Truffula, a mango and passion fruit sour from True Anomaly Brewing. But True Anomaly may be the glass of sudsy adrenaline that Houston needed to break the monotony.įrom outside, the small warehouse building with matte black paint accented by lime green stripes looks like it could be EaDo’s latest CrossFit gym or tech startup - if not for the name painted boldly on the side.
It’s easy to imagine that some brewery fatigue may have set in and that many will shrug at yet another brewery opening. However, these days a fairly thorough brewery tour of Houston would take at least a three-day weekend to accomplish (safely). Houston’s craft-brewery landscape hasn’t yet reached the per-capita saturation of the country’s definitive beer towns (Boulder, Asheville, Ft. True Anomaly Brewing at 2012 Dallas Street. On an uncharacteristically pleasant Sunday afternoon in September, we stopped in for some beers and board games to see if this NASA-themed brewery lived up to the buzz. Since then, it has garnered attention for its elegant, fruity, and sometimes salted sour beers, as well as its contemporary space-age aesthetic. Launching Project Calliope, sponsored by Science 2.True Anomaly Brewing, the latest addition to Houston’s craft beer and EaDo bar scenes, opened its doors at 2012 Dallas this past February. * Keplerian or Two-Line Element Sets (TLEs) * What throws it off (tides, drag, solar, et cetera) * How they determine it (lasers, radar, radio Doppler, inertial, etc) The excellent YouTube channel by 'mrg3' titled "Animation for Physics and Astronomy" has a good presentation of each 'Orbital Elements'.Ĭalliope will have a low eccentricity (e) orbit at 300-350km up (a), polar (i = 90 degrees), with the ω value probably close to 0 due to launching near the equator, Ω depending on the day of launch, and of course a wildly changing (but predictable) value v at any given time. It's an angular measure from the usual reference point of perigee, or orbit's closest approach to Earth. That says, given the orbit, where the satellite is along that path. The final parameter, v, is the mean true anomaly (or alternately, q, the true anomaly, or T p, the time of periapsis passage). Since the Earth is turning underneath the orbit, that's pretty important to calculate. It is measured CCW from vernal equinox (aka intersection of Earth's equator and ecliptic), so it's an absolute measure, and using the date you can translate it to an Earth 'right now' longitude. Called many things- longitude of the ascending node, right ascension of the ascending node, it tells you what longitude in the Earth-reference position the orbit goes over. w (argument of perigee or argument of periapsis) is the twist, the rotation or skew of that ellipse from a straight up-down, given as the angle from that infamous ascending node to the semi-major axis 'longest length diameter' of the ellipse. We define the 'ascending node' as the point where the orbit intersects the equatorial plane. i is the tilt, the angle with which the entire orbit is tilted relative to the ecliptic plane. The 3rd and 4th elements, i & ω, give you the 3D orientation. As a nuance, you can also get the period (time to do 1 orbit) of an elliptical orbit if you have that semi-major axis 'a' (p 2/a 3 = 4 π 2/MG) a gives you the size, and e gives you the squishyness. The first two, a&e, yield the 2-D shape of the orbit. In implementation, then, the 6 elements are:ĥ) Ω = longitude of the ascending node = pin
True anomaly full#
However, since gravity means orbits trace out ellipses (as per Kepler's 3rd Law), and knowing the specific ellipse of an orbit lets you know the full path, defining the orbit elements using an ellipse gives you both the current position and movement, and a way of predicting where it will be next. If you specify the (x,y,z) positions and speeds, that tells you nothing about where the satellite will be next because (x,y,z) space doesn't factor in gravity. However, it results in a set of elements that let you predict future positions.
All of those give you, at any instant, the full position and motion in 3D of the satellite at a specific instance in time.Ī more clever approach still uses 6 elements- the minimum regardless of what dimensional or grid layout you choose. You could use spherical coordinates, or Euler angles.
You could use (x,y,z) for the position and (vx,vy,vz) for the velocities. Since we live in 3-D space, it's equivalent to 3 spatial dimensions and 3 velocities. but what does that actually mean? Here's a brief mini course in orbital mechanics.Īny orbit requires 6 elements to specify the position and motion fully. 'Project Calliope' will have a nearly circular polar low-earth orbit.
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