SpaceX Falcon 9 successfully launches the DSCOVR spacecraft
Nearly fifteen years after its originally planned launch date, the US National Oceanic and Atmospheric Administration’s Deep Space Climate Observatory (DSCOVR) mission has set sail atop a SpaceX Falcon 9 rocket on Wednesday at 18:03 local time. A scrub on Sunday’s was followed by unacceptable Upper Level winds ahead of the second attempt on Tuesday. Wednesday’s conditions were perfect for the launch.
A partnership between the National Oceanic and Atmospheric Administration (NOAA), NASA and the US Air Force, the Deep Space Climate Observatory, or DSCOVR, is being flown to conduct space weather research with Earth observation as a secondary objective.
Its primary objective is to improve forecasting of geomagnetic storms caused by solar emissions, replacing NASA’s Advanced Composition Explorer (ACE) spacecraft which was launched in August 1997. DSCOVR is expected to operate for at least five years.
The 570 kilogram (1,250 lb) DSCOVR satellite carries a suite of instruments for Solar and Earth science research.
The Solar Wind Plasma Sensor and Magnetometer, or PlasMag, consists of a Faraday cup to trap charged particles, a boom-mounted fluxgate vector magnetometer to measure the magnetic fields at the spacecraft’s location and an electrostatic analyser to compare the distribution function of electrons to the solar wind conditions observed.
The PlasMag instrument continues a series of continuous observations begun by the Explorer 50, or IMP-8, satellite which launched in 1973. The WIND, SOHO and ACE missions launched during the mid-1990s have also contributed to this continuing study of the Sun.
The National Institute of Standards and Technology Advanced Radiometer, or NISTAR, is a cavity radiometer which will be used to monitor the total irradiance of the sunlit face of the Earth.
These observations will allow scientists to study changes in the amount of solar energy retained by the Earth, linked with changes in the planet’s climate.
DSCOVR’s Earth Polychromatic Imaging Camera (EPIC) is intended to provide continuous full-disc imaging of the Earth.
With an aperture of 30.5 cm (1 foot) the 63.2 kilogram (139 lb) Cassegrain telescope will be used for Earth science research. The satellite also carries a pulse-height analyser to study the effects of high-energy charged particles upon the spacecraft’s electronics.
Conceived as an Earth science and observation satellite, DSCOVR was originally named Triana after sailor Rodrigo de Triana, a member of Christopher Columbus’ expedition who was reputedly the first to see the American continent.
Proposed in 1998 by US Vice President Al Gore, one of the mission’s original objectives would have been to raise climate awareness by broadcasting a live view of the Earth from space via the EPIC instrument.
The Triana satellite was intended to have been deployed from the Space Shuttle Columbia in 2001; however delays in developing the satellite resulted in it missing this launch opportunity.
The mission was subsequently cancelled, in part due to political changes following the election of George W. Bush as President in 2000.
The mission which was to have carried Triana, STS-107, was flown as a microgravity research flight in 2003, however the mission ended with the loss of Columbia and her crew as the result of heat shield damage sustained during launch.
Following its cancellation, Triana was placed into storage at the Goddard Space Flight Center in Maryland.
The spacecraft, which was later renamed the Deep Space Climate Observatory, remained stored until 2008 when it underwent testing to determine whether it would be usable for a future mission.
Work to revive DSCOVR as a replacement for ACE began in 2011, with the satellite being removed from storage once more in 2012 to undergo the necessary work.
SpaceX were selected as the launch provider for DSCOVR in December 2012.
Contracted by the US Air Force, the mission is in part intended as a way for SpaceX to demonstrate to the Air Force the Falcon’s ability to carry its payloads.
The flight is the first mission SpaceX have flown for the US military since the failure of its third Falcon 1 launch in 2008, which carried a payload for the Operationally Responsive Space office.
Aside from Dragon missions to the International Space Station, which are operated by SpaceX itself on behalf of NASA, DSCOVR is the first major government payload to fly atop a Falcon 9.
The Falcon 9 will be making its fifteenth flight overall and its tenth in the v1.1 configuration that is now the standard for all launches. The mission will be SpaceX’s twentieth orbital launch – prior to the Falcon 9’s introduction the company had mixed results with five flights of its smaller, now-abandoned, Falcon 1 vehicle.
The Falcon 9 v1.1 was introduced in 2013 to replace the configuration – known retrospectively as the v1.0 – which was used for the first five launches.
Compared to its predecessor it features lengthened first and second stages and an octagonal first-stage engine arrangement – called an Octaweb by SpaceX – replacing the square grid layout used on the earlier flights. These changes have allowed SpaceX to increase the rocket’s payload capacity.
For the launch, the Falcon 9 will fly from SpaceX’s east coast site, Space Launch Complex 40 of the Cape Canaveral Air Force Station.
The pad, which was formerly used by Titan III and IV rockets, has supported all but one of the Falcon 9 missions to date – the exception being the launch of the Canadian CASSIOPE satellite, which took place from the west coast pad, Space Launch Complex 4E at Vandenberg Air Force Base.
The launch operations begin ten hours in advance of the planned liftoff, when the Falcon is powered up in preparation for her flight.
Fuelling begins around three hours before launch with the loading of the RP-1 propellant that is burned by both the first and second stages of the rocket.
