ULA – Delta 4-Heavy countdown aborted moments before launch

ULA – NROL-71 Mission patch.

Dec. 9, 2018

Image above: The mobile service tower retracts into position for launch during a countdown Dec. 8. Image Credit: United Launch Alliance.

A dramatic automatic abort 7.5 seconds before the planned liftoff of a United Launch Alliance Delta 4-Heavy rocket Saturday night kept the towering launcher on the pad at Vandenberg Air Force Base, California, with a top secret spy payload for the National Reconnaissance Office.

The 233-foot-tall (71-meter) rocket was counting down to launch at 8:15 p.m. PST Saturday (11:15 p.m. PST; 0415 GMT Sunday), but an automated sequencer detected a technical issue and triggered an abort.

Delta 4-Heavy countdown aborted moments before launch

“Hold hold hold,” a member of the ULA launch team declared on the countdown net.

A burst of flame appeared at the base of the rocket, a normal occurrence in the final seconds of a Delta 4 countdown as sparklers activate near the engines to burn off excess hydrogen gas before ignition, a measure aimed at eliminating the risk of a fireball or explosion.

It was not immediately clear whether any of the rocket’s three Aerojet Rocketdyne RS-68A main engines started their ignition sequences, but a statement later released by ULA said the computer-controlled countdown sequencer ordered an abort at T-minus 7.5 seconds.

In the statement, ULA said the abort was “due to an unexpected condition during terminal count at approximately 7.5 seconds before liftoff.

Image above: The mobile service tower retracts into position for launch during a countdown Dec. 8. Image Credit: United Launch Alliance.

“The team is currently reviewing all data and will determine the path forward. A new launch date will be provided when available,” ULA said.

The Delta 4-Heavy is made up of three Delta 4 first stage boosters bolted together, each with an RS-68A engine burning liquid hydrogen and liquid oxygen propellants. ULA commands the three RS-68A engines to start in a staggered sequence, beginning with the starboard engine at T-minus 7 seconds, followed two seconds later by ignition of the center and port engines.

The timing of the abort at T-minus 7.5 seconds suggests the countdown stopped around a half-second before the first of the Delta 4-Heavy’s three main engines was supposed to ignite.

ULA’s launch team quickly “safed” the rocket, disarmed ordnance, and drained the Delta 4-Heavy of its supply of cryogenic propellants. The launch team did not set a new target launch date, but officials were instructed to plan for an extended turnaround after Saturday night’s scrub, and the Delta 4-Heavy flight was expected to be delayed at least a few days.

Image above: The mobile service tower retracts into position for launch during a countdown Dec. 7. Image Credit: United Launch Alliance.

A similar cutoff in the final seconds of a Delta 4 countdown in 2010 resulted in a three-day slip to resolve the problem responsible for the abort — and replace the hydrogen burn-off sparklers on the pad — before the rocket successfully launched from Cape Canaveral with a GPS navigation satellite.

The upcoming mission from Vandenberg, located around 140 miles (225 kilometers) northwest of Los Angeles, is codenamed NROL-71 by the National Reconnaissance Office, which owns the U.S. government’s classified intelligence-gathering satellites. The NRO has not released any information about the spacecraft aboard the Delta 4-Heavy, but independent observers of NRO space launches believe the payload is heading for an unusual, high-inclination orbit, and is likely a new Keyhole-type high-resolution optical imaging satellite, with an Earth-pointing telescope capable of capturing extremely detailed imagery of sites around the world for review by government intelligence analysts.

The Delta 4-Heavy is ULA’s biggest rocket, and can loft up to 51,950 pounds (23,560 kilograms) of payload mass to a 120-mile-high (200-kilometer) low Earth orbit inclined 90 degrees to the equator.

The heavy-lift variant of the Delta 4 rocket has launched 10 times to date. The NROL-71 mission will be the 11th flight of a Delta 4-Heavy, and the 38th mission overall for the Delta 4 family since November 2002. It will also be ULA’s ninth and final launch of the year, following five Atlas 5 launches, a pair of Delta 4s, and the final liftoff of the company’s now-retired Delta 2 rocket.

A launch attempt for the NROL-71 mission Friday night was scrubbed after the Delta 4 team encountered a problem with a communications link between the control center and the rocket associated with the holdfire system.

