Astronomy Cast Ep. 503: Gravity Mapping

The Earth looks like a perfect sphere, but down here on the surface we see that there are mountains, rivers, oceans, glaciers, all kinds of features with different densities and shapes. Scientists can map this produce a highly detailed gravity map of our planet. And it turns out, this is very useful for other worlds too.

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Twin NASA Science Probes Start Lunar Gravity Mapping

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NASA’s twin lunar orbiting GRAIL (Gravity Recovery and Interior Laboratory) spacecraft christened Ebb and Flow have kicked off their science collection phase aimed at precisely mapping our Moon’s gravity field, interior composition and evolution, the science team informed Universe Today.

“GRAIL’s science mapping phase officially began Tuesday (March 6) and we are collecting science data,” said Maria Zuber, GRAIL principal investigator of the Massachusetts Institute of Technology in Cambridge, to Universe Today.

“It is impossible to overstate how thrilled and excited we are !”

“The data appear to be of excellent quality,” Zuber told me.

GRAIL’s goal is to provide researchers with a better understanding of how the Moon, Earth and other rocky planets in the solar system formed and evolved over its 4.5 billion years of history.

NASA’s Dawn spacecraft is currently mapping the gravity field of Asteroid Vesta in high resolution from low orbit.

Despite more than 100 missions to the Moon there is still a lot we don’t know about the Moon says Zuber, like why the near side is flooded with magma and smooth and the back side is rough, not smooth and completely different.

South pole of the far side of the moon as seen as seen in this 1st image from the MoonKAM camera aboard GRAIL mission’s Ebb spacecraft. Credit: NASA/JPL-Caltech

The formation-flying spacecraft will make detailed science measurements from lunar orbit with unparalleled precision to within 1 micron – the width of a human red blood cell – by transmitting Ka-band radio signals between each other and Earth to help unlock the mysteries of the Moon’s deep interior.

“We’ve worked on calibrating the alignment of the Ka-band antennae to establish the optimal alignment. We’ve verified the data pipeline and are spending a lot of time working with the raw data to make sure that we understand its intricacies,” Zuber explained.

The washing-machine sized probes have been flying in tandem around the Moon since entering lunar orbit in back to back maneuvers over the New Year’s weekend. Engineers have spent the past two months navigating the spaceship duo into lower, near-polar and near-circular orbits with an average altitude of 34 miles (55 kilometers), that are optimized for science data collection, and simultaneously checking out the spacecraft systems.

GRAIL A and B gravity mappers rocket to the moon atop a Delta II Heavy booster on Sept. 10 from Cape Canaveral, Florida. View to Space Launch Complex 17 gantry from Press Site 1. Credit: Ken Kremer

Ebb and Flow were launched to the Moon on September 10, 2011 aboard a Delta II rocket from Cape Canaveral, Florida and took a circuitous 3.5 month low energy path to the moon to minimize the overall costs. The Apollo astronauts reached the Moon in just 3 days.

I asked Zuber to describe the team’s activities putting the mirror image probes to work peering to the central core of our nearest neighbor in unprecedented detail.

“Last Wednesday (Feb. 29) we achieved the science orbit and on Thursday (March 1) we turned the spacecraft to ‘orbiter point’ configuration to test the instrument and to monitor temperatures and power.”

“When we turned on the instrument we established the satellite-to-satellite radio link immediately. All vital signs were nominal so we left the spacecraft in orbiter point configuration and have been collecting science data since then. At the same time, we’ve continued performing calibrations and monitoring spacecraft and instrument performance, such as temperatures, power, currents, voltages, etc., and all is well,” said Zuber.

Measurements gathered over the next 84 days will be used to create high-resolution maps of the Moon’s near side and far side gravitational fields that are 100 to 1000 times more precise than ever before and that will enable researchers to deduce the internal structure and composition of our nearest neighbor from the outer surface crust down to the deep hidden core.

As one satellite follows the other, in the same orbit, they will perform high precision range-rate measurements to precisely measure the changing distance between each other. As they fly over areas of greater and lesser gravity caused by visible features such as mountains, craters and masses hidden beneath the lunar surface, the distance between the two spacecraft will change slightly.

“GRAIL is great. Everything is in place to get science data now,” said Sami Asmar, a GRAIL co-investigator from NASA’s Jet Propulsion Lab in Pasadena, Calif. “Soon we’ll get a very high resolution and global gravity map of the Moon.”

The data collected will be translated into gravitational field maps of the Moon that will help unravel information about the makeup of the Moon’s core and interior composition.

GRAIL will gather three complete gravity maps over the three month mission which is expected to conclude around May 29. If the probes survive a solar eclipse in June and if NASA funding is available, then they may get a bonus 3 month extended mission.

Ebb and Flow - New Names for the GRAIL Twins in Lunar Orbit
4th Grade Students from Montana (inset) win NASA’s contest to rename the GRAIL A and GRAIL B spacecraft. Artist concept of twin GRAIL spacecraft flying in tandem orbits around the Moon to measure its gravity field Credit: NASA/JPL Montage: Ken Kremer

NASA sponsored a nation-wide student contest for America’s Youth to choose new names for the twin probes originally known as GRAIL A and GRAIL B. 4th graders from the Emily Dickinson Elementary School in Bozeman, Montana submitted the winning entries -Ebb and Flow. The new names won because they astutely describe the probes movements in orbit to collect the science data.

