The Insight lander responds to commands to spread its solar arrays during a January 23, 2018 test at the Lockheed Martin clean room in Littleton, Colorado. Image: Lockheed Martin Space
May 2018 is the launch window for NASA’s next mission to Mars, the InSight Lander. InSight is the next member of what could be called a fleet of human vehicles destined for Mars. But rather than working on the question of Martian habitability or suitability for life, InSight will try to understand the deeper structure of Mars.
InSight stands for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport. InSight will be the first robotic explorer to visit Mars and study the red planet’s deep interior. The work InSight does should answer questions about the formation of Mars, and those answers may apply to the history of the other rocky planets in the Solar System. The lander, (InSight is not a rover) will also measure meteorite impacts and tectonic activity happening on Mars currently.
This video helps explain why Mars is a good candidate to answer questions about how all our rocky planets formed, not just Mars itself.
InSight was conceived as part of NASA’s Discovery Program, which are missions focused on important questions all related to the “content, origin, and evolution of the solar system and the potential for life elsewhere”, according to NASA. Understanding how our Solar System and its planets formed is a key part of the Discovery Program, and is the question InSight was built to answer.
This artist’s illustration of InSight on a photo background of Mars shows the lander fully deployed. The solar arrays are open, and in the foreground two of its instruments are shown. On the left is the SEIS instrument, and on the right is the HP3 probe. Image: NASA/Lockheed Martin
To do its work, InSight will deploy three instruments: SEIS, HP³, and RISE.
SEIS
This is InSight’s seismic instrument, designed to take the Martian pulse. It stands for Seismic Experiment for Internal Structure.
In this image, InSight’s Instrument Deployment Arm is practicing placing SEIS on the surface. Image: NASA/Lockheed Martin
SEIS sits patiently under its dome, which protects it from Martian wind and thermal effects, and waits for something to happen. What’s it waiting for? For seismic waves caused by Marsquakes, meteorite impacts, or by the churning of magma deep in the Martian interior. These waves will help scientists understand the nature of the material that first formed Mars and the other rocky planets.
HP³
HP³ is InSight’s heat probe. It stands for Heat Flow and Physical Properties Probe. Upon deployment on the Martian surface, HP³ will burrow 5 meters (16 ft.) into Mars. No other instrument has ever pierced Mars this deeply. Once there, it will measure the heat flowing deeply within Mars.
In this image, the Heat Flow and Physical Properties Probe is shown inserted into Mars. Image: NASA
Scientists hope that the heat measured by HP³ will help them understand whether or not Mars formed from the same material that Earth and the Moon formed from. It should also help them understand how Mars evolved after it was formed.
RISE
RISE stands for Rotation and Interior Structure Experiment. RISE will measure the Martian wobble as it orbits the Sun, by precisely tracking InSight’s position on the surface. This will tell scientists a lot about the deep inner core of Mars. The idea is to determine the depth at which the Martian core is solid. It will also tell us which elements are present in the core. Basically, RISE will tell us how Mars responds to the Sun’s gravity as it orbits the Sun. RISE consists of two antennae on top of InSight.
The two RISE antennae are shown in this image. RISE will reveal information about the Martian core by tracking InSight’s position while Mars orbits the Sun. Image: NASA/Lockheed Martin
InSight will land at Elysium Planitia which is a flat and smooth plain just north of the Martian equator. This is considered a perfect location or InSight to study the Martian interior. The landing sight is not far from where Curiosity landed at Gale Crater in 2012.
InSight will land at Elysium Planitia, just north of the Martian equator. Image: NASA/JPL-CalTech
InSight will be launched to Mars from Vandenberg Air Force Base in California by an Atlas V-401 rocket. The trip to Mars will take about 6 months. Once on the Martian surface, InSight’s mission will have a duration of about 728 Earth days, or just over 1 Martian year.
InSight won’t be launching alone. The Atlas that launches the lander will also launch another NASA technology experiment. MarCO, or Mars Cube One, is two suitcase-size CubeSats that will travel to Mars behind InSight. Once in orbit around Mars, their job is to relay InSight data as the lander enters the Martian atmosphere and lands. This will be the first time that miniaturized CubeSat technology will be tested at another planet.
One of the MarCO Cubesats that will be launched with InSight. This will be the first time that CubeSat technology will be tested at another planet. Image: NASA/JPL-CalTech
If the MarCO experiment is successful, it could be a new way of relaying mission data to Earth. MarCO will relay news of a successful landing, or of any problems, much sooner. However, the success of the InSight lander is not dependent on a successful MarCO experiment.
Artist’s impression of the cool red star and gas-giant planet NGTS-1b against the Milky Way. Credit: University of Warwick/Mark Garlick.
When it comes to how and where planetary systems form, astronomers thought they had a pretty good handle on things. The predominant theory, known as the Nebular Hypothesis, states that stars and planets form from massive clouds of dust and gas (i.e. nebulae). Once this cloud experiences gravitational collapse at the center, its remaining dust and gas forms a protoplanetary disk that eventually accretes to form planets.
However, when studying the distant star NGTS-1 – an M-type (red dwarf) located about 600 light-years away – an international team led by astronomers from the University of Warwick discovered a massive “hot Jupiter” that appeared far too large to be orbiting such a small star. The discovery of this “monster planet” has naturally challenged some previously-held notions about planetary formation.
Artist’s impression of the cool red star above NGTS-1b. Credit: University of Warwick/Mark Garlick.
The discovery was made using data obtained by the ESO’s Next-Generation Transit Survey (NGTS) facility, which is located at the Paranal Observatory in Chile. This facility is run by an international consortium of astronomers who come from the Universities of Warwick, Leicester, Cambridge, Queen’s University Belfast, the Geneva Observatory, the German Aerospace Center, and the University of Chile.
