Mars Close Approach
Mars was 35.8 million miles from Earth at its closest point this month.
Mars won't be that close to Earth until 2287
In October 2020, the Red Planet will reach opposition and but will be 38.6 million miles from Earth, In August 2003, Mars was a closer at 34.6 million miles
Why is Mars covered in rust-colored dust? It mostly comes from a formation on its surface called the Medusae Fossae, a single geological object that is slowly crumbling. The formation stretches roughly a thousand kilometres across the equator.
Astronaut of the Week (Happy Birthday)
Georgy Stepanovich Shonin . August 3, 1935 – April 7, 1997; born in Rovenky Oblast, (now Ukraine)
flew on the Soyuz 6 space mission.
The crew of Georgi Shonin and Valeri Kubasov were due to take high-quality movie photography of the Soyuz 7 and Soyuz 8 docking, but the rendezvous of all three spacecraft failed.
Carried out experiments in space welding.
While welding, Kubasov almost burned through the hull of the vehicle's Living Compartment, ...eeek
Shonin was part of the original group of cosmonauts selected in 1960. He left the space programme in 1979 for medical reasons.
Space News
Boeing shifts schedule for Starliner from August 2018 to the end of this year for an uncrewed orbital flight test
The first flight of the spacecraft with astronauts aboard, moves from November 2018 to mid-2019,
According to some even the new schedules are wildly optimistic from both companies.
Also worth noting Energomash (RUSSIA) has signed a deal to sell six more RD-180 rocket engines to for flights of the Atlas V rocket, to fly Boeing's crewed Starliner spacecraft into orbit ...doh!!! Check out the Troll!!! From russian embassy
Space Word of the Week
specific impulse
Is a measure of efficiency for rocket engines, most easily thought of as the amount of thrust produced by each pound (mass) of propellant burned in a unit of time. It is kind of like a measure of mpg for rockets
Specific impulse is the Impulse or “change in momentum” per unit mass for rocket fuels, So how much more push accumulates as you use that fuel.
Impulse = Thrust x Time , Specific Impulse is basically the Impulse / propellant Mass (specific to the mass, the “specific” value of anything it always means the value-per-unit-mass.)
The amount of propellant is normally measured either in units of mass or weight.
If mass is used, Isp has units of speed, and so specific impulses are often measured in meters per second and are often termed effective exhaust velocity. It can be shown with a few equations that it’s the equivalent of the effective exhaust velocity as well. (in Jet engine Effective is differnt to actual due to the air they breath)
If propellant weight is used, an impulse divided by a force (weight) turns out to be a unit of time, and so specific impulses are measured in seconds. These two formulations are both widely used and differ from each other by a factor of g0, the dimensioned constant of gravitational acceleration at the surface of the Earth.
Newtons 3rd law : The speed of a rocket is roughly the mass of propellant that is thrown out of the back of the rocket and the speed at which that propellant is thrown out compared to the rocket's weight. ...Thrust
The faster the speed at which propellant is thrown out the back of the rocket, the faster the rocket can travel or the more cargo it can carry.
The specific impulse of a rocket propellant is a rough measure of how fast the propellant is ejected out of the back of the rocket.
A rocket with a high specific impulse doesn't need as much fuel as a rocket with low specific impulse. The higher the specific impulse, the more push you get for the fuel that rushes out.
In Many cases the engine with lower specific impulse produces more thrust (i.e Rockets 250 to 500 seconds) and the ones with higher specific impulse produces less thrust. (i.e Ion 3000 range )
The space shuttle main engines had a specific impulse of around 450 seconds. .
The F-1 engine had a specific impulse of 263 seconds means that it was inefficient but very powerful.
The higher the specific impulse, the less propellant is needed to produce a given thrust during a given time. In this regard a propellant is more efficient the greater its specific impulse. This should not be confused with energy efficiency, which can decrease as specific impulse increases, since propulsion systems that give high specific impulse require high energy to do so.
The highest specific impulse for a chemical propellant ever test-fired in a rocket engine was 542 seconds (5,320 m/s) with a tripropellant of lithium, fluorine, and hydrogen. However, this combination is impractical; see rocket fuel
The nuclear rocket typically operates by passing hydrogen gas through a superheated nuclear core. Testing in the 1960s yielded specific impulses of about 850 seconds (8,340 m/s), about twice that of the Space Shuttle engines.
A variety of other non-rocket propulsion methods, such as ion thrusters, give much higher specific impulse but with much lower thrust; for example the Hall effect thruster on the SMART-1 satellite has a specific impulse of 1,640 s (16,100 m/s) but a maximum thrust of only 68 millinewtons.
