Artist's conception of ESA's OTS-2 telecom satellite, which was retired from geostationary orbit in 1991 after nearly 13 years of service. Credit: ESA
Space junk is an ongoing concern for NASA, the European Space Agency and many others. After satellites live out their useful lives in orbit, more and more the agencies are trying to either move them far away from Earth, or to have the satellites burn up in the atmosphere. That’s basically to preserve orbital slots around the planet for others, and to reduce the risk of collisions.
But here’s an alternate approach — why not leave a few satellites handy for other missions to pick up? ESA recently opened a tender exploring this idea, and put a few thoughts out in a press release. Maybe leftover solid rocket fuel could be re-used. Metal alloys could be ground down for potential 3-D printing materials. Life support systems could use biodegradable materials. Since it costs so much to haul stuff into orbit, maybe it might be worthwhile to leave some available for future missions, ESA reasons.
Image plot of space junk. Image credit: NASA
“ESA’s new invitation for ‘Sustainable Materials Concepts’ is seeking companies to study various concepts of this approach, including considering the kinds of materials that could be reused as biological or technical nutrients – serving as resources for new other processes,” ESA stated.
“Also under consideration: what sustainable materials might replace current space-grade materials such as titanium and aluminium alloys or carbon-fibre epoxy resins? And how might the use of materials as biological or technical nutrients work in practice?”
What do you think satellites could be used for? Leave your thoughts in the comments.
The launch of Chan'ge-2 with 3rd stage (arrowed) now known as 2010 Q (Credit CALT).
Can’t find asteroid 2010 QW1 in the Minor Planet Database? No, the “Men in Black” didn’t secretly remove this Earth-orbiting asteroid from the listing… but recent top-notch detective work by astronomers did.
The mystery of this object all started back on August 23rd of this year, when the PanSTARRS sky survey based on the summit of Haleakala on the island of Maui in Hawai’i spotted an asteroid that was given the provisional designation of 2013 QW1.
The object was in a wide-ranging orbit around the Earth, leading astronomers to wonder if it was a naturally captured asteroid or perhaps space debris from a previous launch. Either solution to the dilemma would be fascinating. Our large Moon keeps the Earth pretty well swept clear of debris, though a “second Moon,” however small, would be an interesting find. And if 2013 QW1 were to prove artificial, it just might be a piece of history.
The European Space Agency’s NEO Coordination Centre decided to take up the challenge. A call went out to track and observe the 2013 QW1, and a team led by Elisabetta Dotto of INAF-Observatorio di Roma & Maria Barucci & Davide Perna of the Observatoire de Paris managed to get time on the Italian Telescopio Nazaionale Galileo based at La Palma to obtain a spectrum of the object.
“It was a bit of a challenge, because the object was moving fast with respect to a typical NEO,” said Dr. Perna in a recent ESA press release.
The team used an instrument known as DOLORES to make the crucial measurements. DOLORES stands for the Device Optimized for LOw RESolution. The spectrum obtained in the early morning hours of August 25th shows something much brighter than your typical asteroid, but is characteristic of a painted metallic object.
The launch of Chan’ge-2 with 3rd stage (arrowed) now known as 2013 QW1 (Credit: CALT).
And thus, 2013 QW1 was removed from the ledger of NEO asteroids maintained by the IAU Minor Planet Center (MPEC). And the leading suspect? The third stage booster of a Chinese Long March 3C rocket that launched the Chang’e 2 spacecraft from Xichang, China on October 1st, 2010.
Chang’e-2 entered lunar orbit 8 days after launch, and departed on June 8th of the following year after studying and mapping the Moon. Chang’e-2 then went on to become the first spacecraft to directly reach the L2 Lagrange point 1.5 million kilometres beyond Earth from lunar orbit. The spacecraft also made the first flyby of NEO asteroid 4179 Toutatis on December 13th of last year. The probe is estimated to continue functioning into 2014, and will be used to hone China’s ability to track objects in deep space.
The NORAD tracking identification assigned to the 3rd stage booster that launched Chan’ge-2 is 2010-50B.
This sort of discovery is not without precedent.
