NASA is looking for a 25-foot, 500-ton needle in a haystack. The “needle” is an errant space rock originally from the asteroid belt, and the “haystack” is the interplanetary space of our solar system.
There is a heightened priority at NASA to find small asteroids that pass near Earth. In February, the danger to civilization became apparent when an air burst from a 50-foot meteor over Chelyabinsk, Russia, injured more than 1,500 people as windows were shattered by the resulting shock wave.
Sky surveys, such as the University of Arizona’s Spacewatch, have been under way for more than a decade searching for large asteroids that travel near Earth. Potentially the most dangerous among these near-Earth asteroids are the “Earth-crossers,” asteroids that intersect Earth’s orbit. NASA’s new strategy for understanding these hazardous solar system bodies is to capture a small near-Earth asteroid and tow it closer for direct study.
Using the working title the “Asteroid Capture and Return” mission, the itinerary calls for NASA to locate a small asteroid that is moving in the general direction of Earth, snag it with an “inflatable, asteroid capture bag” and haul it into a new, stable orbit. Since the asteroid is already moving toward Earth, it becomes less formidable to redirect its flight path.
“In its modified orbit, about a quarter million miles from the Earth, there would not be any chance of the asteroid colliding with our planet.”
Astronauts would then travel in the new Orion spacecraft — currently under development — to this repositioned space object by journeying farther from Earth than humans have ever gone. Once at the asteroid, the astronauts would explore its surface and retrieve rock samples for laboratory examination back on Earth.
More than science
The idea of exploring an asteroid is not new. More than 100 years ago, the father of space flight, Konstantin Tsiolkovskii, discussed in his book “The Exploration of Cosmic Space by Means of Reaction Devices” how asteroids could be mined for their metal content. This concept of utilizing the natural resources of a celestial body is called “space exploitation” and private space-mining ventures have praised NASA’s asteroid mission plan because it will help identify asteroids that are useful for robotic mining.
NASA believes that an asteroid capture and return mission warrants serious investigation at this time because the technology necessary to make such a mission possible is becoming available.
NASA points out that there are three key elements to the asteroid capture scenario. First, observatories now have the ability to find and identify a sufficient number of small near-Earth asteroids to choose from for a mission. Second, sufficiently powerful rocket engines are under development that could transport a captured asteroid to lunar space. Finally, the time frame to return humans to the vicinity of the moon is compatible with the time when an asteroid could be delivered there.
Mission time line
An Atlas rocket would launch the capture spacecraft into low Earth orbit. This spacecraft would then take about two years to spiral out to the moon under its own solar-generated power. Once at the moon, it would use the moon’s gravity to fling it toward the selected asteroid, a cruise estimated to take less than two years.
After arriving at the asteroid, the spacecraft would spend 90 days orbiting it. During this time, the robotic craft would deploy its capture bag, snag the asteroid and stop its rotation. It would take at least another two years to get the asteroid back to the moon, depending on the mass of the space rock.
According to NASA, the time line for the Asteroid Capture and Return mission starts by selecting an asteroid for capture in 2016. The spacecraft would ensnare it in 2019 and the first astronauts would be sent to visit the space rock in 2021.
The original feasibility study for the asteroid retrieval idea was an authoritative report by the Keck Institute for Space Studies that pegs the mission cost at $2.6 billion, a cost, NASA says, that is far less than sending a human mission to a near-Earth asteroid in its original orbit.
Space enthusiasts say that this mission will reignite public interest in manned space flight and jump-start the asteroid mining business. Others in the space community say that NASA should return astronauts to the moon before embarking on another major space objective.
Although asteroids are generally too faint for humans to see without using a telescope, what is not faint is the close gathering of three celestial objects low in the western twilight. This trio should be bright enough to detect with eyes alone but, depending on sky conditions, binoculars might be necessary.
Throughout May, the planets Mercury, Venus and Jupiter have all been moving toward the same region of the twilight sky. Tonight (May 26), all three planets can fit in the same field-of-view of ordinary binoculars. This is the tightest gathering of the three, and this planetary get-together will slowly widen as the days pass. Especially be sure to look before 9 p.m. on June 9 and 10 when a thin lunar crescent joins the group.
Jupiter will continue to get lower each evening and will disappear from the evening sky by mid-June. Mercury, however, will first come into view at a greater height every evening through the first week of June. After that, it will appear lower every evening until it is gone from sight by the end of the month. Venus will just continue to get higher in the western sky and will be with us for the rest of the year.
With all that planetary activity in the west, don’t forget to turn to the south and see Saturn. It’s shining at us from the stars of Virgo, just to the left of this constellation’s brightest luminary, the whitish-blue star Spica.