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Understanding the birth of a planet is a challenging puzzle. We know that planets form inside clouds of gas and dust that surround new stars, known as protoplanetary disks. But grasping exactly how that process works – connecting the dots between a dust cloud and a finished planet – is not easy. An international team of astronomers is attempting to unlock some of those secrets, and have recently completed the most extensive chemical composition mapping of several protoplanetary discs around five young stars. Their research allows them to begin to piece together the chemical makeup of future exoplanets, offering a glimpse into the formation of new alien worlds.

The study, nicknamed MAPS, was carried out using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile.  Located at high altitude, in one of the driest deserts on Earth, ALMA has an excellent view of the stars with little interference from Earth’s atmosphere (of course, it has more interference than telescopes in space, like Hubble or the upcoming James Webb Space telescope, but nonetheless ALMA is well situated). ALMA’s specialty is in viewing light at submillimeter wavelengths, below what the human eye can see. At these wavelengths, ALMA is able to detect light given off from cold, dark areas of the Universe, including the protoplanetary dust clouds where planets are born. This capability enables researchers to see the chemical composition of these clouds in high resolution. In other words, ALMA can piece together the molecular building blocks of what will be future planets.

The chemical makeup of the clouds doesn’t just hint at the ingredients of future planets (and whether they might support life), but also suggests how and where within the disc planetary formation will take place. Protoplanetary discs aren’t uniform in composition – they have clumps of material unevenly spread throughout them, meaning that “planets in different disks or even in the same disk at different locations may form in radically different chemical environments,” explains Charles Law, one of the MAPS researchers.

MAPS has demonstrated that regions where gas giants are forming tend to be lacking in carbon, oxygen, and heavier elements, but have plenty of methane. On the other hand, inner solar system discs closer to their star seem to be carbon-rich. Viviana V. Guzmán, a MAPS co-Principal Investigator, explains, “we were able to observe the amount of small organic molecules in the inner regions of disks, where rocky planets are likely assembling…We’re finding that our own Solar System is not particularly unique, and that other planetary systems around other stars have enough of the basic ingredients to form the building blocks of life.”

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In this artist’s conception, planets form from the gas and dust in the protoplanetary disk surrounding the young star. The gas is made up of many different molecules, including hydrogen cyanide and more complex nitriles—linked to the development of life on Earth—and other organic and inorganic compounds. From simple organic compounds to the more complex, the soup of molecules in a particular location in the disk shapes the future of the planet forming there, and determines whether or not that planet could support life as we know it.
Credit: M.Weiss/Center for Astrophysics | Harvard & Smithsonian

MAPS principal investigator Karin Öberg added, “one of the really exciting things we saw is that the planet-forming disks around these five young stars are factories of a special class of organic molecules, so-called nitriles, which are implicated in the origins of life here on Earth.”

With these findings, MAPS is starting to bridge the gap between dust clouds and planets, and helping us model what our own solar system might have looked like in its earliest stages. It’s an exciting time for those working to understand the early history of planets. The results will be published in an upcoming edition of The Astrophysical Journal Supplement Series.

The five stars studied by MAPS are: IM Lup, GM Aur, AS 209, HD 163296, and MWC 480.

Learn More: ALMA Reveals Carbon-Rich, Organic Birth Environments of
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Massive Stars Have the Power to Shape Solar Systems

1024px Orion Nebula Hubble 2006 mosaic 18000 jpg

Stars shape their solar systems. It’s true of ours, and it’s true of others. But for some massive stars, their power to shape still-forming systems is fateful and final.

In their youth, stars are surrounded by a rotating mass of gas and dust called a protoplanetary disk. Planets form in these disks, and the process can take millions of years. But stars have different masses and different radiation outputs that affect how planets form, or if they form at all.

New research examines how the powerful UV radiation from massive stars affects planet formation in disks. The research article is “A far-ultraviolet–driven photoevaporation flow observed in a protoplanetary disk.” It’s published in the journal Science, and the lead author is Olivier Berne from the Institute for Research in Astrophysics and Planetology, University of Toulouse, France.

