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81-698: (Redirected from D-Series ) D series may refer to: Devices [ edit ] SM-65D Atlas "Atlas D" ICBM Nikon digital single lens reflex cameras Media [ edit ] QI (D series) , the fourth series of the BBC TV quiz show QI Vehicles [ edit ] Allis-Chalmers D Series , tractors Bedford D series , trucks Chevrolet Series D , trucks Dodge D series , pickup trucks Ford D series , trucks Group D Production Sports Cars , CAMS class of race car Honda D engine International Harvester light & medium duty trucks of

162-570: A domino effect known as Kessler syndrome . NASA's Orbital Debris Program tracks over 25,000 objects larger than 10 cm diameter in LEO, while the estimated number between 1 and 10 cm is 500,000, and the number of particles bigger than 1 mm exceeds 100 million. The particles travel at speeds up to 7.8 km/s (28,000 km/h; 17,500 mph), so even a small impact can severely damage a spacecraft. [REDACTED]  This article incorporates public domain material from websites or documents of

243-404: A semi-major axis of 8,413 km (5,228 mi). For circular orbits, this in turn corresponds to an altitude of 2,042 km (1,269 mi) above the mean radius of Earth, which is consistent with some of the upper altitude limits in some LEO definitions. The LEO region is defined by some sources as a region in space that LEO orbits occupy. Some highly elliptical orbits may pass through

324-447: A "dry" start method (no inert fluid in the engine tubes). This experiment worked without any apparent problems. The first four Atlas flights of 1960, three CCAS and one VAFB launch, were largely successful. On 6D, several malfunctions of the ground guidance system occurred—spurious yaw commands were sent at T+175 seconds and ground guidance lock on the missile was lost for almost two minutes. The missile continued to be unstable in flight for

405-429: A 320° loop, showering the area around the pad with flaming debris. Although only a few items were telemetered, the telemetry system failed during the prelaunch countdown anyway and film did not reveal any obvious cause of the control loss, but recovered debris discovered that the pitch gyro was either not running or the rotation speed was too low, and that 102D was still using the old Type B gyro canisters which did not have

486-452: A 90° roll transient at liftoff. The AIG managed to correct this problem and the missile completed a successful 3,000 miles (4,800 km) lob downrange. With this string of successful Atlas tests, program officials were lulled into a sense of security that rudely ended on March 11 when Atlas 51D lifted from LC-13. The B-1 engine suffered combustion instability which caused loss of thrust within two seconds of liftoff. An explosion ripped apart

567-457: A collision risk to the many LEO satellites. No human spaceflights other than the lunar missions of the Apollo program (1968-1972) and the 2024 Polaris Dawn have taken place beyond LEO. All space stations to date have operated geocentric within LEO. A wide variety of sources define LEO in terms of altitude . The altitude of an object in an elliptic orbit can vary significantly along

648-495: A couple of cartwheels before the Range Safety destruct command was sent at T+26 seconds. This failure was attributed to wiring in the pitch gyro contacting the casing and shorting out the gyro motor. The guidance system rate beacon also failed at liftoff, thus it would have been impossible to transmit any discrete guidance commands to the missile had the flight continued. Atlas 74D (July 22) broke up 70 seconds into launch due to

729-458: A destructive pad fallback. The exact reason for the rough combustion was unclear, although it had occurred over a dozen times in static firing tests of the MA-2 engines. However, it was noted that the separate exhaust duct for the gas generator vent pipe had been removed from both LC-11 and LC-13 after engineers decided that it was unnecessary and impeded removal and installation of protective covers on

810-402: A failure of the pitch gyro either due to an improper motor speed setting or torquing signals. Missile 47D (September 12) lost sustainer thrust starting at T+220 seconds due to an apparent loss of helium control pressure to the gas generator. The sustainer completely shut down at T+268 seconds and the missile fell 480 miles (772 km) short of the target area. Making postflight analysis difficult

891-524: A four-inch gap in the B-2 nacelle structure which also damaged low-pressure helium lines. The hold-down pin had not retracted due to a sheared retaining bolt in the bell crank pulley system in the right launcher arm. Once again, all other systems in the Atlas functioned well and there were no problems not directly attributable to the launcher malfunction. The flight of 7D resulted in improved maintenance procedures for

