May 12 , 2008: We have been finished with the THEMIS tail season for over a month, that is when the THEMIS probes aligned within Earth's magnetotail. And now the dayside season starts. Last week, late Wednesday night and Thursday during the day, the Mission Operations Center (MOC) team completed the last of the maneuvers which fine tune the entire THEMIS constellation so it will be ready for "day side science" this summer. In this phase, the constellation is a mirror image of the tail season alignment we had last winter. This time, the apogees (farthest point of the orbit from the earth) are in the sun direction. Instead of taking measurements inside or very near the stretched out magneto-tail, we'll be collecting science in the "bow shock" region (just imagine the wave in front of the bow of a ship). This is where the solar wind slams into the earth's magnetic field and starts to warp it back. Probe 1, which is in the most elongated orbit, can actually travel far enough away from the earth to punch through this bow shock and measure the solar wind before it has gotten a chance to be disturbed by the Earth's magnetic field.  

March 5 , 2008: At the all-day monthly THEMIS science meeting last week, Tuesday, many scientists came together to look at the February substorms. Although one person argued for a near-earth neutral line model (reconnection first, current disruption next, then aurora), most scientists were not ready to sign up to one interpretation of the data. As with most scientific endeavors, the answers are not as simple as one might initially hope, leading to deeper understanding of the physics and new discoveries.  With multiple spacecraft available to address the question of where does the onset of substorm begin, the signatures in the particle and magnetic field data demonstrate that the magnetosphere is a very complex and dynamic system. With more than a dozen substorms collected with the THEMIS probes in just the right place and together with computer modeling of the magnetospheric system, it is clear that the upcoming analysis will lead to significant discoveries regarding substorm onsets.  

The THEMIS “tail season” is now coming to an end as the THEMIS probe’s alignment with one another moves out of the magnetotail. More great science is bound to happen in the next 10 months but will not be related to the substorm onset question. More “tail season” data will be collected again, though from somewhat different vantage points, next winter.

February 26, 2008: The company that evaluates our education and public outreach program, Cornerstone Evaluation Associates LLC (Cornerstone), has provided us with a report summarizing findings from our teacher professional development workshops over Fiscal Year 2007 (FY07) - from October 1, 2006 through September 30, 2007. The report also contains a summary of relevant statistics about the use of this website over the Fiscal Year 2006 (FY06) from October 1, 2005 through September 30, 2006 and Fiscal Year 2007 (FY07) from October 1, 2006 through September 30, 2007. You can read the report here.

To find out more about our teacher PD workshops, visit the THEMIS GEONS page and the Center for Science Education teacher PD workshop page.

February 20, 2008: PBS NOVA Science NOW came on February 5th to film several of the THEMIS scientists and engineers for a short NOVA piece about THEMIS. You can view a photograph of our own Manfred Bester, Director of the Missions Operations Center at UC Berkeley, with Neil deGrasse Tyson, the host of NOVA Science NOW, an astrophysicist and the director of the Hayden Planetarium at the American Museum of Natural History in New York City. We will share information here about when the NOVA show will air when we find out the schedule for this program.

February 17, 2008: Today is the first anniversary of THEMIS in orbit. The past year has been filled with discoveries. See the Articles Section to read about some of these discoveries, such as the first detection of a flux transfer event, when the magnetosphere combines with the solar wind in a rope-like fashion, peeling pieces of the magnetosphere off its front-side. We will provide news about some of the other science discoveries when the special THEMIS issue of the Geophysical Research Letters is published.

February 12, 2008: There were substorms throughout last week, including a substorm on Feb. 2nd, the THEMIS wedding day. See Feb. 1st news for a definition of wedding day. Due to technical difficulties, the satellite data was insufficient to tell us which model was at work for this particular substorm. Fortunately, however, there was another substorm on February 6, when the satellites were aligned with each other and close to the Sun-Earth line. The data from this day are currently being analyzed and we have high hopes that we’ll soon be getting some answers to the THEMIS substorm mystery!

To provide an idea of what a substorm look like from the all-sky imager data, here are two images (click to enlarge) showing the imager data as a mosaic across Canada and Alaska. The circles represent the field of view of the camera and the bright lines in those field of view are aurora. These images are 1 minute apart and show the substorm onset brightening right in the middle at 7:39:06 UT on Feb. 2nd. The colored dots represent how the five satellites are connected to the upper atmosphere by way of Earth's magnetic field.

