54 years ago, the US put the first nuclear reactor in orbit and it was a SNAP

Platapus · 04-03-19, 05:45 PM

on 3 April 1965, The US launched SNAP-10A.

Space Nuclear Auxiliary Power, A US experiment in long duration electric power for satellites. Most of the SNAP research was conducted on the ground, but SNAP-10A went into orbit with an experimental fission reactor with a planned experment life of one year.

Due to safety concerns, SNAP-10A was designed to be non-critical until it reached orbit. In case of a malfunction in orbit, explosive bolts and springs will blow away the BE reflectors stopping criticality.

An excellent description of the mission can be accessed at https://www.drewexmachina.com/2015/0...ctor-in-orbit/

As a secondary payload, SNAP-10A also included the first Ion engine used in space orbit. Previous Ion engines were used in suborbital testing. Because of the large amount of electric power needed, this experimental engine was only designed to be powered for one hour at a time and then needed 15 hours of power from the SNAP-10A reactor to recharge. This Ion engine was designed to produce 8.5 millinewtons (0.00191088 Pound force) of thrust.

An additional secondary payload was the SECOR 4 satellite which was testing technology that would be used to create the GPS system. Unfortunately, the transponder of the SECOR-4 satellite malfunctioned preventing the experiment from being conducted

More unfortunately, when the Ion engine was tested, there was insufficient EMR shielding and there was damage to the circuitry of the SNAP-10A spacecraft initially affecting its attitude control and later affecting the reactor. The Ion engine was only activated once.

Because the reactor was continuing to produce the power normally needed to recharge the Ion engine batteries, power was shunted to the other secondary experiments as a way of burning off the extra power so the batteries would not over heat. The SNAP-10A reactor was not "throttle-able". It was either on or permanently off.

Ground controllers were able to get the satellite's attitude readjusted. However by 16 May65, SNAP-10A failed to make contact with the ground stations. After 40 hours of work by the ground controllers, it was determined on 18 May that the reactor's circuits had automatically jettisoned the BE reflectors and stopped the criticality of the reactor. All that was left was residual battery life.

The reactor shut down 45 days after being activated, well short of the one year experiment goal. However, during that 45 day life, the reactor performed well.

SNAP-10A "died" and was in its original 1,287 by 1,306-kilometer polar orbit inclined 90.3° to the equator with an estimated lifetime of around 4,000 years.

But that's not the end of the story.

Starting in November 1979, SNAP-10A started "shedding" Pieces of the satellite and the attached Agena body were breaking off. There were six of these shedding events over the following six years resulting in over 50 track-able piece of debris. There is no indication that any radioactivity was been released. But to this day, it is not known what caused this pattern of shredding.

Orbital impacts is a common theory but considering the orbit and the relative speeds impact with other satellites is not likely. Another current theory is that there is an internal force that is rupturing the satellite from the inside out. However, why this would take place in six discrete events over 6+ years is not explained. Impact with other natural space objects is another theory but it would again not explain the six discrete shedding events. When satellites are hit with natural space objects, the relative speeds are usually so great that the satellite is usually destroyed and does not experience shedding.

It is still a mystery.

So on one hand, the SNAP-10A mission was another failure of our early space experiments. But the knowledge gained from the 45 day life of the reactor provided some valuable data on how reactors ... uh.. well.. react in a space environment.

There were other planned orbital fission reactors but all were canceled. When SDI was canceled, all further development of orbiting fission reactors stopped. The US has not orbited any other fission reactors since. The Soviets were the only ones using fission reactors in orbit with their 33 RORSATs between 1967-1988.

Other means of providing electrical power have been developed.

ikalugin · 04-07-19, 05:48 AM

We have a nuclear powered space tug in development still for interplanetary missions.

Platapus · 04-14-19, 03:44 PM

Is it a fission reactor or a thermal decay power source?

ikalugin · 04-16-19, 01:23 PM

Quote:

Originally Posted by Platapus

Is it a fission reactor or a thermal decay power source?

Fission reactor with turbine cycle I believe.

