John F. Kennedy in his famous Rice University speech referred to space as our New Ocean. And just as an ocean possesses a shore, so do we find a shore above us at the transition from earth to space.
This space shore is often referred to as Near Space.
The realm of Near Space officially lies between 75,000 feet (~23km) and and 62.5 miles (100km) according to the International Aeronautical Federation (FAI). Here we consider a wider range that extends up to 200km or so where it becomes safe for satellites to remain in orbit without immediately becoming dragged down by friction with the residual atmosphere.
The vehicles that traverse this high altitude domain are called nearcraft. These include sub-orbital rockets, which make quick jumps into and out of near space, and high-altitude balloons that can loiter there for extended periods.
Weather balloons routinely go to 27km (~90k ft). Scientific balloons go to 42 km (137k ft or 26mi) and remain at high altitudes for several days. The world record altitude reached by an unmanned balloon is 51.82km (170k ft or 32.2mi).
The record for altitude reached by a crewed balloon was set by Malcom D. Ross and Victor A. Prather who flew to 34.668km (113,740ft or 21.54mi) on April 5, 1961.
Compared to orbital flights and journey's to the Moon and Mars, Near Space may seem of little interest, only an interlude on the way to more exciting places. In fact, Near Space offers numerous exciting benefits and applications.
Here is a list of some possible benefits of utilizing Near Space:
Cheaper and quicker access to space-like conditions are offered by nearcraft as compared to getting a launch to orbit. See the Ballooning and Sub-orbital rocket entries below.
Amateur groups participation: Ham radio enthusiasts, students, and amateur scientists carry out high altitude experiments in astronomy and atmospheric studies, taking high altitude pictures, and testing equipment that will be used on satellites.
High altitude cameras can see for several hundred miles farther than with aerial photography and access to a given area is more flexible than with the infrequent fly-overs by remote sensing satellite.
Development of sub-orbital RLVs will be much quicker and cheaper than orbital vehicles. The technology, operations techniques, etc. learned from sub-orbital systems will then be applicable to second generation vehicles intended for orbit. See the article Sub-orbital Rockets to Space: The Next Logical Step?
Sub-orbital space tourism packages will offer trips that may last in total only half an hour or so. Yet, at the top of 100km trajectory one will see the curvature of the earth below and a dark starry sky above and one will experience the accelerating thrill of riding a rocket and then feel a few minutes of microgravity. Many people may actually prefer this kind of brief initial space experience over a full blown stay in orbit for several days. See the Sub-orbital Space Tourism section
Copyright TVNSP Image of a lake taken from +100k ft by a camera on an amateur high altitude balloon. Cameras can see the horizon out to several hundred miles from Near Space.
So just as there are those who prefer the sea shore for such activities as swimming and fishing rather than sailing out into the open sea, so there will be many people who prefer the Near Space shore over voyages into open space.
Note: This section was inspired by a suggestion from near space enthusiast Paul Verhage.
A near space stack consists of a helium balloon, recovery parachute, and nearcraft, and can reach fifty feet (~17m) in length. Such a stack can fly to over 100,000ft (~33km) in altitude yet costs only a few hundred dollars. The balloon expands as the stack rises and will eventually burst. The payload then parachutes to earth and is tracked with GPS data sent via telemetry on amateur radio .
The cost to launch anything to orbit is usually quite high - thousands of dollars per kilogram. Even a free piggyback ride on someone else's launcher can require long delays.
Sounding rocket flights are not so cheap either and the flights last for only a brief time.
An alternative is to put a payload on a high altitude balloon, which can cost only a few hundred dollars to fly. A balloon can reach as high as 25km and remain aloft for days. At such altitudes the payloads are above much of the atmosphere, they see the black canopy of space, and view clearly a big swath of the earth with a curved horizon out to several hundred miles.
Balloons can be good alternative for educational projects in which students usually only have a year or so to participate.
So it's not surprising that amateur high altitude ballooning has become a growing activity that involves ham radio enthusiasts and educators looking for low cost but exciting science projects for their students.
FAA Liaison - EOSS "Basically, if you're biggest payload box is under 6 lb and total payload weight is under 12 lb, and lateral density is under 3 oz/in^2, then you're exempt and aren't required to notify the FAA at all - it's like you're a party balloon that escaped its tether. See 14 CFR 101.1(a)(4). "
(ARHAB combines amateur radio with high altitude ballooning to explore "Near Space". A standard mission involves a latex weather balloon, a payload, and a recovery parachute for the payload when it is released from the balloon. The payload will typically consists of an transmitter in the amateur radio band and a GPS tracking system that broadcasts the location of the balloon via the transmitter, plus other devices such a camera, atmospheric sensors, etc.