The launch of Apollo 12, with the 3rd stage (arrowed) would one day be “asteroid Joo2E3”. (Credit: NASA).
On September 3rd, 2002, amateur astronomer Bill Yeung discovered an asteroid tentatively designated J002E3. Subsequent studies revealed that the asteroid had a spectrum consistent with that of titanium oxide paint, a decidedly unasteroid-like coating for a space rock to sport. This was, however, a common veneer in use during the Apollo era, and it is now known that J002E3 is the S-IVB third stage booster that launched the second mission to land men on the Moon on November 14th, 1969. Unlike other boosters, such as the one that launched Apollo 14, the Apollo 12 3rd stage did not impact the Moon as part of seismic experiments. After a brief period as a “pseudo-moon” of the Earth, J002E3 was kicked out into solar orbit in June 2003 and may return to our neighborhood once again in the 2040s.
NASA’s Lunar Reconnaissance Orbiter has documented the lunar crash sites of these historic boosters. It’s of note that the Apollo 10 Lunar Module Snoopy remains discarded out in solar orbit as well, having been used as a dress rehearsal for the historic Apollo 11 landing. Apollo 10 never landed on the Moon. Efforts have been made by UK astronomer Nick Howes to recover it as well.
And there are more relics of the Space Age awaiting discovery. One of the first things we always check in the case of a pass by a newly discovered NEO closer than the Moon to the Earth is its history, to see if it matches up with any launches headed out beyond Earth orbit in the past.
And the upcoming Mars launches of MAVEN and India’s Mars Orbiter Mission in October & November will be the first to depart Earth orbit since 2011. These will give future generations of asteroid hunters new human-made space hardware to ponder.
The B612 Foundation’s asteroid-hunting Sentinel Space Telescope will also “up the game,” scouting for asteroids from a vantage point interior to the Earth’s orbit. Sentinel is slated for launch in 2016 atop a SpaceX Falcon 9 rocket.
And no, the fabled “Black Knight” satellite of UFO conspiracy buffs’ dreams is nowhere to be found.
What other fascinating relics of the Space Age lie are out there in the solar system, waiting to tell their tale?
Times are getting tougher in the battle to track space debris. A key asset in the fight to follow and monitor space junk is getting the axe on October 1st of this year. United States Air Force General and commander of Air Force Space Command William Shelton has ordered that the Air Force Space Surveillance System, informally known as Space Fence will be deactivated. The General also directed all related sites across the southern United States to prepare for closure.
This shutdown will be automatically triggered due to the U.S. Air Force electing not to renew its fifth year contract with Five Rivers Services, the Colorado Springs-based LLC that was awarded the contract for the day-to-day management of the Space Fence surveillance system in 2009.
To be sure, the Space Fence system was an aging one and is overdue for an upgrade and replacement.
The Space Fence system was first brought on line in the early days of the Space Age in the 1961. Space Fence was originally known as the Naval Space Surveillance (NAVSPASUR) system until passing into the custody of the U.S. Air Force’s 20th Space Control Squadron in late 2004. Space Fence is a series of multi-static VHF receiving and transmitting sites strung out across the continental United States at latitude 33° north ranging from California to Georgia.
The Worldwide Space Surveillance Network, including Space Fence across the southern United States. (Credit: the U.S. Department of Defense).
Space Fence is part of the greater Space Surveillance Network, and comprises about 40% of the overall observations of space debris and hardware in orbit carried out by the U.S. Air Force. Space Fence is also a unique asset in the battle to track space junk and dangerous debris, as it gives users an “uncued” tracking ability. This means that it’s constantly “on” and tracking objects that pass overhead without being specifically assigned to do so.
Space Fence also has the unique capability to track objects down to 10 centimeters in size out to a distance of 30,000 kilometres. For contrast, the average CubeSat is 10 centimetres on a side, and the tracking capability is out to about 67% of the distance to geosynchronous orbit.
Exact capabilities of the Space Fence have always been classified, but the master transmitter based at Lake Kickapoo, Texas is believed to be the most powerful continuous wave facility in the world, projecting at 768 kilowatts on a frequency of 216.97927 MHz. The original design plans may have called for a setup twice as powerful.
