Farewell, Opportunity: rover dies, but its hugely successful Mars mission is helping us design the next one

Opportunity in Endurance Crater. NASA

Andrew Coates, UCL
NASA’s Opportunity rover on Mars has been officially pronounced dead. Its amazingly successful mission lasted nearly 15 years, well beyond its initial three-month goal. Opportunity provided the first proof that water once existed on Mars and shaped its surface, a crucial piece of knowledge informing both current and future missions.
Opportunity landed on the red planet on January 25, 2004, and was last heard from on June 10, 2018, when a huge dust storm reduced light levels there significantly. This prevented the rover from using its solar panels to charge its batteries. The solar panels had already started to degrade due to the longer than expected mission, and the low light levels and the build up of dust may have caused its ultimate demise.
The rover has driven over 45km on the Martian surface despite being designed to travel for just 1km – an interplanetary record. Lasting almost 60 times its expected lifetime, it is an incredible achievement for space exploration. The mission is therefore helping scientists design new rover missions including NASA’s Mars 2020 rover and the ExoMars 2020 rover that I work on, recently named “Rosalind Franklin” after the DNA pioneer.

Stunning science

The science from the Mars exploration rovers Spirit and Opportunity has been simply groundbreaking. For Opportunity, it started with landing by chance in a 22-metre wide crater called “Eagle” on an otherwise mainly flat plain – a space exploration “hole in one”. Immediately after landing, it spotted a layered rocky outcrop, similar to sedimentary rocks on Earth but never before seen on Mars. And because it was mobile, it could actually examine the rock composition directly after leaving the landing platform.
By illuminating the rocks with radioactive sources, the rover discovered the expected iron (effectively rust) that makes Mars’ surface reddish brown, along with other metals such as nickel and zinc. But it also found more volatile elements like bromine, chlorine and sulphur, which indicated that these rocks may have reacted with ancient water. Most excitingly, it detected the mineral “jarosite”, which is often seen in the outflow of acidic water from mining sites on Earth. This provided direct evidence that acidic water had been involved in the formation of Mars’ rocks 3.8-4 billion years ago.
The rover then moved out of the Eagle crater onto the flat, surrounding plain. In the first weeks, it discovered “blueberries” – millimetre-sized spheres of the mineral hematite. Although this could have formed due to volcanism or meteor impacts, analysis revealed that it most likely formed in water.
Opportunity later visited the spectacular Victoria crater, which is 750 metres in diameter and some 70 metres deep, with dunes on the crater floor. Remarkably, the rover and its tracks were imaged from orbit by NASA’s Mars Reconnaissance Orbiter near the crater rim. There was more hematite here, too, showing that this may have formed underground in water, before being brought to the surface when the crater formed via an impact.

Opportunity at Victoria Crater spotted from orbit. NASA/JPL/University of Arizona

Its next destination was the Endeavour crater, which is 22km in diameter and 300 metres deep. Here it also made a major discovery –- there were clays near the crater rim, which would have required fresh, abundant and non-acidic water for their formation. This was the first indication that Mars was actually habitable 3.8-4 billion years ago, containing drinkable as well as acidic water.
These main science results are key to our scientific exploration of Mars today. The question of habitability is being pursued further by the NASA Curiosity mission, which has already found evidence of a large, ancient lake on early Mars that contained organic matter by drilling into the mudstones that remain.

Digging deeper

Thanks to Opportunity, upcoming missions will look closer at the spots were ancient water flowed. NASA’s Mars 2020 rover will gather samples from Jezero crater, a location where orbiters have detected signs of an ancient river delta. These samples may be returned to Earth by a future international mission. Analysis in labs on Earth may ultimately answer the question of whether there is or ever was life on Mars, if we haven’t already.

