Pow­er­ful rock­ets al­low min­ing in space

More pow­er­ful rock­ets will al­low min­ing com­pa­nies to reach as­ter­oids in­clud­ing valu­able min­er­als more eas­ily. The com­pa­nies par­tic­u­larly fo­cus on 3 types of as­ter­oids.

Science Illustrated - - SPACE -

The count­down hits zero, and 27 awesome rocket en­gines are ac­ti­vated. The world’s most pow­er­ful rocket, Fal­con Heavy, lifts off from the launch­pad for the very first time, and thou­sands of spec­ta­tors cheer ec­stat­i­cally.

6 Fe­bru­ary 2018 was an im­por­tant day in space his­tory, as the huge Fal­con Heavy com­pleted its first test flight with­out any er­rors. Not since the leg­endary Saturn V moon rocket flew its last mis­sion in 1973, had the world seen sim­i­lar lift­ing power. Fal­con Heavy’s en­gines can lift 63,800 kg into an or­bit around Earth – i.e. more than twice as much as its clos­est com­peti­tor, Delta IV Heavy. And Fal­con Heavy is just the first of a new gen­er­a­tion of heavy­weight rock­ets. With new types of fuel and en­gines plus stronger ma­te­ri­als, the new huge rock­ets will al­low quick tourist space mis­sions, min­ing on as­ter­oids, and man re­turn­ing to the Moon.

Rock­ets de­feat grav­ity

The prin­ci­ple be­hind rocket propul­sion was first de­scribed in physi­cist Isaac New­ton’s third law of mo­tion: for ev­ery ac­tion, there is an equal and op­po­site re­ac­tion. In con­nec­tion with rock­ets, the prin­ci­ple is taken ad­van­tage of by ac­cel­er­at­ing gases out through noz­zles. When the fast-mov­ing gases leave the noz­zle, an op­po­site force will push the rocket up­wards. As soon as the force from the push ex­ceeds grav­ity, the rocket will lift off from the ground. The rocket be­gins its jour­ney in a ver­ti­cal po­si­tion, but on its way up through the at­mos­phere, it will travel more and more hor­i­zon­tally. Although the rocket quickly leaves the at­mos­phere, it is still in­flu­enced by Earth’s field of grav­ity, and as soon as the en­gines are de­ac­ti­vated, it will start to fall back to­wards Earth. So, it mu s t ob­tain a hor­i­zon­tal speed that will neu­tralise grav­ity's down­ward pull. A speed of at least 30,000 km/h is re­quired to re­main in or­bit around Earth. If the rocket is meant

to go fur­ther than an or­bit around Earth, such as to Mars, it re­quires a speed of al­most 58,000 km/h. Rock­ets are de­signed to ob­tain as much ter­mi­nal ve­loc­ity as pos­si­ble, as this will al­low them tro travel fur­ther into space.

En­gi­neers are chal­lenged

Un­for­tu­nately for rocket en­gi­neers, higher ter­mi­nal ve­loc­ity con­sti­tutes a chal­lenge that is al­most im­pos­si­ble to over­come. Ac­cord­ing to the clas­si­cal rocket equa­tion, which de­scribes the way in which all rock­ets travel, fuel con­sump­tion in­creases ex­po­nen­tially with the rocket's ter­mi­nal ve­loc­ity. This means that the faster the rocket must be able to travel, the more of its to­tal weight will be ac­counted for by fuel, leav­ing less space for equip­ment and peo­ple. 85 % of the weight on Saturn V’s mis­sions was con­sti­tuted by fuel, 11 % were en­gines and hull, whereas the as­tro­nauts and their gear only made up 4 %.

As ev­ery kg counts, the choice of fuel is one of the first is­sues set­tled by en­gi­neers, when they de­velop a new rocket en­gine. The task of the en­gine is to con­vert the fuel in the tanks into fast emis­sion gases. The speed of the emis­sions de­ter­mines the ter­mi­nal ve­loc­ity of the rocket, so it is im­por­tant to use fuel with high chem­i­cal en­ergy. The most high-en­ergy fu­els such as liq­uid hy­dro­gen are un­for­tu­nately highly un­sta­ble, in­creas­ing the risk of the en­tire rocket ex­plod­ing.

So, most booster rock­ets use a highly re­fined ver­sion of kerosene, which is more re­li­able, but also less en­ergy-ef­fi­cient. Sev­eral pri­vate rocket com­pa­nies are de­vel­op­ing en­gines which can use a third and brand new fuel in the world of rock­ets – meth­ane.

Meth­ane's en­ergy den­sity is lower than that of hy­dro­gen, but it is much eas­ier to keep liq­uid in the tanks. More­over, meth­ane’s den­sity is lower than that of hy­dro­gen, so the tanks need not be as large. Con­se­quently, en­gi­neers save weight, but even with the per­fect fuel, the en­ergy is not only used for propul­sion. Some of the force from the com­bus­tion in the en­gine is used to pump fuel about the rocket, as the ma­jor­ity of the weight must re­main at the tip of the rocket dur­ing launch, al­low­ing it to keep its bal­ance. If the cen­tre of grav­ity is lo­cated too far back, the im­mense forces could quickly make a rocket spin in­stead of stay­ing on its course.

When the ideal fuel has been iden­ti­fied, en­gi­neers must fo­cus on de­sign­ing the rocket in such a way that it can with­stand the most haz­ardous part of a space mis­sion: its pass­ing

S P A C E X

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