04-03-19, 05:45 PM	#1
Platapus Fleet Admiral Join Date: Oct 2006 Posts: 18,948 Downloads: 63 Uploads: 0	54 years ago, the US put the first nuclear reactor in orbit and it was a SNAP on 3 April 1965, The US launched SNAP-10A. Space Nuclear Auxiliary Power, A US experiment in long duration electric power for satellites. Most of the SNAP research was conducted on the ground, but SNAP-10A went into orbit with an experimental fission reactor with a planned experment life of one year. Due to safety concerns, SNAP-10A was designed to be non-critical until it reached orbit. In case of a malfunction in orbit, explosive bolts and springs will blow away the BE reflectors stopping criticality. An excellent description of the mission can be accessed at https://www.drewexmachina.com/2015/0...ctor-in-orbit/ As a secondary payload, SNAP-10A also included the first Ion engine used in space orbit. Previous Ion engines were used in suborbital testing. Because of the large amount of electric power needed, this experimental engine was only designed to be powered for one hour at a time and then needed 15 hours of power from the SNAP-10A reactor to recharge. This Ion engine was designed to produce 8.5 millinewtons (0.00191088 Pound force) of thrust. An additional secondary payload was the SECOR 4 satellite which was testing technology that would be used to create the GPS system. Unfortunately, the transponder of the SECOR-4 satellite malfunctioned preventing the experiment from being conducted More unfortunately, when the Ion engine was tested, there was insufficient EMR shielding and there was damage to the circuitry of the SNAP-10A spacecraft initially affecting its attitude control and later affecting the reactor. The Ion engine was only activated once. Because the reactor was continuing to produce the power normally needed to recharge the Ion engine batteries, power was shunted to the other secondary experiments as a way of burning off the extra power so the batteries would not over heat. The SNAP-10A reactor was not "throttle-able". It was either on or permanently off. Ground controllers were able to get the satellite's attitude readjusted. However by 16 May65, SNAP-10A failed to make contact with the ground stations. After 40 hours of work by the ground controllers, it was determined on 18 May that the reactor's circuits had automatically jettisoned the BE reflectors and stopped the criticality of the reactor. All that was left was residual battery life. The reactor shut down 45 days after being activated, well short of the one year experiment goal. However, during that 45 day life, the reactor performed well. SNAP-10A "died" and was in its original 1,287 by 1,306-kilometer polar orbit inclined 90.3° to the equator with an estimated lifetime of around 4,000 years. But that's not the end of the story. Starting in November 1979, SNAP-10A started "shedding" Pieces of the satellite and the attached Agena body were breaking off. There were six of these shedding events over the following six years resulting in over 50 track-able piece of debris. There is no indication that any radioactivity was been released. But to this day, it is not known what caused this pattern of shredding. Orbital impacts is a common theory but considering the orbit and the relative speeds impact with other satellites is not likely. Another current theory is that there is an internal force that is rupturing the satellite from the inside out. However, why this would take place in six discrete events over 6+ years is not explained. Impact with other natural space objects is another theory but it would again not explain the six discrete shedding events. When satellites are hit with natural space objects, the relative speeds are usually so great that the satellite is usually destroyed and does not experience shedding. It is still a mystery. So on one hand, the SNAP-10A mission was another failure of our early space experiments. But the knowledge gained from the 45 day life of the reactor provided some valuable data on how reactors ... uh.. well.. react in a space environment. There were other planned orbital fission reactors but all were canceled. When SDI was canceled, all further development of orbiting fission reactors stopped. The US has not orbited any other fission reactors since. The Soviets were the only ones using fission reactors in orbit with their 33 RORSATs between 1967-1988. Other means of providing electrical power have been developed. __________________ abusus non tollit usum - A right should NOT be withheld from people on the basis that some tend to abuse that right.

04-07-19, 05:48 AM	#2
ikalugin Ocean Warrior Join Date: Aug 2014 Location: Moscow, Russia Posts: 3,212 Downloads: 8 Uploads: 0	We have a nuclear powered space tug in development still for interplanetary missions. __________________ Grumpy as always.

04-14-19, 03:44 PM	#3
Platapus Fleet Admiral Join Date: Oct 2006 Posts: 18,948 Downloads: 63 Uploads: 0	Is it a fission reactor or a thermal decay power source? __________________ abusus non tollit usum - A right should NOT be withheld from people on the basis that some tend to abuse that right.