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972-560: A fuel leak and fire were suspected but launch film revealed an improperly attached insulation boot which came off at liftoff. Three Atlas Ds then successfully tested Nike-Zeus target missiles. In March, a series of operational SAC tests were carried out with minimal telemetry to reduce weight and allow the missiles to fly for as long a range as possible—five Atlas D and F flights. The first was 102D launched March 10 from 576-B3. The missile began to tumble out of control shortly after liftoff and self-destructed at T+33 seconds after having performed

1053-415: A hydraulic failure in the last few seconds of vernier solo phase and the warhead did not land on target. The missile did not carry temperature probes, but thrust section overheating was suspected. On October 7, Missile 163D exploded at T+75 seconds when the intermediate bulkhead reversed. Postflight investigation found that launch crews had loaded the helium bottles with insufficiently chilled gas, resulting in

1134-410: A lack of helium flow to the propellant tanks, which lost pressure during ascent. The last operational Atlas D missile test was Missile 158D on November 13. The flight was normal until T+112 seconds when sustainer hydraulic pressure began dropping, followed by missile explosion five seconds later. Because this was the program finale, Convair did not perform a full postflight investigation and the cause of

1215-524: A number of design changes implemented as a result of lessons learned during test flights. In addition, the D-series had the full-up Rocketdyne MA-2 propulsion system with 360,000 pounds-force (1,600 kN) of thrust versus the 250,000 pounds-force (1,100 kN) of thrust in the Atlas B/C's engines. Operational Atlas D missiles retained radio ground guidance aside from a few R&D launches which tested

1296-583: A payload to low Earth orbit on its own, and later to geosynchronous orbit , to the Moon , Venus , or Mars with the Agena or Centaur upper stage . Atlas D was launched from Cape Canaveral Air Force Station , at Launch Complexes 11 , 12 , 13 and 14 , and Vandenberg Air Force Base at Launch Complex 576 . The fully operational D-series Atlas was similar to the R&;D model Atlas B and C, but incorporated

1377-422: A row followed, some of which tested Nike-Zeus target missiles. On October 2, Missile 4D failed when the vernier engines shut down at T+33 seconds due to an inadvertent closure of the propellant valves. The propellant feed system sent all of the propellant intended for the verniers into the sustainer engine, which was overpressurized beyond its structure limits. The sustainer shut down at T+181 seconds, likely due to

1458-436: A rupture from the excessive pressure level, and the missile fell an estimated 2,300 miles (3,700 km) short of its target. Roll control had been maintained by the booster engines following vernier shutdown, then lost after BECO. Three more Atlas D flights during the year were successful. After the high degree of success achieved in 1962, the flight record of the D-series took a turn for the worse in 1963. The first flight of

1539-543: A satellite into a LEO, and a satellite there needs less powerful amplifiers for successful transmission, LEO is used for many communication applications, such as the Iridium phone system . Some communication satellites use much higher geostationary orbits and move at the same angular velocity as the Earth as to appear stationary above one location on the planet. Unlike geosynchronous satellites , satellites in low orbit have

1620-441: A small field of view and can only observe and communicate with a fraction of the Earth at a given time. This means that a large network (or constellation ) of satellites is required to provide continuous coverage. Satellites at lower altitudes of orbit are in the atmosphere and suffer from rapid orbital decay , requiring either periodic re-boosting to maintain stable orbits, or the launching of replacements for those that re-enter

1701-549: A stable low Earth orbit is about 7.8 km/s (4.8 mi/s), which translates to 28,000 km/h (17,000 mph). However, this depends on the exact altitude of the orbit. Calculated for a circular orbit of 200 km (120 mi) the orbital velocity is 7.79 km/s (4.84 mi/s), but for a higher 1,500 km (930 mi) orbit the velocity is reduced to 7.12 km/s (4.42 mi/s). The launch vehicle's delta-v needed to achieve low Earth orbit starts around 9.4 km/s (5.8 mi/s). The pull of gravity in LEO