Opportunity outside Endeavour crater. NASA/JPL-Caltech/Cornell/Arizona State Univ. › Full image and caption

Meanwhile, our Rosalind Franklin rover, a collaboration between the European Space Agency and Russia, is due for launch in 2020. It will land in March, 2021, at Oxia Planum, an elevated plain. Here, there are also signs of prolonged exposure to ancient water, clays and a river outflow channel.
Rosalind the rover will pick up where Opportunity and Curiosity left off by examining a key, unexplored dimension on Mars – depth. We will drill down to two metres below the surface of Mars for the first time, much further than Curiosity’s five centimetres. This is enough to take us far enough below the harsh surface environment of Mars – with cold temperatures, a thin carbon dioxide atmosphere and high levels of harmful radiation – to see if anything lives there.
We will decide where to drill using a number of instruments, including the PanCam instrument which I lead. Samples will be vaporised and put into a drawer for analysis by three instruments which will look for markers of life – such as complex carbonates.
One of the key aspects of Opportunity’s success was the teamwork between its science and engineering teams. This is definitely something that will be implemented on upcoming rovers. Many members of the Mars 2020 team, and some on the ExoMars team, have direct experience from Opportunity which will be invaluable as we learn how to operate our rovers on the planet.
Another interesting legacy of Opportunity is that we we don’t have to worry too much about Martian dust, except during exceptional global storms. Opportunity showed that that during the rest of the time, accumulating dust blows away naturally in the wind – helped by the movement of the rover over the ground causing vibration. It was a surprise that Opportunity lasted so long, and it certainly blazed a trail for us.
Rosalind Franklin has the best chance of any currently planned mission for detecting biomarkers and even perhaps evidence for past or present life on Mars. But we are building on the shoulders of giants, like the Opportunity Rover. #ThanksOppy indeed!
Andrew Coates, Professor of Physics, Deputy Director (Solar System) at the Mullard Space Science Laboratory, UCL
This article is republished from The Conversation under a Creative Commons license. Read the original article.

How Ancient Cultures Explained Comets and Meteors

An artist’s rendition of 2016 WF9 as it passes Jupiter’s orbit inbound toward the sun.

Credits: NASA/JPL-Caltech

Eve MacDonald, Cardiff University
Comets and meteors have fascinated the human race since they were first spotted in the night sky. But without science and space exploration to aid understanding of what these chunks of rock and ice are, ancient cultures often turned to myth and legend to explain them.
The Greeks and Romans believed that the appearance of comets, meteors and meteor showers were portentous. They were signs that something good or bad had happened or was about to happen. The arrival of a comet could herald the birth of a great figure, and some people have even argued that the star in the sky which the Persian Magi followed to Bethlehem to see the newborn Jesus was actually a comet.
In the spring of 44BC, a comet that appeared was interpreted as a sign of the deification of Julius Caesar, following his murder. Caesar’s adopted son Octavian (soon to be the Emperor Augustus) made much of the comet, which burned in the sky during the funerary games held for Caesar. This portentous event was frequently celebrated in the ancient sources. In his epic poem, the Aeneid, Virgil describes how “a star appeared in the daytime, and Augustus persuaded people to believe it was Caesar”.

Augustus celebrated the comet and the deification of his father on coins (it did help to be the son of a god when trying to rule the Roman Empire), and many examples survive today.

Meteor showers

The Roman historian Cassius Dio referred to “comet stars” occurring in August 30BC. These are mentioned as among the portents witnessed after the death of the Egyptian queen Cleopatra. Experts are not entirely sure what it means when Dio uses the plural term “comet stars”, but some have connected this recorded event to the annual Perseid meteor shower.
Though it retains an ancient Greek name, we now know that the arrival of the Perseid meteor shower every August is actually the Earth’s orbit passing through debris from the Swift-Tuttle comet.


The meteor shower is named for the Perseidai (Περσείδαι), who were the sons of the ancient Greek hero Perseus. Perseus was a legendary figure with a fine family pedigree – he was the mythical son of Zeus and Argive princess Danaë (she of the golden rain). Perseus earned himself a constellation after a number of epic adventures across the Mediterranean and Near East that included the frequently illustrated murder of the Gorgon sister, Medusa.
Another of Perseus’s celebrated acts was the rescue of the princess Andromeda. Abandoned by her parents to placate a sea monster, the princess was found by Perseus on a rock by the ocean. He married her and they went on to have seven sons and two daughters. Sky watchers believed that the constellation Perseus, located just beside Andromeda in the night sky, was the origin of the shooting stars they could see every summer, and so the name Perseid stuck.