In both stages this propellant is oxidised by liquid oxygen (LOX); loading of this oxidiser begins around twenty five minutes into the fuelling process with initial tanking of both propellant and oxidiser completed about ninety minutes before liftoff.
The LOX tanks continue to be topped up as the countdown progresses in order to replace oxygen which boils off.
At around the ten minute mark the launch countdown entered its terminal phase, during which time control of launch operations will follow an automated sequence, later transferred to the rocket’s onboard computers.
About four minutes and forty seconds before liftoff the Strongback, used to hold the rocket during transport to the launch pad, support it during erection and operations on the pad and to provide umbilical interfaces, is retracted.
Arming of the rocket’s flight termination – or self-destruct – system takes place at the three minute and fifteen second mark in the countdown.
This system will enable the Eastern Range’s Range Safety Officer (RSO) to destroy the vehicle if he believes it poses a danger to populated areas – for example if control of the rocket is lost.
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The final approvals for launch are usually given by the Launch Director and Range Control Officer, at the T-150 second and T-120 second marks in the countdown respectively.
With the countdown going to plan, the rocket proceeded to the one minute mark for the onboard computer to be commanded to conduct its final pre-launch checks and enter the correct mode for launch.
Around this time the launch pad’s water deluge system was activated. Forty seconds before launch the rocket’s propellant tanks were increased to flight pressure.
During Sunday’s first attempt, a scrub was called during the terminal count, due to issues involving the Range Radar, along with a transmitter issue. An attempt on Monday was called off well in advance due to a very poor weather forecast. This proved to be a good decision, as the Space Coast was pummelled by heavy rain.
Tuesday’s realigned attempt suffered from no technical issues, and enjoyed a good weather outlook.
However, the upper level winds were classed as red throughout the count, leaving controllers with a decision to make based on the final weather balloon data. That data showed the winds continued to be unacceptable, resulting in a scrub being called.
The next attempt will take place on Wednesday, aiming for a T-0 of 6:03 pm local time.
THE UPCOMING LAUNCH:
Three seconds before liftoff, the nine Merlin-1D engines which power the first stage ignited, building up to full thrust at the T-0 mark.
Lifting off, the Falcon began a series of roll, pitch and yaw manoeuvres to attain the correct launch azimuth for its planned deployment orbit.
The rocket attained a speed of Mach 1 a little after 70 seconds into its flight, passing through the area of maximum dynamic pressure ten seconds later.
First stage flight lasted around two minutes and 40 seconds, with the stage ending its burn prior to depletion in order to conserve fuel for a landing attempt – albeit not on the barge in the Atlantic.
The relatively low mass of the DSCOVR payload allowed for this fuel to be conserved since the satellite does not require the rocket’s maximum performance to achieve orbit.
First stage separation occurred approximately four seconds after cutoff, with the second stage igniting its Merlin Vacuum engine eight seconds later.
The second stage conducted two firings during the launch; the first to establish a parking orbit and the second to boost DSCOVR into its deployment orbit. Separation of the payload fairing from around the satellite occurred thirty to forty seconds after the second stage ignites.
The second stage’s first burn lasted approximately five minutes and fifty seconds, after which the mission entered a twenty-one and a half minute coast phase.
A fifty-eight second burn following the coast injected DSCOVR into its initial deployment orbit, with spacecraft separation occurring four minutes after the conclusion of powered flight.
The planned parameters for the target orbit are a perigee of 187 kilometres (116 miles, 101 nautical miles), an apogee of 1,241,000 km (833,300 miles, 724,100 nautical miles) and inclination of 37 degrees.
DSCOVR will manoeuvre itself to its final destination; a lissajous orbit around the L1 Lagrangian point between the Earth and the Sun. The spacecraft is expected to take about 110 days to reach the L1 point.
Lagrangian points are positions at which the combined gravity of two bodies – in the case the Earth and the Sun – act on the orbit of a third body in such a way to keep it in the same position relative to both other bodies.
The L1 point is located between the Sun and the Earth, about 1.5 million kilometres (930,000 miles) from Earth, providing a satellite with an uninterrupted view of the Sun and the Sun-facing disc of the Earth.
While the second stage continues towards orbit with DSCOVR, SpaceX were to attempt to land the expended first stage on a floating platform as part of its development plan for a reusable version of the rocket.
This would have been the second attempt to achieve a landing on the platform; the first attempt was made during January’s CRS-5 launch and although the Falcon did reach the barge it came down out of control and at an angle, exploding on impact.
However, due to storm conditions in the Atlantic, no landing will be attempted on the ASDS. Instead, a soft landing on the ocean – with little chance of recovering the stage, will be the goal for Wednesday’s attempt.
Demonstrating successful recoveries at sea could pave the way for SpaceX being granted permission to attempt future landings on land, enabling the first stage to be flown back to its launch site.
A disused Atlas-Agena pad at Cape Canaveral’s Launch Complex 13 has been suggested as a potential landing site.
The launch was the second of the year for SpaceX and its Falcon 9, the fourth for the United States and the seventh worldwide.
The Falcon 9 will be in action again at the end of the month when it is expected to perform a dual-launch of two commercial communications satellites into geostationary transfer orbit.
(Images: via NASA, SpaceX and L2’s SpaceX Section, including renderings created by L2 Artist Nathan Koga – Click here for full resolution F9, F9-R, FH and BFR renderings and more).
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