[Author’s note: This is part of the Project Mars series of short stories.
To start at the beginning go >> HERE << ]

Copyright © 2013 by Christian Bergman, All rights reserved.

All people, places, and events are fictional … except when they aren’t.

 

http://en.almareekhwiki.org.mars/jumper_(spacecraft)

Jumper (spacecraft)
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From AlMareekhWiki, the free encyclopedia of Mars
(Redirected from Ballistic Jumper)

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Jumper, also known as ballistic jumper, is the primary short range transport vehicle for Mars. It is a variant of the lunar jumper in use since the mid twenty-first century. Like the lunar jumper, upon which it is based, it comes in three variants: ballistic crew jumper, ballistic cargo jumper, and fast cargo jumper. SpaceX-Boeing is the manufacturer of the ballistic crew jumper. JPL-EADS is the manufacturer of both the ballistic cargo jumper and the fast cargo jumper.

Contents [hide]

1 History
2 Lunar vs. Martian Jumper
3 Crew Jumper
4 Cargo Jumpers

 

History [edit]
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At the turn of the twenty first century, a number of companies were attempting to develop Single Stage To Orbit (SSTO) and Return To Launch Site (RTLS) technologies. Despite attempts by many established and startup companies, SSTO was never successfully commercialized. The only company to commercialize RTLS technologies was SpaceX. The first developmental platform for this was the “Grasshopper”, a modified version of the company’s hugely successful Falcon 9 launch vehicle. [Archival video of the original Grasshopper (circa 2013) can be found at http://www.spacex-boeing.com/archives/video/grasshopper] The Grasshopper allowed SpaceX to develop the Return To Launch Site capability that made SpaceX-Boeing [stock ticker SPXB] the dominant commercial carrier for Low Earth Orbit, Trans Lunar, and Trans Martian payload delivery into the twenty-second century.

Concurrent with the development of RTLS launch systems, SpaceX developed the Dragon crew capsule. Dragon crew capsule (aka DragonRider) was the manned variant of the ground breaking reusable Dragon cargo capsule. Dragon crew capsule was unique because it was the first ever capsule to return from space under powered flight. Although emergency parachutes were onboard, normal operations consisted of standard reentry followed by a vertical powered descent made possible by the newly developed Super Draco thrusters. [Archival footage of the Dragon crew capsule is available at http://www.spacex-boeing.com/archives/video/dragon-crew ] The Super Draco thrusters served double duty by providing emergency escape capability without the need for a secondary escape tower. The current generation of ballistic crew jumpers in both lunar and martian service are direct descendants of the Dragon crew capsule developed over a hundred years ago.

Just months prior to the time that SpaceX began developing its RTLS launch systems and its Dragon powered-landing crew capsule, NASA and JPL (Jet Propulsion Laboratories) developed the powered Descent Stage for its Mars Science Laboratory (MSL) rover affectionately named Curiosity. The Descent Stage and associated Sky Crane mechanism held on to the Curiosity rover from above. The Descent Stage held on to the MSL rover like a hand holds on to a Yo-Yo (a child’s toy in existence from 500 BCE to present day). At the correct altitude the Sky Crane would lower the rover down on a bridle, analogous to the hand suddenly letting go of the Yo-Yo while holding on to its string. Once the rover touched down, the bridle was severed and the Descent Stage rocketed away to crash safely in the distance. [archival footage of the Curiosity Descent Stage and Sky Crane can be found at http://www.jpl.nasa.gov/videos/archive/msl/20120622/curiosity20120622]

Cargo jumpers are direct descendants of the Curiosity Descent Stage, except that they do not intentionally crash after delivering their payload. The success of the Descent Stage + Sky Crane deployment method for subsequent martian rovers in the early twenty-first century led to the design of upscaled reusable versions for short range lunar cargo “mules”. Basically a cargo module (extraterrestrial shipping container) is attached to the bottom of the robotic cargo jumper. The landing legs and eight descent thrusters straddle the cargo module. Upon landing at its destination the cargo is immediately released and the empty cargo jumper returns to the launch site. Early versions of the cargo jumper were designed and built by JPL, but as demand skyrocketed JPL was unable to keep up with demand.

Not quite fifty years ago JPL approached EADS (European Aeronautic Defence and Space Company N.V., the parent company of Airbus) regarding the formation of a joint venture to manufacture and operate lunar (and eventually martian) cargo jumpers. The rest is, as they say, history. JPL-EADS robotic cargo jumpers are the mainstay of short range resupply at all lunar and martian operations.

The ballistic physics behind jumpers is as old as catapults, mortars, and Inter-Continental Ballistic Missiles (ICBMs); throw something up and it will come back down. Throw it at an angle and it will come back down farther away. Throw it hard enough and at the right angle it will either go into orbit or sail off into space never to be seen again. By adjusting the force and duration of the “throw”, the angle of the throw, and the weight of the object, one can deliver a payload anywhere. On Earth, atmospheric drag must also be accounted for. On airless (or relatively airless) planetary bodies such as the Moon and Mars the lack of atmospheric drag makes ballistic travel the preferred method of short distance travel. Unlike catapults, mortars, and ICBMs, jumpers must carry sufficient fuel to both accelerate at launch, decelerate safely at the destination, and repeat the process in order to return to the original launch site.

 

Lunar vs. Martian Jumper [edit]
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Both crew and cargo jumpers were originally developed and perfected for lunar transport. Lack of atmosphere and the need to travel short distances without having to achieve orbit made the ballistic cargo jumper the ideal solution for short “jump” lunar travel. Since the gravity of the Moon is only one sixth that of the Earth, the thrust and fuel requirements for ballistic travel on the Moon are only a fraction that required for ballistic travel on Earth. The low lunar gravity makes ballistic travel both attractive and technologically possible.