The GRAIL twins are also equipped with a very special camera dubbed MoonKAM (Moon Knowledge Acquired by Middle school students) whose purpose is to inspire kids to study science.

By having their names selected, the 4th graders from Emily Dickinson Elementary have also won the prize to choose the first target on the Moon to photograph with the MoonKAM cameras, which are managed by Dr Sally Ride, America’s first female astronaut.

“MoonKAMs on both Ebb and Flow were turned on Monday, March 5, and all appears well, Zuber said. “The Bozeman 4th graders will have the opportunity to target the first images a week after our science operations begin.”

America’s Youth Christen NASA’s Twin New Lunar Craft – Ebb & Flow

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A classroom of America’s Youth from an elementary school in Bozeman, Montana submitted the stellar winning entry in NASA’s nationwide student essay contest to rename the twin GRAIL lunar probes that just achieved orbit around our Moon on New Year’s Eve and New Year’s Day 2012

“Ebb” & “Flow” – are the dynamic duo’s official new names and were selected because they clearly illuminate the science goals of the gravity mapping spacecraft and how the Moon’s influence mightily affects Earth every day in a manner that’s easy for everyone to understand.

“The 28 students of Nina DiMauro’s class at the Emily Dickinson Elementary School have really hit the nail on the head,” said GRAIL principal investigator Prof. Maria Zuber of the Massachusetts Institute of Technology in Cambridge, Mass.

“We asked the youth of America to assist us in getting better names.”

“We chose Ebb and Flow because it’s the daily example of how the Moon’s gravity is working on the Earth,” said Zuber during a media briefing held today (Jan. 17) at NASA Headquarters in Washington, D.C. The terms ebb and flow refer to the movement of the tides on Earth due to the gravitational pull from the Moon.

“We were really impressed that the students drew their inspiration by researching GRAIL and its goal of measuring gravity. Ebb and Flow truly capture the spirit and excitement of our mission.”

Leland Melvin, NASA Associate Administrator for Education, left, Maria Zuber, GRAIL Prinicipal Investigator at the Massachusetts Institute of Technology, and James Green, Director of the Planetary Science Division in the Science Mission Directorate at NASA Headquarters, right, applaud students from Emily Dickinson Elementary School in Bozeman, Mont. during a news conference, Tuesday, Jan. 17, 2012, at NASA Headquarters in Washington. Nine hundred classrooms and more than 11,000 students from 45 states, as well as Puerto Rico and the District of Columbia, participated in a contest that began in October 2011 to name the twin lunar probes. Credit: NASA/Paul E. Alers

Ebb and Flow are flying in tandem around Earth’s only natural satellite, the first time such a feat has ever been attempted.

As they fly over mountains, craters and basins on the Moon, the spaceships will move back and forth in orbit in an “ebb and flow” like response to the changing lunar gravity field and transmit radio signals to precisely measure the variations to within 1 micron, the width of a red blood cell.

The breakthrough science expected from the mirror image twins will provide unprecedented insight into what lurks mysteriously hidden beneath the surface of our nearest neighbor and deep into the interior.

The winning names from the 4th Graders of Emily Dickinson Elementary School were chosen from essays submitted by nearly 900 classrooms across America with over 11,000 students from 45 states, Puerto Rico and the District of Columbia, Zuber explained.

The students themselves announced “Ebb” and “Flow” in a dramaric live broadcast televised on NASA TV via Skype.

“We are so thrilled that our names were chosen and excited to share this with you. We can’t believe we won! We are so honored. Thank you!” said Ms. DiMauro as the very enthusiastic students spelled out the names by holding up the individual letters one-by-one on big placards from their classroom desks in Montana.

Watch the 4th Grade Kids spell the names in this video!

Until now the pair of probes went by the rather uninspiring monikers of GRAIL “A” and “B”. GRAIL stands for Gravity Recovery And Interior Laboratory.

The twin crafts’ new names were selected jointly by Prof. Zuber and Dr. Sally Ride, America’s first woman astronaut, and announced during today’s NASA briefing.


NASA’s naming competition was open to K-12 students who submitted pairs of names and a short essay to justified their suggestions.

“Ebb” and “Flow” (GRAIL A and GRAIL B) are the size of washing machines and were launched side by side atop a Delta II booster rocket on September 10, 2011 from Cape Canaveral, Florida.

They followed a circuitous 3.5 month low energy path to the Moon to minimize the fuel requirements and overall costs.

So far the probes have completed three burns of their main engines aimed at lowering and circularizing their initial highly elliptical orbits. The orbital period has also been reduced from 11.5 hours to just under 4 hours as of today.

“The science phase begins in early March,” said Zuber. At that time the twins will be flying in tandem at 55 kilometers (34 miles) altitude.

The GRAIL twins are also equipped with a very special camera dubbed MoonKAM (Moon Knowledge Acquired by Middle school students) whose purpose is to inspire kids to study science.

“GRAIL is NASA’s first planetary spacecraft mission carrying instruments entirely dedicated to education and public outreach,” explained Sally Ride. “Over 2100 classrooms have signed up so far to participate.”

Thousands of middle school students in grades five through eight will select target areas on the lunar surface and send requests for study to the GRAIL MoonKAM Mission Operations Center in San Diego which is managed by Dr. Ride in collaboration with undergraduate students at the University of California in San Diego.

