Planners of NASA's next Mars mission have selected a flight schedule that will use favorable positions for two currently orbiting NASA Mars orbiters to obtain maximum information during descent and landing.

Continuing analysis of the geometry and communications options for the arrival at Mars have led planners for the Mars Science Laboratory, or Curiosity, to choose an Earth-to-Mars trajectory that schedules launch between Nov. 25 and Dec. 18, 2011. Landing will take place between Aug. 6 and Aug. 20, 2012. Due to an Earth-Mars planetary alignment, this launch period actually allows for a Mars arrival in the earlier portion of the landing dates under consideration.

"The key factor was a choice between different strategies for sending communications during the critical moments before and during touchdown," said Michael Watkins, mission manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "The shorter trajectory is optimal for keeping both orbiters in view of Curiosity all the way to touchdown on the surface of Mars. The longer trajectory allows direct communication to Earth all the way to touchdown."

The simplicity of direct-to-Earth communication from Curiosity during landing has appeal to mission planners, in comparison to relying on communications relayed via NASA's Mars Odyssey, which has been orbiting Mars since 2001, and NASA's Mars Reconnaissance Orbiter, in operation since 2006. However, the direct-to-Earth option allows a communication rate equivalent to only about 1 bit per second, while the relay option allows about 8,000 bits or more per second.

Landing on Mars is always difficult, with success uncertain. After an unsuccessful attempted Mars landing in 1999 without definitive information on the cause of the mishap, NASA put a high priority on communication during subsequent Mars landings.

"It is important to capture high-quality telemetry to allow us to learn what happens during the entry, descent and landing, which is arguably the most challenging part of the mission," said Fuk Li, manager of NASA's Mars Exploration Program at JPL. "The trajectory we have selected maximizes the amount of information we will learn to mitigate any problems."

Curiosity will use several innovations during entry into the Martian atmosphere, descent and landing in order to hit a relatively small target area on the surface and set down a rover too heavy for the cushioning air bags used in earlier Mars rover landings. In a "sky-crane" maneuver during the final minute of arrival, a rocket-powered descent stage will lower Curiosity on a tether for a wheels-down landing directly onto the surface.

Even though Curiosity won't be communicating directly with Earth at touchdown, data about the landing will reach Earth promptly. Odyssey will be in view of both Earth and Curiosity, in position to immediately forward to Earth the data stream it is receiving during the touchdown. Odyssey performed this type of "bent-pipe" relay during the May 25, 2008, arrival of NASA's Phoenix Mars Lander.

Curiosity will rove extensively on Mars, carrying an analytical laboratory and other instruments to examine a carefully selected landing area. It will investigate whether conditions there have favored development of microbial life and its preservation in the rock record. Plans call for the mission to operate on Mars for a full Martian year, which is equivalent to two Earth years.

Consideration of landing sites for the mission narrowed to four finalist candidates in November 2008. The candidate sites are still being analyzed for safety and science attributes.

Curiosity is managed by JPL for NASA's Science Mission Directorate in Washington. JPL also manages the Mars Odyssey and Mars Reconnaissance Orbiter missions, in partnership with Lockheed Martin Space Systems, Denver.

More information about NASA's Mars Science Laboratory is at: http://www.nasa.gov/msl.

NASA's Mars Exploration Rover Opportunity used its navigation camera for this northward view of tracks the rover left on a drive from one energy-favorable position on the northern end of a sand ripple to another.
› Larger image› Interactive: Mars Exploration Rovers

NASA's Mars Exploration Rover Project will pass a historic Martian longevity record on Thursday, May 20. The Opportunity rover will surpass the duration record set by NASA's Viking 1 Lander of six years and 116 days operating on the surface of Mars. The effects of favorable weather on the red planet could also help the rovers generate more power.

Opportunity's twin rover, Spirit, began working on Mars three weeks before Opportunity. However, Spirit has been out of communication since March 22. If it awakens from hibernation and resumes communication, that rover will attain the Martian surface longevity record.

Spirit's hibernation was anticipated, based on energy forecasts, as the amount of sunshine hitting the robot's solar panels declined during autumn on Mars' southern hemisphere. Unfortunately, mobility problems prevented rover operators from positioning Spirit with a favorable tilt toward the north, as during the first three winters it experienced. The rovers' fourth winter solstice, the day of the Martian year with the least sunshine at their locations, was Wednesday, May 12 (May 13 Universal time).

"Opportunity, and likely Spirit, surpassing the Viking Lander 1 longevity record is truly remarkable, considering these rovers were designed for only a 90-day mission on the surface of Mars," Callas said. "Passing the solstice means we're over the hump for the cold, dark, winter season."

