2013/02/19 - New set of RAX-RISR experiments are being scheduled in the next few days.
2012/11/05 - RAX detects amplitude fluctuations of UHF signals passing through an ionospheric volume heated by HAARP (results from experiment no. 1022). Below are 1-second long MUIR (UHF radar) amplitude plots from the 125th and 151st seconds, corresponding to control and artificial disturbance cases, respectively. Between 135-165 s HAARP heated the volume on the MUIR-RAX path. The 125th second plot (on the left) is the control case where HAARP was heating the volume overhead (not on the MUIR-RAX path). The control case is quite uniform with amplitude fluctuations around 1 percent (excluding the unknown structure and interference). Meanwhile, the plot for the disturbed case (on the right) show amplitude fluctuations of 5-10 percent. SuperDARN detected strong FAI over HAARP during this experiment, see SUPERDARN.
We will continue to analyse these data and report our findings in a journal soon.
2012/10/22 - RAX conducts two more experiments with RISR on 10/15 and 10/16. RISR reported small ion drift velocities. No echoes observed.
2012/08/13 - RAX detects HF heater induced (artificial) ionospheric irregularities. See the plot below. We will download the raw data in the next couple of weeks to look for phase and amplitude scintillations.
2012/08/08 - RAX travels to HAARP to conduct a joint experiment with MUIR in Gakona, Alaska. The purpose of this experiment is to determine if (1) F region irregularities generated by HAARP and illuminated by MUIR are visible to RAX and (2) HAARP-generated irregularities scintillate MUIR signals along the MUIR-RAX path. Below left: an aerial view of HAARP. Below right: MUIR radar.
2012/07/27 - RAX raw data from the experiment 1017 have been processed to provide high-resolution measurements of irregularity distribution in altitude and their alignment (aspect angle) with the geomagnetic field. The contour lines shows aspect angle in increments of 1 degree. (Right click to view image in better resolution).
2012/06/13 - RAX detects Resolute echoes! Expt 1019 conducted on June 12 using RISR.
2012/04/26 - RAX detects echoes again! Expt 1018 conducted on April 25 using PFISR.
2012/03/09 - The first RAX echoes have been detected!
2012/03/09 - (First see the experiment 1017 summary below) The black line in the figure below shows the expected location of the echoes originating from the altitude of 100 km. We notice that echoes arrive somewhat earlier on the left side of the plot and somewhat later on the right side. This is because altitudes lower (higher) than 100 km are contributing on the left (right) side. We understand the right side, because Farley-Buneman instability is most intense around 110 km. But the left side indicade irregularity generation at altitudes as low as 90 km. But, what about the perpendicularity requirement to generate echoes from field-aligned irregularities? It appears that meter-scale field-aligned irregularities for these lower altitudes are much less field-aligned than we think. We are currently analyzing the data (including the raw data to be downloaded) to determine precisely what is happening.
2012/03/09 - Expt 1017 summary:
1) RAX crossed loci-of-perpendicularity for altitudes 300 (F region), 200, and 100 km (E region) at times approximately 175, 205 and 235 seconds into the experiment
2) Echoing occurred between the times 200 and 250 seconds into the experiment, corresponding to an echoing altitude range of approximately 90-210 km
3) The expected delays following the direct pulse arrival were between 0.3-0.5 ms, very well matching the observed delays.
4) Strongest echoes occurred around 235 seconds, corresponding to the E region.
5) The peak SNR was 19 dB.
6) The ion drift velocities measured by the Poker Flat Incoherent Scatter Radar during the 300 s experiment had a magnitude 1400 m/s, well exceeding the threshold (500 m/s) for the Farley-Buneman instability.
7) The electron densities were around 2e11 electrons per meter cube.
8) The Poker Flat magnetometer horizontal component was 550 nT.
9) Therefore, conditions were optimal for echo generation.
2012/03/02 - After about one month delay, we are back to 1-2 experiments per week. So far a total of 15 expriments conducted and the data processed. The next experiment (1015) will be conducted with PFISR around March 6, 2012. Meanwhile, RAX data page is updated with RTI, SuperDARN, magnetometer or ISR plots.
2012/01/19 - The RISR experiments 1011-1013 have been conducted, 1011 processed, see RAX DATA.
2012/01/10 - The next three experiments (1011-1013) to be conducted with the Resolute Bay Incoherent Scatter Radar between 01/13 and 01/16.
2012/01/12 - EXPT1006 Range-time-intensity plot (conducted on 01/07/2012. The magnetic conditions for this experiment were mostly quiet. Check RAX DATA page for magnetic conditions and SuperDARN data for the corresponding pass.
2012/01/12 - EXPT1005 Range-time-intensity plot (conducted on 01/06/2012). Most blobs seem to be clutter coming from a nearby radar. We are not sure if some (near 150 s) areFAI (pending analysis). SuperDARN did not observe echoes for this pass.
