On September 26th, NASA’s Double-Asteroid Redirect Test (DART) will rendezvous with the Near-Earth Asteroid (NEA) Didymos. By 01:14 UTC (07:14 PM EDT; 04:14 PM PDT), this spacecraft will collide with the small moonlet orbiting the asteroid (Dimorphos) to test the “kinetic impactor” method of planetary defense. This method involves a spacecraft striking an asteroid to alter its orbit and divert it from a trajectory that would cause it to collide with Earth. The event will be broadcast live worldwide and feature data streams from the DART during its final 12 hours before it strikes its target.Continue reading “The World’s Ground Stations are Getting Ready to Watch a Spacecraft Crash Into an Asteroid Next Week!”
Every two years, Mars enters what is known as a “Solar Conjunction,” where its orbit takes it behind the Sun relative to Earth. During these periods, the hot plasma regularly expelled by the Sun’s corona can cause interference with radio signals transmitted between Earth and Mars. To avoid signal corruption and the unexpected behaviors that could result, NASA and other space agencies declare a moratorium on communications for two weeks.
What this means is that between Oct. 2nd and Oct. 16th, all of NASA’s Mars missions will experiencing what is known as a “commanding moratorium.” This will consist of NASA sending a series of simple commands to its missions in orbit, which will then be dispatched to landers and rovers on the surface. These simple tasks will keep all of the robotic Martian explorers busy until regular communications can be established.Continue reading “Communication With Mars is About to Become Impossible (for two Weeks)”
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Venus, aka. Earth’s “Sister Planet,” has always been shrouded in mystery for astronomers. Despite being planet Earth’s closest neighbor, scientists remained ignorant of what Venus’ surface even looked like for well into the 20th century, thanks to its incredibly dense and opaque atmosphere. Even in the age of robotic space exploration, its surface has been all but inaccessible to probes and landers.
And so the mysteries of Venus have endured, not the least of which has to do with some of its most basic characteristics – like its internal mass distribution and variations in the length of a day. Thanks to observations conducted by a team led from UCLA, who repeatedly bounced radar off the planet’s surface for the past 15 years, scientists now know the precise length of a day on Venus, the tilt of its axis, and the size of its core.Continue reading “How Long is a Day on Venus? We Finally Know the Exact Answer”
It’s no secret that humanity is poised to embark on a renewed era of space exploration. In addition to new frontiers in astronomical and cosmological research, crewed missions are also planned for the coming decades that will send astronauts back to the Moon and to Mars for the first time. Looking even further, there are also ideas for interstellar missions like Breakthrough Starshot and Project Dragonfly and NASA’s Starlight.
These mission concepts entail pairing a nanocraft with a lightsail, which would then accelerated by a directed-energy array (lasers) to achieve a fraction of the speed of light (aka. relativistic velocity). Naturally, this raises a number of technical and engineering challenges, not the least of which is communications. In a recent study, a team of scientists sought to address that very issue and considered various methods that might be used.Continue reading “What’s the Best Way to Communicate With an Interstellar Probe When it’s Light-Years Away From Earth?”
When it launches next year, the James Webb Space Telescope (JWST) will be the largest, most complex, and most sophisticated observatory ever sent into space. Because of this, the mission has been delayed multiple times as ground crews were forced to put the telescope through a lengthy series of additional tests. All of these are to make sure that the JWST will survive and function in the vacuum and extreme temperature environment of space.
Recently, the testing teams conducted the critical “Ground Segment Test,” where the fully-assembled observatory was powered up and to see how it would respond to commands in space. These commands were issued from its Mission Operations Center at the Space Telescope Science Institute (STScI) in Baltimore. Having passed this latest milestone, the JWST is now on track for its scheduled launch next year in October.Continue reading “James Webb is Working Perfectly! On the Ground. Next Trick: Doing it From Space”
Right, magnetars. Perhaps one of the most ferocious beasts to inhabit the cosmos. Loud, unruly, and temperamental, they blast their host galaxies with wave after wave of electromagnetic radiation, running the gamut from soft radio waves to hard X-rays. They are rare and poorly understood.
Some of these magnetars spit out a lot of radio waves, and frequently. The perfect way to observe them would be to have a network of high-quality radio dishes across the world, all continuously observing to capture every bleep and bloop. Some sort of network of deep-space dishes.