A replacement for Space Fence that will utilize a new and upgraded S-Band radar system is in the works, but ironically, that too is being held up pending review due to the sequestration. Right now, the Department of Defense is preparing for various scenarios that may see its budget slashed by 150 to 500 billion dollars over the next 10 years.
The control center display of the prototype for the next generation Space Fence. (Credit: Lockheed Martin).
The U.S. Air Force has already spent $500 million to design the next generation Space Fence, and awarded contracts to Raytheon, Northrop Grumman and Lockheed Martin in 2009 for its eventual construction.
The eventual $3 billion dollar construction contract is on hold, like so many DoD programs, pending assessment by the Strategic Choices and Management Review, ordered by Secretary of Defense Chuck Hagel earlier this year.
“The AFSSS is much less capable than the space fence radar planned for Kwajalein Island in the Republic of the Marshall Islands,” stated General Shelton in a recent U.S. Air Force press release. “In fact, it’s apples and oranges in trying to compare the two systems.”
One thing’s for certain. There will be a definite capability gap when it comes to tracking space debris starting on October 1st until the next generation Space Fence comes online, which may be years in the future.
In the near term, Air Force Space Command officials have stated that a “solid space situational awareness” will be maintained by utilizing the space surveillance radar at Eglin Air Force Base in the Florida panhandle and the Perimeter Acquisition Radar Characterization System at Cavalier Air Force Station in North Dakota.
We’ve written about the mounting hazards posed by space debris before. Just earlier this year, two satellites were partially damaged due to space debris. Space junk poses a grave risk to the residents of the International Space Station, which must perform periodic Debris Avoidance Maneuvers (DAMs) to avoid collisions. Astronauts have spotted damage on solar arrays and handrails on the ISS due to micro-meteoroids and space junk. And on more than one occasion, the ISS crew has sat out a debris conjunction that was too close to call in their Soyuz spacecraft, ready to evacuate if necessary.
In 2009, a collision between Iridium 33 and the defunct Cosmos 2251 satellite spread debris across low Earth orbit. In 2007, a Chinese anti-satellite missile test also showered low Earth orbit with more of the same. Ironically, Space Fence was crucial in characterizing both events.
Satellites, such as NanoSail-D2, have demonstrated the capability to use solar sails to hasten reentry at the end of a satellites’ useful life, but we’re a long ways from seeing this capability standard on every satellite.
Amateurs will be affected by the closure of Space Fence as well. Space Weather Radio relies on ham radio operators, who listen for the “pings” generated by the Space Fence radar off of meteors, satellites and spacecraft.
“When combined with the new Joint Space Operations Center’s high-performance computing environment, the new fence will truly represent a quantum leap forward in space situational awareness for the nation,” General Shelton said.
But for now, it’s a brave and uncertain world, as Congress searches for the funds to bring this new resource online. Perhaps the old system will be rescued at the 11th hour, or perhaps the hazards of space junk will expedite the implementation of the new system. Should we pass the hat around to “Save Space Fence?”
Artist's concept of a GOES spacecraft in orbit. (Credit: NOAA.gov).
It’s sometimes tough being a satellite in Earth orbit these days.
An interesting commentary came our way recently via NASA’s Orbital Debris Program Office’s Orbital Debris Quarterly News. The article, entitled High-Speed Particle Impacts Suspected in Two Spacecraft Anomalies, highlights a growing trend in the local space environment.
The tale begins with GOES 13 located in geostationary orbit over longitude 75° West. Launched on May 24th, 2006 atop a Delta IV rocket, GOES 13 is an integral part of the U.S. National Oceanic and Atmospheric Administration (NOAA’s) Geostationary Operational Environmental Satellite network.
The problems began when GOES-13 began to suffer an “attitude disturbance of unknown origin” on May 22nd of this year, causing it to drift about two degrees per hour off of its required nadir (the opposite of zenith) pointing.
