Friday, September 2, 2011

Holy Grail! TWINS?

That's right, twins (well nearly identical twins)...Grail A and Grail B. Now you're asking yourself, what does this mean, right?

This is my introductory blog post about NASA's Grail Mission, set to launch on September 8th, to study our celestial neighbor, the Moon. I say this is an "introductory post" because.....(drum roll please).....I have been selected to attend the NASA Launch Tweetup of this mission at Kennedy Space Center. So, I know there will be at least a post-launch article and with luck, some live posting during the tweetup.

Before I get into the real content of this post, if you don't know what a NASATweetup is, I will try to describe it to you in my words (then an official link will follow).

A NASATweetup is: A life changing, heart pounding, emotion filled gathering of people that are infectiously inspired by space, science, and human exploration who use social media to share, educated, and inspire others to reach for the stars!

I do feel I am qualified to make such a statement since I am a veteran of 3 NASATweetups (EarthDay2010, STS-132 Launch, and SunEarthDay2011 - see complete list here). I have also attended the final Space Shuttle roll-out of STS-135 (from INSIDE the VAB) and the final landing for Space Shuttle Endeavour (at the SLF) as a member of the media. Each one of these was a life changing, heart pounding, emotion filled event.

Subject: STS-132 Launch of Space Shuttle Atlantis
Credit: Aaron Cunningham
Subject:  GSFC Centrifuge - 2011 Sun Earth Day Tweetup
Credit: NASA/Pat Izzo
Subject: STS-135 Space Shuttle Atlantis Roll-out
Credit: Aaron Cunningham
Before I share the "official" NASATweetup link, I want give you the list of ways you can follow along and share in the experience of this Grail Launch Tweetup.

Follow on Twitter:

To follow me:
Twitter: @adcunningham
Flickr: adcunningham
YouTube: adcunninghamYT
Ustream: adcunningham This will be LIVE during the event!
Blog: adcunningham
Four Square: adcunningham

OK, now the official NASA Tweetup definition:

"A Tweetup is an informal meeting of people who use the social messaging medium Twitter. NASA Tweetups provide @NASA followers with the opportunity to go behind-the-scenes at NASA facilities and events and speak with scientists, engineers, astronauts and managers. NASA Tweetups range from two hours to two days in length and include a "meet and greet" session to allow participants to mingle with fellow Tweeps and the people behind NASA's Twitter feeds. Registration for NASA Tweetups will be announced on this page, @NASA and @NASATweetup." - via

The link to the Grail Tweetup page is:
NASA Announce Launch Tweetup for Grail Moon Mission

Be sure to follow me, my fellow Tweetup Attendees, and NASA for the launch of Grail (keep in mind there two points of history being made with this launch...keep reading to find out more).

If you want to see the launch in person, you can purchase tickets through the Kennedy Space Center Visitor Complex or you can watch from several nearby view locations.

The Mission Overview:
The GRAIL mission will place two spacecraft into the same orbit around the Moon. As they fly over areas of greater and lesser gravity, caused both by visible features such as mountains and craters and by masses hidden beneath the lunar surface, they will move slightly toward and away from each other. An instrument aboard each spacecraft will measure the changes in their relative velocity very precisely, and scientists will translate this information into a high-resolution map of the Moon's gravitational field. - via and more at Grail Launch News

GRAIL's engineering objectives are to enable the science objectives of mapping lunar gravity and using that information to increase understanding of the Moon's interior and thermal history. Getting the two spacecraft where they need to be, when they need to be there, requires an extremely challenging set of maneuvers never before carried out in solar system exploration missions. Mission design

The two GRAIL spacecraft will be launched together and then will fly similar but separate trajectories to the Moon after separation from the launch vehicle, taking about 3 to 4 months to get there. They will spend about 2 months reshaping and merging their orbits until one spacecraft is following the other in the same low-altitude, near-circular, near-polar orbit, and they begin formation-flying. The next 82 days will constitute the science phase, during which the spacecraft will map the Moon's gravitational field.  - via

Subject: Grail Mission Logo
Credit: NASA

The Spacecraft:
Each of the two GRAIL spacecraft, GRAIL-A and GRAIL-B, is about the size of a washing machine and has about 200 kg of mass. They are nearly identical, but the need to point antennas on each at one another requires differences in the MoonKAM mounting and in the angles of the star trackers used for attitude control and the antennas through which the orbiters measure the changing distances between them. These orientations also require that GRAIL-B precede GRAIL-A in lunar orbit.

