Why do satellites fail?
Although it may seem like a simple question, the
answer is sometimes elusive. When a spacecraft like the European Space
Agency’s Olympus communication satellite in 1993 or the Japan Aerospace
Exploration Agency’s Midori II in 2002 just stops working, it has not
always been possible to determine exactly what went wrong. Micrometeoroid
impacts, space debris collisions, and radiation-induced electronics hangs up can
usually be tracked down. But if none of these culprits fits the available data,
satellite operators have had to mark it up to fickle fortune and eat the loss.
These types of failures caught the attention of Stanford University researcher Sigrid Close. Close’s experiments have pointed to a potential culprit: space dust.
Space dust, or cosmic dust, generally travelling in the range of 10-40 km/s, becomes plasma upon collision with an object. Larger particle collisions also generate plasma, but these collisions are much rarer and generally more detectable, so they are not good candidates to explain unexplained satellite failures. Close has found through ground experiments at the Max Planck Institute that plasma striking satellite-like bodies can emit electromagnetic pulses able to disrupt spacecraft electronics.
“Spacecraft transmit a radio signal, so they can receive one that might potentially disable them,” Close told. “So our question was: Do these plasmas emit radio signals, and if so, at what frequencies and with what power?”
Close and her colleagues proved out the theory by firing 60 km/s dust particles at targets. ”We found that when these particles hit, they create a plasma or quasi-neutral gas of ions and electrons, and that plasma can then emit in the radio frequency range,” Close said. Tellingly, these radio emissions did not always occur, being highly dependent on orientation and thermal variations of the “spacecraft” targets. This variation both explains why the cause of these failures has been so elusive and provides potential protection mechanisms to prevent such failures in future. “There are solutions we could implement to save billions and billions of dollars,” Close avers.
Studying cosmic dust can be challenging, since it is very difficult to capture for study. NASA’s Stardust mission succeeded in capturing some particles of interplanetary dust, only to discover how challenging it is to find miniscule dust particles in an aerogel array. Stardust ended up enlisting thousands of volunteers to pore over thousands of three dimensional image stacks hunting for the elusive particles; they’re still looking, seven years later. Hopefully, Close’s simulated dust behaves sufficiently like the real thing to bypass the need for improved compositional and configurational veracity. Close will determine whether her model fits the bill with her upcoming in situ experiments outside the International Space Station. She is now working with NASA Jet Propulsion Laboratory scientists to prepare that hardware for deployment. Related...
These types of failures caught the attention of Stanford University researcher Sigrid Close. Close’s experiments have pointed to a potential culprit: space dust.
Space dust, or cosmic dust, generally travelling in the range of 10-40 km/s, becomes plasma upon collision with an object. Larger particle collisions also generate plasma, but these collisions are much rarer and generally more detectable, so they are not good candidates to explain unexplained satellite failures. Close has found through ground experiments at the Max Planck Institute that plasma striking satellite-like bodies can emit electromagnetic pulses able to disrupt spacecraft electronics.
“Spacecraft transmit a radio signal, so they can receive one that might potentially disable them,” Close told. “So our question was: Do these plasmas emit radio signals, and if so, at what frequencies and with what power?”
Close and her colleagues proved out the theory by firing 60 km/s dust particles at targets. ”We found that when these particles hit, they create a plasma or quasi-neutral gas of ions and electrons, and that plasma can then emit in the radio frequency range,” Close said. Tellingly, these radio emissions did not always occur, being highly dependent on orientation and thermal variations of the “spacecraft” targets. This variation both explains why the cause of these failures has been so elusive and provides potential protection mechanisms to prevent such failures in future. “There are solutions we could implement to save billions and billions of dollars,” Close avers.
Studying cosmic dust can be challenging, since it is very difficult to capture for study. NASA’s Stardust mission succeeded in capturing some particles of interplanetary dust, only to discover how challenging it is to find miniscule dust particles in an aerogel array. Stardust ended up enlisting thousands of volunteers to pore over thousands of three dimensional image stacks hunting for the elusive particles; they’re still looking, seven years later. Hopefully, Close’s simulated dust behaves sufficiently like the real thing to bypass the need for improved compositional and configurational veracity. Close will determine whether her model fits the bill with her upcoming in situ experiments outside the International Space Station. She is now working with NASA Jet Propulsion Laboratory scientists to prepare that hardware for deployment. Related...
Commercial Space Race Heats Up
The
Falcon 9 rocket, which made its fifth successful flight on 1 March, 2013 has stolen
the spotlight in the commercial space race. Built by SpaceX, a young company
based in Hawthorne, California, the rocket has become NASA’s choice for
hauling cargo to the International Space Station (ISS). But it may soon have
competition from a rocket that has kept a low profile.
After
years of delays, Orbital Sciences of Dulles, Virginia, has launched the first test
flight of its Antares rocket on April 21, 2013. If that goes well, its second mission
could carry an unmanned Cygnus spacecraft to the ISS within months. “There’s
no one main problem, no show-stopper,” says Orbital spokesman Barron Beneski.