The anomaly was similar to a problem encountered by the NOAA 17 spacecraft on November 20th, 2005. At the time, the anomaly was suspected to be due to a micrometeoroid impact. The Leonid meteors, which peak right around the middle of November, were a chief suspect. However, NOAA 17 suffered a second failure 18 days later, which was later traced down to a hydrazine leak from its errant thrusters.
GOES-13 has weathered hard times before. Back in December of 2006, GOES-13’s Solar X-Ray Imager suffered damage after being struck by a solar flare shortly after initial deployment. GOES-13 also began returning degraded imagery in September 2012, forcing it into backup status for Hurricane Sandy.
GOES-13 was restored to functionality last month. Current thinking is that the satellite was struck by a micrometeorite. No major meteor showers were active at the time.
Loss of a GOES satellite would place a definite strain on our weather monitoring and Earth observing capability. Begun with the launch of GOES-1 in 1975, currently six GOES satellites are in operation, including one used to relay data for PeaceSat (GOES-7) and one used as a communications relay for the South Pole research station (GOES-3).
The GOES program cost NOAA billions in cost overruns to execute. The next GOES launch is GOES-R scheduled in 2015.
But the universe seems to love coincidences.
NEE-01 Pegaso before deployment. (Credit: Wikimedia Commons image in the Public Domain).
Less than 26 hours after the GOES 13 anomaly, Ecuador’s first satellite, NEE-01 Pegaso began to have difficulties keeping a stable attitude. The event happened shortly after passage near an old Soviet rocket booster (NORAD designation 1986-058B) which launched Kosmos 1768 on August 2nd, 1986. The U.S. Joint Space Operations Center had warned the fledgling Ecuadorian Space Agency that conjunction was imminent, but of course, there’s not much that could’ve been done to save the tiny CubeSat.
Although the main mass passed Pegaso at a safe distance, current thinking is that the discarded booster may have left a cloud of debris in its wake. Researchers have tracked small “debris clouds” around objects it orbit before- the collision of Iridium 33 and the defunct Kosmos 2251 on February 10th, 2009 left a ring of debris in its wake, and the Chinese anti-satellite test carried out on January 11th, 2007 showered low-Earth orbit with debris for years to come.
The loss represents a blow to Ecuador and their first bid to become a space-faring nation. Launched less than a month prior atop a Long March 2D rocket, Pegaso was a small 10 centimetre nanosatellite equipped with solar panels and dual infrared and visible Earth imaging systems.
A translation from the Ecuadorian Space Agencies site states that;
“The NEE-01 survived the crash and remains in orbit; however it has entered uncontrolled rotation due to the event.
Due to this rotation, (the satellite) cannot point its antenna correctly and stably to the Earth station and although still transmitting and running, the signal cannot be decoded. The Ecuadorian Civilian Space Agency is working tirelessly to stabilize the NEE-01 and recover the use of their signal.
The PEGASUS aired for 7 days your signal to the world via EarthCam, millions could see the Earth seen from space in real time, many for the first time, the files in those 7 days have been published after transmission.”
Ecuador plans to launch another CubeSat, NEE 02 Krysaor later in 2013. A carrier has not yet been named.
While both events suffered by the GOES-13 and NEE-01 Pegaso satellites were unrelated, they underscore problems with space junk and space environmental hazards that are occurring with a higher frequency.
Gabbard diagram displaying a sample disintegration of a Long March 4 booster in 2000. (Credit: the NASA Orbital Debris Office).
Such is the modern hazardous environment of low Earth orbit that new satellites must face. With a growing amount of debris, impact threats are becoming more common. The International Space Station must perform frequent debris avoidance maneuvers to avoid hazards, and more than once, the crew has waited out a pass in their Soyuz escape modules should immediate evacuation become necessary. Punctures from micro-meteoroids or space junk have even been seen recently on the ISS solar panel arrays.
Plans are on the drawing board to deal with space junk, involving everything from “space nets” to lasers and even more exotic ideas. Probably the most immediate solution that can be implemented is to assure new payloads have a way to “self-terminate” via de-orbit at the end of their life span. Solar sail technologies, such as NanoSailD2 launched in 2010 have already demonstrated this capability.