The research looks at large stars in their first million years of life, when they’re not only young but extremely luminous. The researchers focused on several stars in the Orion Nebula and its stellar nurseries. The stars are at least ten times more massive than the Sun and are 10,000 times more luminous. What effect does their luminosity and all that radiation have on disks where planets form?

These powerful young stars emit high levels of Far-Ultraviolet (FUV) radiation, which has the power to remove mass from planet-forming disks. This power extends beyond their own immediate surroundings into the disks around neighbouring low-mass stars.

“Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far ultraviolet (FUV) radiation,” the researchers explain. “Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks.” The PDRs can span several hundred astronomical units (AU).

The researchers examined one protoplanetary disk that’s within range of energetic, high-mass stars residing in the Trapezium Cluster in the heart of the Orion Nebula. The five brightest stars in that cluster range from 15 to 30 solar masses, making them prime candidates to study PDRs in neighbouring planet-forming disks. The Orion Bar PDR is an often-studied and prototypical PDR.

The Orion Nebula. The Trapezium Cluster is above and to the right of the three stars in Orion's Belt in this image. The stars in Trapezium are mostly responsible for illuminating Orion, and their powerful FUV energy can strip gas from the protoplanetary disks surrounding lower-mass stars nearby. Image Credit: NASA, ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team, Public domain, via Wikimedia Commons
The Orion Nebula. The Trapezium Cluster is above and to the right of the three stars in Orion’s Belt in this image. The stars in Trapezium are mostly responsible for illuminating Orion, and their powerful FUV energy can strip gas from the protoplanetary disks surrounding lower-mass stars nearby. Image Credit: NASA, ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team, Public domain, via Wikimedia Commons

The disk in the image, d203-506, is being bombarded by intense FUV radiation from the massive Trapezium stars. The FUV radiation is dispersing matter in the disk, inhibiting planet formation. According to the research, it’s impossible for a Jupiter-mass planet to form in this disk because the radiation is stripping matter away.

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Grabbing Samples from the Surface of Mars

Tharsis and Valles Marineris Mars Orbiter Mission 30055660701 1

As if the Mars Perseverance Rover and Ingenuity Drone were not exciting enough then the next step in this audacious mission takes it to a whole new level. Mars Sample Return Mission is to follow along, collect and return the samples collected by Perseverance back to Earth. However the status of Mars Sample Return is uncertain as engineers are still working on technology to retrieve the samples. The current challenge is the gripper arm that will collect the samples and stow them safely and securely before transportation without damaging them. 

Mars, known as the “Red Planet,” is the fourth planet from the Sun.  It’s named after the Roman god of war and has fascinated humans for centuries. The distinctive rusty-red colour and mysterious terrain has over the years, led many to believe Mars was inhabited by aliens. Exploration has shown us though that Mars is a barren landscape that is home to Olympus Mons, the largest volcano, and Valles Marineris, the deepest canyon, in the solar system. 

Tharsis and Valles Marineris Mars Orbiter Mission 30055660701 1 1
Featured Image: True-color image of the Red Planet taken on October 10, 2014, by India’s Mars Orbiter mission from 76,000 kilometers (47,224 miles) away. (Credit: ISRO/ISSDC/Justin Cowart) (This file is licensed under the Creative Commons Attribution 2.0 Generic license.)

Viking 1 was the first spacecraft to visit Mars, successfully touching down on 20 July 1976 in the Chryse Planitia region. It comprised an orbiter and lander both of which were equipped with high resolution cameras to undertake a detailed examination of the Martian surface and atmosphere. A host of other spacecraft have visited Mars since then, most recently the Perseverance rover which carried with it the Ingenuity aircraft.

One of the mission objectives of Perseverance was to collect samples from Martian rocks and soil using the onboard drill. The samples were collected during a process known as ‘sample caching’ and then stored in tubes before being deposited on the surface for later collection. It’s a procedure that has never been undertaken before but set the foundations for future missions to collect and transport the samples back to Earth. Perseverance has been busy, there are now 23 titanium tubes sat on the Martian surface just waiting to be delivered back to Earth.  