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1782-433: A subset of LEO. These orbits, with low orbital inclination , allow rapid revisit times over low-latitude locations on Earth. Prograde equatorial LEOs also have lower delta-v launch requirements because they take advantage of the Earth's rotation. Other useful LEO orbits including polar orbits and Sun-synchronous orbits have a higher inclinations to the equator and provide coverage for higher latitudes on Earth. Some of

1863-537: A sustainer hydraulic failure following BECO and premature engine shutdown, the latter experienced high thrust section temperatures beginning at T+45 seconds, loss of sustainer gimbaling control at T+135 seconds, loss of vernier control at T+195 seconds, and propulsion system shutdown starting at T+233 seconds. Impact occurred east of Hawaii, about 2,300 miles (3,700 km) downrange. Six Atlas Ds were launched in 1967, five ABRES tests and one OV launch. All were successful and Missile 94D, launched from 576-B2 on November 7,

1944-415: Is different from Wikidata All article disambiguation pages All disambiguation pages SM-65D Atlas The SM-65D Atlas , or Atlas D , was the first operational version of the U.S. Atlas missile. Atlas D was first used as an intercontinental ballistic missile (ICBM) to deliver a nuclear weapon payload on a suborbital trajectory. It was later developed as a launch vehicle to carry

2025-496: Is only slightly less than on the Earth's surface. This is because the distance to LEO from the Earth's surface is much less than the Earth's radius. However, an object in orbit is in a permanent free fall around Earth, because in orbit the gravitational force and the centrifugal force balance each other out. As a result, spacecraft in orbit continue to stay in orbit, and people inside or outside such craft continuously experience weightlessness . Objects in LEO orbit Earth between

2106-826: The D Series - 1930s and International Harvester Light Line pickup , 1969–1975 MCI D-Series motorcoaches built by Motor Coach Industries (MCI) SJ D , locomotives used by Statens Järnvägar (SJ) of Sweden Volkswagen Group D platform , Audi, Bentley, and Volkswagen chassis configuration D-series trains, the designation for high-speed long-distance trains in China less fast than the G-series (see Passenger rail transport in China#Classes ) Other [ edit ] Tool steel D series , high carbon-chromium See also [ edit ] C series (disambiguation) E series (disambiguation) Topics referred to by

2187-516: The "stripped" SAC tests. Missile performance was nominal until T+76 seconds when thrust section temperatures began rising. Pitch stability was lost at T+103 seconds and sustainer hydraulic control failed at T+149 seconds. BECO occurred on time at T+135 seconds, and impact occurred approximately 390 miles (627 km) downrange. This flight resulted in improved installation and stitching for the engine insulation boots. D-series operational tests were suspended for two months while efforts were made to correct

2268-403: The Atlas D was originally the G.E. Mk 2 "heat sink" re-entry vehicle (RV) with a W49 thermonuclear weapon , combined weight 3,700 lb (1,680 kg) and yield of 1.44 megatons (Mt). The W-49 was later placed in a Mk 3 ablative RV, combined weight 2,420 lb (1,100 kg) The Atlas E and F had an AVCO Mk 4 RV containing a W-38 thermonuclear bomb with a yield of 3.75 Mt which

2349-530: The B-2 nacelle structure and caused helium pressurization gas to escape during ascent. At 62 seconds into the launch, the pressure in the LOX tank exceeded the pressure in the RP-1 tank, which reversed the intermediate bulkhead. Two seconds later, the missile exploded. Film review confirmed that the hold-down pin on the right launcher arm failed to retract at liftoff and was jerked from the missile. The resultant force caused

2430-506: The Cape. This missile utilized a dry start method without any hold-down time at liftoff with no apparent ill effects and all airborne systems performed well aside from an unexplained decrease in B-1 and sustainer thrust a few seconds before BECO. This was attributed to a probable fuel line obstruction. Cameras mounted on the nose cone photographed the spent Atlas after capsule separation. Atlas 90D,