Expect reentries also pick up as we approach the peak of solar cycle #24 at the end of 2013 and the beginning of 2014. Increased solar activity energizes the upper atmosphere and creates increased drag on low Earth satellites.
It’s a brave new world “up there,” and hazards, both natural and man-made, are something that space faring nations will have to come to terms with.
-Read and subscribe to the latest edition of NASA’s Orbital Debris Quarterly News for free here.
We love a good space debris mystery. Hey, who doesn’t, right? Regular readers of Universe Today know that it’s a shooting gallery out there, from meteor fireballs caught on dashboard cams to rogue space junk reentries lighting up our skies.
But an unusual story that made its rounds across the internet this past weekend caught our attention. What at first glance was a simple “Man finds space rock” story morphed into an extraordinary claim, which, in the words of the late great Carl Sagan, “demand extraordinary evidence.”
The find was made by Phil Green of Amesbury, Massachusetts. Mr. Green was searching the local riverbed for arrowheads when he came across the unusual find. The black pitted rock immediately struck him as something bizarre. It didn’t register as metallic to his metal detector, but Mr. Green kept it in his backyard for about five years until it was noticed by a friend.
“I didn’t really think much of it, and then a fellow came over, saw it and said that’s a meteor,” Green told local reporters.
From here, the story takes a strange turn. Green told local reporters that the rock was sent off for analysis, only to be returned to him just a few weeks ago. The analysis confirmed that the rock was indeed from space… sort of. It also stated that the vitreous material “shows a composition similar to that used in ballast by the Soviet space program starting in the mid-1980s.”
There are just a few problems with the tale. Mir reentered in 2001, six years before the 2007. A few articles do bother to note this, mentioning that Mir ended its career in the “so-called spacecraft cemetery of the southern Pacific Ocean,” about as far away from Massachusetts as you can get.
A few articles do also mention the possibility of a reentry of a Progress resupply vehicle being a potential source, or perhaps an unrelated Russian space vehicle.
But there seems to be a potential problem of the certification. Several articles state that the piece of debris coming from Mir was “confirmed by NASA.” However, Universe Today contacted NASA Chief Scientist for Orbital Debris Nicholas L. Johnson and NASA Headquarters official Joshua Buck, who both told us that no such NASA validation exists. Mr. Johnson went on to tell Universe Today that, “The NASA Orbital Debris Program Office has not been presented with any claim regarding debris from the Mir space station,” adding “I can tell you that it is not possible for debris from the Mir reentry to have landed in the U.S.”
A name that occasionally turns up in reports online as validating the find (withheld by request) also tells Universe Today that they had nothing to do with the discovery. Mr. Green or the original validation source have thus far been unavailable for comment.
We did uncover two documented reentries that occurred over the general region over the last few decades. One is the reentry of Mir-R 1986-017B (The rocket booster that launched the core module of Mir) seen from a trans-Atlantic airliner on February 24th 1986 about 500 kilometres off of the east coast of Newfoundland. Another possible suspect is the June 26/27th 2004 reentry of a SL-12 auxiliary rocket motor with the NORAD ID 1992-088E, seen to the west from New Jersey to Ontario.
Like the International Space Station, Mir was placed in a 51.6° inclined orbit. This made it accessible from the Baikonur Cosmodrome as well as visits from the U.S. Space Shuttle. Payloads going to and from the station would cover an identical ground track ranging from 51.6° north to south latitude.
The story is also reminiscent of the reentry of debris from Sputnik 4, which struck a small town in Wisconsin in 1962. This was analyzed by mineralogist Ursula Marvin and confirmed to be of Russian origin.
A Progress spacecraft inbound for docking with the International Space Station. (Credit: NASA).
Probably the biggest question in our minds is: what links the object back to an errant Russian spacecraft? What do they use for ballast, anyhow? How did they arrive at the often quoted “85% certainty?” of the object’s origin?
Still, the find does look like something interesting. The pitting and the melted fusion crust are all reminiscent of reentry. We’ll keep researching this story, and for the time being we’ll leave it up to you, the diligent and insightful readers of Universe Today, to make up your own minds on this strange and interesting tale.