Using a full array of fully-robotic compact telescopes, this photometric survey is one of several projects meant to compliment the Kepler Space Telescope. Like Kepler, it monitors distant stars for signs of sudden dips in brightness, which are an indication of a planet passing in front of (aka. “transiting”) the star, relative to the observer. When examining data obtained from NGTS-1, the first star to be found by the survey, they made a surprising discovery.
Based on the signal produced by its exoplanet (NGTS-1b), they determined that it was a gas giant roughly the same size as Jupiter and almost as massive (0.812 Jupiter masses). Its orbital period of 2.6 days also indicated that it orbits very close to its star – about 0.0326 AU – which makes it a “hot Jupiter”. Based on these parameters, the team also estimated that NGTS-1b experiences temperatures of approximately 800 K (530°C; 986 °F).
The discovery threw the team for a loop, as it was believed to be impossible for planets of this size to form around small, M-type stars. In accordance with current theories about planet formation, red dwarf stars are believed to be able to form rocky planets – as evidenced by the many that have been discovered around red dwarfs of late – but are unable to gather enough material to create Jupiter-sized planets.
Artist’s concept of Jupiter-sized exoplanet that orbits relatively close to its star (aka. a “hot Jupiter”). Credit: NASA/JPL-Caltech)
As Dr. Daniel Bayliss, an astronomer with the University of Geneva and the lead-author on the paper, commented in University of Warwick press release:
“The discovery of NGTS-1b was a complete surprise to us – such massive planets were not thought to exist around such small stars. This is the first exoplanet we have found with our new NGTS facility and we are already challenging the received wisdom of how planets form. Our challenge is to now find out how common these types of planets are in the Galaxy, and with the new NGTS facility we are well-placed to do just that.”
What is also impressive is the fact that the astronomers noticed the transit at all. Compared to other classes of stars, M-type stars are the smallest, coolest and dimmest. In the past, rocky bodies have been detected around them by measuring shifts in their position relative to Earth (aka. the Radial Velocity Method). These shifts are caused by the gravitational tug of one or more planets that cause the planet to “wobble” back and forth.
In short, the low light of an M-type star has made monitoring them for dips in brightness (aka. the Transit Method) highly impractical. However, using the NGTS’s red-sensitive cameras, the team was able to monitored patches of the night sky for many months. Over time, they noticed dips coming from NGTS-1 every 2.6 days, which indicated that a planet with a short orbital period was periodically passing in front of it.
Artist’s impression of the planet orbiting a red dwarf star. Credit: ESO/M. Kornmesser
They then tracked the planet’s orbit around the star and combined the transit data with Radial Velocity measurements to determine its size, position and mass. As Professor Peter Wheatley (who leads NGTS) indicated, finding the planet was painstaking work. But in the end, its discovery could lead to the detection of many more gas giants around low-mass stars:
“NGTS-1b was difficult to find, despite being a monster of a planet, because its parent star is small and faint. Small stars are actually the most common in the universe, so it is possible that there are many of these giant planets waiting to found. Having worked for almost a decade to develop the NGTS telescope array, it is thrilling to see it picking out new and unexpected types of planets. I’m looking forward to seeing what other kinds of exciting new planets we can turn up.”
Within the known Universe, M-type stars are by far the most common, accounting for 75% of all stars in the Milky Way Galaxy alone. In the past, the discovery of rocky bodies around stars like Proxima Centauri, LHS 1140, GJ 625, and the seven rocky planets around TRAPPIST-1, led many in the astronomical community to conclude that red dwarf stars were the best place to look for Earth-like planets.
The discovery of a Hot Jupiter orbiting NGTS-1 is therefore seen as an indication that other red dwarf stars could have orbiting gas giants as well. Above all, this latest find once again demonstrates the importance of exoplanet research. With every find we make beyond our Solar System, the more we learn about the ways in which planets form and evolve.
Every discovery we make also advances our understanding of how likely we may be to discover life out there somewhere. For in the end, what greater scientific goal is there than determining whether or not we are alone in the Universe?
Artist's impression of a Mars-sized object crashing into the Earth, starting the process that eventually created our Moon. Credit: Joe Tucciarone
There’s a new type of planet in town, though you won’t find it in well-aged solar systems like our own. It’s more of a stage of formation that planets like Earth can go through. And its existence helps explain the relationship between Earth and our Moon.
The new type of planet is a huge, spinning, donut-shaped mass of hot, vaporized rock, formed as planet-sized objects smash into each other. The pair of scientists behind the study explaining this new planet type have named it a ‘synestia.’ Simon Lock, a graduate student at Harvard University, and Sarah Stewart, a professor in the Department of Earth and Planetary Sciences at the University of California, Davis, say that Earth was at one time a synestia.
Rocky planets like Earth are accreted from smaller bodies over time. Objects with high energy and high angular momentum could form a synestia, a transient stage in planetary formation where vaporized rock orbits the rest of the body. In this image, each of the three stages has the same mass. Image: Simon Lock, Harvard University
The current theory of planetary formation goes like this: When a star forms, the left-over material is in motion around the star. This left-over material is called a protoplanetary disk. The material coagulates into larger bodies as the smaller ones collide and join together.
As the bodies get larger and larger, the force of their collisions becomes greater and greater, and when two large bodies collided, their rocky material melts. Then, the newly created body cools, and becomes spherical. It’s understood that this is how Earth and the other rocky planets in our Solar System formed.
Lock and Stewart looked at this process and asked what would happen if the resulting body was spinning quickly.
When a body is spinning, the law of conservation of angular momentum comes into play. That law says that a spinning body will spin until an external torque slows it down. The often-used example from figure skating helps explain this.
