2017 Apr 30
Sunday, Day 120
A New Launch Site
Soon after the 2012 February 3 launch of the Navid satellite, Iranian news agencies started talking about the country building a new launch site. For one, the news feed on the website of Iran's PressTV channel carried a story "Iran building new launch base for super-heavy satellites".
Defence Minister Ahmad Vahidi was quoted as saying Iran ".... is establishing a new satellite launch base to put super-heavy satellites into orbit" and it will be used to "....launch one-tonne satellites into an orbit of 1,000 kilometers". He also mentioned plans to reach orbits of 36,000 kilometres, implying geosynchronous satellites.
Elsewhere, news items mentioned the new location being in the south eastern part of the country near the coast.
Between 2009 and early 2012, Iran fired four of its Safir space launch vehicles and succesfully placed three satellites into orbit - Omid, Rasad and Navid. All were launched from a missile base in Semnan Province in the north of the country. All reached orbits inclined at 55°-56° to the equator.
The inclinations result from geography, Iran had little in the way of choice because of the location of the only launch area with facilities to assemble and launch Safir.
Semnan's missile facilities were reportedly built with Chinese help sometime in the 1980s. At the time, orbital missions were a long way from appearing on the agenda. The site was probably chosen because of closeness to Teheran (in the region of 200 kilometres) and distance from what might be regarded as unfriendly countries. It also had the benefit of a long range overland within Iran and a range extension over the Arabian Sea was available.
Planning a satellite launch has to allow for where various items of hardware such as spent rocket stages and protective fairings fall to Earth. It also has to allow for the contingency of a launch being cut short and rocket hardware falling back to Earth at some unpredictable point. For these reasons, the first part of the ascent ground track has to be kept within Iran's borders or over international waters. Risking debris falling on another country is not a good idea even though a neighbouring nation might be quite friendly. Relationships can change and there is always the risk of injury or material damage.
Taking these into account, there is a limited range of launch azimuths available from Semnan and it equates to orbital inclinations between 56° and 70°. For any launch site, the most efficient inclination is the lowest than can be achieved as it can take full advantage of the rotational velocity available at the Earth's surface. The 56° inclination used by Iran to date fits this scenario perfectly, being the best available from the site.
A 56° inclination ground track is almost totally over Iranian territory until the final few kilometres over a small corner of Pakistan before crossing the Arabian Sea. At that point, an accident would probably avoid fragments reaching the Earth's surface to cause serious damage because they would fall from above the atmosphere and most would burn up on re-entry.
Much of Iran's talk about its satellite payloads relates to imaging from orbit and a significant part of the initial effort is being directed in that way. Given the political scene in the Middle East and the fact that Israel has an active photo-reconnaissance programme, it is reasonable to assume that Iran has a similar goal.
Add to that a new rocket, Simorgh, that will need a purpose-built new launch pad, then the scene is set to look for a new launch location to handle it and provide access to a range of orbital inclinations more suited to the satellites it is intended to launch.
In technical terms, the ideal inclination for imaging is that of a sun-synchronous orbit, around 97°, so that passes over a given area on successive days are under near identical lighting conditions and there is minimal variation in the lighting over the year. Israel has demonstrated something different. Launch direction was dictated by geography. Offeq satellites orbit at a retrograde 143° inclination because the only launch azimuths avalable to Israel were westward over the Mediterranean Sea. Any others would have taken the ascending vehicle directly over one or more unfriendly neighbour's territory during the rocket-powered phase of the mission.
The complement of the inclination is 37°. The 143°/37° slot gives a relatively-long stay-time over the Middle East with at least two consecutive passes per day over the area.
Location for a New site
The general thrust of news reports is that the site is to be in the south-east of Iran near the coast. The map shows a representative location in the area described and the sort of inclination values that can be achieved from there. Knowledge of the precise location will have to wait until Iran, or some analyst, tells us where it is.
The range of inclinations it can reach is between 45° and 97°. The fit with potential requirements is close but not quite ideal.
Sun-synchronous orbit is possible without crossing anyone else's territory during the ascent, as is a similar inclination to Israel's Offeq constellation. In the latter case, an Iranian reconsat would follow similar ground tracks to Offeq but would travel in the opposite direction and reach slightly higher latitudes.
Within the range of launch azimuths available and the indicative one-tonne capacity to 1000 kilometres, geosynchronous orbit is not attainable from Iranian territory.
The inclination change required is beyond the capacity of Iran's current rocketry if the payload is to provide a meaningful service. As a minimum, it would be necesary to develop and manufacture something in the size range of Russia's Zenit or India's GSLV. Given that the current stage of Iranian rocket development is approaching what the rest of the world had around 1960 then there is some way to go. However, a small payload of several tens of kilogrammes to geosynchronous transfer orbit is possible from either Semnan or the new site. A motor firing at apogee could orbit a small package of equipment at geosynchronous altitude but probably in an inclined orbit.
There are two other possibilities. Iran may have a very large rocket as its aim, or the Defence Minister's reference is to buying launch capacity from a geosynchronous provider such as China. By mixing it in with comments about developments in low orbit, it may be making Iran's current capabilities appear greater than they really are.
It will be a long time before Iran has the expertise and capacity to develop a large rocket, and it is probably beyond its reach in economic terms. There are currently no agreements with other countries either to build or launch an Iranian geosynchronous communications satellite so it is a case of waiting to see what transpires.
Page date: 2012 Feb 12
Update: 2012 Jul 25
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