StarDate

No one knows for sure what living on Mars might be like. The planet is bitterly cold and almost completely dry. The atmosphere is less than one percent as thick as Earth’s. And Mars is a long, long way from home. So scientists and engineers are trying to figure it all out by creating Mars-like conditions here on Earth.

So far, they’ve built habitats in labs, on a volcano in Hawaii, on an island in the Arctic, and even under the sea. Astronauts and others spend weeks or months inside those enclosures. The tests offer ways to check out equipment, procedures, and how “marsnauts” might handle the isolation.

One project began last June, at Johnson Space Center in Houston. Known as Crew Health and Performance Exploration Analog 1, it’s scheduled to last for a full year. Four volunteers are living in a simulated Mars habitat. Daily life includes a delay of up to 22 minutes in contacts with anyone on the outside — the same lag that would be experienced on Mars. The crew is growing crops, maintaining the habitat, and even doing “marswalks” in a special Martian “sandbox.”

Another Mars habitat also opened last year. Space Analog for Moon and Mars is next to Biosphere 2, near Tucson. It includes living quarters, labs, and a Mars-gravity simulator. Up to four researchers can spend weeks or months inside the sealed lab, checking out equipment or doing other work — work that people might someday tackle on Mars.

Script by Damond Benningfield

A couple of dozen missions have studied Mars. And they’ve told us a lot about the history of the Red Planet. We know that it was much warmer and wetter in the distant past. And there might have been pockets of warm and wet conditions much more recently. Those conditions could have supported microscopic life.

Future missions may target some of those locations. To know which sites might be most promising, scientists are looking at Mars-like locations here on Earth. They’re studying spots that are cold and dry, with chemistry that matches interesting Martian locations. That generally means high deserts with lots of ice.

One example is in the Andes Mountains of Chile. Scientists have studied a couple of patches of small lagoons. They’re frozen during winter, but thaw out in the summer. And they’re so high up that they get a heavy dose of ultraviolet light from the Sun — just as Mars does.

The lagoon regions contain rock layers that are much like those deposited on early Earth — and like many regions seen on Mars. The lagoons contain a variety of microscopic organisms that are like the oldest life on Earth. The similarity to some spots on Mars makes those locations more likely targets for future missions — spots that might preserve evidence of ancient Martian life.

Mars is climbing into the dawn sky. It looks like a moderately bright star, low in the east-southeast at first light.

More about Mars-on-Earth tomorrow.

Script by Damond Benningfield

Mars is working hard to climb into view in the dawn sky. But for much of the country, it’s not quite there yet. It’s low in the east-southeast as twilight brightens the sky. It looks like a moderately bright star. Mars is fairly easy to spot from the southern latitudes of the U.S., but harder to see as you go farther north. In fact, it’s almost impossible to see from places like Minneapolis or Seattle.

The planet is struggling because of the time of year. Mars passed behind the Sun in November, moving from the evening sky to the morning sky. Now, it’s more than 30 degrees away from the Sun — more than three times the width of your fist held at arm’s length.

At this time of year, though, Mars and the other planets in the early morning sky rise at a shallow angle. Instead of popping straight up, they move sideways along the horizon. So Mars is still quite low as the sky gets brighter. And while Mars rises a bit earlier each day, so does the Sun — it chases the planet into view.

But as the months roll by, the angle at which Mars rises will improve. And it will continue to creep farther from the Sun. So by late spring or early summer, the Red Planet will be easy to spot not only in the twilight, but well before. At the same time, it’ll shine a tad brighter than it does now — offering a beautiful view for early risers across the entire country.

We’ll talk about some Mars-like places here on Earth tomorrow.

Script by Damond Benningfield

Most astronomical observatories are up high. That gives them a clearer view of the heavens.

But some go deep. They’re submerged in the oceans, or buried deep in the ice at the south pole. They use the water, ice, and the solid Earth to screen out most energy and particles. That occasionally allows them to catch a neutrino — a “ghostly” particle that’s raced far across the universe.

