Comments on: Rocket Lab to build new Neutron rocket at Wallops Island in Virginia

By: Edward

Edward — Wed, 02 Mar 2022 05:37:15 +0000

John Schneider wrote: “Interested in feedback from Robt Z. or readers, as to the long term utility at that latitude.”

Most people incorrectly believe that the best place for a launchpad is the equator, because it gives an advantage of an initial speed of ~1,000 mph, so that not as much propellant is needed to reach orbital speed — or more payload can be lifted to orbit. This is true for an equatorial orbit, such as geostationary. Since this was the market for the Ariane rocket family, Kourou, French Guiana, is where they built their launchpads.

However, for orbits that cross the equator at an angle, such as 30 degrees, 45 degrees, 60 degrees, or 90 degrees (polar), the optimal locations for those orbits are located at those latitudes. This is because the “throw” received at the equator, while greater than at those latitudes, is offset by the necessity of launching toward the north (or south) in order gain the northerly velocity needed to reach those orbits. At those latitudes, an eastward launch puts the rocket and payload directly into that orbit, taking advantage of the reduced “throw” but not requiring any northward velocity. A launch from Wallops, at 38 degrees, to a 45 degree orbit would be more optimal than launching from the equator or from a pad at 60 degrees.

Sun synchronous orbits are somewhat different, as they are greater than 90 degrees (polar but slightly retrograde). There is no similar “optimal” launch latitude, but one can intuit that launch sites farther from the equator are better than those closer to it (Alaska, New Zealand, Norway, and Scotland give nice polar launch latitudes). The table in the Wikipedia article, below, gives an idea (please note the “inclination” column):
https://en.wikipedia.org/wiki/Sun-synchronous_orbit#Technical_details (Scroll down a little way.)

Geostationary orbits are nice for some communication satellites, but several communication constellations use both high inclination and polar orbits in order to cover as much of the Earth’s surface as possible. Globalstar, Iridium, One Web, and Starlink are four such constellations. GPS and similar global position systems also use high inclination orbits.

Having launch sites at a number of latitudes is desirable.

By: Alton

Alton — Wed, 02 Mar 2022 04:18:59 +0000

Wallops Island’s first launch was July 4, 1945 of the research rocket “Tiamat”.
Thus followed over 15,000 more, including the development of ICBM reentry warheads, would be tough slog, that one……

By: John Schneider

John Schneider — Tue, 01 Mar 2022 21:08:18 +0000

As an area resident I have always been a little skeptical about the Wallops site because of its 38N latitude. Downrange southeasterly azimuth over the Atlantic is pretty good as the coast recedes westward, not so for Northing. Interested in feedback from Robt Z. or readers, as to the long term utility at that latitude. The Russian launch sites are of course rather north, but then so is the azimuth of the ISS, and of course polar or sun-synch orbits.
In a rigorously polar orbit one wouldn’t know from where the thing came. Do know a local NASA telemetry who regularly bounced from Vandenberg (polar aim) to East Coast. In any case I love the local technical prospect, and though a retired geezer enough mechanics to report competently.
On second thought Rocketlab’s NZ site ain’t the equator either.
Thanks, in advance.
John S.