Scientists consider space, how it affects earth
Iowa State University Professor Bong Wie hopes that the work he is doing today can prevent an incident that happened near here -74 million years ago.
That’s when an asteroid, an estimated 1.2 miles in diameter, smashed into the earth near present-day Manson leaving a crater about 24 miles in diameter now buried under 90 feet of soil.
“You can’t see it,” Wie joked. “That’s why it’s not that popular.”
Wie was one of three speakers Friday afternoon during a symposium at the Iowa Academy of Science’s 126th annual meeting being held at Iowa Central Community College.
Wie works with the ISU Asteroid Deflection Center. The research it is doing was started after the 2013 Chelyanski event that left 1,500 people injured and damaged 7,200 buildings when a 17-meter meteor exploded at an altitude of about 12 miles with the force of 30 Hiroshima-sized bombs.
“It was a totally unexpected event,” he said.
The project he’s helping with is called ATLAS – Asteroid Terrestrial-Impact Last Alert System. It consists of two low-powered telescopes that will scan the sky for objects on a collision course with earth.
How much warning depends on the size of the object. That also determines what, if anything, can be done about it. He said that the ability to deflect, destroy or evacuate is still in the development phase, but it will ultimately involve using nuclear bombs to blow up incoming objects.
That will require some serious work.
“Nuclear weapons are not designed to work in space,” he said.
Nor are they designed as impact weapons. The bomb would follow a space capsule to the asteroid’s surface. The capsule would impact the rock creating a crater in which the bomb would explode. It would all happen in a millisecond or two, he said.
While an asteroid that gets blown to bits by a nuclear bomb close to the earth would still hit, it would do so in a lot of small pieces rather than one large one.
“You have a choice,” he said. “Get hit by a city-killer-sized asteroid or have 100 smaller impacts.”
Donald Gurnett’s work at the University of Iowa deals with something we have sent into space, not something coming from it.
He’s worked on projects still sending back information from the Voyager 1 Interstellar Mission that officially became the first object to leave the solar system and reach interstellar space on Sept. 12, 2013.
It was launched on Sept. 5, 1977.
Gurnett studies the exact location of that barrier. He said it’s defined by where the solar wind stops and the plasma of interstellar space begins.
He understands it may be a difficult concept to grasp.
“If it’s too complex,” he joked, “come take my plasma physics class.”
Getting the data back from the Voyager 1 probe is no small feat in itself. He said picking up the weak signal requires a 70-meter and a 34-meter antenna working together.
The plutonium-powered craft is also losing juice.
“By 2020 we will not have enough power to operate all the instruments,” he said. “By 2025 we won’t have enough to operate the transmitter. That will be the end of the mission.”
So just how far out is the Voyager craft? That figure increases every second, but it now takes the radio transmissions 17.5 hours to reach earth.
“We’re almost out there a light day,” he said.
Joshua Sebree’s work is a little closer to home – by space standards. At the University of Northern Iowa, he studies the atmosphere of Titan, Saturn’s largest moon, which also is the furthest from it.
He said it’s covered with some rather unpleasant smog.
“Imagine the worst day in Beijing,” he said. “That’s the whole planet.”
The atmosphere is a little denser than earth’s.
“You would feel like you were about 5 feet underwater,” he said.
And forget about taking a big gulp of refreshing Titan air.
“It’s 97 degrees Kelvin,” he said.
That may sound toasty, but on the Fahrenheit scale it’s minus 285.07 degrees. There is no liquid water, although precipitation exists.
“It rains methane,” he said. “There are lakes full of liquid methane and ethane. It’s a rich hydrocarbon soup.”
Sebree has been able to replicate the complex chemical processes at work on Titan in his lab, including producing a substance of which he believes large dunes on the surface are composed.
“It’s a clay-like organic goo,” he said.