Huge numbers of neutrinos are produced by the Sun and other stars. The most powerful appear to come from some of the most violent places in the universe — like the regions around giant black holes. So neutrinos can reveal details about what’s happening in those locales.

But neutrinos zip through space, stars, and planets. They almost never interact with other matter. The only way to “catch” one is to look for a rare flash of light created when a neutrino does hit something.

Those flashes are overpowered by radiation and particles from other sources. So astronomers have built — or are in the process of building — giant observatories in the ice at the south pole, and deep under water. They consist of hundreds or thousands of light detectors spread across a wide volume. The water and ice block out most sources of interference.

Astronomers in China are working on the biggest of all. It would cover several miles of the South China Sea, and contain almost 25,000 detectors — a giant, wet telescope for catching ghostly particles.

Script by Damond Benningfield

The Moon passes by the star Spica the next couple of nights. The brightest star of Virgo is below the Moon as they climb into good view this evening, but closer above the Moon tomorrow night.

One prominent lunar feature is the Sea of Crises. It’s a dark round patch near the top of the lunar disk as the Moon climbs up the sky. It’s the target site for a robotic lander scheduled for launch later this year.

Known as Ghost 1, the lander will carry a suite of experiments. Some of them will study the “regolith” — the layer of dust and small rocks at the surface. One experiment could drill as much as six feet into that layer to measure heat coming from the Moon’s interior. That’ll reveal more about how the Moon is put together.

Another experiment is a vacuum cleaner — Lunar PlanetVac. It will suck up a few ounces of material, and separate it by the sizes of the particles. Dust grains will go into one bin, slightly larger particles into another, and pebbles into yet another. Unlike the “scoops” on robotic arms that’ve been used on other missions, PlanetVac can be moved around the spacecraft, allowing it to suck up material from wherever scientists want.

The experiment is designed mainly to test the technology. Such a system might be used on future missions that will analyze different-sized particles, or sort them for return to Earth — learning about the Moon and other worlds with a vacuum cleaner.

Script by Damond Benningfield

Anyone standing on the Earth-facing hemisphere of the Moon tonight would see a partial solar eclipse, with Earth covering part of the Sun’s disk. From here on Earth, however, all we’ll see is a penumbral lunar eclipse. The eclipse is so faint that few will notice a difference — the full Moon will have only a slight shading.

A penumbral eclipse occurs when the alignment of the Sun, Earth, and Moon isn’t perfect. The Moon catches only the outer part of Earth’s shadow, the penumbra, which isn’t very dark. Tonight, you might notice a light shading across the southern limb of the Moon at the eclipse’s peak, at 1:14 a.m. Central Time.

Nature has a way of balancing the books, though. Eclipses occur in “seasons,” with two or three eclipses — lunar and solar — in about five weeks. Individual eclipses are separated by two weeks. When one eclipse in the season is poor, the other usually is much better.

That’s certainly the case with this set. Tonight’s eclipse is the first of two in the current season. The second eclipse, on April 8th, is a total solar eclipse. The path of totality will slice from Texas to Maine. Skies along that path will turn dark, and the Sun’s faint outer atmosphere will encircle the Moon with a silvery glow. Most of the U.S. outside that path will see a partial eclipse.

So challenge yourself to see the penumbral eclipse tonight, then treat yourself to the easy-to-see solar eclipse two weeks later.

Script by Damond Benningfield

The star that marks the tip of the lion’s tail appears to be a loner. It doesn’t have a companion star. And so far, it doesn’t appear to have any planets, either. But it does have the raw materials for making planets. And one or more worlds could have taken shape from those building blocks.

Denebola is the second-brightest star of Leo, the lion. It’s to the upper left of the almost-full Moon this evening, by about the width of your fist held at arm’s length.

Denebola is 36 light-years away — just down the astronomical block. It’s a little less than twice the size and mass of the Sun, and thousands of degrees hotter than the Sun. And it spins so fast that it bulges outward at its equator.

The star also is much younger than the Sun. Just how young isn’t certain. Estimates range from about 50 million to 400 million years. And that has a bearing on the planet situation.