February 1st, 2008: Tomorrow, Feb. 2nd, 2008, is "wedding day" for THEMIS. This is the day when all the satellites will align with each other and at the same time, the line they form will align with the magnetotail. This orbital configuration is shown in the diagram above with the perspective looking down on Earth's North Pole. So far the satellites have aligned with each other but not exactly in this line connecting the Sun and Earth, where the magnetotail blows out like a wind sock. They have lined up on the dawn side (top side of image) of the magnetosphere. And after this day, they will no longer line up directly downstream of Earth in the length of the magnetotail. They will drift to the dusk side (bottom side of the image.) For more information on the THEMIS orbits, vist the orbits page.

So, tomorrow is one of the best opportunities to really answer the question of what are the timing of the events that cause the sudden release of energy in the magnetotail and start the auroras a-dancin'! And thus, it is dubbed the "wedding day." Will a substorm happen tomorrow? We sure hope it will. Even if it doesn't, though, we still have many more chances in the coming month. Then we may finally have an answer whether this release of energy occurs in the "magnetic reconnection" region or in the "current disruption" region. Of course this will lead to all sorts of new questions, like "What is the physics in this main region that allows for the energy release?" and "How does the energy flow from one region to the other?" Some of these questions THEMIS can answer and others will have to be answered by future missions your students or children are a part of.

January 14, 2008: Two days ago, the THEMIS Electric Fields Instrument (EFI) and Mission Operations Center (MOC) team successfully rolled out, or deployed, the spin-plane Electric Fields Instrument (EFI) to their full extent (40.4 and 46.4 meters tip-to-tip) on the "spare" probe, THEMIS A (or TH-A; Probe 5, P-5). Note that the statue of liberty is 46 meters tall - so these booms really extend very far out into space. See the past two News and Events posts to learn more about this deployment. And the axial EFI booms were deployed successfully this morning. The axial booms are a bit shorter (6.7 meters tip-to-tip) and stiff since they do not have the rotation of the probes to keep them extended. All in all, this deployment took about a week and was very successful. Congratulations to the THEMIS team!

January 10, 2008: The THEMIS Electric Fields Instrument (EFI) and Mission Operations Center (MOC) team successfully rolled out, or deployed, the spin-plane Electric Fields Instrument (EFI) to 10 meters on the "spare" probe, THEMIS A (or TH-A; Probe 5, P-5). An additional 3 meters of very thin wire was also deployed that connects the preamplifier (housed in about a one inch cylinder) to the actual sensor, which is a black ball about the size of an extra-large softball. The preamplifier is used to carefully process the signal from the electric field sensor. The thicker wire connects the preamplifier with the THEMIS probe. This deployment means that the spin-plane booms are deployed a total length of 26-m tip-to-tip on both axes! To get a sense of this scale, see this 85 foot tall (26 meter tall) tree in Illinois next to a house. See May 16th, 2007 for a diagram of the EFI booms (not-to-scale).

January 8, 2008: It's another blistery day in Berkeley, CA but the THEMIS mission operation center (MOC) team operating out of UC Berkeley communicated successfully with the "spare" probe, THEMIS A (or TH-A; Probe 5, P-5) to start to roll out, or deploy, the Electric Fields Instrument (EFI). The spin-plane EFI sensors were rolled out to 5 meters and then the spacecraft spun back up to its original spin rate. This is necessary because of angular momentum - just as a figure skater spinning stretches out her arms to slow down her spin rate, the EFI instruments as they move out will slow down the spin rate of the probe. So boosters have to be used to spin it back up again. See May 16th, 2007 for a diagram of the EFI booms deployed on a THEMIS probe.

The EFI deployment has been done on all the other probes so this is the final deployment. It will take several "satellite passes" over about a week. A satellite pass is when the satellite is in the right place to be able to send electromagnetic (or light) signals back and forth with a ground-based antenna. Luckily the strong winds didn't cause a problem with the Berkeley antenna and thus with the communication opportunities.

January 4, 2008: Happy New Year! THEMIS is officially in its "tail" season and ready to solve the mystery of substorm onset. Will we find that it starts with magnetic reconnection or current disruption? The over 30-year debate will finally be settled this coming year. Stay tuned for this exciting THEMIS science news.

The mission operations center (MOC) here at the University of California at Berkeley will start ramping back up to full staffing next week. The MOC team will finish the last major hurdle: to unfurl the EFI (electric fields instrument) on THEMIS A, which has been a "spare" probe, ready to take over if any of the other four hadn't made it into their intended orbits. In the mean time, Northern California is getting hammered by a severe winter storm, and the winds here in the Berkeley hills are so high that the MOC team had to cancel all the communications passes with our antenna, and install special locking pins to keep the wind from damaging it. The rain has been coming in sideways through our entry doors! We hope you all are safe and warm during this winter season.

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