For more information about United Launch Alliance (ULA): https://www.ulalaunch.com/

Images (mentioned), Video, Text, Credits: ULA/Spaceflight Now.com/Stephen Clark.

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2018 December 9 Aurora Shimmer, Meteor Flash Image Credit &…

2018 December 9

Aurora Shimmer, Meteor Flash
Image Credit & Copyright: Bjørnar G. Hansen

Explanation: Some night skies are serene and passive – others shimmer and flash. The later, in the form of auroras and meteors, haunted skies over the island of Kvaløya, near Tromsø Norway on 2009 December 13. This 30 second long exposure records a shimmering auroral glow gently lighting the wintery coastal scene. A study in contrasts, the image also captures the sudden flash of a fireball meteor from the excellent Geminid meteor shower of 2009. Streaking past familiar stars in the handle of the Big Dipper, the trail points back toward the constellation Gemini, off the top of the view. Both auroras and meteors occur in Earth’s upper atmosphere at altitudes of 100 kilometers or so, but aurora caused by energetic charged particles from the magnetosphere, while meteors are trails of cosmic dust. Nine years after this photograph was taken, toward the end of this week, the yearly 2018 Geminids meteor shower will peak again, although this time their flashes will compete with the din of a half-lit first-quarter moon during the first half of the night.

∞ Source: apod.nasa.gov/apod/ap181209.html

Meteor Activity Outlook for December 8-14, 2018

AMS Event #4926-2018 – Fireball over Schliengen, Germany, Nov 17th 2018
Uploaded on the AMS Website by S. Vetter – © S.Vetter

During this period the moon will wax from a slender crescent phase to nearly half illuminated. This will be a great time to view meteor activity as the moon will have set by the time the more active morning hours arrive.  The moon will be present during the evening hours but successful meteor observing is still possible during this time by simply keeping the moon out of your field of view. The estimated total hourly meteor rates for evening observers this week is near 4 as seen from mid-northern latitudes (45N) and 3 as seen from tropical southern locations (25S). For morning observers the estimated total hourly rates should be near 32 as seen from mid-northern latitudes and 24 from the southern tropics. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Note that the hourly rates listed below are estimates as viewed from dark sky sites away from urban light sources. Observers viewing from urban areas will see less activity as only the brighter meteors will be visible from such locations.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning December 8/9. These positions do not change greatly day to day so the listed coordinates may be used during this entire period. Most star atlases (available at science stores and planetariums) will provide maps with grid lines of the celestial coordinates so that you may find out exactly where these positions are located in the sky. A planisphere or computer planetarium program is also useful in showing the sky at any time of night on any date of the year. Activity from each radiant is best seen when it is positioned highest in the sky, either due north or south along the meridian, depending on your latitude. It must be remembered that meteor activity is rarely seen at the radiant position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies near the edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower member) or in another direction if it is a sporadic. Meteor activity is not seen from radiants that are located far below the horizon. The positions below are listed in a west to east manner in order of right ascension (celestial longitude). The positions listed first are located further west therefore are accessible earlier in the night while those listed further down the list rise later in the night.

Radiant Positions at 5:00am Local Standard Time

Radiant Positions at 7:00pm Local Standard Time

Radiant Positions at 12:00am Local Standard Time

These sources of meteoric activity are expected to be active this week.

The December phi Cassiopeiids (DPC) are the classical return of the Andromedids and the radiant that was active prior to the breakup of comet 3D/Biela in the 1840’s. This source is active from November 28 through December 10th. Maximum activity was expected to occur on December 6th when the Earth passes closest to particles released by 3D/Biela in 1649. The expected radiant is located at 01:36 (024) +50 on the night of maximum activity. This area of the sky is located just northwest of the 4th magnitude star known as Nembus (51 Andromedae). This position is also very close to the border with Cassiopeia and in some years the radiant lies in Cassiopeia, hence the name of phi Cassiopeiids. These meteors are best seen near 2100 (9pm) Local Standard Time (LST). Meteors from the December Phi Cassiopeiids strike the atmosphere at 17km/sec., which would produce meteors of very slow velocity. Expected rates would be low away from maximum. There have been no reports of visual activity so far. Rates could be strong but the meteors may be faint and difficult to see. Therefore those viewing from urban areas may see nothing at all. At only 17 km/sec. the December phi Cassiopeiids would also produce extremely slow meteors.