By having their names selected, the 4th graders from Emily Dickinson Elementary have also won the prize to choose the first target on the Moon to photograph with the MoonKam cameras, said Ride.

Zuber notes that the first MoonKAM images will be snapped shortly after the 82 day science phase begins on March 8.

Ebb & Flow Achieve Lunar Orbit on New Year’s Weekend 2012
NASA’s twin GRAIL-A & GRAIL-B spacecraft are orbiting the Moon in this astrophoto taken on Jan. 2, 2012 shortly after successful Lunar Orbit Insertions on New Year’s Eve and New Year’s Day 2012.
Credit: Ken Kremer

Read continuing features about GRAIL and the Moon by Ken Kremer here:
Dazzling Photos of the International Space Station Crossing the Moon!
Two new Moons join the Moon – GRAIL Twins Achieve New Year’s Orbits
First GRAIL Twin Enters Lunar Orbit – NASA’s New Year’s Gift to Science
2011: Top Stories from the Best Year Ever for NASA Planetary Science!
NASA’s Unprecedented Science Twins are GO to Orbit our Moon on New Year’s Eve
Student Alert: GRAIL Naming Contest – Essay Deadline November 11
GRAIL Lunar Blastoff Gallery
GRAIL Twins Awesome Launch Videos – A Journey to the Center of the Moon
NASA launches Twin Lunar Probes to Unravel Moons Core
GRAIL Unveiled for Lunar Science Trek — Launch Reset to Sept. 10
Last Delta II Rocket to Launch Extraordinary Journey to the Center of the Moon on Sept. 8
NASAs Lunar Mapping Duo Encapsulated and Ready for Sept. 8 Liftoff
GRAIL Lunar Twins Mated to Delta Rocket at Launch Pad
GRAIL Twins ready for NASA Science Expedition to the Moon: Photo Gallery

First GRAIL Twin Enters Lunar Orbit – NASA’s New Year’s Gift to Science

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Cheers erupted after the first of NASA’s twin $496 Million Moon Mapping probes entered orbit on New Year’s Eve (Dec. 31) upon completion of the 40 minute main engine burn essential for insertion into lunar orbit. The small GRAIL spacecraft will map the lunar interior with unprecedented precision to deduce the Moon’s hidden interior composition.

“Engines stopped. It’s in a great initial orbit!!!! ”

– NASA’s Jim Green told Universe Today, just moments after verification of a successful engine burn and injection of the GRAIL-A spacecraft into an initial eliptical orbit. Green is the Director of Planetary Science at NASA HQ and was stationed inside Mission Control at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Ca (see photos below).

“Pop the bubbly & toast the moon! NASA’s GRAIL-A spacecraft is in lunar orbit,” NASA tweeted shortly after verifying the critical firing was done. “Burn complete! GRAIL-A is now orbiting the moon and awaiting the arrival of its twin GRAIL-B on New Year’s Day.”


The firing of the hydrazine fueled thruster was concluded at 5 PM EST (2 PM PST) today, Dec. 31, 2011 and was the capstone to a stupendous year for science at NASA.

“2011 was definitely the best year ever for NASA Planetary Science,” Green told me today. “2011 was the “Year of the Solar System”.

“GRAIL-A is in a highly elliptical polar orbit that takes about 11.5 hours to complete.”

“We see about the first eight to ten minutes of the start of the burn as it heads towards the Moon’s southern hemisphere, continues as GRAIL goes behind the moon and the burn ends about eight minutes or so after it exits and reappears over the north polar region.”

“So we watch the beginning of the burn and the end of the burn via the Deep Space Network (DSN). The same thing will be repeated about 25 hours later with GRAIL-B on New Year’s Day [Jan 1, 2012],” Green explained.

The orbit is approximately 56-miles (90-kilometers) by 5,197-miles (8,363-kilometers around the moon. The probe barreled towards the moon at 4400 MPH and skimmed to within about 68 miles over the South Pole.

“My resolution for the new year is to unlock lunar mysteries and understand how the moon, Earth and other rocky planets evolved,” said Maria Zuber, GRAIL principal investigator at the Massachusetts Institute of Technology in Cambridge. “Now, with GRAIL-A successfully placed in orbit around the moon, we are one step closer to achieving that goal.”

Zuber witnessed the events in Mission Control along with JPL Director Charles Elachi (see photos).

GRAIL team at JPL Mission Control celebrates successful insertion of GRAIL-A into Lunar Orbit of New Year’s Eve. From Left: David Lehman, GRAIL Project Manager of JPL, Prof Maria Zuber, GRAIL Principal Investigator of MIT, Charles Elachi, JPL Director. Credit: NASA/Jim Green

The mirror twin, known as GRAIL-B, was less than 30,000 miles (48,000 km) from the moon as GRAIL A achieved orbit and closing at a rate of 896 mph (1,442 kph). GRAIL-B’s insertion burn is slated to begin on New Year’s Day at 2:05 p.m. PST (5:05 p.m. EST) and will last about 39 minutes.

GRAIL-B is about 25 hours behind GRAIL-A, allowing the teams enough time to rest and prepare, said David Lehman, GRAIL project manager at JPL.

