Sojourner - Blog Posts

Solar System: Things to Know This Week

We marked the 20th anniversary of Pathfinder's landing on Mars this week. 

We have had an active robotic presence there ever since—in fact, no one under 20 has experienced a day without NASA at Mars—but the Pathfinder mission was the first-ever robotic rover to explore the Red Planet. Below are 10 things to know about this iconic mission as we celebrate two decades of unprecedented science and discovery.

1. A Date to Remember

Pathfinder launched from Cape Canaveral, Florida on Dec. 4, 1996, and landed at Mars' Ares Vallis on July 4, 1997. The landing site, an ancient flood plain in Mars' northern hemisphere, is among the rockiest parts of the planet. Scientists chose it because they believed it was a relatively safe surface to land on and contained a wide variety of rocks deposited during a catastrophic flood.

2. Precious Cargo 

Pathfinder delivered to Mars a tiny, 23-pound (11.5 kilogram) rover named Sojourner, which carried scientific instruments to analyze the Martian atmosphere, climate and geology. To put its small size in perspective, the mechanisms at the end of the Curiosity Rover's robotic arm are heavier than all of Sojourner. You can check out a 360 video of Pathfinder and Sojourner here.

3. Who Named the Rover? 

The name Sojourner was chosen after a year-long, worldwide competition in which students up to 18 years old were invited to write about a historical heroine and how she would translate their accomplishments to the Martian environment. Twelve-year-old Valerie Ambroise of Bridgeport, Connecticut, submitted the winning essay on Sojourner Truth, a Civil War-era abolitionist who made it her mission to "travel up and down the land" advocating for the rights of all people to be free and participate fully in society.

4. Quite the Entrance 

Pathfinder's landing was innovative and unprecedented. It entered the thin Martian atmosphere assisted by parachute to slow its descent and with a giant system of airbags to cushion the impact. This mission marked the first time this airbag technique was used. Spirit and Opportunity later used the same method successfully.

5. Mobile Matters 

The wireless modem between Pathfinder and Sojourner was a commercial, off-the-shelf product. The project team acquired several and stress-tested them until they found the best ones to send off to Mars.

6. It's in the Details 

Sojourner had bumpers—actual mechanical fenders—painted with black and white stripes. It also had two forward-facing black-and-white cameras, and one rear-facing camera (all one-third of a Megapixel). And Sojourner's tiny wheels measured just 12.5 centimeters in diameter.

7. Viral-worthy

Pathfinder was widely regarded as one of the first "internet sensations." There was so much web traffic from around the world, the entire internet backbone of France crashed under the load.

8. We're Getting Warmer 

Among the many scientific discoveries from Pathfinder and Sojourner: Rounded pebbles and cobbles at the landing site suggested that Mars might have had running water during a warmer past when liquid water was stable on the planet. Early morning water ice clouds also were seen in the lower atmosphere.

9. Long Live the Mission 

The lander and the rover both outlived their design lives—the lander by nearly three times, and the rover by 12 times.

10. Pathfinder's Photo Album 

Go back in time and see historical photographs of Pathfinder's assembly process here.

Solar System: Things to Know This Week

With only four months left in the mission, Cassini is busy at Saturn. The upcoming cargo launch, anniversaries and more!

As our Cassini spacecraft made its first-ever dive through the gap between Saturn and its rings on April 26, 2017, one of its imaging cameras took a series of rapid-fire images that were used to make this movie sequence. Credits: NASA/JPL-Caltech/Space Science Institute/Hampton University

1-3. The Grand Finale

Our Cassini spacecraft has begun its final mission at Saturn. Some dates to note:

May 28, 2017: Cassini makes its riskiest ring crossing as it ventures deeper into Saturn's innermost ring (D ring).

June 29, 2017: On this day in 2004, the Cassini orbiter and its travel companion the European Space Agency's Huygens probe arrived at Saturn.

September 15, 2017: In a final, spectacular dive, Cassini will plunge into Saturn - beaming science data about Saturn's atmosphere back to Earth to the last second. It's all over at 5:08 a.m. PDT.

More about the Grand Finale

4. Cargo Launch to the International Space Station

June 1, 2017: Target date of the cargo launch. The uncrewed Dragon spacecraft will launch on a Falcon 9 from Launch Complex 39A at our Kennedy Space Center in Florida. The payload includes NICER, an instrument to measure neutron stars, and ROSA, a Roll-Out Solar Array that will test a new solar panel that rolls open in space like a party favor.

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5. Sojourner

July 4, 2017: Twenty years ago, a wagon-sized rover named Sojourner blazed the trail for future Mars explorers - both robots and, one day, humans. Take a trip back in time to the vintage Mars Pathfinder websites:

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6. Voyager

August 20, 2017: Forty years and still going strong, our twin Voyagers mark 40 years since they left Earth.

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7. Total Solar Eclipse

August 21, 2017: All of North America will be treated to a rare celestial event: a total solar eclipse. The path of totality runs from Oregon to South Carolina.

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8. From Science Fiction to Science Fact

Light a candle for the man who took rocketry from science fiction to science fact. On this day in 1882, Robert H. Goddard was born in Worcester, Massachusetts.

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9. Looking at the Moon

October 28, 2017: Howl (or look) at the moon with the rest of the world. It's time for the annual International Observe the Moon Night.

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10. Last Human on the Moon

December 13, 2017: Forty-five years ago, Apollo 17 astronaut Gene Cernan left the last human footprint on the moon.

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Discover more lists of 10 things to know about our solar system HERE.

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