Artist concept of the Fermi Space Telescope. Credit: NASA.
As a space telescope scientist or satellite operator, the last thing you want to hear is that your expensive and possibly one-of-a kind — maybe irreplaceable — spacecraft is in danger of colliding with a piece of space junk. On March 29, 2012, scientists from the Fermi Gamma-ray Space Telescope were notified that their spacecraft was at risk from a collision. And the object heading towards the Fermi spacecraft at a relative speed of 44,000 km/h (27,000 mph) wasn’t just a fleck of paint or tiny bolt.
Fermi was facing a possible direct hit by a 1,400 kg (3,100-pound) defunct Russian spy satellite dating back to the Cold War, named Cosmos 1805. If the two satellites met in orbit, the collision would release as much energy as two and a half tons of high explosives, destroying both spacecraft and creating more pieces of space junk in the process.
But this story has a happy ending, with the Fermi telescope still operating and continuing its mission to map the highest-energy light in the universe, all thanks to a little orbital traffic control.
You can watch the video here for the complete story, or read more at the Fermi website about how the Fermi Space Telescope dodged a speeding bullet.
The International Space Station will have to look out for new debris from an exploded Russian rocket (NASA image)
Traveling through low-Earth orbit just got a little more dangerous; a drifting Russian Breeze M (Briz-M) rocket stage that failed to execute its final burns back on August 6 has recently exploded, sending hundreds of shattered fragments out into orbit.
Russia and the U.S. Defense Department (JFCC-Space) have stated that they are currently tracking 500 pieces of debris from the disintegrated Breeze M, although some sources are saying there are likely much more than that.
After a successful liftoff via Proton rocket on August 6 from the Baikonur Cosmodrome, the Breeze M upper stage’s engines shut off after only 7 seconds as opposed to the normal 18 minutes, leaving its fuel tanks filled with 10 to 15 tons of hydrazine and nitrogen tetroxide propellants. Its payloads, the Indonesian Telkom 3 and the Russian Express-MD2 communications satellites, were subsequently deployed into the wrong orbits as the Breeze M computer continued functioning.
Although originally expected to remain intact for at least another year, the rocket stage “violently disintegrated” on October 16. Evidence of the explosion was first observed by astronomer Robert McNaught at Australia’s Siding Springs Observatory, who counted 70 fragments visible within the narrow field-of-view telescope he was using for near-Earth asteroid observations.
The exact cause of the explosion isn’t known — it may have been sparked by an impact with another piece of space junk or the result of stresses caused by the Breeze M’s eccentric orbit, which varied in altitude from 265 to 5,015 kilometers (165 miles to 3,118 miles) with an inclination of 49.9 degrees.
This was the third such breakup of a partially-full Breeze M upper stage in orbit, the previous events having occurred in 2007 and 2010, and yet another Breeze M still remains in orbit after a failed burn in August 2011.
Most of the latest fragments are still in orbit at altitudes ranging from 250 to 5,000 km (155 to 3,100 miles), where they are expected to remain.
“Although some of the pieces have begun to re-enter, most of the debris will remain in orbit for an extended period of time.”
– Jamie Mannina, US State Department spokesperson
According to NASA the debris currently poses no immediate threat to the Space Station although the cloud is “believed not to be insignificant.” Still, according to a post on Zarya.com the Station’s course will periodically take it within the Breeze M debris cloud, and “will sometimes spend several days at a time with a large part of its orbit within the cloud.”
Source: RT.com and SpaceflightNow.com. Inset image: the Breeze M (Briz-M) upper stage which disintegrated on Oct. 16. (Khrunichev)
UPDATE (9/27/2012, 13:00 UTC) NASA now says that with additional tracking, they have determined the two pieces of space debris do not pose a threat to the ISS, and a debris avoidance maneuver scheduled for Thursday morning was cancelled by the flight control team at Mission Control. The ATV undocking time on Friday is still being decided at the time of this posting. See additional info at NASA’s website.(End of update)
International Space Station officials are keeping a watchful eye on two different pieces of space junk that may require the ISS to steer away from potential impact threats. Debris from the Russian COSMOS satellite and a fragment of a rocket from India may come close enough to the space station to require a debris avoidance maneuver. If needed, the maneuver would be done using the ESA’s Automated Transfer Vehicle (ATV) “Edoardo Amadi.” The ATV was supposed to undock last night, but a communications glitch forced engineers to call off the departure.