2511-557: The LEO region near their lowest altitude (or perigee ) but are not in a LEO orbit because their highest altitude (or apogee ) exceeds 2,000 km (1,243 mi). Sub-orbital objects can also reach the LEO region but are not in a LEO orbit because they re-enter the atmosphere . The distinction between LEO orbits and the LEO region is especially important for analysis of possible collisions between objects which may not themselves be in LEO but could collide with satellites or debris in LEO orbits. The mean orbital velocity needed to maintain

D series - Misplaced Pages Continue

2592-480: The OV (Orbiting Vehicle) flights, which were a series of experimental scientific pods. The first attempt using Atlas 172D miscarried when an incorrectly set sustainer PU valve caused fuel depletion and premature SECO. The guidance system did not issue the separation command to the pods, which remained attached to the sustainer section as it reentered the atmosphere and burned up. The second attempt, using Missile 68D on May 28,

2673-465: The RP-1 fill/drain valve. The propellants then mixed and exploded on the launch stand. Because of the open LOX fill/drain valve, the Atlas's propellant system suffered a loss of fuel flow and pressure that caused the B-2 engine to operate at only 65% thrust. Due to the imbalanced thrust, the Atlas lifted at a slanted angle, which also prevented one of the launcher hold-down arms from retracting properly. Subsequent film review showed that no apparent damage to

2754-614: The Spin Motor Rotation Detection System (SMRD). The SMRD had been conceived back in 1958 after the first Atlas B failed in flight due to an inoperative yaw gyro, but was not phased into Atlas vehicles until 1961. Missile 102D had not been upgraded to the newer Type D gyros which had the SMRD, and a quick examination of the Atlas inventory at VAFB found two more missiles with Type B gyros. They were replaced with spare Type D canisters from Project Mercury. After

2835-458: The West Coast hit a series of snags in the following months as well when IOC testing began. Atlas 25D had flown successfully on April 22 from 576B-1, a coffin silo, after delays following the postflight findings from 51D and 48D. The next attempt was 23D on May 6. Following a normal liftoff, control began to fail the moment the pitch and roll sequence began at T+21 seconds. The missile performed

2916-433: The atmosphere. The effects of adding such quantities of vaporized metals to Earth's stratosphere are potentially of concern but currently unknown. The LEO environment is becoming congested with space debris because of the frequency of object launches. This has caused growing concern in recent years, since collisions at orbital velocities can be dangerous or deadly. Collisions can produce additional space debris, creating

2997-437: The attempted launch, then resumed around 45 seconds. At 60 seconds, the Atlas was completely destroyed when the propellant tanks exploded. Postflight analysis of the back-to-back failures found that in each case, the missile had fallen victim to rough combustion in one booster engine, which destroyed the LOX injector head (the injector damage on 51D was more extensive than 48D) and started a thrust section fire. In both missiles,

3078-418: The back-to-back pad explosions, it was decided to go back to using a wet start (inert fluid in the engine tubes) on the Atlas rather than the failed experiment of a dry start to ensure smoother engine startup. Atlas 56D (launched on May 20) was the first East Coast launch following 48D and it incorporated the modifications to the launch facilities along with cameras mounted on both launcher heads to look down into

3159-455: The denser part of the atmosphere and below the inner Van Allen radiation belt . They encounter atmospheric drag from gases in the thermosphere (approximately 80–600 km above the surface) or exosphere (approximately 600 km or 400 mi and higher), depending on orbit height. Satellites in orbits that reach altitudes below 300 km (190 mi) decay quickly due to atmospheric drag. Equatorial low Earth orbits ( ELEO ) are

3240-601: The final R&D flight of a D-series missile, launched successfully from LC-12 on January 23, 1961. Four operational Atlas D flights from VAFB during the year were successful and the first three flights of 1962 also went without a hitch. Atlas 52D launched from 576-B3 at VAFB on February 21, 1962. Abnormal thrust section temperatures occurred early in the flight, and the sustainer and verniers shut down starting at T+49 seconds. The booster engines experienced thrust decay at T+58 seconds followed by complete loss of thrust at T+68 seconds, and missile breakup five seconds later. This failure