Mars Perseverence rover sent back this image of its parking spot during Mars Solar Conjunction. Courtesy NASA/JPL-Caltech
Mars Perseverence rover sent back this image of its parking spot during Mars Solar Conjunction. Courtesy NASA/JPL-Caltech

Enter Mars Sample Return mission, a joint NASA and ESA project that is planned to collect the tubes and bring them home for study. Engineers are now working on a prototype robotic arm that will collect the tubes from the surface. It uses a grip with two ‘fingers’ to pickup the hermetically sealed tubes from various angles and positions. There is a mechanism that ensures enough grip to pickup but not damage the tube or its contents which are Martian samples about the size of a piece of classroom chalk. It can even collect them direct from the rover itself.

As with all space missions, backup plans must always be considered. In the case of the the Sample Return mission the backup is likely to be two helicopters based on the Ingenuity design that can collect the tubes and deposit them in front of the lander for collection. An audacious mission perhaps but we will

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Curiosity Rover is Climbing Through Dramatic Striped Terrain on Mars

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Just about every day we here on Earth get a breathtaking picture of Mars’s terrain sent back by a rover. But, the view from space can be pretty amazing, too. The Mars Reconnaissance Orbiter (MRO) just sent back a thought-provoking picture of Curiosity as it makes its way up a steep ridge on Mount Sharp.

The rover is a tiny black dot in the center of the image, which gives a good feeling for what MRO’s HiRISE camera accomplished. For scale, the rover is about the size of a dinner table, sitting in a region of alternating dark and light bands of material on the Red Planet.

NASA's Curiosity Mars rover appears as a dark speck in this image captured from directly overhead by the agency's Mars Reconnaissance Orbiter, or MRO. Credit: NASA/JPL-Caltech/University of Arizona
NASA’s Curiosity Mars rover appears as a dark speck in this image captured from directly overhead by the agency’s Mars Reconnaissance Orbiter, or MRO. Credit: NASA/JPL-Caltech/University of Arizona

Where’s Curiosity?

The Curiosity rover is exploring an ancient ridge on the side of Mount Sharp, which is the peak of a crater on Mars. It’s sitting on the side of a feature called Gediz Vallis Ridge, and the terrains and materials preserve a record of what things were like when water last flowed there. That happened about three billion years ago. The force of the flow brought significant amounts of rocks and debris through the region. They piled up to form the ridge. So, much of what you see here is the desiccated remains of that flooding.

Debris flows are pretty common here on Earth, particularly in the aftermath of floods, volcanic eruptions, tsunamis, and other actions. We can see them wherever material floods through a region or down a slope. In a flood-based flow, the speed of the water combines with gravity and the degree of slope to send material rushing across the surface. A debris flow can also be a dry landslide, and those can occur pretty much anywhere on Earth where the conditions are right. Another type of debris flow comes from volcanic activity. That occurs when material erupts from a volcano, or when earthquakes combined with an eruption collapse material into the side of the mountain. That results in what’s called a “lahar”. Folks in North America might recall the Mount St. Helens eruption in 1980; it resulted in several lahars that buried parts of the surrounding terrain.

Now that scientists see similar-seeming regions on Mars, they want to know several things. How did they form? Were they created by the same processes that make them on Earth? And, how long ago did they begin to form? Curiosity and Perseverance and other rovers and landers have been sent to Mars to help answer those questions.

Understanding the Debris Ridge

Did any of these actions happen on Mars? The evidence is pretty strong, which is why Gediz Vallis itself is a major exploration goal for the rover. It’s a canyon that stretches across 9 kilometers of the Martian surface and is carved about 140 meters deep. Gediz was likely carved by so-called “fluvial” activity (meaning flowing action) in the beginning. Later floods deposited a variety of fine-grained sands and rocks. Over time, winds have blown a lot of that material away, leaving behind protected pockets of materials left behind by the flooding. The size of the rocks tells something about the speed of the flows that deposited all the material. Geological studies of those rocks will reveal their mineral compositions, including their exposure to water over time.

The Gediz Vallis ridge resulted from the action of water pushing rocks and dirt around to build it up over time. Planetary scientists now need to figure out the sequence of events that created it. The clues lie in the scattered rocks in the region and the surrounding terrain. Mount Sharp itself (formally known as Aeolis Mons), is about 5 kilometers high and is, essentially, a stack of layered sedimentary rocks. As Curiosity makes its way up the mountain, it explores younger and younger materials.

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