“With GRAIL-A in lunar orbit we are halfway home,” said Lehman. “Tomorrow may be New Year’s everywhere else, but it’s another work day around the moon and here at JPL for the GRAIL team.”

GRAIL-A spacecraft achieved Lunar Orbit Insertion on New Year’s Eve. Artists concept shows twin GRAIL spacecraft orbiting the Moon. GRAIL-A and GRAIL-B flying in tandem using a precision formation-flying technique. Credit: Lockheed Martin

Engineers will then gradually lower the tandem flying satellites into a near-polar near-circular orbital altitude of about 34 miles (55 kilometers) with an average separation of about 200 km. The 82 day science phase will begin in March 2012.

GRAIL will globally map the moon’s gravity field to high precision to deduce information about the interior structure, density and composition of the lunar interior. We’ll evaluate whether there even is a solid or liquid core or a mixture and advance the understanding of the thermal evolution of the moon and the solar system,” explained GRAIL co-investigator Sami Asmar to Universe Today. Asmar is from JPL.


New names for the dynamic duo may be announced on New Year’s Day. Zuber said that the winning names of a student essay contest drew more than 1000 entries.

The GRAIL team is making a major public outreach effort to involve school kids in the mission and inspire them to study science. Each spacecraft carries 4 MoonKAM cameras. Middle school students will help select the targets.

“Over 2100 Middle schools have already signed up to participate in the MoonKAM project,” Zuber told reporters.

“We’ve had a great response to the MoonKAM project and we’re still accepting applications.”

MoonKAM is sponsored by Dr. Sally Ride, America’s first female astronaut. The first images are expected after the science mission begins in March 2012.

The GRAIL twins blasted off from Florida on September 10, 2011 for a 3.5 month low energy path to the moon so a smaller booster rocket could be used to cut costs.

GRAIL team at JPL Mission Control await GRAIL-A Lunar Orbit Insertion on New Year’s Eve. David Lehman, GRAIL Project Manager of JPL, Prof Maria Zuber, GRAIL Principal Investigator of MIT. Credit: NASA/Jim Green
GRAIL Science and Launch teams inside clean room at Astrotech. Credit: Ken Kremer
GRAIL-A and GRAIL-B twin spacecraft inside clean room at Astrotech
GRAIL Co-Investigator Sami Asmar (left) from JPL and Ken Kremer discuss science objectives inside Astrotech clean room prior to encapsulation for launch. Credit: Ken Kremer

Read continuing features about GRAIL by Ken Kremer here:
2011: Top Stories from the Best Year Ever for NASA Planetary Science!
NASA’s Unprecedented Science Twins are GO to Orbit our Moon on New Year’s Eve
Student Alert: GRAIL Naming Contest – Essay Deadline November 11
GRAIL Lunar Blastoff Gallery
GRAIL Twins Awesome Launch Videos – A Journey to the Center of the Moon
NASA launches Twin Lunar Probes to Unravel Moons Core
GRAIL Unveiled for Lunar Science Trek — Launch Reset to Sept. 10
Last Delta II Rocket to Launch Extraordinary Journey to the Center of the Moon on Sept. 8
NASAs Lunar Mapping Duo Encapsulated and Ready for Sept. 8 Liftoff
GRAIL Lunar Twins Mated to Delta Rocket at Launch Pad
GRAIL Twins ready for NASA Science Expedition to the Moon: Photo Gallery

NASA’s Unprecedented Science Twins are GO to Orbit our Moon on New Year’s Eve

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In less than three days, NASA will deliver a double barreled New Year’s package to our Moon when an unprecedented pair of science satellites fire up their critical braking thrusters for insertion into lunar orbit on New Year’s Eve and New Year’s Day.

NASA’s dynamic duo of GRAIL probes are “GO” for Lunar Orbit Insertion said the mission team at a briefing for reporters today, Dec. 28. GRAIL’s goal is to exquisitely map the moons interior from the gritty outer crust to the depths of the mysterious core with unparalled precision.

“GRAIL is a Journey to the Center of the Moon”, said Maria Zuber, GRAIL principal investigator from the Massachusetts Institute of Technology (MIT) in Cambridge at the press briefing.

This newfound knowledge will fundamentally alter our understanding of how the moon and other rocky bodies in our solar system – including Earth – formed and evolved over 4.5 Billion years time.

After a three month voyage of more than 2.5 million miles (4 million kilometers) since launching from Florida on Sept. 10, 2011, NASA’s twin GRAIL spacecraft, dubbed Grail-A and GRAIL-B, are now on final approach and are rapidly closing in on the Moon following a trajectory that will hurl them low over the south pole and into an initially near polar elliptical lunar orbit lasting 11.5 hours.

GRAIL's trajectory to moon since Sept. 10, 2011 blastoff
Credit: NASA/JPL-Caltech

As of today, Dec. 28, GRAIL-A is 65,860 miles (106,000 kilometers) from the moon and closing at a speed of 745 mph (1,200 kph). GRAIL-B is 79,540 miles (128,000 kilometers) from the moon and closing at a speed of 763 mph (1,228 kph).

The lunar bound probes are formally named Gravity Recovery And Interior Laboratory (GRAIL) and each one is the size of a washing machine.

The long-duration trajectory was actually beneficial to the mission controllers and the science team because it permitted more time to assess the spacecraft’s health and check out the probes single science instrument – the Ultra Stable Oscillator – and allow it to equilibrate to a stable operating temperature long before it starts making the crucial science measurements.

