Measuring Mars Anomalies: The MAVEN Magnetometer

When you navigate with a compass you can orient yourself thanks to Earth's global magnetic field. 

But on Mars, if you were to walk around with a compass it would haphazardly point from one anomaly to another, because the Red Planet does not possess a global magnetosphere. 

Scientists think that this lack of a protective magnetic field may have allowed the solar wind to strip away the Martian atmosphere over billions of years, and now NASA's MAVEN spacecraft will study this process in detail with its pair of ring core fluxgate magnetometers. 

To download the original video please go here. Credit: NASA/Goddard/Dan Gallagher

When the Mars Atmosphere and Volatile Evolution (MAVEN) mission begins its journey to the Red Planet in 2013, it will carry a sensitive magnetic-field instrument built and tested by a team at NASA's Goddard Space Flight Center in Greenbelt, Md.

Scheduled for launch in late 2013, MAVEN will be the first mission devoted to understanding the Martian upper atmosphere.

The goal of MAVEN is to determine the history of the loss of atmospheric gases to space through time, providing answers about Mars' climate evolution.

By measuring the current rate of escape to space and gathering enough information about the relevant processes, scientists will be able to infer how the planet's atmosphere evolved.

The trip to Mars takes 10 months, and MAVEN will go into orbit around the planet in September 2014.

The Goddard-built MAVEN magnetometer will be a sensitive tool investigating what remains of the Red Planet's magnetic "shield." It will play a key role in studying the planet's atmosphere and interactions with solar wind, helping answer the question of why a planet once thought to have an abundance of liquid water became a frozen desert.

"The MAVEN magnetometer is key to unraveling the nature of the interactions between the solar wind and the planet," said MAVEN principal investigator Bruce Jakosky from University of Colorado at Boulder's Laboratory for Atmospheric and Space Physics (CU/LASP).

The magnetometer will measure the planet's magnetic field through a series of coils, each containing a magnetic ring wrapped around a metal core. The sensors, known as "flux gates," are driven in and out of saturation by applied magnetic fields.

If there is no ambient magnetic field, the sensors remain balanced. If there is an ambient field present, the sensors will go into saturation more quickly in one direction than the other. It's the imbalance that reveals the presence of an ambient field.

"A magnetometer is like an electronic compass," said Jack Connerney, mission co-investigator at Goddard. "But we measure the strength, as well as the direction, of the magnetic field."

The importance of studying the planet's magnetic field is rooted in the theory that Mars lost its global magnetic field billions of years ago, allowing the solar wind to strip the atmosphere and dry out the planet.

Unlike Earth's global magnetic field, which surrounds the entire planet, Mars only has patches of magnetic field left in its crust. This can create pockets of atmosphere that are protected against solar wind and others that are left vulnerable.

By measuring sections of the planet's magnetic field, the magnetometer could help scientists create a bigger picture of the planet's overall atmosphere.

"The magnetometer helps us see where the atmosphere is protected by mini-magnetospheres and where it's open to solar wind," Connerney said. "We can study the solar wind impact and how efficient it is at stripping the atmosphere."

New Method: Measuring Super-Massive Black Holes

Understanding the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies is one of the most active research areas in astrophysics.

In a letter to Nature, an international team of astronomers, including Marc Sarzi from the University of Hertfordshire, report the exciting discovery of a new way to measure the mass of super-massive black holes in galaxies.

By measuring the speed with which carbon monoxide molecules orbit around such black holes, this new research opens the possibility of making these measurements in many more galaxies than ever before.

Supermassive black holes and galaxies
A black hole is an object so dense that its gravity prevents anything, including light, from escaping.

Supermassive black holes can be as much as a million to a billion times more massive than our Sun, and it is believed that most, if not all galaxies including the Milky Way, contain supermassive black holes at their centres - suggesting that the evolution of black holes and galaxies is very tightly linked.

Understanding the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies is one of the most active research areas in astrophysics.

Intriguing link
Marc Sarzi, from the University of Hertfordshire's Centre for Astrophysics Research, said: "There is an intriguing link between the mass of supermassive black holes and the mass of their host galaxies, but this is based only on quite a small number of estimates.

Until now only three methods were used to measure the mass of supermassive black holes and these only work on relatively nearby galaxies.

With this new technique, we have been able to show that we can measure black hole masses much further out in the universe, which will help understanding the role that supermassive black holes played during the formation of galaxies."

Super-sharp telescope images
Tim Davis, lead author of the paper, from ESA's European Southern Observatory (ESO), commented:

"We observed carbon monoxide molecules in the galaxy we were monitoring using the Combined Array for Research in Millimeter-wave Astronomy (CARMA) telescope.

With its super-sharp images we were able to zoom right into the centre of the galaxy and observe the gas whizzing around the black hole. This gas moves at a speed which is determined by the black-hole's mass, and the distance from it. By measuring the velocity of the gas at each position, we can measure the mass of the black hole."

The CARMA observations were rather challenging, but the new ALMA (Atacama Large Millimeter/submillimeter Array) telescope currently being built in Chile will allow this new technique to be applied more routinely to hundreds of galaxies in the nearby Universe.