If you’ve ever watched figure skaters, and who hasn’t, their actions are very instructive. When a single skater is spinning rapidly, she stretches out her arms to slow the rate of spin. When she folds her arms back into her body, she speeds up again. Her angular momentum is conserved.
This short video shows figure skaters and physics in action.
If you don’t like figure skating, this one uses the Earth to explain angular momentum.
Now take the example from a pair of figure skaters. When they’re both turning, and the two of them join together by holding each other’s hands and arms, their angular momentum is added together and conserved.
Replace two figure skaters with two planets, and this is what the two scientists behind the study wanted to model. What would happen if two large bodies with high energy and high angular momentum collided with each other?
If the two bodies had high enough temperatures and high enough angular momentum, a new type of planetary structure would form: the synestia. “We looked at the statistics of giant impacts, and we found that they can form a completely new structure,” Stewart said.
“We looked at the statistics of giant impacts, and we found that they can form a completely new structure.” – Professor Sarah Stewart, Department of Earth and Planetary Sciences at the University of California, Davis.
As explained in a press release from the UC Davis, for a synestia to form, some of the vaporized material from the collision must go into orbit. When a sphere is solid, every point on it is rotating at the same rate, if not the same speed. But when some of the material is vaporized, its volume expands. If it expands enough, and if its moving fast enough, it leaves orbit and forms a huge disc-shaped synestia.
Other theories have proposed that two large enough bodies could form an orbiting molten mass after colliding. But if the two bodies had high enough energy and temperature to vaporize some of the rock, the resulting synestia would occupy a much larger space.
“The main issue with looking for synestias around other stars is that they don’t last a long time. These are transient, evolving objects that are made during planet formation.” – Professor Sarah Stewart, UC Davis.
These synestias likely wouldn’t last very long. They would cool quickly and condense back into rocky bodies. For a body the size of Earth, the synestia might only last one hundred years.
The synestia structure sheds some light on how moons are formed. The Earth and the Moon are very similar in terms of composition, so it’s likely they formed as a result of a collision. It’s possible that the Earth and Moon formed from the same synestia.
These synestias have been modelled, but they haven’t been observed. However, the James Webb Space Telescope will have the power to peer into protoplanetary disks and watch planets forming. Will it observe a synestia?
“These are transient, evolving objects that are made during planet formation.” – Professor Sarah Stewart, UC Davis
In an email exchange with Universe Today, Dr. Sarah Stewart of UC Davis, one of the scientists behind the study, told us that “The main issue with looking for synestias around other stars is that they don’t last a long time. These are transient, evolving objects that are made during planet formation.”
“So the best bet for finding a rocky synestia is young systems where the body is close to the star. For gas giant planets, they may form a synestia for a period of their formation. We are getting close to being able to image circumplanetary disks in other star systems.”
Once we have the ability to observe planets forming in their circumstellar disks, we may find that synestias are more common than rare. In fact, planets may go through the synestia stage multiple times. Dr. Stewart told us that “Based on the statistics presented in our paper, we expect that most (more than half) of rocky planets that form in a manner similar to Earth became synestias one or more times during the giant impact stage of accretion.”
This artist's illustration shows planetisimals around a young star. New research shows that planetesimals are blasted by headwind, losing debris into space. Image Credit: NASA/JPL
The theory of how planets form has been something of an enduring mystery for scientists. While astronomers have a pretty good understanding of where planetary systems comes from – i.e. protoplanetary disks of dust and gas around new stars (aka. “Nebular Theory“) – a complete understanding of how these discs eventually become objects large enough to collapse under their own gravity has remained elusive.
But thanks to a new study by a team of researchers from France, Australia and the UK, it seems that the missing piece of the puzzle may finally have been found. Using a series of simulations, these researchers have shown how “dust traps” – i.e. regions where pebble-sized fragments could collect and stick together – are common enough to allow for the formation of planetesimals.
An image of a protoplanetary disk, made using results from the new model, after the formation of a spontaneous dust trap, visible as a bright dust ring. Gas is depicted in blue and dust in red. Credit: Jean-Francois Gonzalez.
Until recently, the process by which protoplanetary disks of dust and gas aggregate to form peddle-sized objects, and the process by which planetesimals (objects that are one hundred meters or more in diameter) form planetary cores, have been well understood. But the process that bridges these two – where pebbles come together to form planetesimals – has remained unknown.
Part of the problem has been the fact that the Solar System, which has been our only frame of reference for centuries, formed billions of years ago. But thanks to recent discoveries (3453 confirmed exoplanets and counting), astronomers have had lots of opportunities to study other systems that are in various stages of formation. As Dr. Gonzalez explained in a Royal Astronomical Society press release:
“Until now we have struggled to explain how pebbles can come together to form planets, and yet we’ve now discovered huge numbers of planets in orbit around other stars. That set us thinking about how to solve this mystery.”
In the past, astronomers believed that “dust traps” – which are integral to planet formation – could only exist within certain environments. In these high-pressure regions, large grains of dust are slowed down to the point where they are able to come together. These regions are extremely important since they counteract the two main obstacles to planetary formation, which are drag and high-speed collisions.
Artist’s impression of the planets in our solar system, along with the Sun (at bottom). Credit: NASA
Drag is caused by the effect gas has on dust grains, which causes them to slow down and eventually drift into the central star (where they are consumed). As for high-speed collisions, this is what causes large pebbles to smash into each other and break apart, thus reversing the aggregation process. Dust traps are therefore needed to ensure that dust grains are slowed down just enough so that they won’t annihilate each other when they collide.
To see just how common these dust traps were, Dr. Gonzalez and his colleagues conducted a series of computer simulations that took into account how dust in a protoplanetary disk could exert drag on the gas component – a process known as “aerodynamic drag back-reaction”. Whereas gas typically has an arresting influence on dust particles, in particularly dusty rings, the opposite can be true.