Tears and other traditions

In Christian tradition the Perseid meteor shower has long been connected to the martyrdom of St Lawrence. Laurentius was a deacon in the early church at Rome, martyred in the year 258AD, during the persecutions of the Emperor Valerian. The martyrdom supposedly took place on August 10, when the meteor shower was at its height, and so the shooting stars are equated to the saint’s tears.
Detailed records of astronomical events and sky watching can be found in historical texts from the Far East too. Ancient and medieval records from China, Korea and Japan have all been found to contain detailed accounts of meteor showers. Sometimes these different sources can be correlated, which has allowed astronomers to track, for example, the impact of Halley’s comet on ancient societies both east and west. These sources have also been used to find the first recorded observation of the Perseid meteor shower as a specific event, in Han Chinese records of 36AD.
Though the myths and legends may make one think that ancient civilisations had little scientific understanding of what meteors, comets and asteroids could be, this couldn’t be farther from the truth. The early astronomers of the Near East, those who created the Babylonian and Egyptian calendars, and astronomical data were – by far – the most advanced in antiquity. And a recent study of ancient cuneiform texts has proven that the Babylonian ability to track comets, planetary movements and sky events as far back as the first millennium BC involved a much more complex geometry than had been previously believed.
Eve MacDonald, Lecturer in Ancient History, Cardiff University
This article is republished from The Conversation under a Creative Commons license. Read the original article.


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Now that TESS is Operational, Astronomers Estimate it’ll Find 14,000 Planets. 10 Could Be Earthlike Worlds in a Sunlike Star’s Habitable Zone

A new study from Thomas Barclay of NASA and the University of Maryland, Joshua Pepper at Lehigh University, and Elisa Quintana of NASA, has predicted TESS’s results. Barclay, Pepper, and Quintana ran their simulation 300 times to come up with their predicted yield. There’s a lot of detail in their results related to the type of star the planets orbit, the different observation mode used to detect which planets, and how it all relates to follow-up observations. But in a more brief form, here’s what the three researchers think TESS will find during its planned two-year mission:

• 14,000 total exoplanets
• 2100 of them will be smaller than 4 Earth radius (4R), 280 of those smaller than 2R
• 70 habitable planets orbiting red dwarf stars, 9 of them smaller than 2R
• 10 Earth-like worlds less than 2R which could be in the habitable zone of a star like our Sun

That’s a pretty exciting haul. 14,000 exoplanets, of which 10 could be Earth-like worlds in the habitable zone of a star like the Sun. It doesn’t mean that’s what TESS will find, but it should be a good approximation, and an intriguing one. Especially since, unlike Kepler, TESS’s exoplanets are prime targets for further observation and characterization.

Most exoplanets orbit red dwarf stars because they’re the most plentiful stars. This is an artist’s illustration of what the TRAPPIST-1 system might look like from a vantage point near planet TRAPPIST-1f (at right). Credits: NASA/JPL-Caltech

This isn’t the first yield simulation for TESS. But this one is done with real rather than simulated stellar population, so it should be more accurate. Another yield simulation from 2015 can be viewed here, and one from 2017 here.

The simulation yields show us that we’re likely to find Earth-like planets in habitable zones. Most of them will be orbiting red dwarfs, but a small number should be around Sun-like stars. This is what everybody wants to know.

But maybe more importantly, these simulations show us that TESS will meet its mission goal: to detect an abundance of planets smaller than Neptune that can be examined in follow up studies to determine their masses and atmospheric makeups.

In both cases, TESS is on track to deliver some solid results.

It was written by Evan Gough and originally published on Universe Today.

Will China's moon landing launch a new space race?

