Astronomers Diagnose Kepler to Salvage Microlensing Project
Well this is a bummer. The Kepler spacecraft has gone into emergency mode, which puts it into minimal operations. That means, no science. The mission engineers have priority access on the Deep Space Network so they can communicate with the spacecraft. This lets them diagnose the problems that appeared to have started just before the spacecraft was to orient itself toward the center of the Milky Way to look for microlensing events.
Why Study Microlensing?
As an exoplanet passes in front of a more distant star, its gravity causes the trajectory of the starlight to bend, and in some cases results in a brief brightening of the background star as seen by a telescope. The artistic concept illustrates this effect. This phenomenon of gravitational microlensing enables scientists to search for exoplanets that are too distant and dark to detect any other way. Credits: NASA Ames/JPL-Caltech/T. Pyle
The Kepler mission was originally launched to search out planets, and in particular, Earth-like worlds, looking for changes in brightness of a star as worlds orbited around it. In its “second lifetime”, Kepler, on a mission called K2, is working on surveying stars to find more planets that lie in distant orbits from their stars. Previously, it found many worlds much closer to their stars.
In particular, the spacecraft’s sensors are being used to detect an effect called “microlensing”. That’s where astronomers look for flickers in light from distant stars that are caused by the influence of a star’s gravity. The gravitational effect warps the light, or ‘bends’ it as it passes by. This bending effect can make gravity act as a lens. It concentrates light from a distant object, just as a magnifying glass can focus the light from the Sun.
The warping effect of a massive object, such as a planet, on light that passes between a telescope and a distant background star helps reveal the planet. That’s what the spacecraft is looking for as part of its K2 mission.
This new survey is giving new life to the spacecraft. And, that’s why it’s so important to figure out why it has gone into safe mode and return it to normal operations. Stay tuned!
This is what the planet Mars must have looked like 4 billion years ago, according to a new study published this week. The poles were in a different position and precipitation in a south tropical band resulted in river networks. At the same time, active volcanoes enabled the Tharsis dome to grow, tilting the Martian surface after fluvial activity ended (3.5 billion years ago).
Staying on the topic of Mars this week, there’s a look at a new way of looking at the Red Planet’s ancient past. We all know that Mars’s history has been an enigma for scientist, even as they learn more about it through robotic explorations. Still, after more than 50 years of space missions to Mars, we have questions. Where’s the water? Where WAS the water? When did it flow? What made it flow? Was there a cataclysmic event that changed the face of the planet forever? As it turns out, maybe there’s an idea that helps answer all those questions.
A group of French scientists blames a gigantic structure called the Tharsis Bulge for some of Mars’s most impressive mysteries. They say that Mars experienced a curious “tilt” between 3 and 3.5 billion years ago. It wasn’t an axial tilt, but a shift of the outer layers of the planet (the mantle and crust). They somehow “slipped” around the inner core. That introduced huge changes to the surface that make Mars what it looks like today.
What Caused The Mars Tilt Catastrophe?
A band of scientists using the sciences of geomorphology, geophysics and climatology used observational data from current Mars to explain the Mars of the past. (The team was based at Géosciences Paris Sud (CNRS/Université Paris-Sud), Géosciences Environnement Toulouse (CNRS/Université Toulouse III) and the Laboratoire de Météorrologie Dynamique (CNRS/École polytechnique/UPMC/ENS), together with a researcher from the Lunar and Planetary Laboratory (University of Arizona, U.S.)
Here’s the sequence as the group described it: the gigantic Tharsis volcanic dome began to form nearly 4 billion years ago. It was first located at 20 degrees north latitude (about the location of Hawaii on Earth). It grew taller and wider from repeated volcanic eruptions. Eventually the flows formed a 5,000-kilometer-diameter plateau. (That’s about 3,400 miles, or about the width of North America). This huge volcanic dome was about 12 kilometers deep (about 7.5 miles, or taller than Mt. Everest on Earth), and was extremely massive. Think billions of billions of tons of volcanic deposits distributed in a relatively small part of the planet. That huge mass of rock unbalanced the crust and caused it to shift around. This “Tharsis bulge” migrated to the equator where it lies today, and that shift moved the polar crust, too.
So, if such a shift happened, and the geological evidence may well show that it did, it rearranged the Martian topography. The same theoretical study that speculates on that shift, also shows that Martian rivers containing water from precipitation and ice melt could have flowed at the same time as the formation of the Tharsis bulge. That would make sense, given that climate models from the Laboratoire de Météorologie Dynamique showed a colder, wetter climate with a denser atmosphere than we see today. That would have allowed ice accumulations (such as those suspected to have existed at around latitude 25°S, for example) to melt in response to volcanism, and for water from both the melt and precipitation to flow and create the dry river beds we see today.
So, What Happened to Mars?
Put all these studies together, and you get a slightly different history of Mars of about 3.5 billion years ago. You have a period of liquid water stability that allowed the formation of river valleys on Mars at the same time as the volcanic activity of the Tharsis dome. In fact, the building of the dome may have caused the formation of the river valleys due to volcanic melting of ice. Then, for some reason, the fluvial activity ended some 3.5 billion years ago, and the great tilt triggered by Tharsis’s great heft and influence on the planet took place. That shifted the dome and the poles, and changed the look of the Red Planet.
Since this theory is based on observed geology of Mars, the new geological explanation should be a useful factor as planetary scientists speculate about early Mars and the possibility of life that may have existed in an ancient ocean. I would imagine that these ideas would also help guide future Mars explorers when they get to the Red Planet to study its rocks, plains, mountains, and former oceans, rivers, and lakebeds.