Like NASA’s Deep Space Network.Continue reading “Astronomers are Using NASA’s Deep Space Network to Hunt for Magnetars”
The much-anticipated arrival of NASA’s Juno spacecraft at Jupiter is almost here. Juno will answer many questions about Jupiter, but at the cost of a mission profile full of challenges. One of those challenges is communicating with Juno as it goes about its business in the extreme radiation environment around Jupiter. Communications with Juno rely on a network of radio dishes in strategic locations around the world, receivers cooled to almost absolute zero, and a team of dedicated people.
The task of communicating with Juno falls to NASA’s Deep Space Network (DSN), a system of three facilities around the world whose job it is to communicate with all of the spacecraft that venture outside Earth’s vicinity. That network is in the hands of Harris Corporation, experts in all sorts of communications technologies, who are contracted to run these crucial facilities.
The person responsible is Sonny Giroux, DSN Program Manager at Harris. In an interview with Universe Today, Sonny explained how the DSN works, and describes some of the challenges the Juno mission poses.
“The network itself consists of three primary communication facilities; one in Goldstone, California, out in the middle of the Mojave Desert. The other facility is in Madrid Spain, and the third is in Canberra Australia. These three facilities are separated by about 120 degrees, which means that any spacecraft that’s out there is capable of communicating with Earth at any point in time,” said Giroux.
“Each facility has several antennae, the largest of which is 70 m in diameter, about the size of a football field. These antennae can be aimed at any angle. Then there are smaller antennae at 34 m in size, and we have a number of those at each complex.”
According to Giroux, the dishes can work independently, or be arrayed together, depending on requirements. At the DSN website, you can see which antenna is communicating with which of NASA’s missions at any time.
Juno is a complex mission with a dynamic orbit, and Jupiter itself is an extreme radiation environment. Juno will have to weave its way through Jupiter’s radiation belts in its polar orbit. According to Giroux, this creates additional communication problems for the DSN.
“As Juno goes into its orbital insertion phase, the spacecraft will have to turn away from Earth. Our signal strength will drop dramatically,” Giroux said. “In order to capture the data that Juno is going to send, we’re going to array all of our antennae at Goldstone and Canberra together.”
This means that a total of 9 antennae will be arrayed in two groups to communicate with Juno. The 4 dishes at the Canberra, Australia site will be arrayed together, and the 5 dishes at the Goldstone, California site will be arrayed together.
This combined strength is crucial to the success of Juno during JOI (Juno Orbital Insertion.) Said Giroux, “We need to bring Juno’s signal strength up to the maximum amount that we can. We need to know what phases Juno is in as it executes its sequence.”
“We’ve never arrayed all of our antennae together like this. This is a first for Juno.”
This combined receiving power is a first for the DSN, and another first for the Juno mission. “We’ve never arrayed all of our antennae together like this,” said Giroux. “This is a first for Juno. We’ve done a couple together before for a spacecraft like Voyager, which is pretty far out there, but never all of them like this. In order to maximize our success with Juno, we’re arraying everything. It will be the first time in our history that we’ve had to array together all of our assets.”
Arraying multiple dishes together provides another benefit too, as Giroux told us. “The DSN is able to have two centres view the spacecraft at the same time. If one complex goes down for whatever reason, we would have the other one still available to communicate with the spacecraft.”
The most visible part of the DSN are the antennae themselves. But the electronics at the heart of the system are just as important. And they’re unique in the world, too.
“We cool them
down to almost absolute zero to remove all of the noise out.”
“We have very specialized receivers that are built for the DSN. We cool them down to almost absolute zero to remove all of the noise out. That allows us to really focus on the signal that we’re looking for. These are unique to DSN,” said Giroux.
Juno itself has four different transmitters on-board. Some are able to transmit a lot of data, and some can transmit less. These will be active at different times, and form part of the challenge of communicating with Juno. Giroux told us, “Juno will be cycling through all four as it performs its insertion and comes back out again on the other side of the planet.”
“We just get the ones and zeroes…”
The DSN is a communications powerhouse, the most powerful tool ever devised for communicating in space. But it doesn’t handle the science. “DSN for the most part will receive whatever the spacecraft is sending to us. We just get the ones and zeroes and relay that data over to the mission. It’s the mission that breaks that down and turns it into science data.”