3321-426: The first 14 seconds of vernier solo phase. Furthermore, an erroneous VECO signal was sent at T+278 seconds but the missile programmer did not act on it due to an apparent open circuit. VECO was intended to take place at T+282 seconds but did not occur for the aforementioned reason and it was instead performed 12 seconds later by a backup signal generated by the programmer. The missile landed within 9 miles (14 km) of

D series - Misplaced Pages Continue

3402-461: The first Atlas flight from the West Coast. Eight more D-series ICBM tests were conducted in 1959, as well as two space launches using Atlas D vehicles. Although assorted minor failures and hardware bugs affected these flights, the overall success rate was a major improvement over the first half of the year. Missile 26D on October 29 experienced a premature shutdown of the V-1 vernier when interference from

3483-621: The first dry engine start since 48D, as well as the first test of the Mercury ASIS system. The flight was largely successful however an open circuit resulted in the programmer not receiving the VECO discrete from the guidance system at the intended T+300 seconds. A backup command from the programmer performed VECO eight seconds later, consequently the RV landed 18 miles (28 km) further downrange than intended. The next flight, Missile 27D on June 28,

3564-647: The first generation of Starlink satellites used polar orbits which provide coverage everywhere on Earth. Later Starlink constellations orbit at a lower inclination and provide more coverage for populated areas. Higher orbits include medium Earth orbit (MEO), sometimes called intermediate circular orbit (ICO), and further above, geostationary orbit (GEO). Orbits higher than low orbit can lead to early failure of electronic components due to intense radiation and charge accumulation. In 2017, " very low Earth orbits " ( VLEO ) began to be seen in regulatory filings. These orbits, below about 450 km (280 mi), require

3645-431: The fuel fill/drain valve was traced to an improper procedure during the prelaunch countdown and was not connected to the LOX fill/drain valve problem. LC-13 sustained some damage due to the anomalous liftoff of Atlas 3D, this was quickly repaired and preparations began for the launch of Missile 5D. On May 18, Atlas 7D was prepared for a night launch of an RVX-2 reentry vehicle from LC-14, the second attempt to fly one after

3726-435: The hydraulic failure was not determined. One more Atlas D was flown in 1963, an ABRES RV test on December 18, successfully. On April 23, 1964, Missile 263D launched from CCAS LC-12 as part of Project FIRE , a series of suborbital tests designed to verify Apollo command module ablative heat shield material. This was the first suborbital Atlas D flown from the Cape in over three years. Five RV/ Nike-Zeus tests from VAFB during

3807-484: The inertial guidance system designed for the Atlas E/F, and the Atlas D would be the basis for most space launcher variants of Atlas. The Atlas D testing program began with the launch of Missile 3D from LC-13 on April 14, 1959. Engine startup proceeded normally, but it quickly became apparent that the LOX fill/drain valve had not closed properly. LOX spilled around the base of the thrust section, followed by leakage from

3888-488: The insulation boots on both missile was also ruled out as a probable cause of the failures. Aside from re-installing the exhaust duct, camera coverage of the flame deflector pit at ignition would also be increased and greater efforts made to ensure that the booster engines were free of contaminants. An added backup accelerometer was added to the RCC sensors in case of a failure. Two launch facilities were now in need of repair. LC-13

3969-498: The launch of a C-series Atlas had miscarried two months earlier. The test was conducted with the Mercury astronauts in attendance in order to showcase the vehicle that would take them into orbit, but 64 seconds of flight ended in another explosion, prompting Gus Grissom to remark "Are we really going to get on top of one of those things?" This failure was traced to improper separation of the right launcher hold-down pin, which damaged

4050-400: The launcher equipment at CCAS and use of higher heat steel in the bell crank retaining bolts. Atlas 5D lifted from LC-13 on June 6. The flight went perfectly until booster separation, at which point a fuel leak started. Tank pressure decreased until the intermediate bulkhead reversed at T+157 seconds and the missile exploded. This incident was similar in nature to an Atlas C failure earlier in