NASA’s twin GRAIL A & B Moon mapping probes
The GRAIL satellites are now streaking to the Moon and their arrival for orbit insertion is just days away and hours apart on New Year’s Eve and New Year’s Day 2012. This picture shows how they looked, mounted side by side, during launch preparations inside the clean room at Astrotech Space Operations facility in Florida prior to blasting off for the Moon on Sept. 10, 2011 from Cape Canaveral, Florida. Credit: Ken Kremer

The duo will arrive 25 hours apart and be placed into orbit starting at 1:21 p.m. PST (4:21 p.m. EST) for GRAIL-A on Dec. 31, and 2:05 p.m. PST (5:05 p.m. EST) on Jan. 1 for GRAIL-B, said David Lehman, project manager for GRAIL at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

“The GRAIL A burn will last 40 minutes and the GRAIL-B burn will last 38 minutes. One hour after the burn we will know the results and make an announcement,” Lehman explained.

The thrusters must fire on time and for the full duration for the probes to achieve orbit. The braking maneuver is preprogrammed and done completely automatically.

Over the next few weeks, the altitude of the spacecraft will be gradually lowered to 34 miles (55 kilometers) into a near-polar, near-circular orbit with an orbital period of two hours. The science phase will then begin in March 2012.

“So far there have been over 100 missions to the Moon and hundreds of pounds of rock have been returned. But there is still a lot we don’t know about the Moon even after the Apollo lunar landings,” explained Zuber.

“We don’t know why the near side of the Moon is different from the far side. In fact we know more about Mars than the Moon.”

GRAIL’s science collection phase will last 82 days. The two spacecraft will transmit radio signals that will precisely measure the distance between them to within a few microns, less than the width of a human hair.

Artist concept of twin GRAIL spacecraft flying in tandem orbits around the moon to measure its gravity field in unprecedented detail. Credit: NASA/JPL

As they orbit in tandem, the moons gravity will change – increasing and decreasing due to the influence of both visible surface features such as mountains and craters and unknown concentrations of masses hidden beneath the lunar surface. This will cause the relative velocity and the distance between the probes to change.

The resulting data will be translated into a high-resolution map of the Moon’s gravitational field and also enable determinations of the moon’s inner composition.

The GRAIL mission may be extended for another 6 months if the solar powered probes survive a power draining and potentially deadly lunar eclipse due in June 2012.

Engineers would significantly lower the orbit to an altitude of barely 15 to 20 miles above the surface to gain even further insights into the lunar interior.

The twin probes are also equipped with 4 cameras each – named MoonKAM – that will be used by middle school students to photograph student selected targets.

The MoonKAM project is led Dr. Sally Ride, America’s first woman astronaut as a way to motivate kids to study math and science.

JPL manages the GRAIL mission for NASA.

Stay tuned for Universe Today updates amidst the News Year’s festivities.

Blastoff of twin GRAIL A and B lunar gravity mapping spacecraft on a Delta II Heavy rocket on Sept. 10 from Pad 17B Cape Canaveral Air Force Station in Florida at 9:08 a.m. EDT. Credit: Ken Kremer

Read continuing features about GRAIL by Ken Kremer here:
Student Alert: GRAIL Naming Contest – Essay Deadline November 11
GRAIL Lunar Blastoff Gallery
GRAIL Twins Awesome Launch Videos – A Journey to the Center of the Moon
NASA launches Twin Lunar Probes to Unravel Moons Core
GRAIL Unveiled for Lunar Science Trek — Launch Reset to Sept. 10
Last Delta II Rocket to Launch Extraordinary Journey to the Center of the Moon on Sept. 8
NASAs Lunar Mapping Duo Encapsulated and Ready for Sept. 8 Liftoff
GRAIL Lunar Twins Mated to Delta Rocket at Launch Pad
GRAIL Twins ready for NASA Science Expedition to the Moon: Photo Gallery

Student Alert: GRAIL Naming Contest – Essay Deadline November 11

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Student Alert ! – Here’s your once in a lifetime chance to name Two NASA robots speeding at this moment to the Moon on a super science mission to map the lunar gravity field. They were successfully launched from the Earth to the Moon on September 10, 2011. Right now the robots are called GRAIL A and GRAIL B. But, they need real names that inspire. And they need those names real soon. The goal is to “capture the spirit and excitement of lunar exploration”, says NASA – the US Space Agency.

NASA needs your help and has just announced an essay writing contest open to students in Grades K – 12 at schools in the United States. The deadline to submit your essay is November 11, 2011. GRAIL stands for “Gravity Recovery And Interior Laboratory.”

The rules state you need to pick two names and explain your choices in 500 words or less in English. Your essay can be any length up to 500 words – even as short as a paragraph. But, DO NOT write more than 500 words or your entry will be automatically disqualified.

Learn more about the GRAIL Essay Naming Contest here:

Read all the Official Contest Rules here:

Download the Naming Contest Submission Form here:

Students: NASA Wants You to Name that GRAIL !
Write an Essay and name these twin Lunar mapping satellites. NASA’s twin GRAIL A & B science probes are now streaking to the Moon and arrive on New Year’s Day 2012. This picture shows how they looked, mounted side by side, during launch preparations prior to blasting off for the Moon on Sept. 10, 2011 from Florida. Credit: Ken Kremer

The GRAIL A and B lunar spaceships are twins – just like those other awe inspiring robots “Spirit” and “Opportunity” , which were named by a 10 year old girl student and quickly became famous worldwide and forever because of their exciting science missions of Exploration and Discovery.They arrive in Lunar Orbit on New Year’s Day 2012.