Edge of Space Sciences - An educational program that lets students, both K-12 and university levels, in Colorado build "satellites" for flights on high-altitude balloons. These broadcast data from on board experiments to student receivers.
Organized by Workshop 88, a "hackerspace in the Chicago suburbs", organized this near-space balloon competition that invited hackerspaces worldwide to join in. The project has (as of Feb.10)
HighShips - "low-cost provider of scientific and civic event unmanned ballooning services. We are developing a unique service to keep up to 2 pounds of payload up at 90,000+ feet for two to seven days."
RC Explorer -David Windestål of Sweden attached a RC plane to a balloon which flew to 30km. The plane detached from the balloon and after eventually regaining control, was and flown back to earth
"We launch high altitude weather balloons in collaboration with schools to teach students physics concepts, experimental research skills, and to make space exploration accessible to students. A weather balloon lifts a specially designed payload package that is composed of HD cameras, GPS tracking devices, and other science equipment. The payload is constructed and attached to the balloon by the students with low-cost materials."
The goal of the project is to construct an atmospheric probe and equip it with different sensors. The probe will be mounted on a meteorological balloon, and lifted to approximately 35 000 m (115 000 ft). The ascent and descent will be recorded with two on-board GoPro cameras, and the probe will be tracked via GPS.
The top four teams will be awarded travel expenses and up to $1,000 to develop their flight experiment or technology demonstration. Teams will participate in three flight days to release, track and recover their experiments. In addition, students will tour Glenn facilities and present their findings at Glenn's Balloonsat Symposium.
These commercial projects seek to place platforms at high altitude to provide services such as cell phone and broadband communications relays for urban areas, carry scientific instruments for weather and atmospheric measurements, remote sensing, etc.. (With the recession in telecommunications, most if not all of the telecom balloon projects are on hold.)
Angel Technologies - Scaled Composites' Proteus piloted, fan jet powered aircraft, that reached 19.1km (62,786 ft) in November 2000. Flying in 8 hour shifts, 3 planes would provide 24hour coverage.
Global Aerospace Corp. - developing "guided stratospheric balloons" under a NASA contract.
StratoSail - a sail hung on a tether from the balloon.
Big Blue - student project at Univ. of Kentucky to study Mars glider by releasing prototypes at high altitudes where atmosphere density similar to that on Mars.
High Altitude Glider Project - project by Art Vanden Berg involving a "small, self-guided glider, designed to fly at very high altitudes. The glider is carried up by its tail with a helium weather balloon to altitudes of up to 85,000 feet above sea level, and then released to fly back to the launch point."
Stratofox Aerospace Tracking & Recovery Team - " team of Amateur Radio operators mostly in or near Silicon Valley who perform or participate in tracking and recovery operations for amateur rocketry and high-altitude balloon ("amateur aerospace") flights."
29.4km (96,500 ft) - solar-powered, unmanned Helios in 2001 reached - highest for a non-rocket powered aircraft. Built by Aerovironment with NASA funding.
34.668km (113,740ft or 21.54mi) - highest altitude for a crewed balloon - April 5, 1961 by Malcom D. Ross and Victor A. Prather
51.82km (170,000 ft. or 32.2mi) - highest altitude for unmanned research balloon - launched from Chico, California in 1972.
107.990km (354,300 ft) - X-15 in 1963 - highest altitude for a piloted rocket powered aircraft - (Space shuttle not counted here since it goes to orbit.)
QinetiQ 1 - attempt to break balloon high altitude record and ascend to 132,000 feet - almost 40km high (25 miles).
The technique of carrying a rocket by a balloon to a high altitude for launch has been around since the 1940's. Such combo systems came to be called rockoons. Not only does a balloon give a rocket a head start in altitude, but by launching the rocket above much of the atmosphere it saves the fuel needed to punch through a lot of air when launched from the ground..
However, there are drawbacks in that the balloon does not provide a very stable platform. (JP Aerospace is attempting to build more elaborate balloon borne structures to provide greater stability and flexibility.) Rockoons are obviously affected by the wind and other weather conditions and so launches often get delayed.
Some recent rocket projects, especially amateur groups seeking to break rocket altitude records, have resurrected the rockoon approach and have made launches with them. Here are some groups working with balloon launched rockets:
JP Aerospace Intends to be the first amateur organization to put a payload into space. Following a systematic step-by-step approach, they've developed increasingly complex balloon launch systems for their rockets. Initially, the rocket hung far below a balloon but now they are developing balloon platforms from which rocket launches can take place and also can carry oher payloads such as scientific instruments.
