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.
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.
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.
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.”
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.
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.
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:
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.
When you’re talking to spacecraft billions of miles away, you need a powerful voice. And when you’re listening for their faint replies from those same staggering distances, you need an even bigger set of ears. Fortunately, NASA’s Deep Space Network has both — and last week I had the chance to see some of them up close and in person as one of the lucky participants in a NASA Social! Here’s my overview of what happened on those two exciting days.
(And if this doesn’t make you want to apply for the next Social, I don’t know what will.)
The event began on April 1 (no foolin’) at NASA’s Jet Propulsion Laboratory in Pasadena. Nestled at the feet of steep pine-covered hills northeast of Los Angeles, JPL’s campus is absolutely gorgeous… not quite the location you might imagine for the birthplace of robotic interplanetary explorers! But for over 55 years JPL has been developing some of the world’s most advanced spacecraft, from the Ranger probes which took NASA’s first close-up images of the Moon to the twin Voyagers that toured the Solar System’s outer planets, countless Earth-observing satellites that have revolutionized our ability to monitor global weather, and all of the rovers that have been our first “wheels on the ground” on Mars.
Of course, none of those missions would have been possible if we didn’t have the ability to communicate with the spacecraft. That’s why NASA’s Deep Space Network is such an integral — even if not oft-publicized — part of each and every mission… and has been for 50 years.
In fact, that was the purpose of this Social event which gathered together 50 space fans from across the U.S. — to celebrate the achievements of the DSN with an eye-opening tour of both JPL and the DSN’s Goldstone facility with its flagship 70-meter dish, located amongst the rocky scrub-covered hills in the middle of a military base in California’s Mojave desert.
For many participants — including myself — it was the first time visiting JPL. I can’t tell you how many times I’ve written about the news that comes out of it, featured its amazing images, and typed the credit line “NASA/JPL-Caltech” in the caption of a picture, so for me it was incredible to actually be there in person. Just driving through the front gate at JPL, with “Welcome To Our Universe” mounted over the window of the guard station, was mind-blowing!
From the Visitor’s Center we were gathered into groups and taken into the heart of JPL to get a look at the Mission Control room, aka the “center of the universe.” This is where all the data from ongoing space exploration missions arrives (after being collected by the Deep Space Network, of course.) And we didn’t just get to see Mission Control — we actually set up our computers there and got to take our seats at the very same desks that top JPL and NASA engineers and scientists used during the MSL landing in August 2012! In fact we were treated to a replay of Curiosity’s landing on the screens against the wall that first displayed the rover’s images of Gale Crater. The whole experience was a bit surreal — I vividly recall watching it live, and there we were in the same room as if it were happening all over again! (We even got to re-enact the celebration of the touchdown announcement as our group photo.)
After several presentations and Q&A sessions with NASA mission engineers — recorded live for NASA TV — we all embarked on a tour of JPL’s rock-strewn “Mars Yard” where a stunt double of Curiosity, named “Maggie,” resides in a super high-tech garage. Maggie helps engineers determine what Curiosity can and can’t do on Mars… much more safely than actually having the “real” rover attempt itself.
Watch the NASA TV coverage from Mission Control below:
The group then got the chance to see an actual spacecraft being built in the Spacecraft Assembly Facility, a huge clean room where engineers were building components of the upcoming SMAP (Soil Moisture Active Passive) satellite. Slated for launch in October, SMAP will take measurements of the planet’s soil moisture in its freeze/thaw states from orbit over a period of three years. As we watched from the windowed viewing platform several “bunny-suited” engineers were busy working on SMAP’s 6-meter reflector. In another six months or so the parts that were scattered around that clean room will be performing science in orbit!
From there it was off to the JPL museum and some intimate (and highly animated!) discussions about mission technology with project formulator Randii Wessen and propulsion engineer Todd Barber. Afterward I took the opportunity to talk with Todd a bit about his role on the Cassini mission, for which he’s the lead propulsion engineer.
(You all know how much I adore Cassini, so that was a real treat.)
When we got back to Mission Control we had a chance to meet with and have photos taken with JPL’s very own “Mohawk guy” Bobak Ferdowsi, who achieved widespread fame during the internet broadcast landing of Curiosity. I had Bobak sign my toy Curiosity rover, which now has a “BF” on the back of its die-cast RTG. One for the space shelf!
The second half of the Social began early the next day — for me, very early. After getting up at 3:15 a.m. and making a two-hour drive from Pasadena to Barstow in the dark, I and the other participants met up with the Social bus in a park-and-ride lot at 6:00 just as the Sun was beginning to brighten the eastern sky. (Some had stayed overnight in Barstow, while others made the early drive out like I did.) Once the bus filled, we headed north into the Mojave to arrive at NASA’s Deep Space Network Communications Complex at Goldstone, located within the Fort Irwin military training area.