Blastoff of twin GRAIL A and B lunar gravity mapping spacecraft on a Delta II Heavy rocket on Sept. 10 from Pad 17B Cape Canaveral Air Force Station in Florida at 9:08 a.m. EDT. Credit: Ken Kremer

And there is another way that students can get involved in NASA’s GRAIL mission.

GRAIL A & B are both equipped with four student-run MoonKAM cameras. Students can suggest targets for the cameras. Then the cameras will take close-up views of the lunar surface, taking tens of thousands of images and sending them back to Earth.

“Over 1100 middle schools have signed up to participate in the MoonKAM education and public outreach program to take images and engage in exploration,” said Prof. Maria Zuber of MIT.

Prof. Zuber is the top scientist on the mission and she was very excited to announce the GRAIL Essay Naming contest right after the twin spaceships blasted off to the Moon on Sep 10, 2011 from Cape Canaveral in Florida.

What is the purpose of GRAIL ?

“GRAIL simply put, is a ‘Journey to the Center of the Moon’,” says Dr. Ed Weiler, NASA Associate Administrator of the Science Mission Directorate in Washington, DC.

“It will probe the interior of the moon and map its gravity field by 100 to 1000 times better than ever before. We will learn more about the interior of the moon with GRAIL than all previous lunar missions combined. Precisely knowing what the gravity fields are will be critical in helping to land future human and robotic spacecraft. The moon is not very uniform. So it’s a dicey thing to fly orbits around the moon.”

“There have been many missions that have gone to the moon, orbited the moon, landed on the moon, brought back samples of the moon,” said Zuber. “But the missing piece of the puzzle in trying to understand the moon is what the deep interior is like.”

So, what are you waiting for.

Start thinking and writing. Students – You can be space explorers too !

Read Ken’s continuing features about GRAIL
GRAIL Lunar Blastoff Gallery
GRAIL Twins Awesome Launch Videos – A Journey to the Center of the Moon
NASA launches Twin Lunar Probes to Unravel Moons Core
GRAIL Unveiled for Lunar Science Trek — Launch Reset to Sept. 10
Last Delta II Rocket to Launch Extraordinary Journey to the Center of the Moon on Sept. 8
NASAs Lunar Mapping Duo Encapsulated and Ready for Sept. 8 Liftoff
GRAIL Lunar Twins Mated to Delta Rocket at Launch Pad
GRAIL Twins ready for NASA Science Expedition to the Moon: Photo Gallery

GRAIL Unveiled for Lunar Science Trek — Launch Reset to Sept. 10

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NASA’s Gravity Recovery and Interior Laboratory (GRAIL) moon mapping twins and the mighty Delta II rocket that will blast the high tech physics experiment to space on a lunar science trek were magnificently unveiled in the overnight darkness in anticipation of a liftoff that had originally been planned for the morning of Sept. 8.

Excessively high upper level winds ultimately thwarted Thursday’s launch attempt.

NASA late today has just announced a further postponement by another day to Saturday Sept. 10 to allow engineers additional time to review propulsion system data from Thursday’s detanking operation after the launch attempt was scrubbed to Friday. Additional time is needed by the launch team to review the pertinent data to ensure a safe blastoff of the $496 Million GRAIL mission.

There are two instantaneous launch opportunities at 8:29:45 a.m. and 9:08:52 a.m. EDT at Cape Canaveral, eight minutes earlier than was planned on Sept. 8. The weather forecast for Sept. 10 still shows a 60 percent chance of favorable conditions for a launch attempt.

GRAIL A and B enclosed in nose cone atop Delta II rocket at Cape Canaveral, Florida. Umbilical’s connect from Delta 2 to Fixed Umbilical Tower (FUT).
Credit: Ken Kremer (kenkremer.com)

Despite a rather poor weather prognosis, the heavy space coast cloud cover had almost completely cleared out in the final hours before launch, the surface winds were quite calm and we all expected to witness a thunderous liftoff. But measurements from weather balloons sent aloft indicated that the upper level winds were “red” and violated the launch criteria.

Mobile Service Tower is retracted from around Delta II rocket at Pad 17B. Credit: Ken Kremer

As the launch gantry was quickly retracted at Launch Complex 17B on Sept. 7, the Delta was bathed in xenon spotlights that provided a breathtaking light show as the service structure moved a few hundred feet along rails.

The cocoon like Mobile Service Tower (MST) provides platforms to access the rocket at multiple levels to prepare the vehicle and spacecraft for flight. The MST also protects the rocket from weather and impacts from foreign debris.

The GRAIL A and B mirror image twins ride side by side to space atop the Delta rocket. The washing machine spacecraft weigh about 677 pounds (307 kg) each.

The Delta II rocket stands 128 feet tall and is 8 feet in diameter. The first stage liquid and solid rocket fueled engines will generate about 1.3 million pounds of thrust.

During the Terminal Countdown, the first stage is fueled with cryogenic liquid oxygen and highly refined kerosene (RP-1).