The spacecraft design is based the Experimental Small Satellite-11 technology demonstration mission for the United States Air Force and the avionics are derived from NASA's Mars Reconnaissance Orbiter.

The Attitude Control subsystem, which provides three-axis stabilized control, consists of a sun sensor, star tracker, reaction wheels, and inertial measurement unit.

The electrical power subsystem includes two solar arrays and a lithium ion battery. Each solar array is capable of producing 700 watts at the end of the mission. They are deployed shortly after separation from the launch vehicle and remain fixed throughout the mission. Each battery has a capacity of 30 amp-hours, and is used to provide energy when the spacecraft orbits take them through the Moon's shadow.

The propulsion system includes a hydrazine catalytic thruster for lunar-orbit insertion and trajectory changes, and a warm-gas system with 8 thruster valves for attitude control and other small maneuvers.

The telecom subsystem includes the following:
- 2 S-band transponder antennas to communicate with Earth
- 2 X-band beacon antennas for Doppler ranging measurements from Earth of the Moon's near side
- S-band time-transfer system antenna, which sends a time-synchronization code back and forth between the spacecraft
- Ka-band ranging antenna for precision distance measurement between the spacecraft
Each of the first two pairs of antennas has one antenna mounted on the sunny side of the spacecraft and one on the dark side. The sunny-side antennas point to Earth during the full moon and the dark-side antennas point to Earth during new moons. This system avoids the need to mechanically rotate the antennas during the mission, which would alter the spacecraft's center of mass and disturb the science measurements. - via

Subject: GRAIL Spacecraft
Credit: Stephen Clark/
Subject: GRAIL Spacecraft
Subject: GRAIL arrival at KSC
Credit: NASA/Dimitir Gerondidakis

The Launch Vehicle:
Grail will be launched aboard a United Launch Alliance Delta II with the 7920H-10 configuration.
This is the last planned*** launch (historical bit #1) of a Delta II with was first launched in 1989. The Delta II has carried many notable payloads including: STEREO, Mars Pathfinder, Mars Exploration Rovers, Dawn, and recently MESSENGER. Here is a link for the list of other notable missions.

*** Note: A recent article on talks about possible resurrection of the Delta II for a handful of NASA climate missions. Here is the link to the article.

Subject: ULA Delta II
Subject: Delta II Launch

YouTube Video of a Delta II launch, carrying DAWN, from CCAFS

The Launch Site:
GRAIL will be launched from the Cape Canaveral Air Force Station (CCAFS) at Space Launch Complex 17 (SLC-17B). There are two pads, side by side, that are operated by the USAF 45th Space Wing. There have been over 300 launches from the complex. As of today only Pad B is active and with the  launch of GRAIL (historic point #2) Pad B will be deactivated (unless the Delta II program is kept alive).

Subject: CCAFS SLC-17
Credit: NASA/George Shelton
Subject: A Delta II on Pad B at SLC-17
Credit: NASA/George Shelton
Wrap up:
So, that's it for now. I realize that as one of only 150 selected I have an opportunity and the duty to share my GRAIL launch experience with you live and unedited.

And I mean LIVE. Live tweeting, live picture posting, and live video (via my Ustream Channel) during the 2 day event. I am sure NASA TV will be broadcasting live too, but these are usually only the portions of the event that are in the tent.

Join us next week for the GRAIL Launch Tweetup hosted by NASA, KSC, and the NASATweetup team!

Thanks reading!


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