2012/01/10 - EXPT1008 conducted today. We have been accumulating processed data for EXPT1005-1008 onboard the spacecraft. This enables us to conduct one experiment per day. The data will be downlinked during days without good conjunctions.
2012/01/03 - EXPT1004 Range-time-intensity plot. This experiment was conducted on 12/29/2011 in conunction with PFISR. No echoes from FAI observed. Unlike the previous four experiments, we noticed that the trajectory for this pass was not optimal. The perpendicularity (for scattering) traces for 100 km and 300 km altitudes (shown by the solid and dashed lines, respectively) do not cross the zero angle. That is, FAI that would occur betwen these altitudes would not be detected anyways, although FAI in the lower E region would be detected. In calculating the scattering zones, we have been using a fixed altitude of 650 km. We will fix this for future experiments. Meanwhile, the blob on the left of the image is due to PAWS radar pulses coming from Clear, AK.
2011/12/24 - EXPT1004 PFISR-RAX scheduled for 12/28.
2011/12/24 - EXPT1003 Range-time-intensity plot. This experiment was conducted on 12/18/2011 in conunction with PFISR. In addition to 100 microsecond pulses for RAX reception, PFISR transmitted 480 microsecond pulses in 6 directions for diagnostics measurements of the ionosphere, such as electron density and electric fields. These data are currently under processing. But we know from the quiet solar activity and small magnetic deflections that geomagnetic activity is low and not much FAI generation is expected.
2011/12/21 - 442 MHz noise spectrum. The noise power under 100 KHz is -115 dBm, about 3dB higher than the noise floor for 449 MHz. This could be due to differing receiver gain across frequencies.
2011/12/14 - Repeat of Expt 1003 PFISR-RAX done on 20111214 14:10:16. Onboard processing to be scrubbed due to low geomagnetic activity. Expt 1003 to be repeated on 12/18.
2011/12/13 - Expt 1003 PFISR-RAX conducted on 20111213 134835 UT. Onboard data processing scrubbed due to low geomagnetic activity. This preferential processing of data saves spacecraft power for processing and downlinking the data, and saves time by allowing us quickly move to the next experiment.
2011/12/13 - SuperDARN echoes during Expt 1002. The RISR radar beam at 300 km altitude (marked by the red circle) is at the edge of the echoing region.
2011/12/08 - Expt 1002 using Resolute Bay Incoherent Scatter Radar. Range-Time-Intensity plot. Aspect angles corresponding to the irregularity altitudes of 100 and 300 km are shown by the solid and dashed lines, respectively. For Expt 1002, the geophysical activity was also very low, hence, no FAI backscatter expected and observed. See magnetometer plots on RAX DATA link on the left.
2011/11/27 - Range-Time-Intensity (RTI) plot of EXPT 1001 using RAX II -Poker Flat Incoherent Scatter Radar (PFISR). Aspect angles corresponding to the irregularity altitudes of 100 and 300 km are shown by the solid and dashed lines, respectively. FAI backscatter from those altitudes are expected when the aspect angle dips near zero. For Expt 1001 the geophysical activity was very low, hence, no FAI backscatter expected and observed.
2011/11/23 - RAX II and I 449 MHz noise floor comparison. The -116 dBm RAX II noise power for 100 KHz bandwidth closely matches to -117dBm of RAX I and to the noise floor measured (-116 dBm) in the lab.
2011/11/22 - EXPT1001 RAX-PFISR conducted on 2011/11/22 2205 UT. On board data is being processed. PFISR and magnetometers show very quiet geomagnetic conditions.
2011/10/28 - RAX II launched on October 28, 2011 2:48 am (PDT) from Vandenberg AFB.
2010/11/20 - RAX I launched via the Space Test Program aboard a Minotaur-4 vehicle from Kodiak, Alaska, on November 20, 2010 at 01:25 UTC.
2010/12/10 - EXPT 1000 completed. RAX and PFISR data have been processed. The range-time intensity plot and our initial findings are below. Check RAX DATA page for ionospheric conditions from PFISR and supporting instruments.
PFISR ran about 30 mins before and after the scheduled 300 s RAX experiment. Electron density and los velocity estimates showed that overall the geophysical conditions were quiet. F region densities were low, E region did not even show up, the auroral convection was slow, only couple hundred m/s or 10-15 mV/m. Very small magnetometer deflections confirm this. The only positive is that SuperDARN did see some echoes at the northern shore of Alaska. So, we anticipated very little or no scatter.
The plot above is for the entire 300s PFISR-RAX experiment.
1) The direct PFISR signal is very clear. The intensity is as expected. Modulation along satellite track is a result of PFISR beam pattern.
2) The signals between times 10-40s and delays 460-560 and delay ~850 and longer ranges of ringing are identified as clutter from a nearby radar.