Sometime in the mid to late 2020s, NASA plans to send a manned mission to explore a near-Earth asteroid. Here an astronaut uses rope or cable to climb about a small asteroid. Credit: NASA/JPL
NHATS? The letters hold a mouthful but let’s have a go at it: Near-Earth Object Human Space Flight Accessible Targets Study. It’s NASA’s short list of near-Earth asteroids (NEAs) that would take a robotic or manned expedition a minimum of fuel and time to reach, explore and then return to Earth. The current Presidential administration directed NASA to include NEAs as destinations for future human exploration with plans for a mission in the mid-2020s.
The goal of the program is to identify asteroids that are the most easily accessible. Important factors include:
* An orbit similar to Earth’s that’s nearly circular (comets with cigar-shaped orbits need not apply!)
* An orbit that is nearly flat (low inclination). Extra fuel and time are required to put a spacecraft into a tipped orbit.
* Minimum change in the velocity or speed of the spacecraft to conserve fuel and time. Fuel is needed to leave Earth orbit, enter orbit around the asteroid, depart the asteroid and to slow reentry on return to Earth.
* Planned for missions would last 450 days or less, meaning the asteroid must be within about 9.3 million miles (37 lunar distances) of Earth.
In all the time spent coming and going, astronauts would spend just 8 days exploring the asteroid. NEAs make ideal targets – they’re diverse and extremely ancient, having formed in the early history of the solar system, and much closer than and less demanding time and fuel-wise than say, a mission to Mars.
The huge Arecibo radio telescope is built into a large sinkhole in Puerto Rico. It’s contains the largest curved focusing dish on Earth and often used to study close-approaching asteroids. Credit: H. Schweiker/WIYN and NOAO/AURA/NSF
As plans are being made, observatories like the big 1000-foot radio dish at Arecibo in Puerto Rico are gearing up to track likely candidates to further nail down their orbits, sizes and physical characteristics.
Radio telescopes ping an asteroid with radio waves to take a rough picture of its shape and surface by measuring the returned signal. Surveying the NHATS list of potential targets, I see that 2012 MD7, estimated at between 88 and 394 feet wide, will be in Arecibo’s crosshairs this month. The asteroid does not pose a threat to Earth.
Asteroid 2005 YU55, captured by reflected “radio light” in 2011 by the Arecibo Observatory, is about 1300 feet across. Credit: NASA
Let’s hope the U.S. has the desire and determination to set aside a few tax dollars toward a manned asteroid exploration. What a stimulus it could become for both the space industry and science.
In honor of the fine work Bruce Willis did in the 1998 movie Armageddon, we might consider nicknaming the first asteroid we set foot upon “Bruce”.