The Northern Taurids (NTA) are active from a large radiant located at 05:48 (087) +30. This area of the sky is located in southern Auriga, 4 degrees northeast of the 2nd magnitude star known as El Nath (beta Tauri). This position is close to the Southern Taurids so great care must be taken in separating these meteors. You must have the two radiants near the center of your field of view to properly differentiate these sources. Current rates would be 2 per hour as seen from the northern hemisphere and 1 per hour as seen from south of the equator. These meteors may be seen all night long but the radiant is best placed near midnight local standard time (LST) when it lies on the meridian and is located highest in the sky. With an entry velocity of 28 km/sec., the average Northern Taurid meteor would be of slow velocity.

The Southern Taurids (STA) are active from a large radiant centered near 05:58 (089) +24. This position lies in western Gemini, close to the position occupied by the 4th magnitude star known as 1 Geminorum. These meteors may be seen all night long but the radiant is best placed near midnight LST when it lies on the meridian and is located highest in the sky. Current rates would be 1 per hour as seen from the northern hemisphere and less than 1 per hour as seen from south of the equator. With an entry velocity of 27 km/sec., the average Southern Taurid meteor would be of slow velocity.

The Monocerotids (MON) are active from November 28th through December 27th with the peak activity occurring on December 13th. The radiant is currently located at 06:36 (099) +08. This position lies in northern Monoceros, 7 degrees east of the 1st magnitude orange star known as Betelgeuse (Alpha Orionis). This position is only 7 degrees south of the radiant of the November Orionids so care must be take to distinguish between the two. Current rates should be near 1 per hour no matter your location. Rates at maximum may reach 2 per hour. The Monocerotids are best seen near 0100 LST when the radiant lies highest above the horizon. At 41 km/sec. the Monocerotids produce mostly meteors of medium velocity.

The November Orionids (NOO) are active from a radiant located at 06:46 (102) +15. This area of the sky lies in southern Gemini, 2 degrees east of the 2nd magnitude star known as Alhena (gamma Geminorum). This area of the sky is best placed in the sky near 0100 LST, when it lies highest above the horizon. This stream is active from November 7 through December 17, with maximum activity occurring on November 29. Rates should be near 2 per hour no matter your location. With an entry velocity of 43 km/sec., most activity from this radiant would be of medium speed.

The Geminids (GEM) are active from December 1-22, with peak activity occurring on December 14th. This weekend the radiant is located near 07:14 (109) +33. This position lies in northern Gemini, 3 degrees northwest of the  2nd magnitude star known as Castor (alpha Geminorum). Rates this weekend should be near 10 per hour as sen from the northern hemisphere and 5-7 in the southern hemisphere . Hourly rates will increase dramatically as the week progresses. At 34 km/sec. the Geminids produce mostly meteors of medium velocity.

The Puppid-Velids (PUP) are a vast complex of weak radiants located in the constellations of Puppis and Vela. Visual plots and photographic studies have revealed many radiants in this area during November and December. The combined strength of these radiants can produce a ZHR of 10. Actual hourly rates will be much less unless you happen to be observing from the deep Southern Hemisphere. Activity from this source begins around December 1st. The center of this activity is currently located at 08:16 (124) -45. This position lies on the Puppis/Vela border, 2 degrees north of the 2nd magnitude star known as gamma Velorum. Peak rates occurred near December 7. These meteors are best seen near 0300 LST when the radiant lies highest above the horizon in a dark sky. Observers located in the Southern Hemisphere have an advantage viewing this shower as the radiant will rise higher into their sky allowing more activity to be seen. Since the radiant lies low in the south for most northern hemisphere observers, meteors seen from north of the equator tend to be long in length and long-lasting. At 40 km/sec. the Puppid-Velids produce meteors of average velocity.

The Sigma Hydrids (HYD) are active from November 24 through December 21, with maximum activity occurring on December 6. The radiant is currently located at 08:24 (126) +02 , which places it in extreme western Hydra, 3 degrees southwest of the 4th magnitude star known as sigma Hydrae. These meteors are best seen near 0400 LST when the radiant lies highest above the horizon. Hourly rates are expected to be near 3 per hour no matter your location. With an entry velocity of 62 km/sec., most activity from this radiant would be of swift speed.

