Tag: National Aeronautics and Space Administration

NASA announces Mars 2020 rover payload

Image: NASA/JPL-Caltech
Image: NASA/JPL-Caltech

On July 31, NASA announced the roster of instruments that would hitch a ride on board its planned rover to the red planet in 2020. John Grunsfeld, astronaut and associate administrator for the NASA Science Mission Directorate, Headquarters, Washington, said the instruments would extend the search for life in Mars’s past, conduct geological and environmental investigations to that end, equip it to cache martian material for future explorers to bring back to Earth, and conduct studies that will help the agency land humans on Mars.

Michael Meyer, lead scientist with the Mars Exploration Program, detailed the instruments that would go on board the rover. Going from mast to the body and then to the arm, he laid out seven major instruments developed by over 50 institutions from around the world. Meyer said their guiding principle is that no measurement will be done by only one instrument, that whether it was the chemistry, mineralogy or geology that was being studied, the instruments would overlap, provide multiple perspectives on readings and help constrain error.

The mast would hold the cameras called Mastcam Z and SuperCam. Mastcam Z will be a binocular with zoom capable of rapidly developing terrain models. According to Meyer, the Curiosity rover is slowed down by having to reassess its surroundings once every 10 m for rocky outcrops or surfaces that might threaten it. Mastcam Z will be equipped to plot out greater distances at once. SuperCam, with a significant contribution from France, is the 2020 rover’s counterpart of Curiosity’s ChemCam, which ionizes martian soil samples and studies the missions for their mineral composition. Additionally, SuperCam will also boast a visible and near-infrared spectrometer to make observations at those wavelengths. It will be a remote-sensing instrument to help make important decisions about soil composition and the presence of organic material.

 

The rover’s body will hold instruments called MOXIE, MEDA and RIMFAX, and MOXIE takes the cake for innovation. It will attempt to extract carbon dioxide from Mars’s atmosphere, break it down and produce pure oxygen. Meyer said that the oxygen could comprise rocket fuel for future human explorers. However, Bill Gerstenmaier, associate administrator for the NASA Human Exploration and Operations Directorate, implied that that claim was exaggerated, saying scientists would first study at what rate and efficiency oxygen could be produced and if its presence could pose any risks.

MEDA, from Spain, would be the on-board weather station, providing data on atmospheric conditions. RIMFAX will give the 2020 rover the ability to ‘see’ below Mars’s surface. It’s a ground-penetrating radar that can go up to 0.5 km downward and and help connect outcrops on the surface with geological formations beneath them.

Two instruments will ride the rover’s arm: PIXL, the interfacing instrument that tells scientists where the action is at smaller scales based on samples the other instruments have analysed, and SHERLOC, a deep-UV instrument adept at studying organic material.

Even though all instruments will be capable of performing multiple analyses, the flow of ‘work’ according to Meyer is roughly ordered as: mast instruments look around the landscape for interesting things, mineralogies that might be best at preserving biosignatures and recent outcrops; arm instruments study samples at finer scales and look at features that might’ve attracted microbial growth in the past; then, based on data, scientists decide whether they want to drill and cache that sample for posterity.

Mars-2020 is being envisaged as Curiosity’s next step with bifurcated goals: landing humans on Mars by studying local geological and radiological properties, and looking for life in its past and helping conduct more sophisticated studies on soil samples.

Like with MOXIE, Meyer explained that the caching of samples would also be proof-of-concept: NASA definitely intends to cache samples but isn’t yet sure what it will do with them. Grunsfeld quoted Carl Sagan to say that if they did find signs of life, they’d also have to muster extraordinary evidence to back up their claim – evidence that could only be established if the samples were subjected to tougher tests on Earth. Meyer concluded by adding that the one-metric-ton rover would be landed on Mars the same way Curiosity was – with the sky-crane.

One of the hottest planets cold enough for ice

This article, as written by me, appeared in The Hindu on December 6, 2012.

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Mercury, the innermost planet in the Solar System, is like a small rock orbiting the Sun, continuously assaulted by the star’s heat and radiation. It would have to be the last place to look for water at.

However, observations of NASA’s MESSENGER spacecraft indicate that Mercury seems to harbour enough water-ice to fill 20 billion Olympic skating rinks.

On November 29, during a televised press conference, NASA announced that data recorded since March 2011 by MESSENGER’s on-board instruments hinted that large quantities of water ice were stowed in the shadows of craters around the planet’s North Pole.

Unlike Earth, Mercury’s rotation is not tilted about an axis. This means areas around the planet’s poles that are not sufficiently tilted toward the sun will remain cold for long periods of time.

This characteristic allows the insides of polar craters to maintain low temperatures for millions of years, and capable of storing water-ice. But then, where is the water coming from?

Bright spots were identified by MESSENGER’s infrared laser fired from orbit into nine craters around the North Pole. The spots lined up perfectly with a thermal model of ultra-cold spots on the planet that would never be warmer than -170 degrees centigrade.

These icy spots are surrounded by darker terrain that receives a bit more sunlight and heat. Measurements by the neutron spectrometer aboard MESSENGER suggest that this darker area is a layer of material about 10 cm thick that lies on top of more ice, insulating it.

Dr. David Paige, a planetary scientist at the University of California, Los Angeles, and lead author of one of three papers that indicate the craters might contain ice, said, “The darker material around the bright spots may be made up of complex hydrocarbons expelled from comet or asteroid impacts.” Such compounds must not be mistaken as signs of life since they can be produced by simple chemical reactions as well.

The water-ice could also have been derived from crashing comets, the study by Paige and his team concludes.

Finding water on the system’s hottest planet changes the way scientists perceive the Solar System’s formation.

Indeed, in the mid-1990s, strong radar signals were fired from the US Arecibo radar dish in Puerto Rico, aimed at Mercury’s poles. Bright radar reflections were seen from crater-like regions, which was indicative of water-ice.

“However, other substances might also reflect radar in a similar manner, like sulfur or cold silicate materials,” says David J. Lawrence, a physicist from the Johns Hopkins University Applied Physics Laboratory and lead author of the neutron spectrometer study.

Lawrence and his team observed particles called neutrons bouncing and ricocheting off the planet via a spectrometer aboard MESSENGER. As high-energy cosmic rays from outer space bombarded into atoms on the planet, debris of particles, including neutrons, was the result.

However, hydrogen atoms in the path of neutrons can halt the speeding particles almost completely as both weigh about the same. Since water molecules contain two hydrogen atoms each, areas that could contain water-ice will show a suppressed count of neutrons in the space above them.

Because scientists have been living with the idea of Mercury containing water for the last couple decades, the find by MESSENGER is not likely to be revolutionary. However, it bolsters an exciting idea.

As Lawrence says, “I think this discovery reinforces the reality that water is able to find its way to many places in the Solar System, and this fact should be kept in mind when studying the system and its history.”