4131-446: The loss of a heat shield at liftoff. As a consequence, the tank pressurization system mistakenly sensed a drop in tank pressure and began pumping helium into the tanks to raise their pressure level. Pressures in both propellant tanks began rising at T+39 seconds and the missile self-destructed when excessive LOX tank pressure ruptured the intermediate bulkhead at T+71 seconds. While attempting to launch Missile 32D from LC-12 on August 2,

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4212-426: The missile resulted from either the launcher release or the propellant explosion. The flight control system managed to retain missile stability until T+26 seconds when the loss of pressure to the LOX feed system ruptured propellant ducting and resulted in an explosion that caused the booster section to rip away from the missile. The Atlas sank backwards through its own trail of fire until the Range Safety destruct command

4293-414: The nacelle sections at liftoff, as well as being the first flight from LC-12 in nine months as the pad had suffered major damage in the explosion of Atlas 9C the previous September. This was followed by Atlas 45D, an Agena vehicle used to launch a MIDAS satellite. Missile 54D launched successfully from LC-11, now repaired from the explosion of 48D, on June 11. This was followed by 62D on June 22 which marked

4374-508: The needs of the mission they were performing, but when the Atlas was retired from missile service in 1965, Convair introduced a standardized Atlas vehicle (the SLV-3) for all space missions. Remaining D-series missiles were flown until 1967 for suborbital tests of reentry vehicles and a few space launches. A total of 116 D-series missiles (not including vehicles used for space launches) were flown from 1959 to 1967 with 26 failures. The warhead of

4455-402: The onboard camera package caused temporary loss of ground guidance lock on the missile. Impact occurred 16 miles (26 km) short of the target point. Because of growing confidence in the Atlas, it was decided to abandon PFRF (Pre-Flight Readiness Firing) tests except for the first handful of Atlas E flights as well as space launches. The final test of 1959, Missile 40D on December 19, utilized

4536-426: The orbit. Even for circular orbits , the altitude above ground can vary by as much as 30 km (19 mi) (especially for polar orbits ) due to the oblateness of Earth's spheroid figure and local topography . While definitions based on altitude are inherently ambiguous, most of them fall within the range specified by an orbit period of 128 minutes because, according to Kepler's third law , this corresponds to

4617-438: The pipe during ground testing. It could not be determined with certainty if the lack of an exhaust duct had anything to do with the failures, and in any case, camera coverage did not offer any evidence in support of this theory. Nonetheless, it was decided to put the exhaust duct back on the Atlas pads at CCAS in order to comply with the configuration of operational Atlas missile silos, and as a "just in case" measure. Adjustments to

4698-473: The problems experienced during the first few months of 1963. Then 198D carried out a Nike-Zeus test successfully on June 12. Two operational ICBM tests in July–August were also successful. Missile 63D on September 7 suffered a ruptured vernier hydraulic line from aerodynamic heating at T+110 seconds. The sustainer and verniers shut down just prior to BECO and the mission failed. On September 12, 84D experienced

4779-431: The rough combustion cutoff sensor in the B-1 engine failed to operate. On 48D, the rough combustion did not occur in that engine and the lack of RCC cutoff was not a problem (B-1 thrust was terminated instead by the turbopump overspeed sensor). The B-2 RCC sensor operated correctly and terminated thrust before liftoff could be achieved. On 51D, it resulted in the B-1 continuing to operate until the missile lifted, resulting in

4860-413: The same term [REDACTED] This disambiguation page lists articles associated with the title D series . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=D_series&oldid=1073835947 " Category : Disambiguation pages Hidden categories: Short description

4941-551: The successful flight of 64D on March 12, Missile 46D (March 15) failed when the sustainer hydraulic rise-off heat shield broke off. Radiated heat caused the rise-off disconnect valve to fail, resulting in loss of sustainer engine hydraulic fluid. Sustainer and vernier control failed starting at T+83 seconds, but missile stability was retained until BECO at T+137 seconds. After booster jettison, the missile became unstable in flight. SECO occurred at T+145 seconds and impact occurred approximately 500 miles (804 km) downrange. This incident

