraft structure itself. The spacecraft protects somewhat against lower energy particles, but others can propagate through the structure unchanged or break down into secondary particles."
After Curiosity landed on Mars in August, the RAD instrument continued operating, measuring the radiation environment on the planet's surface. RAD data collected during Curiosity's science mission will continue to inform plans to protect astronauts as NASA designs future missions to Mars in the coming decades.
SwRI, together with Christian Albrechts University in Kiel, Germany, built RAD with funding from NASA's Human Exploration and Operations Mission Directorate and Germany's national aerospace research center, Deutsches Zentrum fur Luft- und Raumfahrt.
NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Science Laboratory Project. The NASA Science Mission Directorate at NASA Headquarters in Washington manages the Mars Exploration Program.
Wednesday, May 22, 2013
NASA / Ken Ulbrich
The Dream Chaser Is Unwrapped in SoCal... A week after arriving at its new test site in California's Mojave Desert, Sierra Nevada's Dream Chaser vehicle is ready to continue its development program at the Dryden Flight Research Center in Edwards Air Force Base. In the photos posted with this entry, NASA Administrator Charlie Bolden is one of many VIP guests to show up at Dryden to speak about the Dream Chaser and its impact on NASA's quest to provide commercial crew and cargo access to the International Space Station...and then some.
NASA / Tom Tschida
NASA / Ken Ulbrich
NASA / Tom Tschida
Wednesday, May 15, 2013
NASA / Tom Tschida
Dream Chaser update...
Sierra Nevada Corporation Dream Chaser Testing Begins at NASA Dryden, Langley (Press Release)
EDWARDS, Calif. -- Sierra Nevada Corporation's (SNC) Space Systems Dream Chaser flight vehicle arrived at NASA's Dryden Flight Research Center in Edwards, Calif., Wednesday to begin tests of its flight and runway landing systems.
The tests are part of pre-negotiated, paid-for-performance milestones with NASA's Commercial Crew Program (CCP), which is facilitating U.S.-led companies' development of spacecraft and rockets that can launch from American soil. The overall goal of CCP is to achieve safe, reliable and cost-effective U.S. human access to and from the International Space Station and low-Earth orbit.
Tests at Dryden will include tow, captive-carry and free-flight tests of the Dream Chaser. A truck will tow the craft down a runway to validate performance of the nose strut, brakes and tires. The captive-carry flights will further examine the loads it will encounter during flight as it is carried by an Erickson Skycrane helicopter. The free flight later this year will test Dream Chaser's aerodynamics through landing.
Meanwhile, on the east coast, several NASA astronauts will be at the agency's Langley Research Center in Hampton, Va., this week to fly simulations of a Dream Chaser approach and landing to help evaluate the spacecraft's subsonic handling. The test will measure how well the spacecraft would handle in a number of different atmospheric conditions and assess its guidance and navigation performance.
"Unique public-private partnerships like the one between NASA and Sierra Nevada Corporation are creating an industry capable of building the next generation of rockets and spacecraft that will carry U.S. astronauts to the scientific proving ground of low-Earth orbit," said William Gerstenmaier, NASA's associate administrator for human exploration and operations in Washington. "NASA centers around the country paved the way for 50 years of American human spaceflight, and they're actively working with our partners to test innovative commercial space systems that will continue to ensure American leadership in exploration and discovery."
The Dream Chaser Space System is based on Langley's Horizontal Lander HL-20 lifting body design concept. The design builds on years of analysis and wind tunnel testing by Langley engineers during the 1980s and 1990s. Langley and SNC joined forces six years ago to update the HL-20 design in the Dream Chaser orbital crew vehicle. In those years SNC has worked with the center to refine the spacecraft design. SNC will continue to test models in Langley wind tunnels. Langley researchers also helped develop a cockpit simulator at SNC's facility in Louisville, Colo., and the flight simulations being assessed at the center.
NASA is partnered with SNC, Space Exploration Technologies (SpaceX) and The Boeing Company to meet CCP milestones for integrated crew transportation systems under the Commercial Crew Integrated Capability (CCiCap) initiative. Advances made by these companies under their funded Space Act Agreements ultimately are intended to lead to the availability of commercial human spaceflight services for government and commercial companies.
While NASA works with U.S. industry partners to develop commercial spaceflight capabilities, the agency also is developing the Orion spacecraft and the Space Launch System (SLS), a crew capsule and heavy-lift rocket to provide an entirely new capability for human exploration. Designed to be flexible for launching spacecraft for crew and cargo missions, SLS and Orion will expand human presence beyond low-Earth orbit and enable new missions of exploration in the solar system.
NASA / Tom Tschida
Sunday, May 12, 2013
Photos of the Day... Earlier yesterday, Expedition 35 astronauts Chris Cassidy and Tom Marshburn inspected and replaced a pump controller box on the P6 truss of the International Space Station in an attempt to stop a recurring ammonia leak. While mission controllers at NASA's Johnson Space Center in Houston, Texas, are still determining whether or not the leak was finally plugged, the 5-hour, 30-minute spacewalk was deemed a success.
Friday, May 10, 2013
Atlantis Nears Her Unveiling... Earlier today, technicians finally re-opened both payload bay doors on the orbiter Atlantis—bringing the retired shuttle that much closer to impressing attendees who will travel to the Kennedy Space Center Visitor Complex in Florida to see the iconic vehicle in person. The 90,000-square-foot Space Shuttle Atlantis exhibit is still on-track to open to the public on June 29.
NASA / Kim Shiflett
NASA / Kim Shiflett