Page 19 - Australian Defence Magazine - July 2018
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imperative also led Israel to develop un- manned aerial vehicles for surveillance.
The US reportedly supplied Israel with some satellite imagery but this was not in real time and coverage was limited. As well, what was provided may not have been the highest resolution possible.
Following the Camp David agreement and the 1979 peace treaty, Israel decided it needed to develop an indigenous obser- vation satellite capability. The Israel Space Agency was founded in 1983 with the first home-built reconnaissance satellite Ofeq-1 launched in 1988.
Eleven Ofeq satellites have been launched, though one was lost in a launch failure.
As well as the Ofeq series, there’s the Amos communications satellites, TechSAR reconnaissance satellite, Earth Resources Observation Satellite (EROS) series of commercial observation satellites plus vari- ous scientific satellites.
Later this year, Israel plans to launch three shoebox sized nano-satellites to demonstrate autonomous operation in formation as well as highly accurate – location of civilian sig- nals from the ground for rescue purposes.
Shalev, who was born in Melbourne, graduated from Monash University and moved to Israel 40 years ago, said they em- ployed two kinds of observation satellites, with electro-optical (EO) and synthetic ap- erture radar (SAR) sensors.
EO sensors produce very high resolution imagery, so good that other people are inter- ested. In 2017 the Israeli-built Optsat-3000 was launched for the Italian Ministry of Defence, aboard a European Space Agency Vega rocket from French Guyana.
For its own military satellites, Israel launches from Palmachim Airbase outside Tel Aviv aboard Israeli Shavit rockets.
“Shavit is a relatively smaller launcher and that gives a very tight constraint for the size and volume of the satellite plus the fact that for geo-political safety reasons we are forced to launch in a westerly direction which is opposed to the earth’s spin,” Sha- lev said. “We can’t launch east because we have rocket stages falling and they (neigh- bouring countries) could get upset. That’s a problem you would never have in Australia.
“We are paying a weight penalty for the lift capacity of the launcher. That has forced us to design these as very lightweight satellites.”
Shalev said their satellites weight less than 400 kilograms at launch but with performance that exceeds similar capa-
bility European satellites weighing three times as much. These technical restraints have forced a culture of innovation when it comes to size and weight concerns.
While EO and SAR satellites have differ- ent capabilities, they feature a common bus – the bottom section containing electron- ics, control systems and rocket propulsion.
“By adding on a payload module we can either have a SAR satellite or an EO satel- lite,” he said. “We also launched another version of this satellite together with the Italian Optsat 3000, a satellite known as Venus which was a scientific research satel- lite which we did in conjunction with the French space agency.”
Israel also builds its satellites to last.
“This is something we are very proud of. Our longest flying observation satellite is going to be celebrating its 16th birthday in a couple of months,” he said. “Lifetime is de- termined by a number of factors. You have to have enough fuel to maintain orbit. We are only adjusting orbit height with fuel. We are using reaction wheels to adjust attitude.
“Of course fuel is not enough to give you a long life satellite. You have to have very high reliability electronics and very robust design. To have something working for 16 years non-stop without being able to service it is pretty difficult.”
To achieve this high level of reliability with least weight, IAI has developed test facili- ties to replicate what a satellite will experi- ence at launch and in space.
At blast-off a satellite endures noise and vibration. In space it’s in a constant vacu- um, with extremes of temperature during each orbit.
Testing for mechanical stresses to en- sure a design is strong enough to withstand launch uses satellite models instrumented with strain gauges and accelerometers.
Shalev said the worst mechanical vibra- tion occurred at the moment of lift off when the rocket was standing on the launch pad.
“This noise is being reflected from the ground and hitting all the external sur- faces. This is quite a mechanical load. We have here a chamber which simulates this noise at exactly the same level. It’s about six jumbo jets taking off simultaneously,” he said. “We have an environmental test where we can put sub-systems into vacuum. Elec- tronic units are being tested in these small vacuum chambers and we can put an entire satellite into the large vacuum chamber which simulates conditions in space.”
Shalev said satellites needed to be con- structed of materials compatible with vacuum.
“The lower the pressure the lower the boil- ing point. If you use paint or glue or things like that, it is being expelled. You get your optical satellite flying in a cloud of pollution. You have to choose the materials very care- fully and we have very strict criteria for this,” he said. “We are doing thorough testing of the satellites in these condition and this is one of the reason we are getting high reliability.”
Israel hasn’t yet embarked on a manned space program but has had an astronaut, Ilan Ramon, a fighter pilot who flew as a payload specialist on the space shuttle Co- lumbia in 2003. He and the six other crew members died when Columbia broke up during re-entry.
Note: The writer travelled to Israel as a guest of IAI.
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