This effect has been largely ignored by astronomers up until recently, since its generally quite negligible. But as the team noted, it is an important factor in protoplanetary disks, which are known for being incredibly dusty environments. In this scenario, the effect of back-reaction is to slow inward-moving dust grains and push gas outwards where it forms high-pressure regions – i.e. “dust traps”.
Once they accounted for these effects, their simulations showed how planets form in three basic stages. In the first stage, dust grains grow in size and move inwards towards the central star. In the second, the now pebble-sized larger grains accumulate and slow down. In the third and final stage, the gas is pushed outwards by the back-reaction, creating the dust trap regions where it accumulates.
These traps then allow the pebbles to aggregate to form planetesimals, and eventually planet-sized worlds. With this model, astronomers now have a solid idea of how planetary formation goes from dusty disks to planetesimals coming together. In addition to resolving a key question as to how the Solar System came to be, this sort of research could prove vital in the study of exoplanets.
Ground-based and space-based observatories have already noted the presence of dark and bright rings that are forming in protoplanetary disks around distant stars – which are believed to be dust traps. These systems could provide astronomers with a chance to test this new model, as they watch planets slowly come together. As Dr. Gonzalez indicated:
“We were thrilled to discover that, with the right ingredients in place, dust traps can form spontaneously, in a wide range of environments. This is a simple and robust solution to a long standing problem in planet formation.”
This is the final view taken by the JunoCam instrument on NASA's Juno spacecraft before Juno's instruments were powered down in preparation for orbit insertion. Juno obtained this color view on June 29, 2016, at a distance of 3.3 million miles (5.3 million kilometers) from Jupiter. See timelapse movie below. Credits: NASA/JPL-Caltech/MSSS
This is the final view taken by the JunoCam instrument on NASA’s Juno spacecraft before Juno’s instruments were powered down in preparation for orbit insertion. Juno obtained this color view on June 29, 2016, at a distance of 3.3 million miles (5.3 million kilometers) from Jupiter. See timelapse movie below. Credits: NASA/JPL-Caltech/MSSS
After a nearly 5 year odyssey across the solar system, NASA’s solar powered Juno orbiter is all set to ignite its main engine late tonight and set off a powerful charge of do-or-die fireworks on America’s ‘Independence Day’ required to place the probe into orbit around Jupiter – the ‘King of the Planets.’
To achieve orbit, Juno must will perform a suspenseful maneuver known as ‘Jupiter Orbit Insertion’ or JOI tonight, Monday, July 4, upon which the entire mission and its fundamental science hinges. There are no second chances!
You can be part of all the excitement and tension building up to and during that moment, which is just hours away – and experience the ‘Joy of JOI’ by tuning into NASA TV tonight!
Watch the live webcast on NASA TV featuring the top scientists and NASA officials starting at 10:30 p.m. EDT (7:30 p.m. PST, 0230 GMT) – direct from NASA’s Jet Propulsion Laboratory: https://www.nasa.gov/nasatv
Illustration of NASA’s Juno spacecraft firing its main engine to slow down and go into orbit around Jupiter. Lockheed Martin built the Juno spacecraft for NASA’s Jet Propulsion Laboratory. Credit: NASA/Lockheed Martin
And for a breathtaking warm-up act, Juno’s on board public outreachJunoCam camera snapped a final gorgeous view of the Jovian system showing Jupiter and its four largest moons, dancing around the largest planet in our solar system.
The newly released color image was taken on June 29, 2016, at a distance of 3.3 million miles (5.3 million kilometers) from Jupiter – just before the probe went into autopilot mode.
It shows a dramatic view of the clouds bands of Jupiter, dominating a spectacular scene that includes the giant planet’s four largest moons — Io, Europa, Ganymede and Callisto.
NASA also released this new time-lapse JunoCam movie today:
Video caption: Juno’s Approach to Jupiter: After nearly five years traveling through space to its destination, NASA’s Juno spacecraft will arrive in orbit around Jupiter on July 4, 2016. This video shows a peek of what the spacecraft saw as it closed in on its destination. Credits: NASA/JPL-Caltech/MSSS
The spacecraft is approaching Jupiter over its north pole, affording an unprecedented perspective on the Jovian system – “which looks like a mini solar system,” said Juno Principal Investigator and chief scientist Scott Bolton, from the Southwest Research Institute (SwRI) in San Antonio, Tx, at today’s media briefing at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif.
“The deep interior of Jupiter is nearly unknown. That’s what we are trying to learn about.”
The 35-minute-long main engine burn is preprogrammed to start at 11:18 p.m. EDT (8:18 p.m. PST, 0318 GMT). It is scheduled to last until approximately 11:53 p.m. (8:53 p.m. PST, 0353 GMT).
Juno mission briefing July 4, 2016 at JPL by Jim Green, Scott Bolton, Rick Nybakken and Heidi Becker. Credit: Roland Keller/rkeusa.blogspot.com
All of the science instruments were turned off on June 30 to keep the focus on the nail-biting insertion maneuver and preserve battery power, said Bolton. Solar powered Juno is pointed away from the sun during the engine firing.
JOI is required to slow the spacecraft so it can be captured into the gas giant’s orbit as it closes in over the north pole.
Initially the spacecraft will enter a long, looping polar orbit lasting about 53 days. That highly elliptical orbit will quickly be trimmed to 14 days for the science orbits.
The orbits are designed to minimize contact with Jupiter’s extremely intense radiation belts. The science instruments are shielded inside a ½ thick vault built of Titanium to protect them from the utterly deadly radiation – of some 20,000,000 rads.
