Center for Space Science
Center for Space Science
News Article | April 11, 2016
The U.S. Naval Research Laboratory (NRL), in collaboration with numerous universities and government laboratories studying the effects of dusty plasmas — charged dust particles that can occur naturally in the mesosphere — generated an artificial plasma cloud in the upper-atmosphere to validate the theory of 'dressed particle scattering' caused by this phenomenon. Named the Charged Aerosol Release Experiment (CARE II), an instrumented rocket was launched Sept. 16, at 19:06 GMT, from Andoya, Norway, utilizing a NASA Black Brant XI sounding rocket. After entering the ionosphere, 37 small rockets were fired simultaneously to inject 68 kilograms (kg) of dust comprised of aluminum oxide particulates, accompanied by 133 kg of molecules such as carbon dioxide, water vapor, and hydrogen. The launch occurred just after sunset placing the dust particles in sunlight for easy viewing by cameras in darkness on the ground and with an airborne platform. The large concentration of dust and exhaust material interacted with the ionosphere to produce a so-called 'dirty plasma' with high-speed pickup ions. Visibly seen from the ground, the released dust produces an optical cloud, and, by attaching the electrons in the ionosphere, forms charged particulates. This plasma then generates waves that scatter radar signals used for remote sensing. "The CARE launch was fully successful," says Dr. Paul A. Bernhardt, CARE principal investigator. "Ground-based radars tracked the effects on the ionosphere for twenty minutes, providing valuable data on how rocket motors affect ionospheric densities. The data will be used to validate simulations of natural disturbances in the upper atmosphere." The NRL Plasma Physics Division's (PPD) Charged Particle Physics Branch and the University of Washington made measurements with plasma probes and electric field booms on a deployable instrument payload. Ionospheric disturbances were monitored with multi-frequency beacon transmissions from the rocket payload that were detected by a network of ground receivers from the Finnish Meteorological Institute (FMI), Sodankylä Geophysical Observatory (SGO), and NRL PPD. Ground radars and optical instruments that recorded the dust release were provided by the European Incoherent Scatter Scientific Association (EISCAT); Institute of Atmospheric Physics (Germany); Institute of Space Physics, (Sweden); and others. The CARE theory effort was based in PPD and the Laboratory for Computational Physics and Fluid Dynamics (LCPFD) at NRL, as well as the Center for Space Science and Engineering Research at Virginia Tech. High frequency receivers were fielded by QinetiQ (UK) and by NRL PPD with stations in Oslo, Tromsö, and the University Center in Svalbard (UNIS). A CARE data review is scheduled for December 2015 in San Francisco. During this review, Bernhardt says, the scientific results from the experiment will be compared with artificial and natural scatter processes to better understand the physics. Also, a follow-on CARE III experiment will be planned. The Department of Defense (DoD) Space Test Program sponsored the launch and payload integration for the NRL CARE II mission. The rocket launch, and payload development was provided by the NASA Sounding Rocket Program. The CARE experiments were designed to test the theory of dusty plasma scatter developed by scientists at the University of Tromsö in Norway and NRL PPD. About the U.S. Naval Research Laboratory The U.S. Naval Research Laboratory provides the advanced scientific capabilities required to bolster our country's position of global naval leadership. The Laboratory, with a total complement of approximately 2,500 personnel, is located in southwest Washington, D.C., with other major sites at the Stennis Space Center, Miss., and Monterey, Calif. NRL has served the Navy and the nation for over 90 years and continues to advance research further than you can imagine. For more information, visit the NRL website or join the conversation on Twitter, Facebook, and YouTube.
