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# 3...2...1...Blast Off!

How the world’s most powerful rockets are the key to reaching—and returning from—Mars

SpaceX

Right now, a Tesla Roadster sports car is zooming through space at about 35,000 miles per hour. Its sole passenger is a mannequin wearing a spacesuit and listening to the David Bowie song “Space Oddity” on repeat.

In February, the world’s most powerful rocket—SpaceX’s Falcon Heavy—launched the car into space. The car was used as the rocket’s test mass, which confirms how much weight a rocket can carry. Since it left Earth, the car has now traveled about 364 million miles. It’s expected to fly by Mars in 2020.

Since the late 1950s, the U.S. government agency NASA has been in charge of developing rockets that launch spacecraft into Earth’s orbit and beyond. But now, private companies like California-based SpaceX are building their own advanced rocket designs. Their next goal: Send humans to Mars.

Right now, a sports car is zooming through space. It’s traveling at about 35,000 miles per hour. Its only passenger is a mannequin wearing a spacesuit. It’s listening to the David Bowie song “Space Oddity” on repeat.

In February, the car was launched into space by the world’s most powerful rocket. The rocket, called the Falcon Heavy, is made by the California company SpaceX. The car was the test mass for the rocket. That helps engineers confirm how much weight a rocket can carry. The car has now traveled about 364 million miles since leaving Earth. It’s expected to fly by Mars in 2020.

Since the late 1950s, the U.S. government agency NASA has been in charge of developing rockets. The agency has used them to launch spacecraft into Earth’s orbit and beyond. But now, private companies like SpaceX have gotten into the business. They’re building their own advanced rocket designs. Their next goal: Send humans to Mars.

## ROCKET SCIENCE

Rockets have been around for more than 700 years. The Chinese made the first rockets for warfare in the 1200s, using gunpowder as fuel. But the basic design hasn’t changed much since then.

The main body of a modern rocket is a cylinder-shaped tube that houses engines and fuel. An aerodynamic cone-shaped nose sits on top. Inside the nose are navigation instruments and the payload, or cargo. Depending on the rocket’s size, the payload can be as small as a simple science experiment or large enough to carry supplies and passengers to Mars.

To launch into space, a rocket’s engines burn liquid fuel. This creates upward thrust, which is the force that pushes the rocket up. Engineers must balance the total weight of the rocket with the right amount of fuel to create enough thrust to leave Earth. “A rocket whose thrust is less than its weight
can’t get off the pad,” says Gwynne Shotwell, SpaceX’s president and chief operating officer.

Rockets have been around for more than 700 years. The Chinese made the first rockets for warfare in the 1200s. They used gunpowder as fuel. The basic design of a rocket hasn’t changed much since then.

The main body of a modern rocket is a cylinder-shaped tube. The tube has engines and fuel inside. A cone-shaped nose sits on top of it. This shape helps air flow around the rocket. Inside the nose are navigation instruments and the rocket’s payload, or cargo. The rocket’s size determines how big the payload can be. Sometimes a payload is as small as a simple science experiment. Eventually, rockets could be large enough to carry supplies and passengers to Mars.

To launch into space, a rocket’s engines burn liquid fuel. This creates thrust, which is the force that pushes the rocket up. Engineers must make sure a rocket will create enough thrust to leave Earth. To do that, they have to balance the total weight of the rocket with the right amount of fuel. “A rocket whose thrust is less than its weight can’t get off the pad,” says Gwynne Shotwell. She’s the president and chief operating officer of SpaceX.

American physicist Robert H. Goddard is considered the father of modern rocketry. In 1926, he launched the first rocket powered by liquid fuel. It flew for less than three seconds, climbed barely 13 feet, and landed in a nearby cabbage patch on his aunt Effie’s farm. Despite these modest results, it was a huge achievement that launched modern rocket science.

In the 1950s, the federal government began developing rockets for military use based on one of Goddard’s designs. Later, it expanded its rocketry research to include space exploration. NASA engineers designed the Saturn V rocket to send astronauts to the moon, and it did just that in 1969.

To reach the moon, the Saturn V had an even more complicated design than earlier rockets. Engineers added rocket boosters that detached from the main rocket after their fuel was used up. This design was used through the 1970s. Today, NASA launches uncrewed spacecraft with the Atlas V rocket, which is smaller and wider than the Saturn V. It’s currently developing a new rocket called the Space Launch System for deep space missions with a human crew. This will be more powerful than the Saturn V.

In recent years, private companies have also been pursuing space exploration. Founded in 2002, SpaceX has been one of the most successful. Its Falcon 9 rocket routinely sends cargo to the International Space Station, a science lab in orbit 250 miles above Earth. After the successful test of the Falcon Heavy rocket in February, SpaceX is now updating the design with the new data. It also has plans for the Big Falcon Rocket. That rocket is capable of carrying a payload more than twice as heavy as the Falcon Heavy’s. SpaceX hopes it will be able to get people and all their cargo to Mars and back.

American physicist Robert H. Goddard is considered the father of modern rocketry. In 1926, he launched the first rocket powered by liquid fuel. It flew for less than three seconds and climbed barely 13 feet. It landed in a nearby cabbage patch on his aunt Effie’s farm. Goddard’s results were modest. But they were still a huge achievement that helped launch modern rocket science.

In the 1950s, the U.S. government began developing rockets for the military. Engineers based them partly on Goddard’s designs. Later, NASA expanded its rocketry research. The government wanted to explore space too. NASA engineers designed the Saturn V rocket to send astronauts to the moon. The first astronauts landed there in 1969.