Artist’s concept of NASA’s Juno spacecraft crossing the orbits of Jupiter’s four largest moons — Callisto, Gaynmede, Europa and Io — on its approach to Jupiter. Credits: NASA/JPL-Caltech
Juno is the fastest spacecraft ever to arrive at Jupiter and is moving at over 165,000 mph relative to Earth and 130,000 mph relative to Jupiter.
After a five-year and 2.8 Billion kilometer (1.7 Billion mile) outbound trek to the Jovian system and the largest planet in our solar system and an intervening Earth flyby speed boost, the moment of truth for Juno is now inexorably at hand.
Signals traveling at the speed of light take 48 minutes to reach Earth, said Rick Nybakken, Juno project manager from NASA’s Jet Propulsion Laboratory, at the media briefing.
So the main engine burn, which is fully automated, will already be over for some 13 minutes before the first indications of the outcome reach Earth via a series of Doppler shifts and tones. It is about 540 million miles (869 million kilometers) from Earth.
“By the time the burn is complete, we won’t even hear about it until 13 minutes later.”
“The engine burn will slow Juno by 542 meters/second (1,212 mph) and is fully automated as it approaches over Jupiter’s North Pole,” explained Nybakken.
“The long five year cruise enabled us to really learn about the spacecraft and how it operates.”
As it travels through space, the basketball court sized Juno is spinning like a windmill with its 3 giant solar arrays.
“Juno is also the farthest mission to rely on solar power. The solar panels are 60 square meters in size. And although they provide only 1/25th the power at Earth, they still provide over 500 watts of power at Jupiter.”
Rick Nybakken, Juno project manager at JPL illustrates how Juno will enter orbit around Jupiter during Juno mission briefing on July 4, 2016 at JPL. Credit: Roland Keller/rkeusa.blogspot.com
The protective cover that shields Juno’s main engine from micrometeorites and interstellar dust was opened on June 20.
During a 20 month long science mission – entailing 37 orbits lasting 14 days each – the probe will plunge to within about 3000 miles of the turbulent cloud tops and collect unprecedented new data that will unveil the hidden inner secrets of Jupiter’s origin and evolution.
“Jupiter is the Rosetta Stone of our solar system,” says Bolton. “It is by far the oldest planet, contains more material than all the other planets, asteroids and comets combined and carries deep inside it the story of not only the solar system but of us. Juno is going there as our emissary — to interpret what Jupiter has to say.”
During the orbits, Juno will probe beneath the obscuring cloud cover of Jupiter and study its auroras to learn more about the planet’s origins, structure, atmosphere and magnetosphere.
The $1.1 Billion Juno was launched on Aug. 5, 2011 from Cape Canaveral, Florida atop the most powerful version of the Atlas V rocket augmented by 5 solid rocket boosters and built by United Launch Alliance (ULA). That same Atlas V 551 version just launched MUOS-5 for the US Navy on June 24.
The Juno spacecraft was built by prime contractor Lockheed Martin in Denver.
Juno soars skyward to Jupiter on Aug. 5, 2011 from launch pad 41 at Cape Canaveral Air Force Station at 12:25 p.m. EDT. View from the VAB roof. Credit: Ken Kremer/kenkremer.com
Along the way Juno made a return trip to Earth on Oct. 9, 2013 for a flyby gravity assist speed boost that enabled the trek to Jupiter.
The flyby provided 70% of the velocity compared to the Atlas V launch, said Nybakken.
During the Earth flyby (EFB), the science team observed Earth using most of Juno’s nine science instruments since the slingshot also serves as an important dress rehearsal and key test of the spacecraft’s instruments, systems and flight operations teams.
What lessons were learned from the safe mode event and applied to JOI, I asked?
“We had the battery at 50% state of charge during the EFB and didn’t accurately predict the sag on the battery when we went into eclipse. We now have a validated high fidelity power model which would have predicted that sag and we would have increased the battery voltage,” Nybakken told Universe Today
“It will not happen at JOI as we don’t go into eclipse and are at 100% SOC. Plus the instruments are off which increases our power margins.”
For example the dazzling portrait of our Home Planet high over the South American coastline and the Atlantic Ocean.
For a hint of what’s to come, see our colorized Junocam mosaic of land, sea and swirling clouds, created by Ken Kremer and Marco Di Lorenzo
NASA’s Juno probe captured the image data for this composite picture during its Earth flyby on Oct. 9 over Argentina, South America and the southern Atlantic Ocean. Raw imagery was reconstructed and aligned by Ken Kremer and Marco Di Lorenzo, and false-color blue has been added to the view taken by a near-infrared filter that is typically used to detect methane. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo
The last NASA spacecraft to orbit Jupiter was Galileo in 1995. It explored the Jovian system until 2003.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
This image shows the moons of our Solar System's four icy dwarf planets. Pluto and Haumea have been considered as cousin planets because it's thought that their moons were formed in collisions. A new study focussed on Haumea's moons raises some interesting questions. Image: D. Ragozzine (FIT)/NASA/JHU/SwRI
The dwarf planets in our Solar System are some of the most interesting objects around. Of course, all of the Solar System objects–and anything in nature, really–are fascinating when you really focus on them. Now, a new study puts the focus squarely on the dwarf planet Haumea, and deepens the mystery surrounding its origins.
Dwarf planets Pluto and Haumea are considered cousins. Both of them, and their respective moons, are thought to be collisional families. This means they have a common origin in the form of an impact event. But the study, from Luke D. Burkhart, Darin Ragozzine, and Michael E. Brown, shows that Haumea doesn’t have the same kinds of moons as Pluto, which has astronomers puzzling over Haumea’s origins.