Pongsat - a split table tennis ball is used to hold simple experiments created by school kids for flights on high altitude balloons and sub-orbital rockets.
Satellite Building - amateur and student satellite projects share many features with Near Space efforts including a low cost approach and building robuts systems that can survive the rigors of a high vacuum environment.
Space Radio - Ham radio enthusiasts have long led the way in amateur involement with space including communication with satellites, building of satellites, and now Near Space projects.
Advanced Concepts
Here we provide a sample of concepts involving Near Space that are particularly ambitious and exciting.
Near Space Tourism
Strato-X This company plans to provide adventure tourists the opportunity to ride a high altitude helium balloon to 100, 000ft (30km). The flight would last for about 40 hours. The balloon reaches the 100kft altitude about 3 hours after launch. The "stratonauts" will have great views of the curvature of the earth, of the black sky, and of a majestic sunrise and sunset.
Airship Hotel- WATG WATG (Wimberley Allison Tong & Goo) is a well respected leisure and entertainment design firm that does speculative, futuristic projects on the website.
zero2infinity This Spanish firm plans a high altitude balloon system that will take paying passengers in a spacious gondola to 36km altitude.
zero2infinity has successfully launched its newest prototype, the microbloon 2.0, to the edge of Space at almost 32km in altitude. The microbloon 2.0, designed by zero2infinity, is 2 m in diameter and is a scale model of bloon, the commercial vehicle that is soon to take 4 passengers and 2 pilots to the edge of Space at an altitude of 36 km.
They plan their first human flight by the end of 2013
World View A similar project to zero2infinity in which a passenger model with 2 pilots and 6 passengers travel via helium balloon to about 30 km. The venture was founded by Paragon Space Development Corp.
Copyright - JPAerospace JP Aerospace's Stratostation concept for a "manned sub-orbital space station. Floating at 140,000 feet this structure will serve as a launch platform, research facility and tourism destination. At over a mile across, it will be supported by multiple Helium lift cells." See ATO Airship To Orbit (pdf) for details
The floating city in the sky has long been a staple of science fiction. City sized platforms such as those in Star Trek or Star Wars require technology far beyond our current capabilties (e.g. anti-gravity systems that violate fundamental physics laws as we currently understand them.)
However, it's quite within our capabilities to float a platform at very high altitudes that is big enough to hold, say, living quarters for a few people and a substantial amount of equipment.
For example, JP Aerospace is proposing to build the Stratostation (see figure above.) It would offer a facility useful for a number of applications such as a place for atmospheric and space scientists to place sensors and observatories. It could also be useful for launching rockets. Vee Airships would provide access to the station.
Note that launching at high altitudes removes the fuel penalty that a ground launched vehicle must pay to punch through the atmosphere. Also, to perform efficiently, rocket nozzles must either compensate for atmospheric pressure (e.g. use an extensible mechanism or the aerospike approach) or the vehicle must use a multi-stage system in which the first stage engine nozzles are optimized for low altitudes and the second and third stages set for low air pressure and vacuum regions.
In 1959-1960 the Air Force carried out a series of tests called Project Excelsior, in which Captan Joseph Kittinger dived from balloon gondolas at increasing altitudes, the highest reaching 31km in altitude. He nearly reached supersonic speed before releasing his parachute. He was testing whether pilots of high altitude aircraft like the U2 spyplane could survive if they had to bail out.
Similar jumps from even higher altitudes, and perhaps eventually even from orbit, may become the ultimate extreme sport.
In the 1960's there were several US projects that investigated whether astronauts could rescue themselves from disabled spacecraft by "bailing out" in various types of personal protection outfits. These included General Electric's MOOSE (Manned Orbital Operations Safety Equipment) scheme in which the astronaut lay in an injection-seat type of pod with a heat shield and small rocket to initiate re-entry.
These and other schemes may some day lead to space diving and space surfing as the ultimate in space thrills!
StratEx - April 14, 2015 - 41 422 m free fall by Alan Eustace of the USA.
The possibility of an orbital system that somehow grabs a vehicle from high altitudes and brings it up to orbit is one of those hand waving kind of concepts that is often proposed but seldom makes sense.
However, with the development of space tethers and high stength fibers, practical proposals have begun to appear:
HASTOL - a concept at Tethers Unlimited in which the end of a rotating tether will rendevous with a rocketplane at 100km and pick up a payload to take to orbit.