What will China discover on the far side of the moon? BeeBright/Shutterstock.com

Wendy Whitman Cobb, Cameron University
China became the third country to land a probe on the Moon on Jan. 2. But, more importantly, it became the first to do so on the far side of the moon, often called the dark side. The ability to land on the far side of the moon is a technical achievement in its own right, one that neither Russia nor the United States has pursued.
The probe, Chang’e 4, is symbolic of the growth of the Chinese space program and the capabilities it has amassed, significant for China and for relations among the great power across the world. The consequences extend to the United States as the Trump administration considers global competition in space as well as the future of space exploration.
One of the major drivers of U.S. space policy historically has been competition with Russia particularly in the context of the Cold War. If China’s successes continue to accumulate, could the United States find itself engaged in a new space race?

China’s achievements in space

Like the U.S. and Russia, the People’s Republic of China first engaged in space activities during the development of ballistic missiles in the 1950s. While they did benefit from some assistance from the Soviet Union, China developed its space program largely on its own. Far from smooth sailing, Mao Zedong’s Great Leap Forward and the Cultural Revolution disrupted this early programs.
The Chinese launched their first satellite in 1970. Following this, an early human spaceflight program was put on hold to focus on commercial satellite applications. In 1978, Deng Xiaoping articulated China’s space policy noting that, as a developing country, China would not take part in a space race. Instead, China’s space efforts have focused on both launch vehicles and satellites - including communications, remote sensing and meteorology.
This does not mean the Chinese were not concerned about the global power space efforts can generate. In 1992, they concluded that having a space station would be a major sign and source of prestige in the 21st century. As such, a human spaceflight program was re-established leading to the development of the Shenzhou spacecraft. The first Chinese astronaut, or taikonaut, Yang Liwei, was launched in 2003. In total, six Shenzhou missions have carried 12 taikonauts into low earth orbit, including two to China’s first space station, Tiangong-1.
In addition to human spaceflight, the Chinese have also undertaken scientific missions like Chang’e 4. Its first lunar mission, Chang’e 1, orbited the moon in October 2007 and a rover landed on the moon in 2013. China’s future plans include a new space station, a lunar base and possible sample return missions from Mars.

A new space race?

The most notable feature of the Chinese space program, especially compared to the early American and Russian programs, is its slow and steady pace. Because of the secrecy that surrounds many aspects of the Chinese space program, its exact capabilities are unknown. However, the program is likely on par with its counterparts.
In terms of military applications, China has also demonstrated significant skills. In 2007, it undertook an anti-satellite test, launching a ground-based missile to destroy a failed weather satellite. While successful, the test created a cloud of orbital debris that continues to threaten other satellites. The movie “Gravity” illustrated the dangers space debris poses to both satellites and humans. In its 2018 report on the Chinese military, the Department of Defense reported that China’s military space program “continues to mature rapidly.”
Despite its capabilities, the U.S., unlike other countries, has not engaged in any substantial cooperation with China because of national security concerns. In fact, a 2011 law bans official contact with Chinese space officials. Does this signal a new space race between the U.S. and China?
As a space policy researcher, I can say the answer is yes and no. Some U.S. officials, including Scott Pace, the executive secretary for the National Space Council, are cautiously optimistic about the potential for cooperation and do not see the beginning of a new space race. NASA Administrator Jim Brindenstine recently met with the head of the Chinese space program at the International Astronautical Conference in Germany and discussed areas where China and the U.S. can work together. However, increased military presence in space might spark increased competition. The Trump administration has used the threat posed by China and Russia to support its argument for a new independent military branch, a Space Force.
Regardless, China’s abilities in space are growing to the extent that is reflected in popular culture. In Andy Weir’s 2011 novel “The Martian” and its later film version, NASA turns to China to help rescue its stranded astronaut. While competition can lead to advances in technology, as the first space race demonstrated, a greater global capacity for space exploration can also be beneficial not only for saving stranded astronauts but increasing knowledge about the universe where we all live. Even if China’s rise heralds a new space race, not all consequences will be negative.

Wendy Whitman Cobb, Associate Professor of Political Science, Cameron University
This article is republished from The Conversation under a Creative Commons license. Read the original article.