Pluto and Haumea are the only two bodies in the outer Solar System that have more than one Moon. Pluto has five moons (Charon, Styx, Nix, Kerberos, and Hydra) while Haumea has two moons, Hi’iaka and Namaka. Haumea is also the parent of a number of icy bodies which were parts of its surface, but now orbit the Sun on their own. The two other dwarf planets in the Kuiper Belt, Eris and Makemake, each have only one moon.
The five moons of Pluto. Image: NASA/JHUAPL/SwRI
One thing that differentiates Haumea from Pluto is Haumea’s family of small icy bodies that came from its surface. While Pluto has a number of small icy moons, Haumea’s icy bodies orbit the Sun independently, and are not moons. Other properties of Haumea, like its inordinately high rate of spin, make Haumea a very interesting object to study. They also differentiate Haumea from Pluto, and are leading to questions about the cousin relationship between the two. If they are indeed cousins, then shouldn’t they share the same formation method?
This shows how Pluto’s moon Charon was created. 1: a Kuiper belt object approaches Pluto; 2: it impacts Pluto; 3: a dust ring forms around Pluto; 4: the debris aggregates to form Charon; 5: Pluto and Charon relax into spherical bodies. It’s thought that the same collision created Pluto’s other Moons as well. Image: Acom, Public Domain.
Haumea’s lack of icy moons similar to Pluto’s was noted by researcher Darin Ragozzine. “While we’ve known about Pluto’s and Haumea’s moons for years, we now know that Haumea does not share tiny moons like Pluto’s, increasing our understanding of this intriguing object,” Ragozzine said.
There are definite similarities between Pluto and Haumea, but this study suggests that the satellite systems of the icy cousins, or former cousins, formed differently. “There is no self-consistent formation hypothesis for either set of satellites,” said Ragozzine.
Two things were at the heart of this new study. The first is the workhorse Hubble Space Telescope. In 2010, the Hubble focussed on Haumea, and captured 10 consecutive orbits to try to understand its family of satellites better.
The second thing at the heart of the study is called a “non-linear shift and stack method.” This is a novel technique which allows the detection of extremely faint and distant objects. When used in this study, it specifically ruled out the existence of small moons like the ones that orbit Pluto. This method may allow for future detection of other moons and Kuiper Belt Objects.
The study itself outlines some of Haumea’s properties that make it such an object of fascination for astronomers. It’s the fastest-rotating large body in the Solar System. In fact it rotates so quickly, that it’s near the rate at which the dwarf planet would break up. Haumea also has an unexpectedly high density, and a high albedo resulting from a surface of water ice. It’s two moons are in dynamically excited orbits, and its family of icy fragments is not near as dispersed as it should be. As the paper says, “There is no simple high-probability formation scenario that naturally explains all of these observational constraints.”
In the paper, the authors emphasize the puzzling nature of Haumea’s formation. To quote the paper, “Though multiple explanations and variations have been proposed, none have adequately and self-consistently explained all of the unique features of this interesting system and its family.”
The semi-major axes and inclinations of all known scattered-disc objects (in blue) up to 100 AU together with Kuiper-belt objects (in grey) and resonant objects (in green). The eccentricity of the orbits is represented by segments (extending from the perihelion to the aphelion) with the inclination represented on Y axis. Image: EuroCommuter http://creativecommons.org/licenses/by-sa/3.0/
Some of the explanations proposed in other studies include a collision between objects in the scattered disk, which overlaps the Kuiper Belt and extends much further, rather than objects in the Kuiper Belt itself. Another proposes that Haumea’s two largest moons–Hi’iaka and Namaka–are themselves second generation moons formed from the breakup of a progenitor moon.
Though the study shows that the Pluto system and the Haumea system, erstwhile cousins in the Solar System, have followed different pathways to formation, it also concludes that a collision was indeed the main event for both dwarf planets. But what happened after that collision, and where exactly those collisions took place, are still intriguing questions.
A new paper says that a Super-Earth may have formed in our Solar System and been swallowed by the Sun. Image Credit: ESA/Hubble, M. Kornmesser
Our Solar System sure seems like an orderly place. The orbits of the planets are predictable enough that we can send spacecraft on multi-year journeys to them and they will reliably reach their destinations. But we’ve only been looking at the Solar System for the blink of an eye, cosmically speaking.
The young Solar System was a much different place. Things were much more chaotic before the planets settled into the orbital stability that they now enjoy. There were crashings and smashings aplenty in the early days, as in the case of Theia, the planet that crashed into Earth, creating the Moon.
Now, a new paper from Rebecca G. Martin and Mario Livio at the University of Nevada, Las Vegas, says that our Solar System may have once had an additional planet that perished when it plunged into the Sun. Strangely enough, the evidence for the formation and existence of this planet may be the lack of evidence itself. The planet, which may have been what’s called a Super-Earth, would have formed quite close to the Sun, and then been destroyed when it was drawn into the Sun by gravity.
In the early days of our Solar System, the Sun would have formed in the centre of a mass of gas and dust. Eventually, when it gained enough mass, it came to life in a burst of atomic fusion. Surrounding the Sun was a protoplanetary disk of gas and dust, out of which the planets formed.
What’s missing in our Solar System is any bodies, or even rocky debris in the zone between Mercury and the Sun. This may seem normal, but the Kepler mission tells us it’s not. In over half of the other solar systems it’s looked at, Kepler has found planets in the same zone where our Solar System has none.
A key part of this idea is that planets don’t always form in situ. That is, they don’t always form at the place where they eventually reach orbital stability. Depending on a number of factors, planets can migrate inward towards their star or outwards away from their star.
Martin and Livio, the authors of the study, think that our Solar System did form a Super-Earth, and rather than it migrating outward, it fell into the Sun. According to them, the Super-Earth most probably formed in the inner regions of our Solar System, on the inside of Mercury’s orbit. The fact that there are no objects there, and no debris of any kind, suggests that the Super-Earth formed close to the Sun, and that its formation cleared that area of any debris. Then, once formed, it fell into the Sun, removing all evidence of its existence.