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5022-473: The sustainer RCC sensor was tripped and an automatic shutdown issued. The sustainer thrust chamber was found to have pinhole leaks in it. It was removed and swapped with a different engine, and 32D was launched successfully seven days later. After this, 66D was launched successfully on August 12 but its RV sank into the ocean and was not recovered. Five more Atlas D tests from CCAS during the year were successful, these were 76D, 79D, 71D, 55D, and 83D. Missile 79D

5103-467: The target area. On March 5, 1960, Missile 19D was undergoing a propellant loading exercise at 576-A2 at VAFB when a fuel leak started a fire on the pad that led to the explosion of the missile. The launch facility was written off due to the damage and not used again for almost 5 years. On March 8, 1960, Missile 44D launched from LC-11 on the first test of the AIG (All Inertial Guidance System) and experienced

5184-423: The thrust section, followed by structural failure of the propellant tanks, causing the Atlas to fall back onto LC-13 in an enormous fireball. The Atlas went in for a repeat performance on April 8 when Missile 48D, launched from LC-11 and intended as the first closed-loop test of the AIG (All Inertial Guidance System), experienced combustion instability again, this time in the B-2 engine. The first indication of trouble

5265-412: The use of novel technologies for orbit raising because they operate in orbits that would ordinarily decay too soon to be economically useful. A low Earth orbit requires the lowest amount of energy for satellite placement. It provides high bandwidth and low communication latency . Satellites and space stations in LEO are more accessible for crew and servicing. Since it requires less energy to place

5346-462: The year achieved most of their mission goals. The Atlas ICBM program concluded in early 1965, however refurbished missiles continued to be flown from VAFB for various orbital and suborbital mission for years afterward. Six successful RV/ Nike-Zeus flights were carried out using D-series missiles from January to April 1965. On May 22, the second Project FIRE test was performed from the Cape using Missile 264D. During 1965, another new program developed,

5427-487: The year and it resulted in a major investigation and redesign effort. The failure point was either the fuel staging disconnect valve or associated plumbing, and modifications were made to the disconnect valve, plumbing, booster separation system, jettison tracks, and even the launcher mechanism, all of which were possible causes of the malfunction. On July 29, Missile 11D was launched with a series of modifications designed to correct problems on previous Atlas launches. The flight

5508-551: The year, Missile 39D, lifted from 576-B2 at VABF shortly after midnight on January 25. Beginning at T+86 seconds, the V-2 vernier shut down followed by loss of B-1 engine gimbaling control, telemetry power failure, and booster thrust decay. The sustainer shut down at T+108 seconds and the boosters at T+126 seconds. The missile tumbled, broke up, and impacted about 99 miles (159 km) downrange. Telemetry data revealed abnormally high thrust section temperatures during powered flight; initially

5589-625: Was fuzed for either air burst or contact burst. The Mk 4 RV also deployed penetration aids in the form of mylar balloons which replicated the radar signature of the Mk 4 RV. The Mk 4 plus W-38 had a combined weight of 4,050 lb (1,840 kg). Low Earth orbit The term LEO region is used for the area of space below an altitude of 2,000 km (1,200 mi) (about one-third of Earth's radius). Objects in orbits that pass through this zone, even if they have an apogee further out or are sub-orbital , are carefully tracked since they present

5670-459: Was a major loss of telemetry data at T+109 seconds caused by a power failure, consequently only 13 telemetry measurements remained active for the rest of the flight. Missile 33D (September 29) failed to stage its booster section when the staging electrical disconnect plug pulled out at T+125 seconds; it impacted 1,200 miles (1,900 km) short of the target area. 81D (October 13) failed when the LOX quick disconnect pressure sensor malfunctioned due to

5751-412: Was a near repeat of a failed Atlas-Agena launch three months earlier, and after another Atlas-Agena the following June fell victim to a hydraulic rise-off heat shield loss, the heat shield was redesigned. Check valves were installed on the hydraulic system of Atlas SLVs, although not ICBMs. Missile 193D was launched on March 16, part of the normal operational test series with full telemetry as opposed to

