Landsat 1 (LS-1), formerly named ERTS-A and ERTS-1, was the first satellite of the United States' Landsat program. It was a modified version of the Nimbus 4 meteorological satellite and was launched on July 23, 1972, by a Delta 900 rocket from Vandenberg Air Force Base in California.
Mission type | Earth imaging |
---|---|
Operator | NASA |
COSPAR ID | 1972-058A |
SATCAT no. | 06126[2] |
Mission duration | 5 years, 5 months and 14 days |
Spacecraft properties | |
Manufacturer | Hughes Aircraft Company |
Launch mass | 1,800 kilograms (4,000 lb) |
Start of mission | |
Launch date | July 23, 1972 (1972-07-23) |
Rocket | Delta 900 |
Launch site | Vandenberg SLC-2W |
End of mission | |
Disposal | Decommissioned |
Deactivated | January 6, 1978 (1978-01-07) |
Orbital parameters | |
Reference system | Geocentric |
Regime | Sun-synchronous |
Semi-major axis | 7,280 kilometres (4,520 mi) |
Perigee altitude | 902 kilometers (560 mi) |
Apogee altitude | 917 kilometers (570 mi) |
Inclination | 99.1 degrees |
Period | 117.04 minutes |
Epoch | August 26, 1972[3] |
It was the first satellite to carry a Multispectral Scanner.
The near-polar orbiting spacecraft served as a stabilized, Earth-oriented platform for obtaining information on agricultural and forestry resources, geology and mineral resources, hydrology and water resources, geography, cartography, environmental pollution, oceanography and marine resources, and meteorological phenomena.
The multi-agency Earth Resources Satellites Program was begun in 1966 by the Department of the Interior. The goal of the program was to gather data from the Earth via remote sensing techniques. The following year a feasibility study was performed for the Earth Resources Technology Satellite. The Bureau of Budget (BOB) did not grant funding to build the satellite, but provided $2 million to continue the feasibility studies.[4]
Definition studies for two Earth observation satellites began in 1967. The satellites were named Earth Resources Technology Satellite and were individually known as ERTS-A and ERTS-B.[5]
In 1970, General Electric was selected as the prime contractor for ERTS-A.[4] It was manufactured by GE's Space Division in Valley Forge, Pennsylvania.[6]
The spacecraft was 3 meters (9.8 ft) tall with a 1.5 m (4.9 ft) diameter. Two solar panel arrays that were 4 m (13 ft) long each, with single axis articulation, generated power for the spacecraft. ERTS-A had a liftoff weight of 953 kilograms (2,101 lb).[6]
The main spacecraft propulsion was three hydrazine thrusters. An attitude control system permitted the spacecraft's orientation to be maintained within plus or minus 0.7 degrees in all three axes.[6]
Spacecraft communications included a command subsystem operating at 154.2 and 2106.4 MHz and a PCM narrow-band telemetry subsystem, operating at 2287.5 and 137.86 MHz, for spacecraft housekeeping, attitude, and sensor performance data. Video data from the three-camera RBV system was transmitted in both real-time and tape recorder modes at 2265.5 MHz, while information from the MSS was constrained to a 20 MHz radio-frequency bandwidth at 2229.5 MHz.[2]
The satellite also carried two wide-band video tape recorders (WBVTR) capable of storing up to 30 minutes of scanner or camera data, giving the spacecraft's sensors a near-global coverage capability.[6]
The satellite was also equipped with a data collection system (DCS) to collect information from remote, individually equipped ground stations and to relay the data to central acquisition stations. Due to the orbit of the satellite, data could be obtained at a minimum of every 12 hours. No data processing or signal multiplexing occurred on the satellite.[7] The design of the DCS came from the Nimbus-3 platform, then known as the interrogation, recording, and location system (IRLS).[8]
ERTS-A had two sensors to achieve its primary objectives: the return beam vidicon (RBV) and the multispectral scanner (MSS).[1]
The RBV was manufactured by the Radio Corporation of America (RCA). The RBV obtained visible light and near infrared photographic images of Earth. At launch, the RBV was considered the primary sensor.[1]
