Donald Yeomans

With the recent discovery of the amino acid glycine in the comet dust samples returned to Earth by the Stardust spacecraft, it is becoming a bit more clear how life may have originated on Earth. Water is a well-known ingredient in both comets and living organisms, and now it appears that amino acids are also common to comets and living organisms. Amino acids are used to make proteins, which are chains of amino acids, and proteins are vital in maintaining the cell structures of plants and animals.

Amino acids had previously been identified in meteorite samples, and these samples are thought to be the surviving fragments from asteroid collisions with the Earth. So now it appears that both comets and asteroids in the Earth’s neighborhood, the so-called near-Earth objects, delivered some of the building blocks of life to the early Earth.

Asteroid Eros - Mosaic of Northern Hemisphere. Image Credit: NASA/JPL/JHUAPL
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Impacts of comets and asteroids with the early Earth likely laid down the veneer of carbon-based molecules and water that allowed life to form. Once life did form, subsequent collisions of these near-Earth objects frustrated the evolution of all but the most adaptable species. The dinosaurs checked out some 65 million years ago because of an impact by a six mile-wide comet or asteroid off the coast of the Yucatan peninsula. Fortunately, the small, furry mammalian creatures at the time were far more adaptable and survived this impact event. Thus, present day mammals like us may owe our origin and current position atop Earth’s food chain to these near-Earth objects, one of which took out our dinosaur competitors some 65 million years ago.

Today, most of the attention directed toward near-Earth objects has to do with the potential future threat they can pose to life on Earth. However, the recent Stardust discovery of a cometary amino acid reminds us that, were it not for past impacts by these objects, the Earth may not have received the necessary building blocks of life, and humans may not have evolved to our current preeminent position on Earth. While giving thanks to these near-Earth objects, we still need to make sure we find the potentially hazardous comets and asteroids early enough so we don’t go the way of the dinosaurs.

For more information on near-Earth objects, see: http://www.jpl.nasa.gov/asteroidwatch/index.cfm

Jane Houston Jones

If you’re like me, you may have received an e-mail this summer telling you go outside on August 27 and look up in the sky. The e-mail, most likely forwarded to you by a friend or relative, promises that Mars will look as big as the moon on that date, and that no one will ever see this view again. Hmmm, it looks like the same e-mail I received last summer and the summer before that, too. In fact this same e-mail has been circulating since 2003, but with a few important omissions from the original announcement.

I’m Jane Jones, an amateur astronomer and outreach specialist for the Cassini mission at Saturn, and I’m here to set the record straight on when and how you can actually see Mars this month.

1. How did the “Mars in August” e-mail get started in the first place?

In 2003, when Mars neared opposition — its closest approach to Earth in its 22-month orbit around the sun — it was less than 56 million kilometers (less than 35 million miles) away. This was the closest it had been in over 50,000 years. The e-mail that circulated back then said that Mars, when viewed through a telescope magnified 75 times, would look as large as the moon does with the unaided eye. Even back in 2003, to the unaided eye, Mars looked like a reddish star in the sky to our eyes, and through a backyard telescope it looked like a small disc with some dark markings and maybe a hint of its polar ice cap. Without magnification, it never looked as large as the moon, even back in 2003!

2. Can the moon and Mars ever look the same size?

No. The moon is one-quarter the size of Earth and is relatively close — only about 384,000 kilometers (about 239, 000 miles) away. On the other hand, Mars is one-half the size of Earth and it orbits the sun 1-1/2 times farther out than Earth’s orbit. The closest it ever gets to Earth is at opposition every 26 months. The next opposition is in January 2010.

A sky chart shows where Mars will be in August. Image credit: NASA/JPL.
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At that time, Mars will be 98 million kilometers (61 million miles) from Earth, almost twice as far as in 2003. So from that distance, Mars could never look the same as our moon.

3. Is Mars visible in August 2009?

Mars rises in the east at about 1:30 a.m. this month and is best seen closer to dawn. It is a ruddy star-like object about the same brightness as the brightest stars you’ll see. Look for Mars above the constellation Orion in the pre-dawn sky. The moon is close by on the mornings of August 15 and 16. The brighter object in the sky below and left of Mars is Venus!

4. Can I see Mars and the moon at the same time this month?

If you get up before sunrise on August 15 and 16, you can see the waning crescent moon pass by Mars. The next two mornings, August 17 and 18, you’ll see the moon pass by Venus, which is the bright object below Mars in the morning sky. This will be a great time to compare the sizes of the moon and Mars for yourself!

5. Will the “Mars in August” e-mail return next year?

Most certainly! But next year, you’ll be armed with facts, and perhaps you will have looked at the red planet for yourself and will know what to expect. And you will know exactly where to put that email. In the trash!

Bjorn Lambrigtsen

JPL scientist Bjorn Lambrigtsen goes on hurricane watch every June. He is part of a large effort to track hurricanes and understand what powers them. Lambrigtsen specializes in the field of microwave instruments, which fly aboard research planes and spacecraft, penetrating through thick clouds to see the heart of a hurricane.

While scientists are adept at predicting where these powerful storms will hit land, there are crucial aspects they still need to wrench from these potentially killer storms.

Here are thoughts and factoids from Lambrigtsen in the field of hurricane research.

1. Pinpointing the moment of birth

Hurricane Gustav moved along the southern side of Jamaica on Aug. 29, 2008. Image credit: NASA MODIS Rapid Response

Most Atlantic hurricanes start as a collection of thunderstorms off the coast of Africa. These storm clusters move across the Atlantic, ending up in the Caribbean, Gulf of Mexico or Central America. While only one in 10 of these clusters evolve into hurricanes, scientists do not yet know what triggers this powerful transformation.

Pinpointing a hurricane’s origin will be a major goal of a joint field campaign in 2010 between NASA and the National Oceanic and Atmospheric Administration (NOAA).

2. Predicting intensity

Another focus of next year’s research campaign will be learning how to better predict a storm’s intensity. It is difficult for emergency personnel and the public to gauge storm preparations when they don’t know if the storm will be mild or one with tremendous force. NASA’s uncrewed Global Hawk will be added to the 2010 research armada. This drone airplane, which can fly for 30 straight hours, will provide an unprecedented long-duration view of hurricanes in action, giving a window into what fuels storm intensity.

3. Deadly force raining down

Think about a hurricane. You imagine high, gusting winds and pounding waves. However, one of the deadliest hurricanes in recent history was one that parked itself over Central America in October 1998 and dumped torrential rain. Even with diminished winds, rain from Hurricane Mitch reached a rate of more than 4 inches per hour. This caused catastrophic floods and landslides throughout the region.

4. Replenishing “spring”

Even though hurricanes can wreak havoc, they also carry out the important task of replenishing the freshwater supply along the Florida and southeastern U.S. coast and Gulf of Mexico. The freshwater deposited is good for the fish and the ecological environment.

5. One size doesn’t fit all

Hurricanes come in a huge a variety of sizes. Massive ones can cover the entire Gulf of Mexico (about 1,000 miles across), while others are just as deadly at only 100 miles across. This is a mystery scientists are still trying to unravel.

NASA and NOAA conduct joint field campaigns to study hurricanes. The agencies use research planes to fly through and above hurricanes, and scientists collect data from NASA spacecraft that fly overhead. NOAA, along with its National Hurricane Center, is the U.S. government agency tasked with hurricane forecasting.

For more information on how NASA and JPL study hurricanes, go to www.nasa.gov/hurricane and http://tropicalcyclone.jpl.nasa.gov