The location is rugged and remote — the perfect place to listen for the faint signals from spacecraft trundling across dusty Mars and soaring through the farthest reaches of the Solar System! The nine main DSN antennas at Goldstone are scattered across several square miles of desert, enormous dishes pointed more-or-less directly upward, aiming at the locations of distant spacecraft in order to both receive and transmit data. All of them are huge, but by far the most impressive is the gigantic 70-meter DSS-14 dish that towers above the rest in both height and width.
Recently renovated , the fully-positionable DSS-14 “Mars antenna” dish (so called because of its first mission tracking the Mariner 4 spacecraft in 1965) weighs in at 2.7 million kilograms yet “floats” atop a thin film of oil a quarter of a millimeter thick!
How smoothly does a three-thousand-ton radar dish move? We got to find out — check out the video below:
(Note: as it turned out, DSS-14 wasn’t turning to communicate with anything… the show was just for us!)
Of course, we all spent plenty of time taking pictures of the 70-meter, both inside and out — we were treated to a tour of this and several other dish sites hosted by JPL’s Jeff Osman, a specialist in the DSN antennas and their operations.
(One of us even chose to record the DSS-14 antenna with pencils and paper — watch fellow Social participant Jedediah Dore’s sketch and account of the experience here.)
The highlight of the day at Goldstone was (if not just being there!) was being present for the official celebration of the facility’s 50th anniversary. Featuring speakers from JPL and DSN, as well as many esteemed guests, the event — held indoors because of strong winds outside — commemorated the impact and important contributions of the complex over the past half-century of space exploration. According to speaker Jim Erickson of JPL, “There hasn’t been a time in my career when the DSN wasn’t there for us.”
After that the NASA Social group was invited to take a few moments to mingle with speakers and guests — when else would I have a chance to chat with JPL director Dr. Charles Elachi? — and then we all returned to our own meeting room where refreshments were waiting and a (quite delicious) DSN50 cake was cut and served.
It was truly a fantastic and well-planned event, giving 50 people the chance to see an integral part of our space program that, although it doesn’t usually receive the same kind of exposure that rocket launches and planetary landings enjoy, makes all of it possible.
Here’s to 50 more years of DSN and its long-distance relationship with all of our intrepid space explorers!
See what communications are currently coming in and going out of the DSN dishes — in Goldstone as well as in Madrid and Canberra — here, and learn more about the history of Goldstone here.
And a big thanks to Courtney O’Connor, Veronica McGregor, John Yembrick, and Stephanie Smith for putting this NASA Social together, Annie Wynn and Shannon Moore for setting up and organizing participant groups on Facebook and Google (which makes offsite planning so much easier), Jeff Osman and Shannon McConnell for the tours of the DSN sites and, of course, everyone at JPL and Goldstone who helped to make the event a wonderful success!
Would you like to be a part of a NASA Social? Find out what events are coming up and how to apply for them here.
How do scientists and engineers communicate with their spacecraft? All the robotic missions going to various points in our Solar System wouldn’t be possible if not for the Deep Space Network. And now there’s a fun new tool to watch how that communication works.
DSN Now is a live visualization of NASA’s Deep Space Network usage and which spacecraft the various antennae are talking to.
It shows realtime data of which of the three antenna complexes are being used to communicate with the various missions, how far away the spacecraft are, and various other details about data rates, speeds and modes. DSN Now is from NASA’s wonderful Eyes on the Solar System website (which uses real data to provide simulated 3-D views from of the Solar System). DSN Now came online today, March 14, 2014.
The Deep Space Network is not only used for sending commands and receiving data, but also for orbit determination, which is keeping track of where the spacecraft are with radiometric tracking data so that spacecraft navigators can get probes exactly where the scientists want them to go. The three 70-meter antennas, located at the DSN complexes at Goldstone, California, Madrid, Spain, and Canberra, Australia.
Now that’s a tune for a space geek’s ears. This is a highly modified sound bite of ranging signals between the Pluto-bound New Horizons spacecraft with NASA’s Deep Space Network (DSN) receiving stations.
What are the changes? The frequency has been altered to something that human ears can hear, explained a scientist in a New Horizons blog post this week:
“The ranging technique is just like seeing how much time it takes to hear the echo of your voice reflected off some object to measure how far away you are,” stated Chris DeBoy, New Horizons telecommunications system lead engineer who is with the Johns Hopkins Applied Physics Laboratory.
The ranging code first emanated from the DSN, which sent it to New Horizons. The spacecraft demodulated (or processed) the signal and sent it back to Earth. The DSN then calculated the delay (in seconds) between when it sent the signal, and when the answer was received.
“The DSN’s ‘voice’ is a million or more times higher in frequency than your voice, travels almost a million times faster than the speed of sound, and the round-trip distance is more than four billion miles,” DeBoy added.
In this case, the signals were sent June 29, 2012 from a DSN station in Goldstone, California. The answer arrived at a fellow DSN station in Canberra, Australia and yielded a round trip time of six hours, 14 minutes and 29 seconds.
Despite its great distance away, New Horizons is still almost two years from its brief encounter with Pluto and its moons in July 2015. Some interesting trivia about the mission: some Plutonian moons were discovered while the spacecraft was en route. Shows how quickly science changes in a few years.