The December Leonis Minorids (DLM) are a shower of long duration active from December 6th through January 18th. Maximum occurs near December 21st when rates may reach 3 an hour. During this period I would expect an hourly rates near 1 from a radiant located at 09:57 (149) +35. This position lies in western Leo Minor, 2 degrees southwest of the faint star known as 21 Leo Minoris. These meteors are best seen near 0400 LST when the radiant lies highest above the horizon.  At 63 km/sec. the December Leonis Minorids produce mostly swift meteors.

The last of the Psi Ursa Majorids (PSU) are expected this weekend. This shower is active from December 2-10 with maximum activity occurring on December 5th. The radiant is currently located at 11:31 (173) +41. This position lies in central Ursa Major, 4 degrees southeast of the third magnitude star known as Psi Ursae Majoris. This area of the sky is best placed during the last hour before dawn, when it lies highest above the horizon in a dark sky. Current rates would most likely be less than one per hour and may reach 1 per hour at maximum. Observers south of the equator would see rates less than 1 per hour due to the lower radiant elevation. At 62km/sec., the average Psi Ursa Majorid meteor would be swift.

The December Sigma Virginids (DSV) was discovered by John Greaves using the data of SonotaCo. IMO video cameras confirmed that this source is active during the month of December. Peak rates occur near December 14th. The current radiant location is at 13:05 (196) +08 which places it in northern Virgo, 3 degrees south of the 3rd magnitude star known as Vindemiatrix (epsilon Virginis). Current hourly rates should be near 1 shower member no matter you location. These meteors are best seen during the last dark hour before dawn, when the radiant lies highest above the horizon in a dark sky. At 68 km/sec. the December Sigma Virginids would produce mostly swift meteors.

The December Alpha Draconids (DAD) were discovered by the Japanese observers using data from SonotaCo and is active from November 30-December 15. They are predicted to peak on December 8th from a radiant located at 13:34 (204) +58. This position actually lies in northeastern Ursa Major, 3 degrees northeast of the second magnitude star known as Mizar (zeta Ursae Majoris). These meteors are best seen during the last dark hour before dawn, when the radiant lies highest above the horizon in a dark sky. This shower is not well seen from the southern hemisphere. Current rates would most likely be near 1 per hour as seen from the northern hemisphere. Observers south of the equator would see rates less than 1 per hour due to the lower radiant elevation. Some meteor experts feel these meteors are part of the Quadrantid shower, which peaks in early January.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately 11 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 3 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 9 per hour as seen from rural observing sites and 2 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.

The list below offers the information from above in tabular form. Rates and positions are exact for Saturday night/Sunday morning except where noted in the shower descriptions.

SHOWER DATE OF MAXIMUM ACTIVITY CELESTIAL POSITION ENTRY VELOCITY CULMINATION HOURLY RATE CLASS
RA (RA in Deg.) DEC Km/Sec Local Standard Time North-South
Dec. Phi Cassiopeiids (DPC) Dec 06 01:36 (024) +50 17 21:00 <1 – <1 III
Northern Taurids (NTA) Nov 11 05:48 (087) +30 28 00:00 2 – 1 II
Southern Taurids (STA) Oct 30-Nov 02 05:58 (089) +24 27 00:00 1 – <1 II
Monocerotids (MON) Dec 13 06:36 (099) +08 41 01:00 1 – 1 II
November Orionids (NOO) Nov 29 06:46 (102) +15 43 01:00 2 – 2 II
Geminids (GEM) Dec 14 07:14 (109) +33 34 02:00 10 – 6 I
Puppid/Velids (PUP) Dec 07 08:20 (125) -45 40 03:00 <1 – 1 II
sigma Hydrids (HYD) Dec 06 & Dec 18 08:28 (127) +02 61 03:00 3 – 3 II
December Leonis Minorids (DLM) Dec 21 09:57 (149) +35 63 04:00 1 – <1 II
psi Ursa Majorids (PSU) Dec 05 11:31 (173) +41 62 05:00 <1 – <1 IV
December sigma Virginids (DSV) Dec 13 13:05 (196) +08 66 07:00 1 – 1 IV
December alpha Draconids (DAD) Dec 04 13:34 (204) +58 44 08:00 <1 – <1 IV

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