News Article | January 28, 2016
Many of the teachers are retired now. They have gray hair. A few limp. But they still believe strongly in what McAuliffe hoped to accomplish aboard Challenger before disaster struck during liftoff on Jan. 28, 1986. "It's really hard" to be back, said William Dillon, 77, a retired teacher who represented California in the competition back in the mid-1980s. He was at Kennedy Space Center for Challenger's launch and had gotten to know not only McAuliffe, but a few of the other astronauts on board the doomed flight. Linda Preston, also retired as a teacher, choked up as the names of the Challenger dead were read during the memorial service. The former astronaut reciting the names of all 24 astronauts killed in the line of duty over the years, Jon McBride, had to fight back tears. "I couldn't breathe," Preston later confided to a reporter. She represented Utah in the teacher competition. Close to 40 of the 113 remaining semifinalists for teacher-in-space traveled to Cape Canaveral for the anniversary commemoration, the biggest gathering ever for a NASA memorial like this. "We felt we all wanted to be part of it," said Connecticut semifinalist David Warner, who still teaches science, robotics and rocketry. Another first: McAuliffe's son, Scott, 39, took part in the ceremony. He said having his own two sons there with him—ages 6 and 8—made it easier. It's time, he said, that his children see and learn firsthand all about astronauts and the space program. As the families of the lost Challenger crew marked the space shuttle's 30th anniversary, there was a new voice to address the crowd. June Scobee Rodgers—widow of Challenger commander Dick Scobee and longtime spokeswoman for the group—passed the torch to daughter Kathie Scobee Fulgham. Fulgham—not Rodgers—was on the stage for Thursday morning's ceremony at the Kennedy Space Center Visitor Complex. Because of a steady drizzle, the gathering was moved indoors, where the retired space shuttle Atlantis was suspended overhead. The crowd numbered close to 400 and included family members of astronauts killed in all three of NASA's spacecraft tragedies: Challenger; Columbia's catastrophic descent on Feb. 1, 2003; and the Apollo 1 fire on Jan. 27, 1967. For the seven astronauts' loved ones, Jan. 28, 1986, remains fresh in their minds. Steven McAuliffe, a federal judge in Concord, New Hampshire, still declines interviews about his late wife Christa, who was poised to become the first schoolteacher in space. But he noted in a statement that although 30 years have passed, "Challenger will always be an event that occurred just recently. Our thoughts and memories of Christa will always be fresh and comforting." McAuliffe said he's pleased that "Christa's goals have been largely accomplished in that she has inspired generations of classroom teachers and students." McAuliffe was presiding over a trial this week in Concord, and so Scott represented the family. Scott and his sister are now in their 30s. The McAuliffes normally do not take part in these NASA memorials, so Scott's presence is especially noteworthy. Along with the other Challenger families, Rodgers established the Challenger Center for Space Science Education just three months after the shuttle disintegrated in the Florida sky. A leak in the right booster doomed the ship; unusually cold weather that morning left Challenger's booster rockets with stiff O-ring seals. Today, there are more than 40 Challenger Learning Centers focusing on science, technology, engineering and math, mostly in the U.S. More are being built. "They're not just a field trip for kids. They're actually lessons learned," said Rodgers, an educator who lives in Chattanooga, Tennessee. "That's why they've lasted." McAuliffe's backup, Barbara Morgan, a schoolteacher from Idaho who finally made it to orbit in 2007, poignantly shared memories of each member of the Challenger crew. Besides Dick Scobee and Christa McAuliffe, the Challenger dead include pilot Michael Smith, Judith Resnik, Ronald McNair, Ellison Onizuka and Gregory Jarvis. At Kennedy, the Scobee contingent numbered 12, including June's son Richard, a major general in the Air Force, and a 16-year-old granddaughter. Dick Scobee was 46 years old when he died aboard Challenger barely a minute into the flight. Both his children are now in their 50s. "For so many people, 30 years, it's definitely history. It's in the history books," Rodgers said. For the family, "it's like it's just happened, which in a way keeps Dick Scobee young in our hearts, and the joy and excitement he had for flying."
Zaman M.R.,Center for Space Science |
Islam M.T.,National University of Malaysia |
Kibria S.,Center for Space Science
Applied Computational Electromagnetics Society Journal | Year: 2015
A novel electromagnetically short antenna with parasitic microstrip cap shape is shown in this paper. The antenna is composed of a U-shaped parasitic microstrip line (cap) excited by coupling with the feed line at patch. The antenna is fabricated in FR4 substrate with dielectric constant, Er=4.55 and thickness of 1.6 mm. Optimization of the proposed antenna is done using modified Particle Swarm Optimization (PSO) algorithm in ZELAND IE3D software environment. That gives resonance at selected frequencies and increased gain than the initial design. By using circular slot at the ground plane with miniaturized structure, dualband covering 5.29 GHz to 5.89 GHz (C-band) and 7.93 GHz to 8.86 GHz (X-band) is achieved. A fractional bandwidth of 10.74% at C-band and 11.08% at X-band is achieved. A measured gain of 5.65 dBi and 6.61 dBi is achieved at C-band and Xband respectively, with a circular polarization. Gain improvement is achieved compared to the initial design by more than 2 dBi (average) in the selected frequency for the given resonance using modified PSO optimization.