GRAIL is an extraordinary first ever journey to the center of the moon that will — with its instruments from orbit — peer into the moons interior from crust to core and map its gravity field by 100 to 1000 times better than ever before. The mission employs two satellites flying in tandem formation some 50 km in near circular polar orbit above the lunar surface.

GRAIL A and B will perform high precision range-rate measurements between them using a Ka-band instrument. The mission will provide unprecedented insight into the formation and thermal evolution of the moon that can be applied to the other rocky planets in our solar system: Mercury, Venus, Earth and Mars.

After a 3.5 month journey to the moon, the probes will arrive about a day apart on New Year’s Eve and New Year’s Day 2012 for an 82 day science mapping phase as the moon rotates three times beneath the GRAIL orbit.

Photojournalists watch as Mobile Service Tower is retracted from around Delta II rocket at Pad 17B.
Credit: Ken Kremer

Xenon spotlights bathe Delta II rocket as Mobile Service Tower is retracted at Pad 17 and photojournalists watch from nearby at Pad 17B. Credit: Ken Kremer

Read Ken’s continuing features about GRAIL
Last Delta II Rocket to Launch Extraordinary Journey to the Center of the Moon on Sept. 8
NASAs Lunar Mapping Duo Encapsulated and Ready for Sept. 8 Liftoff
GRAIL Lunar Twins Mated to Delta Rocket at Launch Pad
GRAIL Twins ready for NASA Science Expedition to the Moon: Photo Gallery

Last Delta II Rocket to Launch Extraordinary Journey to the Center of the Moon on Sept. 8

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Another American rocket Era is about to end. The venerable Delta II rocket, steeped in history, will fly what is almost certainly its final mission from Cape Canaveral. And it will do so quite fittingly by blasting twin satellites to the moon for NASA on a unique path for a truly challenging mission to do “extraordinary science”.

On Sept. 8, the most powerful version of the Delta II, dubbed the Delta II Heavy, is slated to launch NASA’s duo of GRAIL lunar mappers on an unprecedented science mission to unlock the mysteries of the moons deep interior. There are two instantaneous launch windows at 8:37:06 a.m. and 9:16:12 a.m. EDT lasting one second each.

GRAIL simply put, is a journey to the center of the moon,” said Ed Weiler, NASA Associate Administrator of the Science Mission Directorate in Washington,DC at a pre-launch briefing for reporters on Sept. 6.

“It will probe the interior of the moon and map its gravity field by 100 to 1000 times better than ever before. We will learn more about the interior of the moon with GRAIL than all previous lunar missions combined.”

View of Delta II rocket looking out to Atlantic Ocean from upper level of Launch Complex 17. ULA and GRAIL logos painted on side of 8 ft diameter Delta rocket. Credit: Ken Kremer

GRAIL will depart Earth from Space Launch Complex 17B (SLC-17B) at Cape Canaveral Air Force Station, Florida, which is also the last scheduled use of Pad 17B.

GRAIL logo painted on the side of Delta II Rocket 1st Stage. Photo taken from inside upper level of launch gantry. GRAIL stands for Gravity Recovery and Interior Laboratory. Credit: Ken Kremer

“Trying to understand how the moon formed, and how it evolved over its history, is one of the things we’re trying to address with the GRAIL mission,” says Maria Zuber, principal investigator for GRAIL from the Massachusetts Institute of Technology. “But also, (we’re) trying to understand how the moon is an example of how terrestrial planets in general have formed.”

“GRAIL is a mission that will study the inside of the moon from crust to core,” Zuber says.

Delta II Heavy rocket is augmented by 9 wider diameter solid rocket motors providing more thrust. Credit: Ken Kremer

So far there have been 355 launches of the Delta II family, according to NASA’s Delta II Launch Manager Tim Dunn. The Delta II is built by United Launch Alliance.

“GRAIL is the last contracted Delta II mission to be launched from Complex 17. And it will be the 356th overall Delta to be launched. Complex 17 at the Cape has a proud heritage of hosting 258 of those 355 total Delta launches to date.

Hypergolic propellants have been loaded onto the 2nd stage after assessing all the preparations for the rocket, spacecraft, the range and facilities required for launch.

“The Launch Readiness Review was successfully completed and we can proceed with the countdown,” said Dunn.
The Delta II Heavy is augmented with nine larger diameter ATK solid rocket motors.

The Mobile Service Tower will be rolled back from the Delta II rocket tonight, starting at about 10:30 p.m. EDT depending on the weather.

The weather forecast for launch remains very iffy at a 60% percent chance of “NO GO” according to NASA and Air Force officials.

A launch decision will be made tomorrow morning Sept. 8 right after the weather briefing but before fueling begins at 6:30 a.m.

The weather forecast for rollback of the Mobile Service Tower tonight remains generally favorable. There is a 40% chance of a weather issue at 10:30 p.m. which drops to 30% after midnight. Tower rollback can be pushed back about 2 hours without impacting the countdown, says NASA.

Weather remains at 60% NO GO in case of a 24 hour delay but improves over the weekend. The team has about 42 days time in the launch window.

After entering lunar orbit, the two GRAIL spacecraft will fly in a tandem formation just 55 kilometers above the lunar surface with an average separation of 200 km during the three month science phase.

Stay tuned to Universe Today for updates overnight leading to liftoff at 8:37 a.m.