5832-445: Was a pressure surge in the B-2 combustion chamber, followed by unstable thrust, engine shutdown, and an explosion that started a thrust section fire. The B-1 engine then shut down, followed by the sustainer and verniers. Since the propulsion system had not attained sufficient thrust, the launcher hold-down mechanism did not release the missile, which stayed in place and burned on the pad. The thrust section fire slowed down 15 seconds after

5913-742: Was an even bigger fiasco when a LOX leak during ascent resulted in a thrust section explosion two minutes into launch. Although booster jettison was performed successfully, damage from the explosion resulted in eventual sustainer shutdown and missile self-destruction. Afterwards, it was decided that suborbital flights were insufficient for the OV program and that full orbital tests were needed. There were eleven more Atlas D launches in 1965, ten ABRES/ Nike-Zeus tests and OV 1–2 on October 5. All of these were successful. Fourteen Atlas Ds were launched in 1966, these included ten ABRES and Nike-Zeus tests and two OV launches. Two flights failed. These were respectively 303D on March 4 and 208D on May 3. The former suffered

5994-472: Was deployed in limited numbers as an ICBM due to its radio guidance while the fully operational E and F-series missiles had inertial guidance packages and a different ignition system that allowed faster engine starts. For Mercury, the Atlas D was used to launch four crewed Mercury spacecraft into low Earth orbit . The modified version of the Atlas D used for Project Mercury was designated Atlas LV-3B . Atlas Ds used for space launches were custom-built for

6075-544: Was issued at T+36 seconds. The sustainer and verniers continued operating until missile destruction. All other missile systems had functioned well during the brief flight and the LOX fill/drain valve malfunction was attributed to a breakdown of the butterfly actuator shaft, possibly during the Pre-Flight Readiness Firing a few weeks earlier, so Atlas vehicles starting with Missile 26D would use an actuator made of steel rather than aluminum. The leakage from

6156-538: Was mostly successful and booster section separation was performed successfully on a D-series Atlas for the first time, but some difficulties with the hydraulic system occurred due to low engine compartment temperatures caused by a probable LOX leak. Missile 14D launched from LC-13 on August 11, at which point the Air Force somewhat reluctantly declared the Atlas to be operational as a missile system. On September 9, Missile 12D launched from Vandenberg Air Force Base, marking

6237-485: Was severely damaged by the fallback of 51D and would not be used again for six months, while damage to LC-11 was less extensive and repairs were completed in only two months. After restoration, LC-13 was converted for the Atlas E and would not host further D-series tests. Attention shifted to LC-12 where Atlas 56D flew over 9,000 miles (14,000 km) with an instrumented nose cone, impacting the Indian Ocean . After

6318-492: Was successful. Missile 60D launched July 2. The vernier start tanks were inadvertently vented and refilled several times during the flight. This resulted in depletion of control helium and decay in propulsion system performance, and so the Mark III Mod 1B reentry vehicle landed some 40 miles (64 km) short of its intended target point. An electrical short in the engine relay control box was suspected. Atlas D tests on

6399-506: Was the final Atlas D flight as ABRES testing would continue using E and F-series missiles. Most Atlas D launches were sub-orbital missile tests; however several were used for other missions, including orbital launches of crewed Mercury , and uncrewed OV1 spacecraft. Two were also used as sounding rockets as part of Project FIRE . A number were also used with upper stages, such as the RM-81 Agena , to launch satellites. The Atlas D

6480-504: Was the last test flight from LC-14, which had otherwise been turned over to NASA for Project Mercury but the failure of Mercury-Atlas 1 in July caused a lengthy delay between flights and so LC-14 was temporarily free for use. The most notable flight in this stretch was Atlas 71D on October 13 which carried three mice and other experiments in a biological nose cone which successfully completed a 5,000-mile (8,000 km) lob downrange from LC-11 at

6561-437: Was traced to a leak in the booster engine gas generator that caused thrust section overheating and loss of engine thrust, and it occurred a mere five hours after John Glenn 's Mercury launch, driving home the point that Atlas was still far from a reliable vehicle. The next flight after 52D was Missile 134D (March 24), witnessed by President Kennedy , who was making a tour of VAFB. Eight successful Atlas D operational flights in

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