Juno will be about 450 million miles away at Jupiter, which is about a 96 minute round trip for any signal. That great distance means that Juno’s signal strength is extremely weak. But it won’t be the weakest signal that the DSN contends with. A testament to the strength of the DSN is the fact that it’s still receiving transmissions from the Voyager probes, which are transmitting at miniscule power levels. According to Giroux, “Voyager is at a billionth of a billionth of a watt in terms of its signal strength.”
Juno is different than other missions like New Horizons and Voyager 1 and 2. Once Juno is done, it will plunge into Jupiter and be destroyed. So all of its data has to be captured quickly and efficiently. According to Giroux, that intensifies the DSN’s workload for the Juno mission.
“Juno is different. We’ve got to make sure to capture that data regularly.”
“Juno has a very defined mission length, with start and stop dates. It will de-orbit into Jupiter when it’s finished its science phase. That’s different than other missions like New Horizons where it has long periods where its able to download all of the data it’s captured. Juno is different. We’ve got to make sure to capture that data regularly. After JOI we’ll be in constant communication with Juno to make sure that’s happening.”
The next most important event in Juno’s mission is its orbital insertion around Jupiter, and Giroux and the team are waiting for that just like the rest of us are. “Juno’s big burn as it slows itself enough to be captured by Jupiter is a huge milestone that we’ll be watching for,” said Giroux.
The first signal that the DSN receives will be a simple three second beep. “Confirmation of the insertion will occur at about 9:40 p.m.,” said Giroux. That signal will have been sent about 45 minutes before that, but the enormous distance between Earth and Jupiter means a long delay in receiving it. But once we receive it, it will tell us that Juno has finished firing its engine for orbital insertion. Real science data, including images of Jupiter, will come later.
“We want to see a successful mission as much as anybody else.”
All of the data from the DSN flows through the nerve center at NASA’s Jet Propulsion Laboratory. When the signal arrives indicating that Juno has fired its engines successfully, Giroux and his team will be focussed on that facility, where news of Juno’s insertion will first be received. And they’ll be as excited as the rest of us to hear that signal.
“We want to see a successful mission as much as anybody else. Communicating with spacecraft is our business. We’ll be watching the same channels and websites that everybody else will be watching with bated breath,” said Giroux.
“Its great to be a part of the network. It’s pretty special.”
If you thought the New Horizons spacecraft flyby of the Pluto system happened waaaay too fast and you’re pining for more images and data, you are in luck. What the spacecraft has been able to send back so far is just the tip of the icy dwarf planet, so to speak.
Starting tomorrow, Saturday, September 5, 2015, the spacecraft will begin an “intensive” downlink session that will last for a year or more, sending back the tens of gigabits of data the spacecraft collected and stored on its digital recorders during the flyby. What will come first are “selected high priority” data-sets that the science team has been anxiously waiting for.
“This is what we came for – these images, spectra and other data types that are going to help us understand the origin and the evolution of the Pluto system for the first time,” said New Horizons Principal Investigator Alan Stern. “And what’s coming is not just the remaining 95 percent of the data that’s still aboard the spacecraft – it’s the best datasets, the highest-resolution images and spectra, the most important atmospheric datasets, and more. It’s a treasure trove.”
Can I get a fist pump, all you Plutophiles?
— NASA New Horizons (@NASANewHorizons) August 27, 2015
Plus, every Friday from here on out, you can count on getting new, unprocessed pictures from the Long Range Reconnaissance Imager (LORRI) on the New Horizons project website. Here’s where you can find the images, and the next LORRI set is scheduled for posting on Sept. 11, so set your calendars.
It’s been 7 weeks since New Horions’ historic flyby of the Pluto system, and during this quick pass, the spacecraft was designed “to gather as much information as it could, as quickly as it could, as it sped past Pluto and its family of moons – then store its wealth of data to its digital recorders for later transmission to Earth,” said the mission team.
Why is it taking so long? The spacecraft runs on between 2-10 watts of power, and it had to prioritize on data collection during the flyby. The data has been stored on two onboard, solid-state, 8 gigabyte memory banks. The spacecraft’s main processor compresses, reformats, sorts and stored the data on a recorder, similar to a flash memory card for a digital camera.
