While ICESat-2 will open a new era of Earth observation, the era of Delta II is about to close

NASA's ICESat-2 mission marks the end of an era as it will be the last time a Delta II rocket will take off. Image credit: NASA

LOMPOC, California – NASA and United Launch Alliance (ULA) are ready to fly the ice, cloud and earth-2 elevation satellite (ICESat-2) at the top of a Delta II Space Launch Complex-2 rocket at Vandenberg Air Force Base in California. The takeoff is scheduled for the opening of a 40-minute launch window at 5:46 am local time (8:46 am Eastern time). The launch will be the final of the ULA Delta II rocket launched on February 14, 1989.

"It's the end of an era, as we prepare to launch the final Delta II rocket," said Gary Wentz, vice-president of ULA government and business programs, in a statement published by the company. "This vehicle has truly created a legacy throughout its history by launching NASA, critical US military satellites and commercial customers."

If all goes as planned, ICESat-2 will provide accurate measurements of the changing height of glaciers, ice caps and sea ice on the Earth. ICESat-2 should be able to measure the average annual rise in icecaps covering Greenland and Antarctica to the width of a # 2 pencil, capturing 60,000 measurements per second.

"ICESat-2's new observational technologies – a major recommendation from the scientific community in NASA's first ten-year Earth Science study – will shed light on how the ice caps of Greenland and Antarctica contribute to the rise of the sea level " m said Michael Freilich, Director of the Earth Sciences Division of NASA's Science Missions Directorate.

United Launch Alliance's Delta II rocket, which will launch the ICESat-2 Ice, Cloud and Land-lift (ICESat-2) satellite, is going vertically on the Space Launch Complex's launch pad. 2 of the Vandenberg Air Base. Photo Credit: Chris Giersch NASA EDGE Langley

ICESat-2 will continue and improve NASA's monitoring of polar ice height changes, which began with the launch of the ICESat in 2003 and continued in 2009 with Operation IceBridge, a research mission that observed annual changes in ice using airborne instruments.

ICESat-2 has a single scientific instrument, the Advanced Laser Altimetry System (ATLAS), which measures the height by timing the time required for individual light photons to travel from the spacecraft to the Earth and back.

"ATLAS has forced us to develop new technologies to get the scientists needed to advance research," said Doug McLennan, ICESat-2 Project Leader. "It meant we had to design a satellite instrument that would not only collect incredibly accurate data, but also collect more than 250 times more height measurements than its predecessor."

ATLAS will launch its six beams of green light 10,000 times a second, sending hundreds of billions of photons to the ground. ATLAS uses a beryllium telescope 2.6 feet (about 72 centimeters) in diameter to capture the returned photons. The round trip of individual photons to and from the Earth is programmed to the billionth of a second to accurately measure the elevation. The location of the spacecraft is precisely measured using GPS and star trackers.

With so many photons coming back from its six beams, ICESat-2 will have a much more detailed view of the ice surface than its predecessor, ICESat. If both satellites fly over the same football field, ICESat would only take two measurements, one in each end zone, but ICESat-2 would collect 130 measurements between the end zones.

ICESat-2 was designed and built by Northrop Grumman. The spaceship uses Northrop Grumman's Leostar-3 satellite bus to provide power control and orbit for ATLAS, as well as propulsion, navigation, attitude control. thermal control, terrestrial communications and more. The spacecraft measures 8.1 feet x 6.1 feet x 12.5 feet (2.5 meters x 1.9 meters x 3.8 meters) and weighs 3,338 pounds (1,514 kilograms) with propellant.

The four solar panels of the spacecraft will be deployed after launch and should provide an average of 3,800 watts. The panels will charge the ICESat-2 lithium-ion battery.

ICESat-2 will launch a ULA Delta II 7420-10 rocket, which is commissioned in the field to deliver the spacecraft in a nearly circular polar orbit of 250 nautical miles (463 kilometers). This will be the final launch of the Delta II, which has been used on more than 50 NASA missions, including the Mars Rovers. Spirit and Opportunity.

The launcher payload (PLF) is a two-piece, 10-foot (3-meter) diameter hull that encapsulates the spacecraft to protect it from the launch environment as it ascends. The height of the rocket with the PLF is about 40 meters.

The Delta II second stage is a hypergolic powered vehicle with corrosion resistant stainless steel propellant tanks. It uses a single AJ10-118K rocket engine producing 9,850 pounds of thrust. The guidance section of the second stage provides structural support for propellant tanks, PLF fixtures for vehicle electronics, and structural and electronic interfaces with the spacecraft.

The Delta II first floor has a diameter of 8 feet (about 2.5 meters) and a length of about 87 feet (26.5 meters). First-stage propulsion is provided by an RS-27A engine that burns RP-1 (highly purified kerosene) and liquid oxygen. The RS-27A is capable of delivering 200,000 pounds of thrust at sea level. First-stage flight orientation and control are provided by the second-stage avionics systems.

The Delta II 7420-20 rocket uses four graphite epoxy engines (GEM), which have a diameter of about 40 inches (1 meter) and a length of 42 feet (12.8 meters). GEMs consist of a graphite-epoxy composite and are dropped by structural propellants.

In addition to the ICESat-2 spacecraft, this flight will also carry four CubeSats, which will be launched from the distributors installed on the second leg of the Delta II. The CubeSats were designed and built by UCLA, the University of Central Florida and Cal Poly. Small satellites will conduct space weather research, loading the electrical potential and resulting discharge events on spacecraft and the damping behavior of tungsten powder in a non-gravity environment.

Once in orbit, ICESat-2 will undergo a 60-day verification period during which the spacecraft and the ATLAS instrument will be tested to ensure that everything is working properly. ICESat-2 has an expected life of three years and a propellant sufficient to last seven years.

Video courtesy of NASA

Tagged: Cloud and Earth Altitude-2 Ice Delta II Ice ICESat-2 NASA Heading Stories Northrop Launch Alliance Grumman United Vandenberg Air Force Station

<! –

->

Jim Sharkey

Jim Sharkey is a laboratory assistant, writer and general science enthusiast. He grew up in Enid, Oklahoma, home town of Skylab and astronaut Owen K. Garriott. As a young fan of Star Trek, he participated in the letter writing campaign that resulted in the creation of the Enterprise Space Shuttle prototype.

While his university studies range from psychology and archeology to biology, he has never lost his passion for space exploration. Jim started blogging on science, science fiction and futurism in 2004.

Jim resides in the San Francisco Bay Area and attended NASA Socials for the Mars Science Laboratory's Curiosity Rover Landing and the launch of NASA's LADEE Lunar Orbiter.