Unless dust interferes, which is unlikely in the coming months, the solar panels on both rovers should gradually generate more electricity. Operators hope that Spirit will recharge its batteries enough to awaken from hibernation, start communicating and resume science tasks.

Unlike recent operations, Opportunity will not have to rest to regain energy between driving days. The gradual increase in available sunshine will eventually improve the rate of Opportunity's progress across a vast plain toward its long-term destination, the Endeavour Crater.

This month, some of Opportunity's drives have been planned to end at an energy-favorable tilt on the northern face of small Martian plain surface ripples. The positioning sacrifices some distance to regain energy sooner for the next drive. Opportunity's cameras can see a portion of the rim of Endeavour on the horizon, approximately eight miles away, across the plain's ripples of windblown sand.

"The ripples look like waves on the ocean, like we're out in the middle of the ocean with land on the horizon, our destination," said Steve Squyres of Cornell University in Ithaca, N.Y. Squyres is the principal investigator for Opportunity and Spirit. "Even though we know we might never get there, Endeavour is the goal that drives our exploration."

The team chose Endeavour as a destination in mid-2008, after Opportunity finished two years examining the smaller Victoria Crater. Since then, the goal became even more alluring when orbital observations found clay minerals exposed at Endeavour. Clay minerals have been found extensively on Mars from orbit, but have not been examined on the surface.

"Those minerals form under wet conditions more neutral than the wet, acidic environment that formed the sulfates we've found with Opportunity," said Squyres. "The clay minerals at Endeavour speak to a time when the chemistry was much friendlier to life than the environments that formed the minerals Opportunity has seen so far. We want to get there to learn their context. Was there flowing water? Were there steam vents? Hot springs? We want to find out."

Launched in 1975, Project Viking consisted of two orbiters, each carrying a stationary lander. Viking Lander 1 was the first successful mission to the surface of Mars, touching down on July 20, 1976. It operated until Nov. 13, 1982, more than two years longer than its twin lander or either of the Viking orbiters.

The record for longest working lifetime by a spacecraft at Mars belongs to a later orbiter: NASA's Mars Global Surveyor operated for more than 9 years after arriving in 1997. NASA's Mars Odyssey, in orbit since in 2001, has been working at Mars longer than any other current mission and is on track to take the Mars longevity record late this year.

Science discoveries by the Mars Exploration Rover have included Opportunity finding the first mineralogical evidence that Mars had liquid water, and Spirit finding evidence for hot springs or steam vents and a past environment of explosive volcanism.

JPL manages the Mars rovers for NASA's Science Mission Directorate in Washington. For more information about the rovers, visit http://www.nasa.gov/rovers . The California Institute of Technology in Pasadena manages JPL for NASA.

It's no secret that America is going to need many more young people to pursue science and technology professions in the future. As we celebrate National Lab Day on May 12, we have an opportunity for people currently in these careers to work with students and teachers and get them excited about science, technology, engineering and mathematics (STEM) subjects. But National Lab Day is more than just one single day in the year. It's really a collaborative movement to support people who work in our classrooms to inspire tomorrow’s innovators.

I have a particular interest in activities like this. I was born and raised in Columbia, SC – the son of two public school teachers who, despite very long hours and modest wages, loved each and every day of their work. They made the hard choice to remain in public education because they knew it was their opportunity to inspire thousands of students and to give them the foundation they would need to take their places in national, state, and local leadership. My parents’ dedication instilled in me a deep and personal passion for education.

Yesterday, I had the opportunity to follow in my parents’ footsteps for a day and work with Lisa Miller’s fifth grade students at Langdon Education Campus, a school located in Washington, DC. These students have been studying the solar system, and I had the opportunity to share with them my experience of living and working in space as a NASA astronaut before I became the NASA Administrator. We spent time discussing Newton’s Laws of Motion with me giving them examples of ways in which we are able to demonstrate those laws real-time while in the weightless environment of space. We had an energetic discussion on how these laws are present in everyday life.

After this opening exchange, NASA education staff and I joined the students in their adventure to become rocket scientists for a day, as we built large paper rockets and test flew them using a high-power launcher. Following their rockets’ flight, the students evaluated their designs, modified them, and flew them again to determine if their changes affected the rocket's performance. It was amazing to see these young future engineers at work – to see the determination on their faces as they designed their rocket and the ensuing pride as they saw their rockets successfully launch.