One issue is the time it takes to get data from New Horizons as it speeds even farther away from Earth, past the Pluto system. Even moving at light speed, the radio signals from New Horizons containing data need more than 4 ½ hours to cover the 4 billion km (3 billion miles) to reach Earth.
But the biggest issue is the relatively low “downlink” rate at which data can be transmitted to Earth, especially when you compare it to rates now common for high-speed Internet surfers.
During the Jupiter flyby in February 2007, New Horizons data return rate was about 38 kilobits per second (kbps), which is slightly slower than the transmission speed for most computer modems. Now, after the flyby, the average downlink rate is going to be approximately 1-4 kilobits per second, depending on how the data is sent and which Deep Space Network antenna is receiving it. Sometimes, when possible, the spacecraft will be able to increase the rate by downlinking with both of its transmitters through NASA’s largest antennas of the DSN. But even then, it will take until late 2016 to send Pluto flyby data stored on the spacecraft’s recorders.
Patience you must have, my young padawan.
“The New Horizons mission has required patience for many years, but from the small amount of data we saw around the Pluto flyby, we know the results to come will be well worth the wait,” said Hal Weaver, New Horizons project scientist.
The data received by the DSN (you can watch the live data link happen on the Eyes of the Solar System DSN NOW page) will be sent to the New Horizons Mission Operations Center at the Applied Physics Lab a Johns Hopkins University, where data will be “unpacked” and stored. Then mission operations and instrument teams will scour the engineering data for performance trend information, while science data will be copied to the Science Operations Center at the Southwest Research Institute in Boulder, Colorado.
At the Science Ops Center, data will pass through “pipeline” software that converts the data from instrumental units to scientific units, based on calibration data obtained for each instrument. Both the raw and calibrated data files will be formatted for New Horizons science team members to analyze. Both the raw and calibrated data, along with various ancillary files (such as documents describing the pipeline process or the science instruments) will be archived at the Small Bodies Node of NASA’s Planetary Data System.
More info: New Horizons
We are now in the final hours before Rosetta’s Philae lander is released to attempt a first-ever landing on a comet. At 9:03 GMT (1:03 AM PST) on Wednesday, November 12, 2014, Philae will be released and directed towards the surface of comet 67P/Churyumov–Gerasimenko. 7 hours later, the lander will touch down.
Below you’ll find a timeline of events, info on how to watch the landing, and an overview of how the landing will (hopefully) work.
In human affairs, we build contingencies for missteps, failures. With spacecraft, engineers try to eliminate all single point failures and likewise have contingency plans. The landing of a spacecraft, be it on Mars, Earth, or the Moon, always involves unavoidable single point failures and points of no return, and with comet 67P/Churyumov–Gerasimenko, Rosetta’s Philae lander is no exception.
Rosetta’s and Philae’s software and hardware must work near flawlessly to give Philae the best chance possible of landing safely. And even with flawless execution, it all depends on Philae’s intercepting a good landing spot on the surface. Philae’s trajectory is ballistic on this one way trip to a comet’s surface. It’s like a 1 mile per hour bullet. Once fired, it’s on its own, and for Philae, its trajectory could lead to a pristine flat step or it could be crevasse, ledge, or sharp rock.
Watch ESA’s live feed:
The accuracy of the landing is critical but it has left a 1 square kilometer of uncertainty. For this reason, engineers and scientists had to survey the whole surface for the most mild features. Comet 67P has few areas that are not extreme in one way or another. Site J, now called Agilkia, is one such site.
When first announced in late September, the time of release was 08:35 GMT (12:35 AM PST). Now the time is 9:03 GMT. The engineers and computer scientists have had six weeks to further refine their trajectory. It’s a complicated calculation that has required running the computer simulation of the descent backwards. Backwards because they can set a landing time then run Philae backwards to the moment of release. The solution is not just one but many, thousands or millions if you want to look in such detail. With each release point, the engineers had to determine how, or if, Rosetta could be navigated to that coordinate point in space and time.
