Subject:†††††††††††††††††††††††††††††††††††† Spacex Does it Again!!!!! - But this time from GEO not LEO? (What the heck is GEO and LEO Tyler, and why is your subject line so incredibly long?)

 

Hello,

 

SpaceX sticks the landing for the second time in a row, but not in the same conditions as the first. As you all probably know, SpaceX had been attempting this drone ship landing for some time. First they landed on the firm land and then on April 8th, they had their first successful drone ship landing that I sent everyone the email for. But those were both LEO (low earth orbit) velocities. Last nightís landing was a launch to GEO (Geosynchronous Orbit) with a much higher starting velocity. This means the first stage re-entry was 2 km/second re-entry rather than 1 km/second re-entry. This in turn imparts 4 times the force (energy is the square of the velocity) and 8 times as much re-entry heating. All and All, a much greater test of their landing ability and huge technical feat.

 

http://static4.techinsider.io/image/572c383b52bcd023008c1309-3000-2000/spacex-may-6-2016-night-launch-stars-time-lapse.jpg

http://spaceflightnow.com/wp-content/uploads/2016/05/f9_asds_flight24.jpg

http://www.spacex.com/sites/spacex/files/6jcsat_deploy.jpg

Spacex Ė JCSAT-14 Ė Launch on May 6, 2015.

Drone Ship Landing of First Stage on Drone Ship (Telemetry is tracking Second Stage)

JCSAT-14 Deployment

 

Ok, so now for some learnings, what is LEO and GEO:

 

The shuttle, ISS, and all other manned Spacecraft (with the notable exception of the Apollo program) to date has all been in LEO (Low Earth Orbit). The ISS for example orbits at around ~249miles from Sea Level on Earth depending on the last orbit boost burn to account for gradual atmospheric friction of trace gases but Iíll save that for another discussion. What we define as Space (the Karman Line) starts at 62 miles in altitude. To maintain LEO orbit at the average ISS altitude, it must be traveling around 17,500 mph. This means to maintain LEO they have to continue travelling around the Earth very quickly so they donít just fall back into the atmosphere with gravity. As a result of this orbit, they are continually going faster than the rotation of the Earth and orbit ďAround) the Earth. They got a funny bumper sticker on the ISS to notate this orbit speed:

 

http://www.collectspace.com/images/news-110210a/001.jpg

 

Now, what is GEO? GEO (Geosynchronous Orbit) is the common orbit for Communication Satellites that must maintain constant communication and orientation over a specific spot on Earth. For example, Satellite TV Dishes only have to be pointed once during the initial setup (assuming nothing ever bumps/block the alignment) toward the GEO Satellite as it will always maintain that same spot in the sky. How can this be achieved? The answer is Physics. The higher the orbit, the slower it has to go to maintain that orbit, so in hence, it can match Earthís rotational speed. LEO Orbit is 7.8 km/s whereas GEO orbit is only 3.07 km/s.

 

The below picture is not to scale, but gives you an idea of the orbit. Now remember for SpaceX to get to GEO orbit, it has to be going much faster on the first stage booster to ignite the second stage with enough velocity and altitude to carry onto GEO orbit. This means that the re-entry burn and landing, was even more difficult and faster than the last landing from LEO orbit.

 

http://techforspace.com/wp-content/uploads/2014/08/earth-orbits1.png

 

I hope you enjoyed this science Email update and look forward to your comments and suggestions.

 

Thanks,

Tyler W