The MSS was designed by Virginia Norwood at Hughes Aircraft Company, which also manufactured it. Norwood is called "The Mother of Landsat."[9] The sensor was considered an experimental sensor, and was the secondary sensor, until scientists reviewed the data that was beamed back to Earth. After the data was reviewed, the MSS was considered the primary sensor. The MSS was a four-channel scanner that obtained radiometric images of Earth.[1]
ERTS-A was launched July 23, 1972, on a Delta 0900 out of Vandenberg Air Force Base in California.[6][10] The spacecraft was placed in a sun-synchronous orbit, with an altitude between 907 and 915 km. The spacecraft was placed in an orbit with an inclination of 99 degrees which orbited the Earth every 103 minutes.[8] It was the first satellite launched with the sole purpose of studying and monitoring the planet.[1][11]
Upon reaching orbit, it was renamed to ERTS-1. On January 14, 1975, eight days before ERTS-B was to launch, NASA announced that ERTS-1 was renamed Landsat 1 and ERTS-B would be Landsat 2 after launch.[5]
Landsat 1's tape recorders malfunctioned in January 1978, and the satellite was taken out of service.[12]
From launch until 1974, Landsat 1 transmitted over 100,000 images, which covered more than 75% of the Earth's surface.[4] The majority of these images were taken with the multispectral scanner. On 5 August 1972 the return beam vidicon failed after taking only 1690 images.[8]
In 1976, Landsat 1 discovered a tiny uninhabited island 20 kilometers off the eastern coast of Canada. This island was thereafter designated Landsat Island after the satellite.[13]
The MSS provided more than 300,000 images over the lifespan of the satellite. NASA oversaw 300 researchers that evaluated the data that Landsat 1 transmitted back to Earth.[1]
Landsat 1 images were used in the first study of the normalized difference vegetation index (NDVI), now an ubiquitous measure of global plant greenness.[14]
← 1971 · Orbital launches in 1972 · 1973 → | |
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Kosmos 471 | OPS 1737 · OPS 7719 | Intelsat IV F-4 | Kosmos 472 | HEOS-2 | Kosmos 473 | Luna 20 | Kosmos 474 | OPS 1844 | Kosmos 475 | OPS 1570 | Kosmos 476 | Pioneer 10 | Kosmos 477 · Nauka-14KS No.1 | TD-1A | Kosmos 478 | OPS 1678 | Kosmos 479 | OPS 5058 | Kosmos 480 | Kosmos 481 | Venera 8 | Meteor-MV No.23 | Kosmos 482 | Kosmos 483 | Molniya-1 No.27 · SRET-1 | Kosmos 484 · Nauka-5KS No.3 | Interkosmos 6 | Kosmos 485 | Prognoz 1 | Kosmos 486 | Apollo 16 (PFS-2) | OPS 5640 | Kosmos 487 | DS-P1-Yu No. 51 | Kosmos 488 | Kosmos 489 | Kosmos 490 · Nauka-1KS No.5 | Molniya-2-2 | OPS 6574 | Kosmos 491 | OPS 6371 | Kosmos 492 | Intelsat IV F-5 | Kosmos 493 | Kosmos 494 | Kosmos 495 | Kosmos 496 | Prognoz 2 | Interkosmos 7 | Kosmos 497 | Meteor-MV No.26 | Kosmos 498 | Kosmos 499 | OPS 7293 · OPS 7803 | Kosmos 500 | Kosmos 501 | Kosmos 502 | Kosmos 503 | Kosmos 504 · Kosmos 505 · Kosmos 506 · Kosmos 507 · Kosmos 508 · Kosmos 509 · Kosmos 510 · Kosmos 511 | ERTS-1 | Kosmos 512 | DOS No.122 | Kosmos 513 | Explorer 46 | Kosmos 514 | Kosmos 515 | Denpa | Copernicus | Kosmos 516 | Kosmos 517 | OPS 8888 | Unnamed | Triad 1 | Kosmos 518 | Kosmos 519 | Kosmos 520 | Explorer 47 | Kosmos 521 | Molniya-2-3 | Radcat 2 · Radsat | Kosmos 522 | Kosmos 523 | OPS 8314 · OPS 8314/2 | Kosmos 524 | Molniya-1 No.26 | NOAA-2 · OSCAR-6 | Unnamed | Kosmos 525 · Nauka-16KS No.1L | Kosmos 526 | Meteor-M No.25 | Kosmos 527 | Kosmos 528 · Kosmos 529 · Kosmos 530 · Kosmos 531 · Kosmos 532 · Kosmos 533 · Kosmos 534 · Kosmos 535 | Kosmos 536 | OPS 7323 | Anik A1 | Explorer 48 | ESRO-4 | Unnamed | Kosmos 537 | Interkosmos 8 | Molniya-1 No.28 | Apollo 17 | Nimbus 5 | Molniya-2-4 | Kosmos 538 | Aeros 1 | OPS 9390 | Kosmos 539 | OPS 3978 | Kosmos 540 | Kosmos 541 | Kosmos 542 | |
Payloads are separated by bullets ( · ), launches by pipes ( | ). Crewed flights are indicated in underline. Uncatalogued launch failures are listed in italics. Payloads deployed from other spacecraft are denoted in (brackets). |