NASA as an agency has embraced National Lab Day and has scheduled activities at schools throughout the week supported by volunteers from its field centers across the nation and from its headquarters here in Washington DC. For instance, Kennedy Space Center in Florida is hosting an educational event for students from local-area high schools who will learn about NASA and the benefits of science, technology, engineering and mathematics, fields related to our world and beyond.

There is a crisis in the United States that stems from the gap between the nation’s growing need for scientists, engineers, and other technically skilled workers, and our supply. This crisis in education, if not resolved, will contribute to future declines in qualified employees to meet demands in critical career fields that affect U.S. global competitiveness and the national economy. However, seeing the engagement and enthusiasm of those fifth grade students, I am hopeful that given the opportunity, our youth shall be inspired and motivated to consider STEM careers.

I have said this before -- NASA inspires the next generation through our compelling missions, but we must do more. We will continue to move things to the next level by directly exposing students to dynamic STEM activities that form the basis of our work. When students can get involved directly with NASA's missions in all their diversity, they just might take that next step to join us and take part in the nation's future in exploration. And National Lab Day really gets students involved.

A direct compliment to National Lab Day is a new project that I have directed to be implemented this summer, the Summer of Innovation project, which supports the President’s Educate to Innovate campaign. This is NASA’s first initiative supporting intensive STEM summer learning opportunities for middle school students and teachers focused on students who are underrepresented, underserved and underperforming in STEM.

I hope that this summer thousands of students across the country will feel the same excitement that the students at Langdon Education Campus felt yesterday as they learned first-hand what it was like to tackle a design challenge like an engineer – a real rocket scientist! And that’s just the launch pad for much more to come.

Artist's concept of Cassini's flyby of Saturn's moon Enceladus.

NASA's Cassini spacecraft will be gliding low over Saturn's moon Enceladus for a gravity experiment designed to probe the moon's interior composition. The flyby, which will take Cassini through the water-rich plume flaring out from Enceladus's south polar region, will occur on April 27 Pacific time and April 28 UTC. At closest approach, Cassini will be flying about 100 kilometers (60 miles) above the moon's surface.

Cassini's scientists plan to use the radio science instrument to measure the gravitational pull of Enceladus against the steady radio link to NASA's Deep Space Network on Earth. Detecting any wiggle will help scientists understand what is under the famous "tiger stripe" fractures that spew water vapor and organic particles from the south polar region. Is it an ocean, a pond or a great salt lake?

The experiment will also help scientists find out if the sub-surface south polar region resembles a lava lamp. Scientists have hypothesized that a bubble of warmer ice periodically moves up to the crust and repaves it, explaining the quirky heat behavior and intriguing surface features.

The Cassini-Huygens mission is a cooperative project of NASA, 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 Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL.

More information about the Cassini-Huygens mission is at:
http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.

How different does the world look from 100,000 feet in the air? How do cities and suburbs, fields and forests appear when viewed from a vantage point of nearly twenty miles above Earth's surface?

Through an innovative program at NASA's Glenn Research Center in Cleveland, local high school students have the opportunity to make these discoveries firsthand while learning practical math, science and engineering skills. Participants in the BalloonSAT Exploring Program launch a 6-foot diameter weather balloon, complete with experiments and cameras, into the space-like regions of Earth's upper atmosphere.

Exploring with Balloons

The Exploring Program is affiliated with the Boy Scouts of America. This program is designed to give high school students opportunities to experience different potential careers. Throughout the country, students in the Exploring Program learn from various professionals -- like firemen, police officers and medical workers -- about the skills necessary for these jobs. At Glenn, students explore what it's like to be a scientist or engineer in one of four Exploring Posts: Aeronautics, Computer, Human Space Exploration and BalloonSAT. Stephanie Brown-Houston, from the Glenn Educational Program, is the program manager for the Exploring Program → at Glenn.

The use of weather balloons as satellites (BalloonSAT) first began at Glenn a decade ago as a way of investigating solar cell calibration in space. A small payload which tracked the sun was suspended by a weather balloon and flown to gather data. The balloon served as an inexpensive high-altitude launch system.

The BalloonSAT Exploring Post 632 began in 2004. Dr. David Snyder, a physicist and electrical engineer in the Photovoltaic and Power Technologies branch of the Power & In-Space Propulsion division at Glenn, is the lead advisor for BalloonSAT Exploring Post.

"The overall goal is to give high school kids a chance to explore these professions," Snyder says. "It's about getting them interested in science and space and technology."

Learning by Doing

Each academic year, a group of 10 to 15 high school students join the BalloonSAT Exploring Post. These diverse students, from multiple high schools around the Cleveland area, work together to perform one or two launches every year. When the first launch occurs, it is more of a demonstration launch and takes place early in the program, in the fall. The second launch, which takes place in early spring, is coordinated and executed by the students and features the experiments they designed.