Both pieces of debris are edging just inside the so-called “red zone” of miss distance to the station with a time of closest approach calculated to occur Thursday at 14:42 UTC (10:42 a.m. Eastern time.) It is not known how large the object is.
An approach of debris is considered close only when it enters an imaginary “pizza box” shaped region around the station, measuring 1.5 x 50 x 50 kilometers (about a mile deep by 30 miles across by 30 miles long) with the vehicle in the center.
NASA says the three-person Expedition 33 crew is in no danger and continues its work on scientific research and routine maintenance. The current crew includes NASA astronaut Sunita Williams, Japanese astronaut Akihiko Hoshide and Russian cosmonaut Yuri Malenchenko.
If the maneuver is required – and NASA said it could be called off any time — it would occur at 12:12 UTC (8:12 a.m. EDT) Thursday, using the engines on the ATV, which remains docked to the aft port of the Zvezda Service Module. It usually takes about 30 hours to plan for and verify the need for an avoidance maneuver.
Debris avoidance maneuvers are conducted when the probability of collision is greater than 1 in 100,000, if it will not result in significant impact to mission objectives. If it is greater than 1 in 10,000, a maneuver will be conducted unless it will result in additional risk to the crew.
Only three times during the nearly 12 years of continual human presence on the ISS has a collision threat been so great that the crew has taken shelter in the Soyuz vehicles. (Those events occured on March 12, 2009, June 28, 2011 and March 24, 2012.) During those events, the station was not impacted. While the ISS likely receives small micrometeoroid hits frequently (based on experiments left outside the ISS and visual inspections of the station’s hull) no large debris impacts have occurred that have caused depressurization or other problems on the ISS.
Tuesday’s initial attempt to undock the ATV was called off due to a communications error between the Zvezda module’s proximity communications equipment and computers on the ATV. Russian engineers told mission managers that they fully understand the nature of the error and are prepared to proceed to a second undocking attempt, which has been postponed to Friday at the earliest, due to the potential space debris threat.
Once it is undocked, the ATV will move to a safe distance away from the station for a pair of engine firings that will send the cargo ship back into the Earth’s atmosphere to burn up over the Pacific Ocean.
The ATV still has extra fuel on board, and so the decision was made that if need, that available resource would be used.
Artist's impression of debris in low Earth orbit. Credit: ESA
Caption: Artist’s impression of debris in low earth orbit Credit: ESA
Space may be big — vastly, hugely, mind-bogglingly big — but the space around Earth is beginning to get cluttered with space junk. This poses a threat, not only to other satellites, space stations and missions, but to us here on Earth as well. While we wrestle with environmental issues posed by human activity on our planet, ESA’s new ‘Clean Space’ initiative aims to address the same issues for its missions, making them greener by using more eco-friendly materials and finding ways to cut down levels of space debris.
Last month ESA and Eurospace organized the Clean Space Eco-design and Green Technologies Workshop 2012 held in the Netherlands. Clean Space is a major objective of Agenda 2015, the Agency’s upcoming action plan. The aim was outlined by ESA Director General Jean-Jacques Dordain: “If we are convinced that space infrastructure will become more and more essential, then we must transmit the space environment to future generations as we found it, that is, pristine.”
The workshop looked at all aspects of space missions, their total environment impact, from concept development to end of life. The impact of regulations regarding substances such as hydrazine, which is used widely as a propellant in space programs and the development of Green Propulsion with propellants that have a reduced toxicity. Environmental friendliness and sustainability often mean increased efficiency, which ESA hopes will give the industry a competitive advantage, so they are looking at technologies which will consume less energy and produce less waste, therefore cutting costs.
