Asteroid Redirect Mission facts for kids
The Asteroid Redirect Mission (ARM) was a space mission that NASA planned in 2013. It was also known as the Asteroid Retrieval and Utilization (ARU) mission. This mission was later cancelled in 2017.
The plan was for a robotic spacecraft, called the Asteroid Retrieval Robotic Mission (ARRM), to meet a large near-Earth asteroid. It would use robotic arms with special grippers to pick up a 4-meter (about 13-foot) boulder from the asteroid.
The spacecraft would study the asteroid and show how we could protect Earth from space rocks. After that, it would bring the boulder to a stable orbit around the Moon. There, robots and future astronauts could study it more closely. This part of the mission was called the Asteroid Redirect Crewed Mission (ARCM).
If the mission had continued, it would have launched in December 2021. It also aimed to test new technologies for future human trips into deep space. This included advanced ion thrusters, which are very efficient engines.
However, the proposed NASA budget in 2018 called for ARM to be cancelled. NASA officially stopped funding it in April 2017 and announced its "close out" in June 2017. Even though the mission was cancelled, important technologies developed for ARM are still being used. The ion thruster propulsion system, for example, is still being worked on.
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What Were the Mission Goals?
The main goal of the Asteroid Redirect Mission was to develop ways to explore deep space. These skills were needed to prepare for a human mission to Mars and other places in our Solar System. This was part of NASA's "Journey to Mars" plan.
Preparing for Mars Missions
Sending supplies to Mars ahead of astronauts can save a lot of money. It can also make the mission safer. This is especially true if advanced solar electric propulsion (like ion engines) are used. These engines are very fuel-efficient.
The technologies and designs from the Asteroid Redirect Robotic Mission (ARRM) would be used for future missions. The ARRM spacecraft itself could even be reused. It was designed so that the asteroid-grabbing part could be removed or replaced. This would leave a useful "space tug" in orbit around the Moon.
Exploring Deep Space Safely
Both the robotic and crewed parts of the mission would show that we can operate beyond Earth's orbit. Yet, they would still be close enough for a quick return to Earth if needed. The Moon's Distant Retrograde Orbit (DRO) is a good spot for this. It's like a hub for leaving or returning to the Earth-Moon system.
This orbit would be even more useful if an Exploration Augmentation Module (EAM) was brought along. This module would allow astronauts to stay longer. When astronauts return from Mars, they could save a lot of fuel by stopping in DRO. From there, they could transfer to a parked Orion spacecraft to return to Earth.
Other Important Goals
Another goal was to develop the technology to bring a small near-Earth asteroid into orbit around the Moon. The asteroid itself was seen as an extra benefit. Astronauts on the Orion EM-5 or EM-6 ARCM mission in 2026 would then be able to study it.
The mission also aimed to test ways to protect Earth from dangerous asteroids. This is called planetary defense. One idea was to grab an asteroid and move it directly. Another was to use a "gravity tractor" technique. This involves collecting a boulder from the asteroid to make it heavier. This extra mass would then help a spacecraft's gravity gently pull the asteroid off course.
The mission would also test advanced solar electric propulsion (ion engines) and fast laser communication in space. These new technologies are important for sending large amounts of cargo, living spaces, and fuel to Mars before humans arrive.
How the Spacecraft Would Work
The spacecraft would land on a large asteroid. Robotic arms with grippers would grab and hold a boulder from the asteroid's surface. The grippers would dig in to get a strong hold. A built-in drill would help anchor the boulder securely. Once the boulder was held tight, the spacecraft's legs would push off. This would give it an initial lift without needing to use its engines.
Powerful Engines
The spacecraft would be powered by advanced solar electric propulsion (SEP). This might include a Hall effect thruster, which is a type of Ion thruster. Large, efficient solar panels would provide 50 kilowatts of electricity for the engines.
These advanced ion engines use only 10% of the fuel that regular chemical rockets need. They can also handle three times more power and are 50% more efficient than older designs. They use the Hall effect, which creates a gentle push. But they can fire continuously for many years, pushing a large spacecraft to very high speeds.
Hall effect thrusters work by trapping electrons in a magnetic field. These electrons then ionize (electrically charge) the xenon gas fuel. The magnetic field also creates an electric field that speeds up these charged ions. This creates a plume of plasma that pushes the spacecraft forward. The spacecraft was designed to weigh 5.5 tons without fuel and could carry up to 13 tons of xenon propellant.
