10 Things: Mars Helicopter

When our next Mars rover lands on the Red Planet in
2021, it will deliver a groundbreaking technology demonstration: the
first helicopter to ever fly on a planetary body other than Earth. This
Mars Helicopter will demonstrate the first controlled, powered,
sustained flight on another world. It could also pave the way for future
missions that guide rovers and gather science data and images at
locations previously inaccessible on Mars. This exciting new technology
could change the way we explore Mars.

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1. Its body is small, but its blades are mighty.

One of the biggest engineering challenges is getting the
Mars Helicopter’s blades just right. They need to push enough air
downward to receive an upward force that allows for thrust and
controlled flight — a big concern on a planet where the atmosphere is
only one percent as dense as Earth’s. “No helicopter has flown in those
flight conditions – equivalent to 100,000 feet (30,000 meters) on
Earth,” said Bob Balaram, chief engineer for the project at our Jet
Propulsion Laboratory.

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2. It has to fly in really thin Martian air.

To compensate for Mars’ thin atmosphere, the blades must
spin much faster than on an Earth helicopter, and the blade size
relative to the weight of the helicopter has to be larger too. The Mars
Helicopter’s rotors measure 4 feet wide (about 1.2 meters) long, tip to
tip. At 2,800 rotations per minute, it will spin about 10 times faster
than an Earth helicopter.

At the same time, the blades shouldn’t flap around too much, as
the helicopter’s design team discovered during testing. Their solution:
make the blades more rigid. “Our blades are much stiffer than any
terrestrial helicopter’s would need to be,” Balaram said.  

The body, meanwhile, is tiny — about the size of a softball. In
total, the helicopter will weigh just under 4 pounds (1.8 kilograms).

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3. It will make up to five flights on Mars.

Over a 30-day period on Mars, the helicopter will attempt
up to five flights, each time going farther than the last. The
helicopter will fly up to 90 seconds at a time, at heights of up to 10
to 15 feet (3 to 5 meters). Engineers will learn a lot about flying a
helicopter on Mars with each flight, since it’s never been done before!

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4. The Mars Helicopter team has already completed groundbreaking tests.

Because a helicopter has never visited Mars before, the
Mars Helicopter team has worked hard to figure out how to predict the
helicopter’s performance on the Red Planet. “We had to invent how to do
planetary helicopter testing on Earth,” said Joe Melko, deputy chief
engineer of Mars Helicopter, based at JPL.

The team, led by JPL and including members from JPL,
AeroVironment Inc.,  Ames Research Center, and Langley Research
Center, has designed, built and tested a series of test vehicles.

In 2016, the team flew a full-scale prototype test model
of the helicopter in the 25-foot (7.6-meter) space simulator at JPL. The
chamber simulated the low pressure of the Martian atmosphere. More
recently, in 2018, the team built a fully autonomous helicopter designed
to operate on Mars, and successfully flew it in the 25-foot chamber in
Mars-like atmospheric density.

Engineers have also exercised the rotors of a test
helicopter in a cold chamber to simulate the low temperatures of Mars at
night. In addition, they have taken design steps to deal with Mars-like
radiation conditions. They have also tested the helicopter’s landing
gear on Mars-like terrain. More tests are coming to see how it performs
with Mars-like winds and other conditions.

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5. The camera is as good as your cell phone camera.

The helicopter’s first priority is successfully flying on
Mars, so engineering information takes priority. An added bonus is its
camera. The Mars Helicopter has the ability to take color photos with a
13-megapixel camera — the same type commonly found in smart phones
today. Engineers will attempt to take plenty of good pictures.

6. It’s battery-powered, but the battery is rechargeable.

The helicopter requires 360 watts of power for each
second it hovers in the Martian atmosphere – equivalent to the power
required by six regular lightbulbs. But it isn’t out of luck when its
lithium-ion batteries run dry. A solar array on the helicopter will
recharge the batteries, making it a self-sufficient system as long as
there is adequate sunlight. Most of the energy will be used to keep the
helicopter warm, since nighttime temperatures on Mars plummet to around
minus 130 degrees Fahrenheit (minus 90 Celsius). During daytime flights,
temperatures may rise to a much warmer minus 13 to minus 58 degrees
Fahrenheit to (minus 25 to minus 50 degrees Celsius) — still chilly by
Earth standards. The solar panel makes an average of 3 watts of power
continuously during a 12-hour Martian day.

7. The helicopter will be carried to Mars under the belly of the rover.

Somewhere between 60 to 90 Martian days (or sols) after
the Mars 2020 rover lands, the helicopter will be deployed from the
underside of the rover. Mars Helicopter Delivery System on the rover
will rotate the helicopter down from the rover and release it onto the
ground. The rover will then drive away to a safe distance.

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8. The helicopter will talk to the rover.

The Mars 2020 rover will act as a telecommunication
relay, receiving commands from engineers back on Earth and relaying them
to the helicopter. The helicopter will then send images and information
about its own performance to the rover, which will send them back to
Earth. The rover will also take measurements of wind and atmospheric
data to help flight controllers on Earth.

9. It has to fly by itself, with some help.

Radio signals take time to travel to Mars — between four
and 21 minutes, depending on where Earth and Mars are in their orbits —
so instantaneous communication with the helicopter will be impossible.
That means flight controllers can’t use a joystick to fly it in real
time, like a video game. Instead, they need to send commands to the
helicopter in advance, and the little flying robot will follow through.
Autonomous systems will allow the helicopter to look at the ground,
analyze the terrain to look how fast it’s moving, and land on its own.

10. It could pave the way for future missions.

A future Mars helicopter could scout points of interest,
help scientists and engineers select new locations and plan driving
routes for a rover. Larger standalone helicopters could carry science
payloads to investigate multiple sites at Mars. Future helicopters could
also be used to fly to places on Mars that rovers cannot reach, such as
cliffs or walls of craters. They could even assist with human
exploration one day. Says Balaram: “Someday, if we send astronauts,
these could be the eyes of the astronauts across Mars.”

Read the full version of this week’s ‘10 Things to Know’ article on the web HERE.

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