Arrival time of the radio signal with landing status: 16:30 GMT
Rosetta/Philae at 500 million km [320 million miles], 28.5 minutes light time
Arrival of First Images: 06:00 GMT, November 13, 2014
The gravity field of the comet is so weak, it is primarily the initial velocity from Rosetta that delivers Philae to the surface. But the gravity is there and because of the chaotic shape and unknown (as yet) mass distribution inside, the gravity will make Philae move like a major league knuckleball wobbling to the plate and a batter. Furthermore, the comet during the seven hour trip will make half a rotation. The landing site will not be in site when Philae is released.
And as Philae is on final approach, it will use a small rocket not to slow down but rather thrust it at the comet, landing harpoons will be fired, foot screws will try to burrow into the comet, and everyone on Earth will wait several minutes for a message to be relayed from Philae to Rosetta to the Deep Space Network (DSN) antennas on Earth. Philae will be on its own as soon as it leaves Rosetta and its fate is a few hours away.
Why travel to a comet? Comets represent primordial material leftover from the formation of the solar system. Because cometary bodies were formed and remained at a distance from the heat of the sun, the materials have remained nearly unchanged since formation, ~4.5 billion years ago. By looking at Rosetta’s comet, 67P/Churyumov–Gerasimenko, scientists will gain the best yet measurements of a comet’s chemical makeup, its internal structure created during formation, and the dynamics of the comet as it approaches the warmth of the Sun. Theories propose that comets impacting on Earth delivered most of the water of our oceans. If correct, then we are not just made of star-stuff, as Carl Sagan proclaimed, we are made of comet stuff, too. Comets may also have delivered the raw organic materials needed to start the formation of life on Earth.
Besides the ESA live feeds, one can take a peek at NASA’s Deep Space Network (DSN) at work to see which telescopes are communicating with Rosetta. JPL’s webcast can watched below:
Past Universe Today Articles on the Rosetta Mission:
A Comet’s Tale – Rosetta’s Philae, Five Days from Touchdown
Stinky! Rosetta’s Comet Smells Like Rotten Eggs And Ammonia
Why Watch ESA Rosetta’s Movie ‘Ambition’? Because We Want to Know What is Possible
Rosetta’s Philae Lander: A Swiss Army Knife of Scientific Instruments
ESA’s Rosetta Mission sets November 12th as the Landing Date for Philae
Creepy Comet Looms In The Background Of Newest Philae Spacecraft Selfie
How Do You Land on a Comet? Very Carefully.
How Rosetta Will Send Philae Lander To Comet’s Surface (Plus, Landing Site Contest!)
Spider-Like Spacecraft Aims To Touch A Comet Next Year After Rosetta Reactivates
Rosetta’s Comet Springs Spectacular Leaks As It Gets Closer To The Sun
How Dust Lightens Up The ‘Dark Side’ Of Rosetta’s Comet
It’s Alive! Rosetta’s Comet Flares As It Approaches The Sun
India’s Mars Orbiter Mission (MOM) spacecraft was greeted via Twitter after successfully entering orbit of the Red Planet. The Curiosity Rover, a Mars old-timer of two years, sent a welcoming tweet: “Namaste @MarsOrbiter. Congratulations to @ISRO and India’s first interplanetary mission upon achieving Mars orbit.”
We jest, of course, about using Twitter for space communications. The Deep Space Network provides critical two-way communications between spacecraft and Earth.
The DSN sends information that guides and controls the spacecraft for navigation, and it collects telemetry of the data — images and scientific information — sent back by the spacecraft. NASA is not the only space agency to benefit from the international network of communications facilities that make up the DSN, as spacecraft from around the world use DSN for communications. In fact, MOM is currently sending and receiving telemetry from the DSN, as well as ISRO’s tracking station in Bangalore.
DSN is the largest and most sensitive scientific telecommunications system in the world. It consists of three deep-space communications facilities placed approximately 120 degrees apart on the globe: at Goldstone, California; near Madrid, Spain; and near Canberra, Australia. This strategic placement permits constant observation of spacecraft as the Earth rotates.
MOM now joins seven spacecraft currently operating on Mars surface or in orbit – including the newly arrived MAVEN orbiter, three longtime Mars orbiters: Mars Odyssey, Mars Reconnaissance Orbiter (MRO) and Mars Express (MEX), and two rovers on the surface, Curiosity and Opportunity.