The variable specific impulse magnetoplasma rocket (VASIMR) engine currently in development will theoretically yield 20,000−300,000 m/s, and a maximum thrust of 5.7 newtons
Although liquid hydrogen delivers the largest specific impulse of the plausible rocket fuels, it also requires huge structures to hold it due to its low density. These structures can weigh a lot, offsetting the light weight of the fuel itself to some degree, and also result in higher drag while in the atmosphere.
While kerosene has lower specific impulse, its higher density results in smaller structures, which reduces stage mass, and furthermore reduces losses to atmospheric drag. In addition, kerosene-based engines generally provide higher thrust, which is important for takeoff, reducing gravity drag.
So in general terms there is a "sweet spot" in altitude where one type of fuel becomes more practical than the other.
Why are we interested in specific impulse?
a quick way to determine the thrust of a rocket, if we know the weight flow rate through the nozzle.
it is an indication of engine efficiency. Ie higher values produce more thrust for the same amount of propellant.
Simplifies mathematical analysis of rocket thermodynamics. The units of specific impulse are the same whether we use English units or metric units.
easy way to "size" an engine during preliminary analysis. The result of our thermodynamic analysis is a certain value of specific impulse. The rocket weight will define the required value of thrust. Dividing the thrust required by the specific impulse will tell us how much weight flow of propellants our engine must produce. This information determines the physical size of the engine.
Space ain’t so high anymore
Former Guest Jonathon Mcdowell has been working on reducing the Karman Line, McDowell turned to the math of the Kármán line. For his calculations, he looked at a satellite’s return to Earth, rather than its exit. That meant comparing orbital velocity, which is derived from gravity, against the drag of the atmosphere. McDowell used a standard atmospheric model to simulate the past 50 years, calculating how the line behaved at different latitudes and longitudes. He found that the atmosphere’s tug turns negligible between 66 kilometers and 88 kilometers, he will report in an upcoming issue of Acta Astronautica.
George Whitesides, CEO of Virgin Galactic, agrees. "he lays out a solid case that … a reasonable position for ‘where space begins’ is around 80 kilometers That’s consistent with the precedent set by NASA and the Air Force, which award astronaut wings to X-15 pilots who fly above 80 kilometers a recognition we have always respected.”
Space Station
A report from the space agency's inspector general concludes that NASA has stinky choice when it comes to the future of the massive International Space Station
(1) to the extent practicable, establish plans for additional one-year missions to the ISS;
(2) ensure development of a contingency plan foreach human health risk not scheduled to be mitigated prior to 2024, such as identification of alternate testing platforms,impact of health risks for astronauts, and impact to the mitigation schedule;
(3) develop a contingency plan for each exploration-enabling technology demonstration not scheduled to be fully tested by 2024, such as identification of
alternate testing platforms, impact to technical risk of exploration systems, and impact to the technology demonstration schedule;
(4) complete all end-of-mission critical systems and open work related to nominal and contingency deorbit operations; and
(5) develop options for obtaining supplemental emergency deorbit propellant support from U.S. commercial vehicles. the Agency currently does not have the capability to ensure the ISS will reenter the Earth’s atmosphere and land in a targeted location in the South Pacific Ocean
NASA was officially born 60 years ago when President Dwight D. Eisenhower signed legislation bringing the agency into existence on July 29, 1958.
Anyway lets hear about that from David Baker
Launches
August 4: Falcon 9 - Merah Putih - Cape Canaveral Air Force Station
August 11: Delta IV Heavy - Parker Solar Probe - Cape Canaveral Air Force Station
Space Fact
Siblings have never been in space at that same time, but it was close!!
STS-134 was planned to be the final regularly scheduled mission of the NASA Space Shuttle Program, but with the passing in 2011 of an appropriations bill authorizing the conversion of STS-335 to STS-135, this was no longer the case.[27] It was also originally scheduled to coincide with Expedition 26 before delays in the Space Shuttle launch schedule pushed it past that Expedition. If STS-134 had launched during Expedition 26, then Mark Kelly Commander an don his Fourth and last spaceflight and Expedition 26 commander Scott Kelly would have become the first siblings (and twins) to fly in space at the same time. STS-134 also had current ISS Commander Andrew Feustel on his second flight.
Hindu folktales interpret lunar eclipses as the result of the demon Rahu drinking the elixir of immortality. Twin deities the sun and moon promptly decapitate Rahu, but having consumed the elixir, Rahu’s head remains immortal. Seeking revenge, Rahu’s head chases the sun and moon to devour them. If he catches them we have an eclipse – Rahu swallows the moon, which reappears out of his severed neck.