"BalloonSAT attempts to simulate a satellite mission," Snyder says. "We give students the chance to design experiments and fly them with a flight program, and get results."

The students work all year to research, develop, design and fabricate experiments that will be flown when they launch their balloon. In the seven missions that BalloonSAT has flown, dozens of student-designed experiments have been launched 100,000 feet in the air.

Previous experiments have included:

• Exposure experiments with rubber bands, seeds and mold
• Light and temperature sensors
• Aerogel particle capture
• Cosmic ray detection
• Geiger counters
• Electronic compass correlation
• Carbon Dioxide/Ozone detectors
• Solar cell measurements
• Latex balloon expansion
• Yeast growth and carbon dioxide generation

• 3-D photography
• Video image transmission
• Chemical hand warmer testing
• Electric field disturbances
• Glass fragility during flight
• Wood glue exposure
• Humidity measurements

• Communications and telemetry
• Problem solving
• Power and battery issues
• Tracking
• Flight Prediction
• Coordination with the Federal Aviation Administration (FAA)

Up, Up and Away

On launch day, all of the students' and their mentors' hard work comes to fruition at the exciting launch. The latex balloon, initially 6-feet in diameter, is launched into the mid-to-upper stratosphere, about 100,000 feet above Earth's surface. The mid-to-upper stratosphere is above 99% of the atmosphere -- much higher than even commercial aircraft fly. The conditions here are similar to conditions on Mars.

The balloon rises at a rate of 1,000 feet a minute, so it takes about 2 hours for the balloon to reach its apex. It then bursts, and returns to Earth in about an hour. The balloon, which expands to about 18-feet in diameter as it passes through different temperatures during its ascent, is typically visible to the naked eye throughout its entire journey.

"It's kind of amazing," Snyder says.

The BalloonSAT team tracks the balloon visually and via GPS and Ham Radio, and collects the deflated balloon after it lands. Then the team starts investigating the results of their carefully-planned experiments, and reviews the footage the cameras on the balloon produced.

The digital cameras installed on the balloon take a picture every 30 seconds. The sideways shots display the atmosphere and some of the ground, while the straight down shots display details of Earth. The photographs are taken by inexpensive, point-and-shoot digital cameras that have been modified to have an external switch rather than the factory-installed button. The resulting images are informational and visually intriguing.

"It's impressive to see the images," Snyder says.

Mentoring Young Scientists

NASA funds the Exploring Program at Glenn, including the BalloonSAT post. A minimum of $1,000 provides supplies for the activities, including the cameras, equipment to build and construct payloads, balloons and helium.

The BalloonSAT Exploring Post has proven so successful that a nation-wide competition for high school students will be hosted by Glenn this May. Winning entries were submitted by schools in Utah, North Carolina, Pennsylvania and Virginia, and the students will converge at Glenn to launch their experiments aloft in a balloon.

The pairing of high school STEM students and experienced NASA scientists has proven effective -- many of the students who have participated in the program have gone on to study engineering and related fields in college. This experiential learning, as one of Snyder's Exploring Program students told him, brings science to life.

"She said that this is not just learning in a book. It is a chance to actually do things and have the experience. The hands-on aspect, to her, was very important," Snyder says.

This spring, engineers are testing a radar system that will serve during the next landing on Mars.

Recent tests included some near Lancaster, Calif., against a backdrop of blooming California poppy fields. In those tests, a helicopter carried an engineering test model of the landing radar for NASA's Mars Science Laboratory on prescribed descent paths. The descents at different angles and from different heights simulated paths associated with specific candidate sites for the mission.

The Mars Science Laboratory mission, managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA, is in its assembly and testing phase, in advance of a launch in autumn 2011 and delivery of a rover named Curiosity to Mars in summer 2012.

During the final stage of the spacecraft's arrival at Mars in 2012, a rocket-powered descent stage will lower the rover on a tether directly to the ground. This rover is too big for the airbag-cushioned landing method used by NASA's Mars Pathfinder mission in 1997 and Mars Exploration Rover landings in 2004.

At Mars, a radar on the descent stage will track the spacecraft's decreasing distance from the surface. Additional helicopter-flown testing of the mission's radar system will include checks of whether the suspended rover might confuse the radar about the speed of descent toward the ground.

Wolfe Air Aviation, of Pasadena, Calif., is providing the helicopter and flight services for the testing by a team of JPL engineers. The engineering test radar is affixed to a gimbal mounting at the front of the helicopter, which is more often used for aerial photography.