See my photo album from a recent tour of Launch Complex 17 and the Mobile Service Tower

GRAIL Flying in Formation. Using a precision formation-flying technique, the twin GRAIL spacecraft will map the moon's gravity field. The mission also will answer longstanding questions about Earth's moon, including the size of a possible inner core, and it should provide scientists with a better understanding of how Earth and other rocky planets in the solar system formed. GRAIL is a part of NASA's Discovery Program.

Read Ken’s continuing features about GRAIL

NASAs Lunar Mapping Duo Encapsulated and Ready for Sept. 8 Liftoff
GRAIL Lunar Twins Mated to Delta Rocket at Launch Pad
GRAIL Twins ready for NASA Science Expedition to the Moon: Photo Gallery

NASAs Lunar Mapping Duo Encapsulated and Ready for Sept. 8 Liftoff

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NASA’s powerful lunar mapping duo of GRAIL spacecraft are now poised for liftoff in just one weeks time on Thursday, Sept. 8.

Mission managers held a Flight Readiness Review on Wednesday (Aug.31) and gave a tentative approval to begin fueling the Delta II rockets second stage on Sept. 2 and 3 after evaluating all issues related to the rocket, launch pad and payloads.

Launch preparations are proceeding on schedule towards an early morning lift off from the seaside Space Launch Complex 17B (SLC-17B) at Cape Canaveral Air Force Station, Florida. There are two instantaneous launch windows at 8:37:06 a.m. and 9:16:12 a.m. EDT lasting one second each.

“Launch vehicle and spacecraft closeouts will begin on Tuesday, and the Launch Readiness Review is also scheduled for Tuesday morning,” NASA KSC spokesman George Diller told Universe Today.

“This morning’s launch countdown dress rehearsal went fine.”

“Delta II 2nd stage fueling has been rescheduled for Friday and Saturday [Sept. 2 and 3]. Last evening a software error was found in the launch processing system data base. ULA (United Launch Alliance) decided they would like to look for any additional errors before the fueling begins. There is no impact to the launch date and currently no work is scheduled on Sunday or on Labor Day,” said Diller.

The launch period extends through Oct. 19, with liftoff occurring approximately four minutes earlier each day in case of a delay. The flight plan was designed to avoid a pair of lunar eclipses occurring on December 10th, 2011 and June 4th 2012 which would interfere with the missions operations and science.

The team is keeping a close watch on the weather as the season’s next Atlantic Ocean storm heads westwards. Katia has just been upgraded to Hurricane status and follows closely on the heels of the continuing vast destruction, misery and deaths caused by Hurricane Irene earlier this week.

“The preliminary weather forecast is favorable for launch day as long as the wind remains out of the west as is currently forecast for that time of the morning,” Diller told me.

Twin GRAIL Lunar Mappers are secured atop Delta II rocket and await enclose in the Delta payload fairing. The fairing will protect the spacecraft from the impact of aerodynamic pressure and heating during ascent and will be jettisoned once the spacecraft is outside the Earth's atmosphere. Credit: NASA/Jim Grossmann

The twin probes known as GRAIL-A and GRAIL-B (Gravity Recovery and Interior Laboratory) were encapsulated inside the clamshell like payload fairing on Aug. 23 The nearly identical spacecraft are mounted side by side and sit atop the Centaur upper stage.

The fairing shields the spacecraft from aerodynamic pressures, friction and extreme heating for the first few minutes of flight during ascent through the Earth atmosphere.

This Delta II Heavy booster rocket is the most powerful version of the Delta II family built by ULA. The booster’s first stage is augmented with larger diameter solid rocket motors.

GRAIL was processed for launch inside at the Astrotech payload processing facility in Titusville, Fla. See my GRAIL spacecraft photos from inside the Astrotech clean room facilities here.

“The GRAIL spacecraft inside the handling can departed Astrotech and arrived at the launch pad, SLC-17B on Aug. 18” said Tim Dunn, NASA’s Delta II Launch Director in an interview with Universe Today. “The spacecraft was then hoisted by crane onto the Delta II launch vehicle and the spacecraft mate operation was flawlessly executed by the combined ULA and NASA Delta II Team.”

An Integrated Systems Test (IST) of the mated booster and payload was completed on Aug. 22

Technicians prepare twin GRAIL spacecraft for enclosure in the Delta payload fairing. Credit: NASA/Jim Grossmann

The dynamic duo will orbit the moon in a tandam formation just 50 kilometers above the lunar surface with an average separation of 200 km. During the 90 day science phase the goal is to determine the structure of the lunar interior from crust to core and to advance understanding of the thermal evolution of the moon.

GRAIL-A & GRAIL-B will measure the lunar gravity field with unprecedented resolution up to 100 times improvement on the near side and 1000 times improvement for the far side.

NASA’s twin GRAIL Science Probes ready for Lunar Expedition
GRAIL B (left) and GRAIL A (right) spacecraft are mounted side by side on top of a payload adapter inside the clean room at Astrotech Space Operations facility. The spacecraft await lunar launch on Sept. 8, 2011. Credit: Ken Kremer

Read Ken’s continuing features about GRAIL

GRAIL Lunar Twins Mated to Delta Rocket at Launch Pad
GRAIL Twins ready for NASA Science Expedition to the Moon: Photo Gallery