WEBVTT 00:00:06.000 --> 00:00:07.666 The EROS Radome: 00:00:07.666 --> 00:00:11.625 20 Things You Didn't Know 00:00:14.000 --> 00:00:17.000 Landsat satellites move in a polar orbit from north 00:00:17.000 --> 00:00:20.333 to south at over 27,000 kilometers per hour. 00:00:21.416 --> 00:00:24.458 For the ten meter antenna at EROS, a typical flyover, 00:00:24.666 --> 00:00:27.875 also known as a pass, lasts 14 minutes from horizon 00:00:27.875 --> 00:00:30.291 to horizon. 00:00:45.333 --> 00:00:46.500 The primary radome 00:00:46.500 --> 00:00:49.791 is a 60 foot sphere resting on a 12 foot ring wall. 00:00:50.666 --> 00:00:53.708 An air traffic light and a lightning rod are mounted on top. 00:00:55.375 --> 00:00:59.250 The antenna within has a ten meter dish. 00:01:04.333 --> 00:01:05.041 The ten meter 00:01:05.041 --> 00:01:08.833 EROS antenna has counterweights to offset its four ton reflector. 00:01:09.333 --> 00:01:12.541 The entire system is so well balanced it can be moved 00:01:12.541 --> 00:01:15.875 by hand. 00:01:21.833 --> 00:01:25.000 The radome’s 267 fiberglass panels 00:01:25.000 --> 00:01:29.000 are held together by 13,866 bolts, 00:01:29.333 --> 00:01:33.625 which must be checked for tightness every five years. 00:01:49.916 --> 00:01:53.125 The EROS antenna requires an extremely stable base. 00:01:53.666 --> 00:01:57.625 Its concrete footings reach 29.5 feet down to the bedrock. 00:01:58.500 --> 00:02:00.708 16 anchor bolts reach the entire depth 00:02:01.041 --> 00:02:04.333 and connect to the pedestal. 00:02:08.208 --> 00:02:08.958 The ten meter 00:02:08.958 --> 00:02:14.000 antenna at EROS has two primary axis motors: azimuth and elevation. 00:02:14.333 --> 00:02:19.041 They allow a full range of motion in theory, but for a full overhead pass, 00:02:19.166 --> 00:02:20.375 the motors would need to move 00:02:20.375 --> 00:02:24.000 impossibly fast near the zenith point to keep up with satellites. 00:02:24.250 --> 00:02:27.791 With a two axis system, zenith data is often lost. 00:02:28.458 --> 00:02:31.125 To account for this the EROS antenna includes 00:02:31.125 --> 00:02:33.958 a third motor installed with a seven degree offset. 00:02:34.791 --> 00:02:38.041 The three rotation points work together to execute full passes 00:02:38.041 --> 00:02:40.125 without overworking any single motor. 00:02:45.791 --> 00:02:48.500 Signals coming in from orbit are thousands of times 00:02:48.500 --> 00:02:52.583 weaker than a cell phone, which is why a dish is necessary to receive them. 00:02:53.708 --> 00:02:56.625 The antenna’s transmitter sends commands at 100 watts 00:02:56.833 --> 00:03:01.458 and must be aimed extremely accurately to hit satellites over 400 miles away. 00:03:05.750 --> 00:03:06.916 Between passes, 00:03:06.916 --> 00:03:10.458 the EROS antenna moves to stow position, the point of balance 00:03:10.458 --> 00:03:14.833 where the least amount of pressure is on all moving parts. 00:03:15.000 --> 00:03:18.083 This stow position is sometimes referred to as birdbath 00:03:18.083 --> 00:03:20.125 mode. 00:03:26.666 --> 00:03:29.666 The waxy and warm surface of the radome typically sheds snow, 00:03:30.625 --> 00:03:33.000 but sometimes a crust can form. 00:03:33.000 --> 00:03:36.750 Two snow ropes are attached to the top of the dome for removal. 00:03:37.708 --> 00:03:41.541 It's not high tech, but it works. 00:03:46.708 --> 00:03:49.375 The radome is washed and waxed every five years. 00:03:50.166 --> 00:03:53.125 The bolts are tested at the same time and tightened if needed. 00:03:53.791 --> 00:03:57.166 In 2023 nine gallons of wax were needed to cover 00:03:57.166 --> 00:03:59.541 the dome. 00:04:04.250 --> 00:04:07.125 The EROS campus is also home to a 5.4 00:04:07.166 --> 00:04:10.916 meter antenna with its own dome. 00:04:14.000 --> 00:04:15.375 It's primarily used for the 00:04:15.375 --> 00:04:18.750 Landsat 7 mission today. 00:04:23.666 --> 00:04:24.083 The first 00:04:24.083 --> 00:04:28.750 ten meter antenna was installed in 1996, and just prior to commissioning 00:04:28.875 --> 00:04:33.125 it was destroyed by softball sized hail. 00:04:34.375 --> 00:04:38.000 It was rebuilt in 1997 and covered by a dome structure 00:04:38.000 --> 00:04:41.250 to avoid a similar fate. 00:04:45.375 --> 00:04:46.375 Most of the time 00:04:46.375 --> 00:04:49.583 there are no staff in the radome. 00:04:49.583 --> 00:04:52.000 Data moves between the antenna and control room 00:04:52.000 --> 00:04:56.250 within the building via solid underground cables. 00:04:56.458 --> 00:05:00.291 Control room staff monitor passes and data flow 24 seven 00:05:00.291 --> 00:05:03.500 every day of the year. 00:05:22.500 --> 00:05:26.833 Visitors to EROS often comment that the radome resembles a giant golf ball. 00:05:27.416 --> 00:05:31.708 To be exact, it’s 429 times larger than a standard golf ball. 00:05:32.250 --> 00:05:35.083 To play 18 holes with it, you'd need a super sized 00:05:35.083 --> 00:05:37.416 course over 62,000 acres. 00:05:38.083 --> 00:05:42.750 That's approximately the size of Milwaukee, Wisconsin. 00:05:46.916 --> 00:05:47.500 The EROS 00:05:47.500 --> 00:05:50.583 water tower was originally installed to support the film lab. 00:05:51.625 --> 00:05:52.291 Today, it 00:05:52.291 --> 00:05:54.958 provides pressure to the building and local area. 00:05:56.333 --> 00:06:00.125 The antennas must avoid a small notch around the tower to avoid problems 00:06:00.125 --> 00:06:03.375 when transmitting and receiving. 00:06:05.458 --> 00:06:08.000 The radome’s 267 fiberglass 00:06:08.000 --> 00:06:11.625 panels have little effect on the reception or transmission of signals. 00:06:12.208 --> 00:06:14.833 Dirt buildup, rain and snow accumulation 00:06:14.833 --> 00:06:17.125 affect signals more than the panels themselves. 00:06:18.000 --> 00:06:21.000 Occasionally, data transmissions are missed due to heavy 00:06:21.000 --> 00:06:24.458 snow, ice or rain, but recovered on subsequent 00:06:24.458 --> 00:06:28.583 passes. 00:06:28.583 --> 00:06:32.333 EROS isn't the only ground station used to collect Landsat data. 00:06:32.916 --> 00:06:37.083 In fact, over 40 international stations have worked together over the past 00:06:37.083 --> 00:06:40.250 50 years, and there are currently 15 stations 00:06:40.250 --> 00:06:43.291 actively receiving data from Landsats 8 and 9.