Each thruster would have a power level of 30 to 50 kilowatts. Several thrusters could be combined to make an SEP spacecraft even more powerful. This type of engine can be scaled up to 300 kilowatts or more. Companies like Northrop Grumman are working on this technology with Sandia National Laboratories and the University of Michigan. NASA Glenn Research Center helps manage this project.
Even when it reaches its destination, the SEP system could provide power. This would keep systems running or prevent fuel from boiling away before astronauts arrive. However, current solar-electric propulsion systems that are ready for flight only produce 1 to 5 kilowatts. A cargo mission to Mars would need about 100 kilowatts, and a crewed flight would need 150 to 300 kilowatts.
When Was It Planned?
The mission was first planned for 2017, then 2020, and finally for December 2021. However, it was officially cancelled in April 2017. The spacecraft would have launched on a Delta IV Heavy, SLS, or Falcon Heavy rocket. The boulder was expected to arrive in lunar orbit by late 2025.
Which Asteroid Was the Target?
As of late 2017, about 16,950 near-Earth asteroids were known. These are asteroids that come close to Earth. NASA had not yet picked a final target for ARM. But for planning and practice, they used the asteroid (341843) 2008 EV5 as an example. The spacecraft would have picked up a single 4-meter (13-foot) boulder from it. Other possible asteroids included Itokawa, Bennu, and Ryugu.
The type of boulder the mission would have captured was carbon-rich (called a carbonaceous boulder). It would have been no bigger than 6 meters (20 feet) across and weighed up to 20 tons. This size of rock is too small to harm Earth because it would burn up in our atmosphere. Moving the asteroid's mass to a distant orbit around the Moon would ensure it could not hit Earth. It would also keep it in a stable orbit for future studies.
Mission History
In July 1980, NASA Administrator Robert Frosch spoke to Congress about bringing an asteroid to Earth. However, he said it wasn't possible at that time.
In 2012, the Keck Institute for Space Studies looked into the idea of the ARU mission. This study did not include any human missions to an asteroid. The Glenn Research Center estimated the mission would cost about $2.6 billion. In 2014, $105 million was funded to develop the idea further. NASA officials stressed that ARM was just one step in their long-term plans for a human mission to Mars.
Two main ways to retrieve a small asteroid were studied: Option A and Option B. Option A would use a large 50-foot (15-meter) capture bag. This bag could hold a small asteroid up to 8 meters (26 feet) wide and weighing up to 500 tons. Option B was chosen in March 2015. This plan involved the spacecraft landing on a large asteroid. It would then use robotic arms to lift a boulder up to 4 meters (13 feet) wide from the surface. This boulder would then be transported and placed into lunar orbit. This option was seen as more helpful for developing future technologies. These include meeting spacecraft in space, docking automatically, landing, collecting samples, planetary defense, mining, and servicing spacecraft.
Some people criticized the part of the mission that involved astronauts retrieving asteroid samples from Moon orbit (Orion EM-3). They argued that thousands of meteorites have already been studied. They also said that the technology to retrieve one boulder doesn't directly help develop a crewed mission to Mars. Despite suggestions from the NASA Advisory Council in April 2015 to cancel ARM, the plans were not changed. The Council suggested NASA should instead focus on developing solar electric propulsion for a round-trip flight to Mars.
In January 2016, NASA's Jet Propulsion Laboratory (JPL) gave contracts for designing a solar electric propulsion spacecraft. The robotic ARRM mission would have been the first part of ARM. Companies like Lockheed Martin Space Systems, Boeing Phantom Works, Orbital ATK, and Space Systems/Loral won these contracts.
In May 2016, ASI (the Italian Space Agency) agreed to study the mission together and possibly participate.
Under the 2018 NASA budget proposed by the Trump administration in March 2017, this mission was cancelled. On June 13, 2017, NASA announced the "closeout phase" after the funding was stopped. NASA has emphasized that key technologies from ARM are still being developed. Especially the solar electric propulsion system, which would have been on the robotic mission, will now be used for the Lunar Gateway as the Power and Propulsion Element.
See also
In Spanish: Misión de redirección de asteroides para niños
Images for kids
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The 'Option A' was to deploy a container large enough to capture a free-flying asteroid up to 8 meters (26 feet) in diameter.