“In hindsight, this has just taken us longer to do than we thought it would.”
Both
companies have received hundreds of millions of dollars from NASA’s Commercial
Orbital Transportation Services (COTS) programme. With the space shuttle
retiring in 2011, the agency wanted alternatives to paying for ISS deliveries
aboard the Russian Progress and Soyuz craft. NASA deliberately put two companies
in competition with each other to keep prices down over the long run and to
attract other customers. “The government is the necessary anchor tenant for
commercial cargo, but it’s not sufficient to build a new economic ecosystem,”
says Scott Hubbard, an aeronautics researcher at Stanford University in
California and former director of NASA’s Ames Research Center in Moffett
Field, California.
With
30 years of experience in making satellites and rockets, Orbital once seemed the
safer bet. Instead of assembling its vehicles from scratch like SpaceX, Orbital
uses parts made by companies with proven track records. The core of the first
stage of Antares was designed and built by veterans KB Yuzhnoye and Yuzhmash,
both based in Dnipropetrovsk, Ukraine. Cygnus’s sensors come from Mitsubishi
Electric in Tokyo and its pressurized cargo module was built at a Thales Alenia
Space plant in Turin, Italy. “Orbital used more heritage technology,” says
Alan Lindenmoyer, manager of NASA’s commercial crew and cargo programme. “That
was less risky for us.” More
Chinese FAST Telescope to Surpass Arecibo
Chinese FAST Telescope to Surpass
AreciboWhen it comes to understand what's going on in deep space, whether
asteroids and Kuiper belt objects or pulsars and galaxies, it's all about size.
The bigger the telescope, the more it can detect. Since its completion in 1963,
the Arecibo radio telescope in Puerto Rico has been the world's largest single
aperture telescope with a diameter of 305 m. China is looking to break
that long held record with the upcoming FAST telescope. Construction on FAST
began in 2011; the telescope is expected to be completed in 2016 with a diameter
of 500 m. More
Rescuing Orion After Off-Nominal Landing
Rescuing Orion After Off-Nominal
LandingRescue divers secure a flotation ring around a mockup of NASA's new Orion
spacecraft during water splashdown tests in Florida in 2009 (Credits:
NASA/Dmitri Gerondidakis). NASA is setting up the mission rules for the Orion
spacecraft with a Concept of Operations (CONOPS) that includes scenarios for
keeping a crew alive after end of mission splashdown. The scenarios include
off-nominal landings to remote areas of the ocean, and crew rescue by US
Department of Defense (DoD) assets.During the last thirty years, Space Shuttle
crews have been landing at Kennedy Space Center, with an alternative option
being Edwards Air Force Base ... More
Why Do Astronauts Grow Taller in Space?
Did you ever wish you could be just a teensy bit taller? Well, if you spend a few months in space, you could get your wish — temporarily. It is a commonly known fact that astronauts living aboard the International Space Station grow up to 3 percent taller while living in microgravity. They return to their normal height when back on Earth. Studying the impact of this change on the spine and advancing medical imaging technologies are the goals of the Spinal Ultrasound investigation. “This is the very first time that spinal ultrasound will be used to evaluate the changes in the spine,” said Scott A. Dulchavsky, M.D., Ph.D., principal investigator for the station study. “Spinal ultrasound is more challenging to perform than many of the previous ultrasound examinations done in space.” Part of the difficulty with imaging the spine is quite simply human anatomy. Using Ultrasound 2, the machine aboard station as a facility for human health studies, astronauts have an advanced tool to view the inner workings of their bodies. More
Mostly Successful Spacewalk Releases New Debris
On April 19, cosmonauts Pavel Vinogradov and
Roman Romanenko conducted a nearly seven hour extravehicular activity
(EVA) outside the International Space Station (ISS). The spacewalk
involved installation and retrieval of experiments and installation of a
navigational aid needed for the upcoming ATV-4 mission. Vinogradov is a
veteran spacewalker; this was his seventh foray and a record making one.
Vinogradov is ... More
Flying to Mars on a Fusion Rocket
One of the most challenging aspects of
sending humans to Mars is the duration of the
flight that takes them there: over 500 days of
putting up with the same crewmates while
being barraged by cosmic radiation. It’s enough
to make anyone stay in Earth orbit. But a group
of researchers at the University of Washington is
determined to go ... More
sending humans to Mars is the duration of the
flight that takes them there: over 500 days of
putting up with the same crewmates while
being barraged by cosmic radiation. It’s enough
to make anyone stay in Earth orbit. But a group
of researchers at the University of Washington is
determined to go ... More
D-Orbit Add-on Deorbits Satellites without Sacrificing Fuel
Luca
Rossettini, CEO and co-founder of D-Orbit, a start-up targeting the space
debris mitigation market, has always dreamt of going to space. His dream led
him from Italy to the US and back, with a revolutionary idea and a reliable
business plan on how to deal with satellite disposal. Before starting D-Orbit,
Rossettini joined the Italian army as a parachute ... More