The authors also note another possible cause for the Super-Earth to have fallen into the Sun. They propose that Jupiter may have migrated inward to about 1.5 AUs from the Sun. At that point, it got locked into resonance with Saturn. Then, both gas giants migrated outward to their current orbits. This process would have shepherded a Super-Earth into the Sun, destroying it.
Some of the thinking behind this whole theory involves the size of the inner terrestrial planets in our Solar System. They’re very small in comparison to other systems studied by the Kepler Mission. If a Super-Earth had formed in the inner part of our System, it would have dominated the accretion of available material, leaving Mercury, Venus, Earth and Mars starved for matter.
A key idea behind this study is what’s known as a dead zone. In terms of a solar system and a protoplanetary disk, a dead zone is a zone of low turbulence which favors the formation of planets. A system with a dead zone would have enough material to allow Super-Earths to form in-situ, and they would not have to migrate inward from further out in the system. However, since large planets like Super-Earths take a long time to fully form, this dead zone would have to be long-lived.
If a protoplanetary disk lacks a dead zone, it is likely too turbulent for the formation of a Super-Earth close to the star. A turbulent protoplanetary disk favors the formation of Super-Earths further out, which would then migrate inwards towards the star. Also, a turbulent disk allows for quicker migration of planets, while a pronounced dead zone inhibits migration.
As the authors say in the conclusion of their study, “The lack of Super–Earths in our solar system is somewhat puzzling given that more than half of observed exoplanetary systems contain one. However, the fact that there is nothing
inside of Mercury’s orbit may not be a coincidence.” They go on to conclude that in our Solar System, the likely scenario is the in situ formation of a Super-Earth which subsequently fell into the Sun.
There are a lot of variables that have to be fine-tuned for this scenario to happen. The young solar system would need a dead zone, the depth of the turbulence in the protoplanetary disk would have to be just right, and the disk would have to be the right temperature. The fact that these things have to be within a certain range may explain why we don’t have a Super-Earth in our system, while over half of the systems studied by Kepler do have one.
Young stars have a disk of gas and dust around them called a protoplanetary disk. Credit: NASA/JPL-Caltech
It might seem incongruous to find water ice in the disk of gas and dust surrounding a star. Fire and ice just don’t mix. We would never find ice near our Sun.
But our Sun is old. About 5 billion years old, with about 5 billion more to go. Some younger stars, of a type called Herbig Ae/Be stars (after American astronomer George Herbig,) are so young that they are surrounded by a circumstellar disk of gas and dust which hasn’t been used up by the formation of planets yet. For these types of stars, the presence of water ice is not necessarily unexpected.
Water ice plays an important role in a young solar system. Astronomers think that water ice helps large, gaseous, planets to form. The presence of ice makes the outer section of a planetary disk more dense. This increased density allows the cores of gas planets to coalesce and form.
Young solar systems have what is called a snowline. It is the boundary between terrestrial and gaseous planets. Beyond this snowline, ice in the protoplanetary disk encourages gas planets to form. Inside this snowline, the lack of water ice contributes to the formation of terrestrial planets. You can see this in our own Solar System, where the snowline must have been between Mars and Jupiter.
A team of astronomers using the Gemini telescope observed the presence of water ice in the protoplanetary disk surrounding the star HD 100546, a Herbig Ae/Be star about 320 light years from us. At only 10 million years old, this star is rather young, and it is a well-studied star. The Hubble has found complex, spiral patterns in the disk, and so far these patterns are unexplained.
HD 100546 is also notable because in 2013, research showed the probable ongoing formation of a planet in its disk. This presented a rare opportunity to study the early stages of planet formation. Finding ice in the disk, and discovering how deep it exists in the disk, is a key piece of information in understanding planet formation in young solar systems.
Finding this ice took some clever astro-sleuthing. The Gemini telescope was used, with its Near-Infrared Coronagraphic Imager (NICI), a tool used to study gas giants. The team installed H2O ice filters to help zero in on the presence of water ice. The protoplanetary disk around young stars, as in the case of HD 100546, is a mixed up combination of dusts and gases, and isolating types of materials in the disk is not easy.
Water ice has been found in disks around other Herbig Ae/Be stars, but the depth of distribution of that ice has not been easy to understand. This paper shows that the ice is present in the disk, but only shallowly, with UV photo desorption processes responsible for destroying water ice grains closer to the star.
It may seem trite so say that more study is needed, as the authors of the study say. But really, in science, isn’t more study always needed? Will we ever reach the end of understanding? Certainly not. And certainly not when it comes to the formation of planets, which is a pretty important thing to understand.
ALMA’s best image of a protoplanetary disk to date. This picture of the nearby young star TW Hydrae reveals the classic rings and gaps that signify planets are in formation in this system. Credit: S. Andrews (Harvard-Smithsonian CfA); B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO)
ALMA’s best image of a protoplanetary disk to date. This picture of the nearby young star TW Hydrae reveals the classic rings and gaps that signify planets are in formation in this system. Credit: S. Andrews (Harvard-Smithsonian CfA); B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO)
TW Hydrae is a special star. Located 175 light years from Earth in the constellation Hydra the Water Snake, it sits at the center of a dense disk of gas and dust that astronomers think resembles our solar system when it was just 10 million years old. The disk is incredibly clear in images made using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, which employs 66 radio telescopes sensitive to light just beyond that of infrared. Spread across more than 9 miles (15 kilometers), the ALMA array acts as a gigantic single telescope that can make images 10 times sharper than even the Hubble Space Telescope.