If the star is near the upper end of that age range, then its planet-building days probably are over. But near the lower end, it could still be giving birth to planets.

Denebola is encircled by wide, massive bands of dust — material that can clump together to make planets. So some of that debris could be coming together now.

There are some gaps in those dust bands, though. Such voids could have been cleared out by the gravity of orbiting planets. So the search for worlds around the lion’s tail continues.

Tomorrow: the poor half of an eclipse season.

Script by Damond Benningfield

Only two planets in our solar system are moonless: Mercury and Venus, the planets closest to the Sun. But 50 years ago this month, it looked like Mercury might have to drop off the list — but only for a while.

The excitement began as Mariner 10 sped toward the planet, in 1974.

Mariner was the first spacecraft to visit Mercury. Before then, astronomers were limited to views through telescopes. But Mercury is so close to the Sun that it could be hard to see a moon in a tight orbit around the planet.

On March 27th, just two days before Mariner’s closest approach, one of its instruments showed a jump in the ultraviolet energy coming from the planet. Three days later, as Mariner flew away from Mercury, the source of energy seemed to pull away from the planet, as though it were a separate object — like a moon.

Mariner’s cameras didn’t see a moon, though. So scientists quickly realized that they were seeing not a moon, but a distant star. The star was so hot that it was producing a lot of ultraviolet energy, which Mariner picked up.

Mercury probably is moonless because it formed so close to the Sun. Solar heat and radiation made it impossible for Mercury to hold on to the material that might have formed a moon.

Mercury is in the evening sky the next few days. It’ll stand farthest from the Sun for its current evening appearance on Sunday. It looks like a bright star, quite low in the west not long after sunset.

Script by Damond Benningfield

It’s been more than half a century since the final Apollo mission left the Moon. But scientists are still learning from it. A few years ago, they started examining samples from Apollo 17 that hadn’t been touched before — a project that’s ongoing. They’re also analyzing observations made by instruments left on the Moon. That work says that lots of little tremors rattle the landing site.

Astronauts Gene Cernan and Jack Schmidt set up a quartet of special microphones to “listen” for moonquakes. The gear worked for about five years. Using techniques from AI, a recent study found more than 3200 quakes in just eight months of data.

Almost 400 of the tremors came from the direction of the base of the lunar module, Challenger. They were most common around sunrise and sunset, when the temperature changed in a hurry. Researchers say the tiny quakes probably were triggered by the lander as it heated and cooled, expanding and contracting in the process.

They’re still analyzing the other quakes. But many of them may have been triggered as minerals in the lunar dust expanded and contracted as well — tiny tremors that scientists are just learning about, decades after they took place.

The Moon is sliding through the constellation Leo right now. Tonight, the lion’s bright heart, the star Regulus, is close to the lower right of the Moon at nightfall, and closer below the Moon as they set, in the wee hours of the morning.

Script by Damond Benningfield

It may be a cliche, but it’s true: If at first you don’t succeed, try, try again. That’s certainly the case for the scientists hunting for dark matter. They’ve conducted many big experiments over the past few decades. So far, though, they haven’t found a thing. So the hunt is going smaller — looking for extremely light particles known as axions.

Astronomers see the effects of dark matter all across the universe. The dark matter itself emits no energy, but its gravity pulls on the visible matter around it. Measuring the mass of that gravitational effect shows that there’s about five times more dark matter than normal matter.

For a long time, the leading theory of dark matter said it was made of WIMPs — weakly interacting massive particles. Such particles would be much heavier than the protons and neutrons that make up normal matter. Physicists have built detectors to look for WIMPs. The detectors are far underground, so other types of particles are filtered out. But the experiments have come up empty.

So in the past few years, the search has begun turning toward axions. If they exist, they’d be billions of times less massive than electrons, which are by far the puniest parts of atoms. As with WIMPs, axion detectors are far underground. The University of Washington has been operating one for years. And a group in Europe is just getting cranked up. So the search for most of the mass in the universe is going small.

Script by Damond Benningfield