Mars on the other hand has slightly more than twice the gravity of the Moon and a thin atmosphere as well. Which means that for the same power rocket motors and fuel capacity there is less than half the cargo capacity. For this reason martian jumpers tend to have rocket motors that are twice as powerful and carry up to twice the fuel, but also carry slightly less cargo by weight and/or have shorter jump distances. The presence of an atmosphere, however thin, allows for aerobraking and thus mitigates the amount of fuel required to decelerate on landing.

 

Crew Jumper [edit]
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The crew jumper in use on Mars today is the evolutionary descendent of the SpaceX Dragon crew capsule that pioneered commercial manned space flight over a hundred years ago. However the martian crew jumpers in use today are radically different from the original Dragon crew capsule.

The interior pressurized crew vessel and significant portions of the outer structure are made of ultra-low-weight, ultra-high-strength woven carbon nano-tube fabric.

There are no solar panels; all electric power is supplied by twenty-second century low-weight, ultra-high-power-density batteries.

There is no forward docking hatch. The capsule has instead been extended forward to provide support for the aerobraking system which helps to slow the jumper down during the descent stage through the thin martian atmosphere. When retracted, the aerobrakes lie flush against the jumper sides. When deployed, they appear reminiscent of turbine blades except that they are oriented parallel to the base of the jumper (no tilt).

The cabin is pressurized using compressed martian atmosphere to an Earth equivalent of 12,000 feet above (Earth) sea level. The crew must still wear their pressure suits and breath an oxygen-nitrogen air mix because the 92% carbon dioxide content of martian air is poisonous, however the increased cabin pressure takes stress off of the suits making them more comfortable and flexible. The pressurized cabin also enhances the structural rigidity of the capsule. Pressure is maintained through high pressure tanks that store high pressure martian atmosphere as a liquid (like a carbon dioxide fire extinguisher). These tanks are used to re-pressurize the cabin before return to launch site.

The landing gear are non-retractable and designed to contribute minimal drag during the ascent phase.

There is no heat shield.

Range and travel time are largely constrained by fuel capacity, crew weight, rocket motor thrust, and passenger g-load. Crew jumpers are generally limited to sustained g-loads of 3 – 6 g (where g is the force equivalent to one standard Earth gravity), with higher g-load permissible in emergency situations. A crew jumper can reach anywhere on Mars in under an hour.

Cargo Jumpers [edit]
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As stated above, cargo jumpers are highly evolved descendants of the Powered Descent + Sky Crane hardware used to successfully land many martian rovers including the legendary Curiosity rover (circa 2012). Originally developed to deliver mobile science platforms to Mars in the early part of the twenty-first century, this design was enlarged to support lunar hardware delivery and later lunar hardware relocation. The former being the initial hardware delivery from Earth; the later being the relocation of hardware to other lunar sites. The success of the lunar cargo jumpers was the primary reason for continued use of that design on Mars.

Both lunar and martian cargo jumpers would be immediately recognizable by the original designers of the Curiosity rover. The design of the cargo jumper is as follows:

A rectangular frame structure similar to that of a 3×5 aspect-ratio kitchen table with four legs connected to the four corners of the table. These “legs” are hydraulically damped landing gear terminating in a circular landing pad.

On the under side of the frame structure is the winch system the lowers the cargo away from the jumper prior touchdown and release.

On top of the “table” frame are the fuel tanks, control modules, and communications equipment.

At each corner of the “table” frame, outboard of the landing gear, are the thruster pods comprised of four downward aiming primary thrusters per pod plus additional smaller maneuvering thrusters pointing forward, back, left, right, up, and down.

Along the sides of the “table” frame: left, right, front, and back are the carbon nano-tube fabric aerobrakes; folded down like leaves on a drop-leaf table. The aerobrakes are folded down during takeoff and then opened into position after the jumper has passed the highest point of its ballistic flight path. When fully deployed the aerobrakes extend straight out from the jumper frame providing maximum aerodynamic drag to assist with deceleration.

Cargo is loaded by maneuvering it directly underneath the jumper between the four legs where it is connected to the winch cable. Then it is winched up until it is securely attached to the four attachment points used to secure cargo during flight. Cargo can be in the form of both pressurized or unpressurized cargo modules (trans-martian shipping containers), vehicles and equipment, or housing modules.

Cargo jumpers are fully robotic and achieve higher g-loads at both launch and landing than humans or animals can tolerate. Launch, coast, and deceleration phases are nearly identical to that of crew jumpers with the exception of higher g-load. As the cargo jumper approaches the ground, the four attachment points release and the winch lowers the cargo below the landing gear. Once the cargo touches ground, it is immediately released from the winch cable and the jumper takes off again on a return ballistic flight back to its launch site while retracting the winch cable and folding down the aerobrakes. The now empty cargo jumper repeats the flight path processes except that now it actually lands after returning to the launch site.

A variation of the cargo jumper is the fast cargo jumper. It is often no more than a standard cargo jumper following a one-way path. Fast cargo jumpers can carry more cargo by weight and/or sustain higher g-load during acceleration and deceleration specifically because they are one-way trips. All of the fuel is used up during acceleration and deceleration en route to the destination. Unless or until fuel can be delivered, the fast cargo jumper is (temporarily) abandoned after it delivers it’s cargo. After dropping off its cargo and retracting the winch cable, it flys a safe distance away and safely lands.

See Also [edit]
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New Masdar [مصدر جديد]

Project Mars [مشروع المريخ]

The CME of 2135 [CME من 2135]

Phobos [فوبوس]

SpaceX-Boeing

JPL-EADS