This photo of the ALMA antennas on the Chajnantor Plateau in Chile, more than 16,000 feet (5000 meters) above sea level, was taken a few days before the start of ALMA Early Science and shows only one cluster of the 66 dishes. ALMA views the sky in submillimeter light, a slice of the spectrum invisible to the human eye that lies between infrared and radio waves. Credit: ALMA (ESO/NAOJ/NRAO)/W. Garnier (ALMA)
Astronomers everywhere point their telescopes at TW Hydraebecause it’s the closest infant star in the sky. With an age of between 5 and 10 million years, it’s not even running on hydrogen fusion yet, the process by which stars convert hydrogen into helium to produce energy. TW Hydrae shines from the energy released as it contracts through gravity. Fusion and official stardom won’t begin until it’s dense enough and hot enough for fusion to fire up in its belly.
ALMA image of the planet-forming disk around the young, sun-like star TW Hydrae. The inset image (upper right) zooms in on the gap nearest to the star, which is at the same distance as the Earth is from the sun, and may show an infant version of our home planet emerging from the dust and gas. The additional concentric light and dark features represent other planet-forming regions farther out in the disk. Credit: S. Andrews (Harvard-Smithsonian CfA), ALMA (ESO/NAOJ/NRAO)
We see most protoplanetary disks at various angles, but TW’s has a face-on orientation as seen from Earth, giving astronomers a rare, undistorted view of the complete disk around the star. The new images show amazing detail, revealing a series of concentric bright rings of dust separated by dark gaps. There’s even indications that a planet with an Earth-like orbit has begun clearing an orbit.
“Previous studies with optical and radio telescopes confirm that TW Hydrae hosts a prominent disk with features that strongly suggest planets are beginning to coalesce,” said Sean Andrews with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, USA and lead author on a paper published today in the Astrophysical Journal Letters.
The model (at left) of a protoplanetary disk shows a newly forming star at the center of a saucer-shaped dust cloud. At right, a close up of TW Hydrae taken by ALMA shows a gap about 93 million miles from the central star, suggesting that a planet with a similar orbit to Earth is forming there. Credit: (Left: L. Calcada). Right: S. Andrews (Harvard-Smithsonian CfA); B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO)
Pronounced gaps that show up in the photos above are located at 1.9 and 3.7 billion miles (3-6 billion kilometers) from the central star, similar to the average distances from the sun to Uranus and Pluto in the solar system. They too are likely to be the results of particles that came together to form planets, which then swept their orbits clear of dust and gas to sculpt the remaining material into well-defined bands. ALMA picks up the faint emission of submillimeter light emitted by dust grains in the disk, revealing details as small as 93 million miles (150 million kilometers) or the distance of Earth from the sun
This image compares the size of the solar system with HL Tauri and its surrounding protoplanetary disc. Although the star is much smaller than the Sun, the disc around HL Tauri stretches out to almost three times as far from the star as Neptune is from the Sun. Credit:ALMA (ESO/NAOJ/NRAO)
“This is the highest spatial resolution image ever of a protoplanetary disk from ALMA, and that won’t be easily beaten in the future!” said Andrews.
Earlier ALMA observations of another system, HL Tauri, show that even younger protoplanetary disks — a mere 1 million years old — look remarkably similar. By studying the older TW Hydrae disk, astronomers hope to better understand the evolution of our own planet and the prospects for similar systems throughout the Milky Way.
The million-year-old star HL Tau and its protoplanetary disk. Image: Carrasco-Gonzalez et. al.; Bill Saxton, NRAO/AUI/NSF
The currently accepted theory of planet formation goes like this: clouds of gas and dust are compressed or begin to draw together. When enough material clumps together, a star is formed and begins fusion. As the star, and its cloud of gas and dust rotate, other clumps of matter coagulate within the cloud, eventually forming planets. Voila, solar system.
There’s lots of evidence to support this, but getting a good look at the early stages of planetary formation has been difficult.
But now, an international team of astronomers using the Karl G. Jansky Very Large Array (VLA) have captured the earliest image yet of the process of planetary formation. “We believe this clump of dust represents the earliest stage in the formation of protoplanets, and this is the first time we’ve seen that stage,” said Thomas Henning, of the Max Planck Institute for Astronomy (MPIA).
This story actually started back in 2014, when astronomers studied the star HL Tau and its dusty disk with the Atacama Large Millimetre/sub-millimetre Array (ALMA.) That image, which showed gaps in HL Tau’s proto-planetary disk caused by proto-planets sweeping up dust in their orbits, was at the time the earliest image we had of planet formation. HL Tau is only about a million years old, so planet formation in HL Tau’s system was in its early days.
Now, astronomers have studied the same star, and its disk, with the VLA. The capabilities of the VLA allowed them do get an even better look at HL Tau and its disk, in particular the denser area closest to the star. What VLA revealed was a distinct clump of dust in the innermost region of the disk that contains between 3 to 8 times the mass of the Earth. That’s enough to form a few terrestrial planets of the type that inhabit our inner Solar System.
On the left is the ALMA image of HL Tau. On the right is the VLA image showing the clump of dust near the star. Image: Carrasco-Gonzalez et al,; Bill Saxton, NRAO/AUI/NSF
“This is an important discovery, because we have not yet been able to observe most stages in the process of planet formation,” said Carlos Carrasco-Gonzalez from the Institute of Radio Astronomy and Astrophysics (IRyA) of the National Autonomous University of Mexico (UNAM).
Of course the star in question, HL Tau, is interesting as well. But the formation and evolution of stars is much more easily studied. It’s our theory of planet formation which needed some observational confirmation. “This is quite different from the case of star formation, where, in different objects, we have seen stars in different stages of their life cycle. With planets, we haven’t been so fortunate, so getting a look at this very early stage in planet formation is extremely valuable,” said Carrasco-Gonzalez.