To reach the moon, the Saturn V had an even more complicated design than earlier rockets. Engineers added parts called rocket boosters. These detached from the main rocket after their fuel was used up. This design was used through the 1970s. Today, NASA uses a different rocket to launch uncrewed spacecraft. It’s called the Atlas V. The Atlas V is smaller and wider than the Saturn V. NASA is also developing a new rocket called the Space Launch System (SLS). The agency plans to use the SLS for missions with a human crew. These missions will travel to deep space. For that, the SLS needs to be more powerful than the Saturn V.

In recent years, private companies have also been pursuing space exploration. SpaceX has been one of the most successful. It was founded in 2002. The company’s Falcon 9 rocket regularly sends cargo to the International Space Station. This space science lab orbits 250 miles above Earth. SpaceX successfully tested the Falcon Heavy rocket in February. Now the company is updating the design with the data it got from the test. It also has plans for another rocket called the Big Falcon. It can carry a payload more than twice as heavy as the Falcon Heavy’s. SpaceX hopes this rocket will be able to get people and all their cargo to Mars and back.

Historically, rocket launches have been expensive and wasteful—costing between $50 million and$100 million! Why such a high price tag? One reason is that most rockets and boosters are discarded after one use.

To cut down on costs, SpaceX has designed its rockets to be reusable, like an airplane. They use a technique called propulsive landing, where the rocket’s engines fire to slow it down for a gentle touchdown. This ensures the rocket can return to its landing pad and be used again, saving tens of millions of dollars per launch. During the Falcon Heavy test launch in February, SpaceX was able to recover two out of the three rocket boosters. Reusable rockets also ensure that future astronauts can return to Earth. “In order to get to Mars and back, you have to have these rockets and spaceships be reusable,” says Shotwell.

Now that SpaceX has proved its reusable rocket technology works, it is working with NASA on some even tougher engineering challenges. The biggest problem is figuring out how to make sure that humans can survive using only their cargo and the Red Planet’s resources. Engineers at SpaceX are confident that they will solve that problem soon. They have plans to send their first mission to Mars in 2022. “Getting to Mars will definitely happen in our lifetime,” says Shotwell.

Historically, rocket launches have been expensive and wasteful. They cost between $50 million and$100 million! Why such a high price tag? One reason is that most rockets and boosters are discarded after one use.

SpaceX has found a way to reduce that cost. The company designed its rockets to be reusable, like an airplane. They use a technique called propulsive landing. That means the rocket’s engines fire again on the way down. This slows the rockets down for a gentle touchdown instead of a crash. The rocket can then be hauled back to its landing pad and used again. That saves tens of millions of dollars per launch. The Falcon Heavy test launch in February used three rocket boosters. Two of them landed successfully back on Earth. Reusable rockets would also help future astronauts return to Earth. “In order to get to Mars and back, you have to have these rockets and spaceships be reusable,” says Shotwell.

SpaceX has proved that its reusable rocket technology works. Now it is working with NASA on some even tougher engineering challenges. The biggest problem is figuring out how humans can survive on Mars. They’ll need to use only their cargo and resources that are already on the Red Planet. Engineers at SpaceX are confident that they will solve that problem soon. They plan to send their first mission to Mars in 2022. “Getting to Mars will definitely happen in our lifetime,” Shotwell says.

Use the information in the sidebar and in the chart below to compare the dimensions of select rockets with familiar objects. Round answers to the nearest whole number. Record your work and answers on our answer sheet.

Use the information in the sidebar and in the chart below to compare the dimensions of select rockets with familiar objects. Round answers to the nearest whole number. Record your work and answers on our answer sheet.

YoungID/Getty Images (car); iStock/Getty Images (whale, girl); Nikada/E+/Getty Images (statue of liberty); Kate Francis (pool illustration)

Which rocket is closest in height to the Statue of Liberty?

Which rocket is closest in height to the Statue of Liberty?

How many blue whales are equal to the total mass of an Atlas V rocket?

How many blue whales are equal to the total mass of an Atlas V rocket?

Would a class of 35 seventh-graders standing on top of each other’s head be taller than or shorter than the space shuttle? Explain your answer.

Would a class of 35 seventh-graders standing on top of each other’s head be taller than or shorter than the space shuttle? Explain your answer.

A. About how many compact cars could the Falcon Heavy rocket take as a payload to Mars?

A. About how many compact cars could the Falcon Heavy rocket take as a payload to Mars?

B. About how many compact cars could the Falcon Heavy rocket take as a payload to low Earth orbit?

B. About how many compact cars could the Falcon Heavy rocket take as a payload to low Earth orbit?

C. How many more cars can the Falcon Heavy take to low Earth orbit than to Mars? Why do you think this is so?

C. How many more cars can the Falcon Heavy take to low Earth orbit than to Mars? Why do you think this is so?

A. It would take the fuel volume of how many Falcon 9 rockets to fill an Olympic-sized swimming pool?

A. It would take the fuel volume of how many Falcon 9 rockets to fill an Olympic-sized swimming pool?

B. Which rocket’s fuel supply would overflow an Olympic-sized swimming pool? By how much?

B. Which rocket’s fuel supply would overflow an Olympic-sized swimming pool? By how much?

C. What trend do you notice about the volume of each rocket’s fuel supply compared to its total mass? What could explain this trend?

C. What trend do you notice about the volume of each rocket’s fuel supply compared to its total mass? What could explain this trend?