Finally they looked at debris mitigation to minimize the impact to the space environment as well as the debris footprint on Earth using controlled and uncontrolled re-entry events and passive de-orbiting systems along with active de-orbiting and re-orbiting systems. They are even considering tethers or sails to help drag abandoned satellites out of low orbit within 25 years. New ‘design for demise’ concepts hope to prevent chunks of satellites surviving re-entry and hitting the ground intact. Active removal of existing debris is also needed, including robotic missions to repair or de-orbit satellites.
6,000 satellites have been launched during the Space Age; less than 1000 of these are still in operation. The rest are derelict and liable to fragment as leftover fuel or batteries explode. Traveling at around 7.5 km/s, a 2 cm screw has a ‘lethal diameter’ sufficient to take out a satellite. Taking the recent loss of the Envisat satellite as an example, this satellite now poses a considerable threat as space junk. An analysis of space debris at Envisat’s orbit suggests there is a 15% to 30% chance of collision with another piece of junk during the 150 years it is thought Envisat could remain in orbit. The satellite’s complexity and size means even a small piece of debris could cause a “fragmentation event” producing its own population of space garbage. Envisat is also too big to be allowed to drift back into the Earth’s atmosphere. The choices seem to be to raise the satellite to a higher, unused orbit, or guide it back in over the Pacific Ocean.
As ESA Director General Jean-Jacques Dordain says “We will not succeed alone; we will need everyone’s help. The entire space sector has to be with us.”
Find out more about ESA’s Clean Space initiative here
Simulation of how Space Fence will track orbital space debris. Image courtesy Lockheed Martin
[/caption]
Several times a year, the International Space Station needs to perform Debris Avoidance Maneuvers to dodge the ever-growing amount of space junk hurtling around in Earth orbit. Additionally, our increased dependence on satellites for communications and navigation is threatened by the risk of potential collisions with space debris. The existing system for finding and tracking objects, the Air Force Space Surveillance System, or VHF Fence, has been in service since the early 1960s, and is sorely out of date. But a prototype system called Space Fence has now been tested in a series of demonstrations, and successfully tracked more and smaller pieces of debris than the current system.
“The current system has the ability to track about 20,000 objects,” Lockheed Martin spokesperson Chip Eschenfelder told Universe Today, “but there millions of objects out there, many of which are not being tracked. Space Fence will find and catalog smaller objects than what are not being tracked now.”
Space Fence will use powerful new ground-based S-band radars to enhance the way the U.S. detects, tracks, measures and catalogs orbiting objects and space debris with improved accuracy, better timeliness and increased surveillance coverage, Lockheed Martin said. In recent tests, the Space Fence prototype proved it could detect more and smaller objects than the current system.
Space debris includes non-operational satellites, and leftover rocket parts from launches. Basically, every time there is a launch, more debris is created. Collisions between the current debris create even more pieces that are smaller and harder to detect. With the debris traveling at lightning-fast orbital speeds, even pieces as small as a paint chip could be deadly to an astronaut on EVA at the space station, or could take out a telecommunications or navigation satellite.
A look at the Space Fence control center. Credit: Lockheed Martin
The developers of Space Fence say the new system will revolutionize what’s called ‘space situational awareness,’ which characterizes the space environment and how it will affect activities in space.
“Space Fence will detect, track and catalog over 200,000 orbiting objects and help transform space situational awareness from being reactive to predictive,” said Steve Bruce, vice president of the Space Fence program. “The Air Force will have more time to anticipate events potentially impacting space assets and missions.
The current system has tracking locations in the US only and has a huge ‘blind spot’ by not supplying information about debris in the southern hemisphere. But Space Fence will provide global coverage from three ground-based radar located at strategic sites around the world.
On February 29, 2012, the Air Force granted its final approval of Lockheed Martin’s preliminary design, and they expect the new system’s initial operational capability to be sometime in 2017.
“The successful detection and tracking of resident space objects are important steps in demonstrating technology maturity, cost certainty and low program risk,” said Bruce in a statement. “Our final system design incorporates a scalable, solid-state S-band radar, with a higher wavelength frequency capable of detecting much smaller objects than the Air Force’s current system.”
